diff --git a/contrib/bc/Makefile.in b/contrib/bc/Makefile.in
index 8ae982bd99fe..dbb5debd44cc 100644
--- a/contrib/bc/Makefile.in
+++ b/contrib/bc/Makefile.in
@@ -1,445 +1,445 @@
#
# SPDX-License-Identifier: BSD-2-Clause
#
# Copyright (c) 2018-2021 Gavin D. Howard and contributors.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# * Redistributions of source code must retain the above copyright notice, this
# list of conditions and the following disclaimer.
#
# * Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
#
# %%WARNING%%
#
.POSIX:
-VERSION = 3.2.6
+VERSION = 3.3.0
SRC = %%SRC%%
OBJ = %%OBJ%%
GCDA = %%GCDA%%
GCNO = %%GCNO%%
BC_ENABLED_NAME = BC_ENABLED
BC_ENABLED = %%BC_ENABLED%%
DC_ENABLED_NAME = DC_ENABLED
DC_ENABLED = %%DC_ENABLED%%
HEADERS = include/args.h include/file.h include/lang.h include/lex.h include/num.h include/opt.h include/parse.h include/program.h include/read.h include/status.h include/vector.h include/vm.h
BC_HEADERS = include/bc.h
DC_HEADERS = include/dc.h
HISTORY_HEADERS = include/history.h
EXTRA_MATH_HEADERS = include/rand.h
LIBRARY_HEADERS = include/bcl.h include/library.h
GEN_DIR = gen
GEN = %%GEN%%
GEN_EXEC = $(GEN_DIR)/$(GEN)
GEN_C = $(GEN_DIR)/$(GEN).c
GEN_EMU = %%GEN_EMU%%
BC_LIB = $(GEN_DIR)/lib.bc
BC_LIB_C = $(GEN_DIR)/lib.c
BC_LIB_O = %%BC_LIB_O%%
BC_LIB_GCDA = $(GEN_DIR)/lib.gcda
BC_LIB_GCNO = $(GEN_DIR)/lib.gcno
BC_LIB2 = $(GEN_DIR)/lib2.bc
BC_LIB2_C = $(GEN_DIR)/lib2.c
BC_LIB2_O = %%BC_LIB2_O%%
BC_LIB2_GCDA = $(GEN_DIR)/lib2.gcda
BC_LIB2_GCNO = $(GEN_DIR)/lib2.gcno
BC_HELP = $(GEN_DIR)/bc_help.txt
BC_HELP_C = $(GEN_DIR)/bc_help.c
BC_HELP_O = %%BC_HELP_O%%
BC_HELP_GCDA = $(GEN_DIR)/bc_help.gcda
BC_HELP_GCNO = $(GEN_DIR)/bc_help.gcno
DC_HELP = $(GEN_DIR)/dc_help.txt
DC_HELP_C = $(GEN_DIR)/dc_help.c
DC_HELP_O = %%DC_HELP_O%%
DC_HELP_GCDA = $(GEN_DIR)/dc_help.gcda
DC_HELP_GCNO = $(GEN_DIR)/dc_help.gcno
BIN = bin
LOCALES = locales
EXEC_SUFFIX = %%EXECSUFFIX%%
EXEC_PREFIX = %%EXECPREFIX%%
BC = bc
DC = dc
BC_EXEC = $(BIN)/$(EXEC_PREFIX)$(BC)
DC_EXEC = $(BIN)/$(EXEC_PREFIX)$(DC)
BC_TEST_OUTPUTS = tests/bc_outputs
BC_FUZZ_OUTPUTS = tests/fuzzing/bc_outputs1 tests/fuzzing/bc_outputs2 tests/fuzzing/bc_outputs3
DC_TEST_OUTPUTS = tests/dc_outputs
DC_FUZZ_OUTPUTS = tests/fuzzing/dc_outputs
LIB = libbcl
LIB_NAME = $(LIB).a
LIBBC = $(BIN)/$(LIB_NAME)
BCL = bcl
BCL_TEST = $(BIN)/$(BCL)
BCL_TEST_C = tests/$(BCL).c
MANUALS = manuals
BC_MANPAGE_NAME = $(EXEC_PREFIX)$(BC)$(EXEC_SUFFIX).1
BC_MANPAGE = $(MANUALS)/$(BC).1
BC_MD = $(BC_MANPAGE).md
DC_MANPAGE_NAME = $(EXEC_PREFIX)$(DC)$(EXEC_SUFFIX).1
DC_MANPAGE = $(MANUALS)/$(DC).1
DC_MD = $(DC_MANPAGE).md
BCL_MANPAGE_NAME = bcl.3
BCL_MANPAGE = $(MANUALS)/$(BCL_MANPAGE_NAME)
BCL_MD = $(BCL_MANPAGE).md
MANPAGE_INSTALL_ARGS = -Dm644
BINARY_INSTALL_ARGS = -Dm755
BCL_HEADER_NAME = bcl.h
BCL_HEADER = include/$(BCL_HEADER_NAME)
%%DESTDIR%%
BINDIR = %%BINDIR%%
INCLUDEDIR = %%INCLUDEDIR%%
LIBDIR = %%LIBDIR%%
MAN1DIR = %%MAN1DIR%%
MAN3DIR = %%MAN3DIR%%
MAIN_EXEC = $(EXEC_PREFIX)$(%%MAIN_EXEC%%)$(EXEC_SUFFIX)
EXEC = $(%%EXEC%%)
NLSPATH = %%NLSPATH%%
BC_ENABLE_LIBRARY = %%LIBRARY%%
BC_ENABLE_HISTORY = %%HISTORY%%
BC_ENABLE_EXTRA_MATH_NAME = BC_ENABLE_EXTRA_MATH
BC_ENABLE_EXTRA_MATH = %%EXTRA_MATH%%
BC_ENABLE_NLS = %%NLS%%
BC_ENABLE_PROMPT = %%PROMPT%%
BC_LONG_BIT = %%LONG_BIT%%
BC_ENABLE_AFL = %%FUZZ%%
BC_ENABLE_MEMCHECK = %%MEMCHECK%%
RM = rm
MKDIR = mkdir
INSTALL = ./exec-install.sh
SAFE_INSTALL = ./safe-install.sh
LINK = ./link.sh
MANPAGE = ./manpage.sh
KARATSUBA = ./karatsuba.py
LOCALE_INSTALL = ./locale_install.sh
LOCALE_UNINSTALL = ./locale_uninstall.sh
VALGRIND_ARGS = --error-exitcode=100 --leak-check=full --show-leak-kinds=all --errors-for-leak-kinds=all
TEST_STARS = "***********************************************************************"
BC_NUM_KARATSUBA_LEN = %%KARATSUBA_LEN%%
CPPFLAGS1 = -D$(BC_ENABLED_NAME)=$(BC_ENABLED) -D$(DC_ENABLED_NAME)=$(DC_ENABLED)
CPPFLAGS2 = $(CPPFLAGS1) -I./include/ -DVERSION=$(VERSION) %%LONG_BIT_DEFINE%%
CPPFLAGS3 = $(CPPFLAGS2) -DEXECPREFIX=$(EXEC_PREFIX) -DMAINEXEC=$(MAIN_EXEC)
CPPFLAGS4 = $(CPPFLAGS3) -D_POSIX_C_SOURCE=200809L -D_XOPEN_SOURCE=700
CPPFLAGS5 = $(CPPFLAGS4) -DBC_NUM_KARATSUBA_LEN=$(BC_NUM_KARATSUBA_LEN)
CPPFLAGS6 = $(CPPFLAGS5) -DBC_ENABLE_NLS=$(BC_ENABLE_NLS) -DBC_ENABLE_PROMPT=$(BC_ENABLE_PROMPT)
CPPFLAGS7 = $(CPPFLAGS6) -D$(BC_ENABLE_EXTRA_MATH_NAME)=$(BC_ENABLE_EXTRA_MATH)
CPPFLAGS8 = $(CPPFLAGS7) -DBC_ENABLE_HISTORY=$(BC_ENABLE_HISTORY) -DBC_ENABLE_LIBRARY=$(BC_ENABLE_LIBRARY)
CPPFLAGS = $(CPPFLAGS8) -DBC_ENABLE_MEMCHECK=$(BC_ENABLE_MEMCHECK) -DBC_ENABLE_AFL=$(BC_ENABLE_AFL)
CFLAGS = $(CPPFLAGS) %%CPPFLAGS%% %%CFLAGS%%
LDFLAGS = %%LDFLAGS%%
HOSTCFLAGS = %%HOSTCFLAGS%%
CC = %%CC%%
HOSTCC = %%HOSTCC%%
BC_LIB_C_ARGS = bc_lib bc_lib_name $(BC_ENABLED_NAME) 1
BC_LIB2_C_ARGS = bc_lib2 bc_lib2_name "$(BC_ENABLED_NAME) && $(BC_ENABLE_EXTRA_MATH_NAME)" 1
OBJS = $(DC_HELP_O) $(BC_HELP_O) $(BC_LIB_O) $(BC_LIB2_O) $(OBJ)
all: %%DEFAULT_TARGET%%
%%DEFAULT_TARGET%%: %%DEFAULT_TARGET_PREREQS%%
%%DEFAULT_TARGET_CMD%%
%%SECOND_TARGET%%: %%SECOND_TARGET_PREREQS%%
%%SECOND_TARGET_CMD%%
$(GEN_EXEC):
%%GEN_EXEC_TARGET%%
$(BC_LIB_C): $(GEN_EXEC) $(BC_LIB)
$(GEN_EMU) $(GEN_EXEC) $(BC_LIB) $(BC_LIB_C) $(BC_LIB_C_ARGS)
$(BC_LIB_O): $(BC_LIB_C)
$(CC) $(CFLAGS) -o $@ -c $<
$(BC_LIB2_C): $(GEN_EXEC) $(BC_LIB2)
$(GEN_EMU) $(GEN_EXEC) $(BC_LIB2) $(BC_LIB2_C) $(BC_LIB2_C_ARGS)
$(BC_LIB2_O): $(BC_LIB2_C)
$(CC) $(CFLAGS) -o $@ -c $<
$(BC_HELP_C): $(GEN_EXEC) $(BC_HELP)
$(GEN_EMU) $(GEN_EXEC) $(BC_HELP) $(BC_HELP_C) bc_help "" $(BC_ENABLED_NAME)
$(BC_HELP_O): $(BC_HELP_C)
$(CC) $(CFLAGS) -o $@ -c $<
$(DC_HELP_C): $(GEN_EXEC) $(DC_HELP)
$(GEN_EMU) $(GEN_EXEC) $(DC_HELP) $(DC_HELP_C) dc_help "" $(DC_ENABLED_NAME)
$(DC_HELP_O): $(DC_HELP_C)
$(CC) $(CFLAGS) -o $@ -c $<
$(BIN):
$(MKDIR) -p $(BIN)
headers: %%HEADERS%%
help:
@printf 'available targets:\n'
@printf '\n'
@printf ' all (default) builds %%EXECUTABLES%%\n'
@printf ' check alias for `make test`\n'
@printf ' clean removes all build files\n'
@printf ' clean_config removes all build files as well as the generated Makefile\n'
@printf ' clean_tests removes all build files, the generated Makefile,\n'
@printf ' and generated tests\n'
@printf ' install installs binaries to "%s%s"\n' "$(DESTDIR)" "$(BINDIR)"
@printf ' and (if enabled) manpages to "%s%s"\n' "$(DESTDIR)" "$(MAN1DIR)"
@printf ' karatsuba runs the karatsuba script (requires Python 3)\n'
@printf ' karatsuba_test runs the karatsuba script while running tests\n'
@printf ' (requires Python 3)\n'
@printf ' uninstall uninstalls binaries from "%s%s"\n' "$(DESTDIR)" "$(BINDIR)"
@printf ' and (if enabled) manpages from "%s%s"\n' "$(DESTDIR)" "$(MAN1DIR)"
@printf ' test runs the test suite\n'
@printf ' test_bc runs the bc test suite, if bc has been built\n'
@printf ' test_dc runs the dc test suite, if dc has been built\n'
@printf ' time_test runs the test suite, displaying times for some things\n'
@printf ' time_test_bc runs the bc test suite, displaying times for some things\n'
@printf ' time_test_dc runs the dc test suite, displaying times for some things\n'
@printf ' timeconst runs the test on the Linux timeconst.bc script,\n'
@printf ' if it exists and bc has been built\n'
@printf ' valgrind runs the test suite through valgrind\n'
@printf ' valgrind_bc runs the bc test suite, if bc has been built,\n'
@printf ' through valgrind\n'
@printf ' valgrind_dc runs the dc test suite, if dc has been built,\n'
@printf ' through valgrind\n'
run_all_tests:
%%BC_ALL_TESTS%%
%%TIMECONST_ALL_TESTS%%
%%DC_ALL_TESTS%%
check: test
test: %%TESTS%%
test_bc: test_bc_header test_bc_tests test_bc_scripts test_bc_stdin test_bc_read test_bc_errors test_bc_other
@printf '\nAll bc tests passed.\n\n$(TEST_STARS)\n'
test_bc_tests:%%BC_TESTS%%
test_bc_scripts:%%BC_SCRIPT_TESTS%%
test_bc_stdin:
@sh tests/stdin.sh bc %%BC_TEST_EXEC%%
test_bc_read:
@sh tests/read.sh bc %%BC_TEST_EXEC%%
test_bc_errors:
@sh tests/errors.sh bc %%BC_TEST_EXEC%%
test_bc_other:
@sh tests/other.sh bc %%BC_TEST_EXEC%%
test_bc_header:
@printf '$(TEST_STARS)\n\nRunning bc tests...\n\n'
test_dc: test_dc_header test_dc_tests test_dc_scripts test_dc_stdin test_dc_read test_dc_errors test_dc_other
@printf '\nAll dc tests passed.\n\n$(TEST_STARS)\n'
test_dc_tests:%%DC_TESTS%%
test_dc_scripts:%%DC_SCRIPT_TESTS%%
test_dc_stdin:
@sh tests/stdin.sh dc %%DC_TEST_EXEC%%
test_dc_read:
@sh tests/read.sh dc %%DC_TEST_EXEC%%
test_dc_errors:
@sh tests/errors.sh dc %%DC_TEST_EXEC%%
test_dc_other:
@sh tests/other.sh dc %%DC_TEST_EXEC%%
test_dc_header:
@printf '$(TEST_STARS)\n\nRunning dc tests...\n\n'
timeconst:
%%TIMECONST%%
library_test: $(LIBBC)
$(CC) $(CFLAGS) $(BCL_TEST_C) $(LIBBC) -o $(BCL_TEST)
test_library: library_test
$(BCL_TEST)
karatsuba:
%%KARATSUBA%%
karatsuba_test:
%%KARATSUBA_TEST%%
coverage_output:
%%COVERAGE_OUTPUT%%
coverage:%%COVERAGE_PREREQS%%
version:
@printf '%s' "$(VERSION)"
libcname:
@printf '%s' "$(BC_LIB_C)"
extra_math:
@printf '%s' "$(BC_ENABLE_EXTRA_MATH)"
manpages:
$(MANPAGE) bc
$(MANPAGE) dc
$(MANPAGE) bcl
clean_gen:
@$(RM) -f $(GEN_EXEC)
clean:%%CLEAN_PREREQS%%
@printf 'Cleaning files...\n'
@$(RM) -f $(OBJ)
@$(RM) -f $(BC_EXEC)
@$(RM) -f $(DC_EXEC)
@$(RM) -fr $(BIN)
@$(RM) -f $(LOCALES)/*.cat
@$(RM) -f $(BC_LIB_C) $(BC_LIB_O)
@$(RM) -f $(BC_LIB2_C) $(BC_LIB2_O)
@$(RM) -f $(BC_HELP_C) $(BC_HELP_O)
@$(RM) -f $(DC_HELP_C) $(DC_HELP_O)
@$(RM) -fr $(BC_TEST_OUTPUTS) $(DC_TEST_OUTPUTS)
@$(RM) -fr $(BC_FUZZ_OUTPUTS) $(DC_FUZZ_OUTPUTS)
clean_config: clean
@printf 'Cleaning config...\n'
@$(RM) -f Makefile
@$(RM) -f $(BC_MD) $(DC_MD)
@$(RM) -f $(BC_MANPAGE) $(DC_MANPAGE)
clean_coverage:
@printf 'Cleaning coverage files...\n'
@$(RM) -f *.gcov
@$(RM) -f *.html
@$(RM) -f *.gcda *.gcno
@$(RM) -f *.profraw
@$(RM) -f $(GCDA) $(GCNO)
@$(RM) -f $(BC_GCDA) $(BC_GCNO)
@$(RM) -f $(DC_GCDA) $(DC_GCNO)
@$(RM) -f $(HISTORY_GCDA) $(HISTORY_GCNO)
@$(RM) -f $(RAND_GCDA) $(RAND_GCNO)
@$(RM) -f $(BC_LIB_GCDA) $(BC_LIB_GCNO)
@$(RM) -f $(BC_LIB2_GCDA) $(BC_LIB2_GCNO)
@$(RM) -f $(BC_HELP_GCDA) $(BC_HELP_GCNO)
@$(RM) -f $(DC_HELP_GCDA) $(DC_HELP_GCNO)
clean_tests: clean clean_config clean_coverage
@printf 'Cleaning test files...\n'
@$(RM) -f tests/bc/parse.txt tests/bc/parse_results.txt
@$(RM) -f tests/bc/print.txt tests/bc/print_results.txt
@$(RM) -f tests/bc/bessel.txt tests/bc/bessel_results.txt
@$(RM) -f tests/bc/scripts/bessel.txt
@$(RM) -f tests/bc/scripts/parse.txt
@$(RM) -f tests/bc/scripts/print.txt
@$(RM) -f tests/bc/scripts/add.txt
@$(RM) -f tests/bc/scripts/divide.txt
@$(RM) -f tests/bc/scripts/multiply.txt
@$(RM) -f tests/bc/scripts/subtract.txt
@$(RM) -f tests/dc/scripts/prime.txt tests/dc/scripts/stream.txt
@$(RM) -f .log_*.txt
@$(RM) -f .math.txt .results.txt .ops.txt
@$(RM) -f .test.txt
@$(RM) -f tags .gdbbreakpoints .gdb_history .gdbsetup
@$(RM) -f cscope.*
@$(RM) -f bc.old
install_locales:
%%INSTALL_LOCALES%%
install_bc_manpage:
$(SAFE_INSTALL) $(MANPAGE_INSTALL_ARGS) $(BC_MANPAGE) $(DESTDIR)$(MAN1DIR)/$(BC_MANPAGE_NAME)
install_dc_manpage:
$(SAFE_INSTALL) $(MANPAGE_INSTALL_ARGS) $(DC_MANPAGE) $(DESTDIR)$(MAN1DIR)/$(DC_MANPAGE_NAME)
install_bcl_manpage:
$(SAFE_INSTALL) $(MANPAGE_INSTALL_ARGS) $(BCL_MANPAGE) $(DESTDIR)$(MAN3DIR)/$(BCL_MANPAGE_NAME)
install_bcl_header:
$(SAFE_INSTALL) $(MANPAGE_INSTALL_ARGS) $(BCL_HEADER) $(DESTDIR)$(INCLUDEDIR)/$(BCL_HEADER_NAME)
install_execs:
$(INSTALL) $(DESTDIR)$(BINDIR) "$(EXEC_SUFFIX)"
install_library:
$(SAFE_INSTALL) $(BINARY_INSTALL_ARGS) $(LIBBC) $(DESTDIR)$(LIBDIR)/$(LIB_NAME)
install:%%INSTALL_LOCALES_PREREQS%%%%INSTALL_MAN_PREREQS%%%%INSTALL_PREREQS%%
uninstall_locales:
$(LOCALE_UNINSTALL) $(NLSPATH) $(MAIN_EXEC) $(DESTDIR)
uninstall_bc_manpage:
$(RM) -f $(DESTDIR)$(MAN1DIR)/$(BC_MANPAGE_NAME)
uninstall_bc:
$(RM) -f $(DESTDIR)$(BINDIR)/$(EXEC_PREFIX)$(BC)$(EXEC_SUFFIX)
uninstall_dc_manpage:
$(RM) -f $(DESTDIR)$(MAN1DIR)/$(DC_MANPAGE_NAME)
uninstall_dc:
$(RM) -f $(DESTDIR)$(BINDIR)/$(EXEC_PREFIX)$(DC)$(EXEC_SUFFIX)
uninstall_library:
$(RM) -f $(DESTDIR)$(LIBDIR)/$(LIB_NAME)
uninstall_bcl_header:
$(RM) -f $(DESTDIR)$(INCLUDEDIR)/$(BCL_HEADER_NAME)
uninstall_bcl_manpage:
$(RM) -f $(DESTDIR)$(MAN3DIR)/$(BCL_MANPAGE_NAME)
uninstall:%%UNINSTALL_LOCALES_PREREQS%%%%UNINSTALL_MAN_PREREQS%%%%UNINSTALL_PREREQS%%
diff --git a/contrib/bc/NEWS.md b/contrib/bc/NEWS.md
index 5982defb754c..6a8899200f4a 100644
--- a/contrib/bc/NEWS.md
+++ b/contrib/bc/NEWS.md
@@ -1,1010 +1,1030 @@
# News
+## 3.3.0
+
+This is a production release that changes one behavior and fixes documentation
+bugs.
+
+The changed behavior is the treatment of `-e` and `-f` when given through
+`BC_ENV_ARGS` or `DC_ENV_ARGS`. Now `bc` and `dc` do not exit when those options
+(or their equivalents) are given through those environment variables. However,
+`bc` and `dc` still exit when they or their equivalents are given on the
+command-line.
+
+## 3.2.7
+
+This is a production release that removes a small non-portable shell operation
+in `configure.sh`. This problem was only noticed on OpenBSD, not FreeBSD or
+Linux.
+
+Non-OpenBSD users do ***NOT*** need to upgrade, although NetBSD users may also
+need to upgrade.
+
## 3.2.6
This is a production release that fixes the build on FreeBSD.
There was a syntax error in `configure.sh` that the Linux shell did not catch,
and FreeBSD depends on the existence of `tests/all.sh`.
All users that already upgraded to `3.2.5` should update to this release, with
my apologies for the poor release of `3.2.5`. Other users should skip `3.2.5` in
favor of this version.
## 3.2.5
This is a production release that fixes several bugs and adds a couple small
things.
The two most important bugs were bugs that causes `dc` to access memory
out-of-bounds (crash in debug builds). This was found by upgrading to `afl++`
from `afl`. Both were caused by a failure to distinguish between the same two
cases.
Another bug was the failure to put all of the licenses in the `LICENSE.md` file.
Third, some warnings by `scan-build` were found and eliminated. This needed one
big change: `bc` and `dc` now bail out as fast as possible on fatal errors
instead of unwinding the stack.
Fourth, the pseudo-random number now attempts to seed itself with `/dev/random`
if `/dev/urandom` fails.
Finally, this release has a few quality-of-life changes to the build system. The
usage should not change at all; the only thing that changed was making sure the
`Makefile.in` was written to rebuild properly when headers changed and to not
rebuild when not necessary.
## 3.2.4
This is a production release that fixes a warning on `gcc` 6 or older, which
does not have an attribute that is used.
Users do ***NOT*** need to upgrade if they don't use `gcc` 6 or older.
## 3.2.3
This is a production release that fixes a bug in `gen/strgen.sh`. I recently
changed `gen/strgen.c`, but I did not change `gen/strgen.sh`.
Users that do not use `gen/strgen.sh` do not need to upgrade.
## 3.2.2
This is a production release that fixes a portability bug in `configure.sh`. The
bug was using the GNU `find` extension `-wholename`.
## 3.2.1
This is a production release that has one fix for `bcl(3)`. It is technically
not a bug fix since the behavior is undefined, but the `BclNumber`s that
`bcl_divmod()` returns will be set to `BCL_ERROR_INVALID_NUM` if there is an
error. Previously, they were not set.
## 3.2.0
This is a production release that has one bug fix and a major addition.
The bug fix was a missing `auto` variable in the bessel `j()` function in the
math library.
The major addition is a way to build a version of `bc`'s math code as a library.
This is done with the `-a` option to `configure.sh`. The API for the library can
be read in `./manuals/bcl.3.md` or `man bcl` once the library is installed with
`make install`.
This library was requested by developers before I even finished version 1.0, but
I could not figure out how to do it until now.
If the library has API breaking changes, the major version of `bc` will be
incremented.
## 3.1.6
This is a production release that fixes a new warning from Clang 12 for FreeBSD
and also removes some possible undefined behavior found by UBSan that compilers
did not seem to take advantage of.
Users do ***NOT*** need to upgrade, if they do not want to.
## 3.1.5
This is a production release that fixes the Chinese locales (which caused `bc`
to crash) and a crash caused by `bc` executing code when it should not have been
able to.
***ALL USERS SHOULD UPGRADE.***
## 3.1.4
This is a production release that fixes one bug, changes two behaviors, and
removes one environment variable.
The bug is like the one in the last release except it applies if files are being
executed. I also made the fix more general.
The behavior that was changed is that `bc` now exits when given `-e`, `-f`,
`--expression` or `--file`. However, if the last one of those is `-f-` (using
`stdin` as the file), `bc` does not exit. If `-f-` exists and is not the last of
the `-e` and `-f` options (and equivalents), `bc` gives a fatal error and exits.
Next, I removed the `BC_EXPR_EXIT` and `DC_EXPR_EXIT` environment variables
since their use is not needed with the behavior change.
Finally, I made it so `bc` does not print the header, though the `-q` and
`--quiet` options were kept for compatibility with GNU `bc`.
## 3.1.3
This is a production release that fixes one minor bug: if `bc` was invoked like
the following, it would error:
```
echo "if (1 < 3) 1" | bc
```
Unless users run into this bug, they do not need to upgrade, but it is suggested
that they do.
## 3.1.2
This is a production release that adds a way to install *all* locales. Users do
***NOT*** need to upgrade.
For package maintainers wishing to make use of the change, just pass `-l` to
`configure.sh`.
## 3.1.1
This is a production release that adds two Spanish locales. Users do ***NOT***
need to upgrade, unless they want those locales.
## 3.1.0
This is a production release that adjusts one behavior, fixes eight bugs, and
improves manpages for FreeBSD. Because this release fixes bugs, **users and
package maintainers should update to this version as soon as possible**.
The behavior that was adjusted was how code from the `-e` and `-f` arguments
(and equivalents) were executed. They used to be executed as one big chunk, but
in this release, they are now executed line-by-line.
The first bug fix in how output to `stdout` was handled in `SIGINT`. If a
`SIGINT` came in, the `stdout` buffer was not correctly flushed. In fact, a
clean-up function was not getting called. This release fixes that bug.
The second bug is in how `dc` handled input from `stdin`. This affected `bc` as
well since it was a mishandling of the `stdin` buffer.
The third fixed bug was that `bc` and `dc` could `abort()` (in debug mode) when
receiving a `SIGTERM`. This one was a race condition with pushing and popping
items onto and out of vectors.
The fourth bug fixed was that `bc` could leave extra items on the stack and
thus, not properly clean up some memory. (The memory would still get
`free()`'ed, but it would not be `free()`'ed when it could have been.)
The next two bugs were bugs in `bc`'s parser that caused crashes when executing
the resulting code.
The last two bugs were crashes in `dc` that resulted from mishandling of
strings.
The manpage improvement was done by switching from [ronn][20] to [Pandoc][21] to
generate manpages. Pandoc generates much cleaner manpages and doesn't leave
blank lines where they shouldn't be.
## 3.0.3
This is a production release that adds one new feature: specific manpages.
Before this release, `bc` and `dc` only used one manpage each that referred to
various build options. This release changes it so there is one manpage set per
relevant build type. Each manual only has information about its particular
build, and `configure.sh` selects the correct set for install.
## 3.0.2
This is a production release that adds `utf8` locale symlinks and removes an
unused `auto` variable from the `ceil()` function in the [extended math
library][16].
Users do ***NOT*** need to update unless they want the locales.
## 3.0.1
This is a production release with two small changes. Users do ***NOT*** need to
upgrade to this release; however, if they haven't upgraded to `3.0.0` yet, it
may be worthwhile to upgrade to this release.
The first change is fixing a compiler warning on FreeBSD with strict warnings
on.
The second change is to make the new implementation of `ceil()` in `lib2.bc`
much more efficient.
## 3.0.0
*Notes for package maintainers:*
*First, the `2.7.0` release series saw a change in the option parsing. This made
me change one error message and add a few others. The error message that was
changed removed one format specifier. This means that `printf()` will seqfault
on old locale files. Unfortunately, `bc` cannot use any locale files except the
global ones that are already installed, so it will use the previous ones while
running tests during install. **If `bc` segfaults while running arg tests when
updating, it is because the global locale files have not been replaced. Make
sure to either prevent the test suite from running on update or remove the old
locale files before updating.** (Removing the locale files can be done with
`make uninstall` or by running the `locale_uninstall.sh` script.) Once this is
done, `bc` should install without problems.*
*Second, **the option to build without signal support has been removed**. See
below for the reasons why.*
This is a production release with some small bug fixes, a few improvements,
three major bug fixes, and a complete redesign of `bc`'s error and signal
handling. **Users and package maintainers should update to this version as soon
as possible.**
The first major bug fix was in how `bc` executed files. Previously, a whole file
was parsed before it was executed, but if a function is defined *after* code,
especially if the function definition was actually a redefinition, and the code
before the definition referred to the previous function, this `bc` would replace
the function before executing any code. The fix was to make sure that all code
that existed before a function definition was executed.
The second major bug fix was in `bc`'s `lib2.bc`. The `ceil()` function had a
bug where a `0` in the decimal place after the truncation position, caused it to
output the wrong numbers if there was any non-zero digit after.
The third major bug is that when passing parameters to functions, if an
expression included an array (not an array element) as a parameter, it was
accepted, when it should have been rejected. It is now correctly rejected.
Beyond that, this `bc` got several improvements that both sped it up, improved
the handling of signals, and improved the error handling.
First, the requirements for `bc` were pushed back to POSIX 2008. `bc` uses one
function, `strdup()`, which is not in POSIX 2001, and it is in the X/Open System
Interfaces group 2001. It is, however, in POSIX 2008, and since POSIX 2008 is
old enough to be supported anywhere that I care, that should be the requirement.
Second, the BcVm global variable was put into `bss`. This actually slightly
reduces the size of the executable from a massive code shrink, and it will stop
`bc` from allocating a large set of memory when `bc` starts.
Third, the default Karatsuba length was updated from 64 to 32 after making the
optimization changes below, since 32 is going to be better than 64 after the
changes.
Fourth, Spanish translations were added.
Fifth, the interpreter received a speedup to make performance on non-math-heavy
scripts more competitive with GNU `bc`. While improvements did, in fact, get it
much closer (see the [benchmarks][19]), it isn't quite there.
There were several things done to speed up the interpreter:
First, several small inefficiencies were removed. These inefficiencies included
calling the function `bc_vec_pop(v)` twice instead of calling
`bc_vec_npop(v, 2)`. They also included an extra function call for checking the
size of the stack and checking the size of the stack more than once on several
operations.
Second, since the current `bc` function is the one that stores constants and
strings, the program caches pointers to the current function's vectors of
constants and strings to prevent needing to grab the current function in order
to grab a constant or a string.
Third, `bc` tries to reuse `BcNum`'s (the internal representation of
arbitary-precision numbers). If a `BcNum` has the default capacity of
`BC_NUM_DEF_SIZE` (32 on 64-bit and 16 on 32-bit) when it is freed, it is added
to a list of available `BcNum`'s. And then, when a `BcNum` is allocated with a
capacity of `BC_NUM_DEF_SIZE` and any `BcNum`'s exist on the list of reusable
ones, one of those ones is grabbed instead.
In order to support these changes, the `BC_NUM_DEF_SIZE` was changed. It used to
be 16 bytes on all systems, but it was changed to more closely align with the
minimum allocation size on Linux, which is either 32 bytes (64-bit musl), 24
bytes (64-bit glibc), 16 bytes (32-bit musl), or 12 bytes (32-bit glibc). Since
these are the minimum allocation sizes, these are the sizes that would be
allocated anyway, making it worth it to just use the whole space, so the value
of `BC_NUM_DEF_SIZE` on 64-bit systems was changed to 32 bytes.
On top of that, at least on 64-bit, `BC_NUM_DEF_SIZE` supports numbers with
either 72 integer digits or 45 integer digits and 27 fractional digits. This
should be more than enough for most cases since `bc`'s default `scale` values
are 0 or 20, meaning that, by default, it has at most 20 fractional digits. And
45 integer digits are *a lot*; it's enough to calculate the amount of mass in
the Milky Way galaxy in kilograms. Also, 72 digits is enough to calculate the
diameter of the universe in Planck lengths.
(For 32-bit, these numbers are either 32 integer digits or 12 integer digits and
20 fractional digits. These are also quite big, and going much bigger on a
32-bit system seems a little pointless since 12 digits in just under a trillion
and 20 fractional digits is still enough for about any use since `10^-20` light
years is just under a millimeter.)
All of this together means that for ordinary uses, and even uses in scientific
work, the default number size will be all that is needed, which means that
nearly all, if not all, numbers will be reused, relieving pressure on the system
allocator.
I did several experiments to find the changes that had the most impact,
especially with regard to reusing `BcNum`'s. One was putting `BcNum`'s into
buckets according to their capacity in powers of 2 up to 512. That performed
worse than `bc` did in `2.7.2`. Another was putting any `BcNum` on the reuse
list that had a capacity of `BC_NUM_DEF_SIZE * 2` and reusing them for `BcNum`'s
that requested `BC_NUM_DEF_SIZE`. This did reduce the amount of time spent, but
it also spent a lot of time in the system allocator for an unknown reason. (When
using `strace`, a bunch more `brk` calls showed up.) Just reusing `BcNum`'s that
had exactly `BC_NUM_DEF_SIZE` capacity spent the smallest amount of time in both
user and system time. This makes sense, especially with the changes to make
`BC_NUM_DEF_SIZE` bigger on 64-bit systems, since the vast majority of numbers
will only ever use numbers with a size less than or equal to `BC_NUM_DEF_SIZE`.
Last of all, `bc`'s signal handling underwent a complete redesign. (This is the
reason that this version is `3.0.0` and not `2.8.0`.) The change was to move
from a polling approach to signal handling to an interrupt-based approach.
Previously, every single loop condition had a check for signals. I suspect that
this could be expensive when in tight loops.
Now, the signal handler just uses `longjmp()` (actually `siglongjmp()`) to start
an unwinding of the stack until it is stopped or the stack is unwound to
`main()`, which just returns. If `bc` is currently executing code that cannot be
safely interrupted (according to POSIX), then signals are "locked." The signal
handler checks if the lock is taken, and if it is, it just sets the status to
indicate that a signal arrived. Later, when the signal lock is released, the
status is checked to see if a signal came in. If so, the stack unwinding starts.
This design eliminates polling in favor of maintaining a stack of `jmp_buf`'s.
This has its own performance implications, but it gives better interaction. And
the cost of pushing and popping a `jmp_buf` in a function is paid at most twice.
Most functions do not pay that price, and most of the rest only pay it once.
(There are only some 3 functions in `bc` that push and pop a `jmp_buf` twice.)
As a side effect of this change, I had to eliminate the use of `stdio.h` in `bc`
because `stdio` does not play nice with signals and `longjmp()`. I implemented
custom I/O buffer code that takes a fraction of the size. This means that static
builds will be smaller, but non-static builds will be bigger, though they will
have less linking time.
This change is also good because my history implementation was already bypassing
`stdio` for good reasons, and unifying the architecture was a win.
Another reason for this change is that my `bc` should *always* behave correctly
in the presence of signals like `SIGINT`, `SIGTERM`, and `SIGQUIT`. With the
addition of my own I/O buffering, I needed to also make sure that the buffers
were correctly flushed even when such signals happened.
For this reason, I **removed the option to build without signal support**.
As a nice side effect of this change, the error handling code could be changed
to take advantage of the stack unwinding that signals used. This means that
signals and error handling use the same code paths, which means that the stack
unwinding is well-tested. (Errors are tested heavily in the test suite.)
It also means that functions do not need to return a status code that
***every*** caller needs to check. This eliminated over 100 branches that simply
checked return codes and then passed that return code up the stack if necessary.
The code bloat savings from this is at least 1700 bytes on `x86_64`, *before*
taking into account the extra code from removing `stdio.h`.
## 2.7.2
This is a production release with one major bug fix.
The `length()` built-in function can take either a number or an array. If it
takes an array, it returns the length of the array. Arrays can be passed by
reference. The bug is that the `length()` function would not properly
dereference arrays that were references. This is a bug that affects all users.
**ALL USERS SHOULD UPDATE `bc`**.
## 2.7.1
This is a production release with fixes for new locales and fixes for compiler
warnings on FreeBSD.
## 2.7.0
This is a production release with a bug fix for Linux, new translations, and new
features.
Bug fixes:
* Option parsing in `BC_ENV_ARGS` was broken on Linux in 2.6.1 because `glibc`'s
`getopt_long()` is broken. To get around that, and to support long options on
every platform, an adapted version of [`optparse`][17] was added. Now, `bc`
does not even use `getopt()`.
* Parsing `BC_ENV_ARGS` with quotes now works. It isn't the smartest, but it
does the job if there are spaces in file names.
The following new languages are supported:
* Dutch
* Polish
* Russian
* Japanes
* Simplified Chinese
All of these translations were generated using [DeepL][18], so improvements are
welcome.
There is only one new feature: **`bc` now has a built-in pseudo-random number
generator** (PRNG).
The PRNG is seeded, making it useful for applications where
`/dev/urandom` does not work because output needs to be reproducible. However,
it also uses `/dev/urandom` to seed itself by default, so it will start with a
good seed by default.
It also outputs 32 bits on 32-bit platforms and 64 bits on 64-bit platforms, far
better than the 15 bits of C's `rand()` and `bash`'s `$RANDOM`.
In addition, the PRNG can take a bound, and when it gets a bound, it
automatically adjusts to remove bias. It can also generate numbers of arbitrary
size. (As of the time of release, the largest pseudo-random number generated by
this `bc` was generated with a bound of `2^(2^20)`.)
***IMPORTANT: read the [`bc` manual][9] and the [`dc` manual][10] to find out
exactly what guarantees the PRNG provides. The underlying implementation is not
guaranteed to stay the same, but the guarantees that it provides are guaranteed
to stay the same regardless of the implementation.***
On top of that, four functions were added to `bc`'s [extended math library][16]
to make using the PRNG easier:
* `frand(p)`: Generates a number between `[0,1)` to `p` decimal places.
* `ifrand(i, p)`: Generates an integer with bound `i` and adds it to `frand(p)`.
* `srand(x)`: Randomizes the sign of `x`. In other words, it flips the sign of
`x` with probability `0.5`.
* `brand()`: Returns a random boolean value (either `0` or `1`).
## 2.6.1
This is a production release with a bug fix for FreeBSD.
The bug was that when `bc` was built without long options, it would give a fatal
error on every run. This was caused by a mishandling of `optind`.
## 2.6.0
This release is a production release ***with no bugfixes***. If you do not want
to upgrade, you don't have to.
No source code changed; the only thing that changed was `lib2.bc`.
This release adds one function to the [extended math library][16]: `p(x, y)`,
which calculates `x` to the power of `y`, whether or not `y` is an integer. (The
`^` operator can only accept integer powers.)
This release also includes a couple of small tweaks to the [extended math
library][16], mostly to fix returning numbers with too high of `scale`.
## 2.5.3
This release is a production release which addresses inconsistencies in the
Portuguese locales. No `bc` code was changed.
The issues were that the ISO files used different naming, and also that the
files that should have been symlinks were not. I did not catch that because
GitHub rendered them the exact same way.
## 2.5.2
This release is a production release.
No code was changed, but the build system was changed to allow `CFLAGS` to be
given to `CC`, like this:
```
CC="gcc -O3 -march=native" ./configure.sh
```
If this happens, the flags are automatically put into `CFLAGS`, and the compiler
is set appropriately. In the example above this means that `CC` will be "gcc"
and `CFLAGS` will be "-O3 -march=native".
This behavior was added to conform to GNU autotools practices.
## 2.5.1
This is a production release which addresses portability concerns discovered
in the `bc` build system. No `bc` code was changed.
* Support for Solaris SPARC and AIX were added.
* Minor documentations edits were performed.
* An option for `configure.sh` was added to disable long options if
`getopt_long()` is missing.
## 2.5.0
This is a production release with new translations. No code changed.
The translations were contributed by [bugcrazy][15], and they are for
Portuguese, both Portugal and Brazil locales.
## 2.4.0
This is a production release primarily aimed at improving `dc`.
* A couple of copy and paste errors in the [`dc` manual][10] were fixed.
* `dc` startup was optimized by making sure it didn't have to set up `bc`-only
things.
* The `bc` `&&` and `||` operators were made available to `dc` through the `M`
and `m` commands, respectively.
* `dc` macros were changed to be tail call-optimized.
The last item, tail call optimization, means that if the last thing in a macro
is a call to another macro, then the old macro is popped before executing the
new macro. This change was made to stop `dc` from consuming more and more memory
as macros are executed in a loop.
The `q` and `Q` commands still respect the "hidden" macros by way of recording
how many macros were removed by tail call optimization.
## 2.3.2
This is a production release meant to fix warnings in the Gentoo `ebuild` by
making it possible to disable binary stripping. Other users do *not* need to
upgrade.
## 2.3.1
This is a production release. It fixes a bug that caused `-1000000000 < -1` to
return `0`. This only happened with negative numbers and only if the value on
the left was more negative by a certain amount. That said, this bug *is* a bad
bug, and needs to be fixed.
**ALL USERS SHOULD UPDATE `bc`**.
## 2.3.0
This is a production release with changes to the build system.
## 2.2.0
This release is a production release. It only has new features and performance
improvements.
1. The performance of `sqrt(x)` was improved.
2. The new function `root(x, n)` was added to the extended math library to
calculate `n`th roots.
3. The new function `cbrt(x)` was added to the extended math library to
calculate cube roots.
## 2.1.3
This is a non-critical release; it just changes the build system, and in
non-breaking ways:
1. Linked locale files were changed to link to their sources with a relative
link.
2. A bug in `configure.sh` that caused long option parsing to fail under `bash`
was fixed.
## 2.1.2
This release is not a critical release.
1. A few codes were added to history.
2. Multiplication was optimized a bit more.
3. Addition and subtraction were both optimized a bit more.
## 2.1.1
This release contains a fix for the test suite made for Linux from Scratch: now
the test suite prints `pass` when a test is passed.
Other than that, there is no change in this release, so distros and other users
do not need to upgrade.
## 2.1.0
This release is a production release.
The following bugs were fixed:
1. A `dc` bug that caused stack mishandling was fixed.
2. A warning on OpenBSD was fixed.
3. Bugs in `ctrl+arrow` operations in history were fixed.
4. The ability to paste multiple lines in history was added.
5. A `bc` bug, mishandling of array arguments to functions, was fixed.
6. A crash caused by freeing the wrong pointer was fixed.
7. A `dc` bug where strings, in a rare case, were mishandled in parsing was
fixed.
In addition, the following changes were made:
1. Division was slightly optimized.
2. An option was added to the build to disable printing of prompts.
3. The special case of empty arguments is now handled. This is to prevent
errors in scripts that end up passing empty arguments.
4. A harmless bug was fixed. This bug was that, with the pop instructions
(mostly) removed (see below), `bc` would leave extra values on its stack for
`void` functions and in a few other cases. These extra items would not
affect anything put on the stack and would not cause any sort of crash or
even buggy behavior, but they would cause `bc` to take more memory than it
needed.
On top of the above changes, the following optimizations were added:
1. The need for pop instructions in `bc` was removed.
2. Extra tests on every iteration of the interpreter loop were removed.
3. Updating function and code pointers on every iteration of the interpreter
loop was changed to only updating them when necessary.
4. Extra assignments to pointers were removed.
Altogether, these changes sped up the interpreter by around 2x.
***NOTE***: This is the last release with new features because this `bc` is now
considered complete. From now on, only bug fixes and new translations will be
added to this `bc`.
## 2.0.3
This is a production, bug-fix release.
Two bugs were fixed in this release:
1. A rare and subtle signal handling bug was fixed.
2. A misbehavior on `0` to a negative power was fixed.
The last bug bears some mentioning.
When I originally wrote power, I did not thoroughly check its error cases;
instead, I had it check if the first number was `0` and then if so, just return
`0`. However, `0` to a negative power means that `1` will be divided by `0`,
which is an error.
I caught this, but only after I stopped being cocky. You see, sometime later, I
had noticed that GNU `bc` returned an error, correctly, but I thought it was
wrong simply because that's not what my `bc` did. I saw it again later and had a
double take. I checked for real, finally, and found out that my `bc` was wrong
all along.
That was bad on me. But the bug was easy to fix, so it is fixed now.
There are two other things in this release:
1. Subtraction was optimized by [Stefan Eßer][14].
2. Division was also optimized, also by Stefan Eßer.
## 2.0.2
This release contains a fix for a possible overflow in the signal handling. I
would be surprised if any users ran into it because it would only happen after 2
billion (`2^31-1`) `SIGINT`'s, but I saw it and had to fix it.
## 2.0.1
This release contains very few things that will apply to any users.
1. A slight bug in `dc`'s interactive mode was fixed.
2. A bug in the test suite that was only triggered on NetBSD was fixed.
3. **The `-P`/`--no-prompt` option** was added for users that do not want a
prompt.
4. A `make check` target was added as an alias for `make test`.
5. `dc` got its own read prompt: `?> `.
## 2.0.0
This release is a production release.
This release is also a little different from previous releases. From here on
out, I do not plan on adding any more features to this `bc`; I believe that it
is complete. However, there may be bug fix releases in the future, if I or any
others manage to find bugs.
This release has only a few new features:
1. `atan2(y, x)` was added to the extended math library as both `a2(y, x)` and
`atan2(y, x)`.
2. Locales were fixed.
3. A **POSIX shell-compatible script was added as an alternative to compiling
`gen/strgen.c`** on a host machine. More details about making the choice
between the two can be found by running `./configure.sh --help` or reading
the [build manual][13].
4. Multiplication was optimized by using **diagonal multiplication**, rather
than straight brute force.
5. The `locale_install.sh` script was fixed.
6. `dc` was given the ability to **use the environment variable
`DC_ENV_ARGS`**.
7. `dc` was also given the ability to **use the `-i` or `--interactive`**
options.
8. Printing the prompt was fixed so that it did not print when it shouldn't.
9. Signal handling was fixed.
10. **Handling of `SIGTERM` and `SIGQUIT`** was fixed.
11. The **built-in functions `maxibase()`, `maxobase()`, and `maxscale()`** (the
commands `T`, `U`, `V` in `dc`, respectively) were added to allow scripts to
query for the max allowable values of those globals.
12. Some incompatibilities with POSIX were fixed.
In addition, this release is `2.0.0` for a big reason: the internal format for
numbers changed. They used to be a `char` array. Now, they are an array of
larger integers, packing more decimal digits into each integer. This has
delivered ***HUGE*** performance improvements, especially for multiplication,
division, and power.
This `bc` should now be the fastest `bc` available, but I may be wrong.
## 1.2.8
This release contains a fix for a harmless bug (it is harmless in that it still
works, but it just copies extra data) in the [`locale_install.sh`][12] script.
## 1.2.7
This version contains fixes for the build on Arch Linux.
## 1.2.6
This release removes the use of `local` in shell scripts because it's not POSIX
shell-compatible, and also updates a man page that should have been updated a
long time ago but was missed.
## 1.2.5
This release contains some missing locale `*.msg` files.
## 1.2.4
This release contains a few bug fixes and new French translations.
## 1.2.3
This release contains a fix for a bug: use of uninitialized data. Such data was
only used when outputting an error message, but I am striving for perfection. As
Michelangelo said, "Trifles make perfection, and perfection is no trifle."
## 1.2.2
This release contains fixes for OpenBSD.
## 1.2.1
This release contains bug fixes for some rare bugs.
## 1.2.0
This is a production release.
There have been several changes since `1.1.0`:
1. The build system had some changes.
2. Locale support has been added. (Patches welcome for translations.)
3. **The ability to turn `ibase`, `obase`, and `scale` into stacks** was added
with the `-g` command-line option. (See the [`bc` manual][9] for more
details.)
4. Support for compiling on Mac OSX out of the box was added.
5. The extended math library got `t(x)`, `ceil(x)`, and some aliases.
6. The extended math library also got `r2d(x)` (for converting from radians to
degrees) and `d2r(x)` (for converting from degrees to radians). This is to
allow using degrees with the standard library.
7. Both calculators now accept numbers in **scientific notation**. See the
[`bc` manual][9] and the [`dc` manual][10] for details.
8. Both calculators can **output in either scientific or engineering
notation**. See the [`bc` manual][9] and the [`dc` manual][10] for details.
9. Some inefficiencies were removed.
10. Some bugs were fixed.
11. Some bugs in the extended library were fixed.
12. Some defects from [Coverity Scan][11] were fixed.
## 1.1.4
This release contains a fix to the build system that allows it to build on older
versions of `glibc`.
## 1.1.3
This release contains a fix for a bug in the test suite where `bc` tests and
`dc` tests could not be run in parallel.
## 1.1.2
This release has a fix for a history bug; the down arrow did not work.
## 1.1.1
This release fixes a bug in the `1.1.0` build system. The source is exactly the
same.
The bug that was fixed was a failure to install if no `EXECSUFFIX` was used.
## 1.1.0
This is a production release. However, many new features were added since `1.0`.
1. **The build system has been changed** to use a custom, POSIX
shell-compatible configure script ([`configure.sh`][6]) to generate a POSIX
make-compatible `Makefile`, which means that `bc` and `dc` now build out of
the box on any POSIX-compatible system.
2. Out-of-memory and output errors now cause the `bc` to report the error,
clean up, and die, rather than just reporting and trying to continue.
3. **Strings and constants are now garbage collected** when possible.
4. Signal handling and checking has been made more simple and more thorough.
5. `BcGlobals` was refactored into `BcVm` and `BcVm` was made global. Some
procedure names were changed to reflect its difference to everything else.
6. Addition got a speed improvement.
7. Some common code for addition and multiplication was refactored into its own
procedure.
8. A bug was removed where `dc` could have been selected, but the internal
`#define` that returned `true` for a query about `dc` would not have
returned `true`.
9. Useless calls to `bc_num_zero()` were removed.
10. **History support was added.** The history support is based off of a
[UTF-8 aware fork][7] of [`linenoise`][8], which has been customized with
`bc`'s own data structures and signal handling.
11. Generating C source from the math library now removes tabs from the library,
shrinking the size of the executable.
12. The math library was shrunk.
13. Error handling and reporting was improved.
14. Reallocations were reduced by giving access to the request size for each
operation.
15. **`abs()` (`b` command for `dc`) was added as a builtin.**
16. Both calculators were tested on FreeBSD.
17. Many obscure parse bugs were fixed.
18. Markdown and man page manuals were added, and the man pages are installed by
`make install`.
19. Executable size was reduced, though the added features probably made the
executable end up bigger.
20. **GNU-style array references were added as a supported feature.**
21. Allocations were reduced.
22. **New operators were added**: `$` (`$` for `dc`), `@` (`@` for `dc`), `@=`,
`<<` (`H` for `dc`), `<<=`, `>>` (`h` for `dc`), and `>>=`. See the
[`bc` manual][9] and the [`dc` manual][10] for more details.
23. **An extended math library was added.** This library contains code that
makes it so I can replace my desktop calculator with this `bc`. See the
[`bc` manual][3] for more details.
24. Support for all capital letters as numbers was added.
25. **Support for GNU-style void functions was added.**
26. A bug fix for improper handling of function parameters was added.
27. Precedence for the or (`||`) operator was changed to match GNU `bc`.
28. `dc` was given an explicit negation command.
29. `dc` was changed to be able to handle strings in arrays.
## 1.1 Release Candidate 3
This release is the eighth release candidate for 1.1, though it is the third
release candidate meant as a general release candidate. The new code has not
been tested as thoroughly as it should for release.
## 1.1 Release Candidate 2
This release is the seventh release candidate for 1.1, though it is the second
release candidate meant as a general release candidate. The new code has not
been tested as thoroughly as it should for release.
## 1.1 FreeBSD Beta 5
This release is the sixth release candidate for 1.1, though it is the fifth
release candidate meant specifically to test if `bc` works on FreeBSD. The new
code has not been tested as thoroughly as it should for release.
## 1.1 FreeBSD Beta 4
This release is the fifth release candidate for 1.1, though it is the fourth
release candidate meant specifically to test if `bc` works on FreeBSD. The new
code has not been tested as thoroughly as it should for release.
## 1.1 FreeBSD Beta 3
This release is the fourth release candidate for 1.1, though it is the third
release candidate meant specifically to test if `bc` works on FreeBSD. The new
code has not been tested as thoroughly as it should for release.
## 1.1 FreeBSD Beta 2
This release is the third release candidate for 1.1, though it is the second
release candidate meant specifically to test if `bc` works on FreeBSD. The new
code has not been tested as thoroughly as it should for release.
## 1.1 FreeBSD Beta 1
This release is the second release candidate for 1.1, though it is meant
specifically to test if `bc` works on FreeBSD. The new code has not been tested as
thoroughly as it should for release.
## 1.1 Release Candidate 1
This is the first release candidate for 1.1. The new code has not been tested as
thoroughly as it should for release.
## 1.0
This is the first non-beta release. `bc` is ready for production use.
As such, a lot has changed since 0.5.
1. `dc` has been added. It has been tested even more thoroughly than `bc` was
for `0.5`. It does not have the `!` command, and for security reasons, it
never will, so it is complete.
2. `bc` has been more thoroughly tested. An entire section of the test suite
(for both programs) has been added to test for errors.
3. A prompt (`>>> `) has been added for interactive mode, making it easier to
see inputs and outputs.
4. Interrupt handling has been improved, including elimination of race
conditions (as much as possible).
5. MinGW and [Windows Subsystem for Linux][1] support has been added (see
[xstatic][2] for binaries).
6. Memory leaks and errors have been eliminated (as far as ASan and Valgrind
can tell).
7. Crashes have been eliminated (as far as [afl][3] can tell).
8. Karatsuba multiplication was added (and thoroughly) tested, speeding up
multiplication and power by orders of magnitude.
9. Performance was further enhanced by using a "divmod" function to reduce
redundant divisions and by removing superfluous `memset()` calls.
10. To switch between Karatsuba and `O(n^2)` multiplication, the config variable
`BC_NUM_KARATSUBA_LEN` was added. It is set to a sane default, but the
optimal number can be found with [`karatsuba.py`][4] (requires Python 3)
and then configured through `make`.
11. The random math test generator script was changed to Python 3 and improved.
`bc` and `dc` have together been run through 30+ million random tests.
12. All known math bugs have been fixed, including out of control memory
allocations in `sine` and `cosine` (that was actually a parse bug), certain
cases of infinite loop on square root, and slight inaccuracies (as much as
possible; see the [README][5]) in transcendental functions.
13. Parsing has been fixed as much as possible.
14. Test coverage was improved to 94.8%. The only paths not covered are ones
that happen when `malloc()` or `realloc()` fails.
15. An extension to get the length of an array was added.
16. The boolean not (`!`) had its precedence change to match negation.
17. Data input was hardened.
18. `bc` was made fully compliant with POSIX when the `-s` flag is used or
`POSIXLY_CORRECT` is defined.
19. Error handling was improved.
20. `bc` now checks that files it is given are not directories.
## 1.0 Release Candidate 7
This is the seventh release candidate for 1.0. It fixes a few bugs in 1.0
Release Candidate 6.
## 1.0 Release Candidate 6
This is the sixth release candidate for 1.0. It fixes a few bugs in 1.0 Release
Candidate 5.
## 1.0 Release Candidate 5
This is the fifth release candidate for 1.0. It fixes a few bugs in 1.0 Release
Candidate 4.
## 1.0 Release Candidate 4
This is the fourth release candidate for 1.0. It fixes a few bugs in 1.0 Release
Candidate 3.
## 1.0 Release Candidate 3
This is the third release candidate for 1.0. It fixes a few bugs in 1.0 Release
Candidate 2.
## 1.0 Release Candidate 2
This is the second release candidate for 1.0. It fixes a few bugs in 1.0 Release
Candidate 1.
## 1.0 Release Candidate 1
This is the first Release Candidate for 1.0. `bc` is complete, with `dc`, but it
is not tested.
## 0.5
This beta release completes more features, but it is still not complete nor
tested as thoroughly as necessary.
## 0.4.1
This beta release fixes a few bugs in 0.4.
## 0.4
This is a beta release. It does not have the complete set of features, and it is
not thoroughly tested.
[1]: https://docs.microsoft.com/en-us/windows/wsl/install-win10
[2]: https://pkg.musl.cc/bc/
[3]: http://lcamtuf.coredump.cx/afl/
[4]: ./karatsuba.py
[5]: ./README.md
[6]: ./configure.sh
[7]: https://github.com/rain-1/linenoise-mob
[8]: https://github.com/antirez/linenoise
[9]: ./manuals/bc/A.1.md
[10]: ./manuals/dc/A.1.md
[11]: https://scan.coverity.com/projects/gavinhoward-bc
[12]: ./locale_install.sh
[13]: ./manuals/build.md
[14]: https://github.com/stesser
[15]: https://github.com/bugcrazy
[16]: ./manuals/bc/A.1.md#extended-library
[17]: https://github.com/skeeto/optparse
[18]: https://www.deepl.com/translator
[19]: ./manuals/benchmarks.md
[20]: https://github.com/apjanke/ronn-ng
[21]: https://pandoc.org/
diff --git a/contrib/bc/README.md b/contrib/bc/README.md
index beda88d23f90..2f95e16ed246 100644
--- a/contrib/bc/README.md
+++ b/contrib/bc/README.md
@@ -1,348 +1,348 @@
# `bc`
[![Coverity Scan Build Status][17]][18]
***WARNING: This project has moved to [https://git.yzena.com/][20] for [these
reasons][21], though GitHub will remain a mirror.***
This is an implementation of the [POSIX `bc` calculator][12] that implements
[GNU `bc`][1] extensions, as well as the period (`.`) extension for the BSD
flavor of `bc`.
For more information, see this `bc`'s full manual.
This `bc` also includes an implementation of `dc` in the same binary, accessible
via a symbolic link, which implements all FreeBSD and GNU extensions. (If a
standalone `dc` binary is desired, `bc` can be copied and renamed to `dc`.) The
`!` command is omitted; I believe this poses security concerns and that such
functionality is unnecessary.
For more information, see the `dc`'s full manual.
This `bc` is Free and Open Source Software (FOSS). It is offered under the BSD
2-clause License. Full license text may be found in the [`LICENSE.md`][4] file.
## Prerequisites
This `bc` only requires a C99-compatible compiler and a (mostly) POSIX
2008-compatible system with the XSI (X/Open System Interfaces) option group.
Since POSIX 2008 with XSI requires the existence of a C99 compiler as `c99`, any
POSIX and XSI-compatible system will have everything needed.
Systems that are known to work:
* Linux
* FreeBSD
* OpenBSD
* NetBSD
* Mac OSX
* Solaris* (as long as the Solaris version supports POSIX 2008)
* AIX
* HP-UX* (except for history)
Please submit bug reports if this `bc` does not build out of the box on any
system besides Windows. If Windows binaries are needed, they can be found at
[xstatic][6].
## Build
This `bc` should build unmodified on any POSIX-compliant system.
For more complex build requirements than the ones below, see the
[build manual][5].
### Pre-built Binaries
It is possible to download pre-compiled binaries for a wide list of platforms,
including Linux- and Windows-based systems, from [xstatic][6]. This link always
points to the latest release of `bc`.
### Default
For the default build with optimization, use the following commands in the root
directory:
```
./configure.sh -O3
make
```
### One Calculator
To only build `bc`, use the following commands:
```
./configure.sh --disable-dc
make
```
To only build `dc`, use the following commands:
```
./configure.sh --disable-bc
make
```
### Debug
For debug builds, use the following commands in the root directory:
```
./configure.sh -g
make
```
### Install
To install, use the following command:
```
make install
```
By default, `bc` and `dc` will be installed in `/usr/local`. For installing in
other locations, use the `PREFIX` environment variable when running
`configure.sh` or pass the `--prefix=<prefix>` option to `configure.sh`. See the
[build manual][5], or run `./configure.sh --help`, for more details.
### Library
This `bc` does provide a way to build a math library with C bindings. This is
done by the `-a` or `--library` options to `configure.sh`:
```
./configure.sh -a
```
When building the library, the executables are not built. For more information,
see the [build manual][5].
The library API can be found in [`manuals/bcl.3.md`][26] or `man bcl` once the
library is installed.
The library is built as `bin/libbcl.a`.
### Package and Distro Maintainers
#### Recommended Compiler
When I ran benchmarks with my `bc` compiled under `clang`, it performed much
better than when compiled under `gcc`. I recommend compiling this `bc` with
`clang`.
I also recommend building this `bc` with C11 if you can because `bc` will detect
a C11 compiler and add `_Noreturn` to any relevant function(s).
#### Recommended Optimizations
I wrote this `bc` with Separation of Concerns, which means that there are many
small functions that could be inlined. However, they are often called across
file boundaries, and the default optimizer can only look at the current file,
which means that they are not inlined.
Thus, because of the way this `bc` is built, it will automatically be slower
than other `bc` implementations when running scripts with no math. (My `bc`'s
math is *much* faster, so any non-trivial script should run faster in my `bc`.)
Some, or all, of the difference can be made up with the right optimizations. The
optimizations I recommend are:
1. `-O3`
2. `-flto` (link-time optimization)
in that order.
Link-time optimization, in particular, speeds up the `bc` a lot. This is because
when link-time optimization is turned on, the optimizer can look across files
and inline *much* more heavily.
However, I recommend ***NOT*** using `-march=native`. Doing so will reduce this
`bc`'s performance, at least when building with link-time optimization. See the
[benchmarks][19] for more details.
#### Stripping Binaries
By default, non-debug binaries are stripped, but stripping can be disabled with
the `-T` option to `configure.sh`.
#### Using This `bc` as an Alternative
If this `bc` is packaged as an alternative to an already existing `bc` package,
it is possible to rename it in the build to prevent name collision. To prepend
to the name, just run the following:
```
EXECPREFIX=<some_prefix> ./configure.sh
```
To append to the name, just run the following:
```
EXECSUFFIX=<some_suffix> ./configure.sh
```
If a package maintainer wishes to add both a prefix and a suffix, that is
allowed.
**Note**: The suggested name (and package name) when `bc` is not available is
`bc-gh`.
#### Karatsuba Number
Package and distro maintainers have one tool at their disposal to build this
`bc` in the optimal configuration: `karatsuba.py`.
This script is not a compile-time or runtime prerequisite; it is for package and
distro maintainers to run once when a package is being created. It finds the
optimal Karatsuba number (see the [algorithms manual][7] for more information)
for the machine that it is running on.
The easiest way to run this script is with `make karatsuba`.
If desired, maintainers can also skip running this script because there is a
sane default for the Karatsuba number.
## Status
This `bc` is robust.
It is well-tested, fuzzed, and fully standards-compliant (though not certified)
with POSIX `bc`. The math has been tested with 40+ million random problems, so
it is as correct as I can make it.
This `bc` can be used as a drop-in replacement for any existing `bc`. This `bc`
is also compatible with MinGW toolchains, though history is not supported on
Windows.
In addition, this `bc` is considered complete; i.e., there will be no more
releases with additional features. However, it *is* actively maintained, so if
any bugs are found, they will be fixed in new releases. Also, additional
translations will also be added as they are provided.
## Comparison to GNU `bc`
This `bc` compares favorably to GNU `bc`.
* It has more extensions, which make this `bc` more useful for scripting.
* This `bc` is a bit more POSIX compliant.
* It has a much less buggy parser. The GNU `bc` will give parse errors for what
is actually valid `bc` code, or should be. For example, putting an `else` on
a new line after a brace can cause GNU `bc` to give a parse error.
* This `bc` has fewer crashes.
* GNU `bc` calculates the wrong number of significant digits for `length(x)`.
* GNU `bc` will sometimes print numbers incorrectly. For example, when running
it on the file `tests/bc/power.txt` in this repo, GNU `bc` gets all the right
answers, but it fails to wrap the numbers at the proper place when outputting
to a file.
* This `bc` is faster. (See [Performance](#performance).)
### Performance
Because this `bc` packs more than `1` decimal digit per hardware integer, this
`bc` is faster than GNU `bc` and can be *much* faster. Full benchmarks can be
found at [manuals/benchmarks.md][19].
There is one instance where this `bc` is slower: if scripts are light on math.
This is because this `bc`'s intepreter is slightly slower than GNU `bc`, but
that is because it is more robust. See the [benchmarks][19].
## Algorithms
To see what algorithms this `bc` uses, see the [algorithms manual][7].
## Locales
Currently, this `bc` only has support for English (and US English), French,
German, Portuguese, Dutch, Polish, Russian, Japanese, and Chinese locales.
Patches are welcome for translations; use the existing `*.msg` files in
`locales/` as a starting point.
In addition, patches for improvements are welcome; the last two messages in
Portuguese were made with Google Translate, and the Dutch, Polish, Russian,
Japanese, and Chinese locales were all generated with [DeepL][22].
The message files provided assume that locales apply to all regions where a
language is used, but this might not be true for, e.g., `fr_CA` and `fr_CH`.
Any corrections or a confirmation that the current texts are acceptable for
those regions would be appreciated, too.
## Other Projects
Other projects based on this bc are:
* [busybox `bc`][8]. The busybox maintainers have made their own changes, so any
bugs in the busybox `bc` should be reported to them.
* [toybox `bc`][9]. The maintainer has also made his own changes, so bugs in the
toybox `bc` should be reported there.
* [FreeBSD `bc`][23]. While the `bc` in FreeBSD is kept up-to-date, it is better
to [report bugs there][24], as well as [submit patches][25], and the
maintainers of the package will contact me if necessary.
## Language
This `bc` is written in pure ISO C99, using POSIX 2008 APIs.
## Commit Messages
This `bc` uses the commit message guidelines laid out in [this blog post][10].
## Semantic Versioning
This `bc` uses [semantic versioning][11].
## Contents
Items labeled with `(maintainer use only)` are not included in release source
tarballs.
Files:
.gitignore The git ignore file (maintainer use only).
configure A symlink to configure.sh to make packaging easier.
configure.sh The configure script.
functions.sh A script with functions used by other scripts.
install.sh Install script.
karatsuba.py Script to find the optimal Karatsuba number.
LICENSE.md A Markdown form of the BSD 2-clause License.
link.sh A script to link dc to bc.
locale_install.sh A script to install locales, if desired.
locale_uninstall.sh A script to uninstall locales.
Makefile.in The Makefile template.
manpage.sh Script to generate man pages from markdown files.
NOTICE.md List of contributors and copyright owners.
RELEASE.md A checklist for making a release (maintainer use only).
release.sh A script to test for release (maintainer use only).
safe-install.sh Safe install script from musl libc.
Folders:
gen The bc math library, help texts, and code to generate C source.
include All header files.
locales Locale files, in .msg format. Patches welcome for translations.
manuals Manuals for both programs.
src All source code.
tests All tests.
[1]: https://www.gnu.org/software/bc/
[4]: ./LICENSE.md
[5]: ./manuals/build.md
[6]: https://pkg.musl.cc/bc/
[7]: ./manuals/algorithms.md
[8]: https://git.busybox.net/busybox/tree/miscutils/bc.c
[9]: https://github.com/landley/toybox/blob/master/toys/pending/bc.c
[10]: http://tbaggery.com/2008/04/19/a-note-about-git-commit-messages.html
[11]: http://semver.org/
[12]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
[17]: https://img.shields.io/coverity/scan/16609.svg
[18]: https://scan.coverity.com/projects/gavinhoward-bc
[19]: ./manuals/benchmarks.md
[20]: https://git.yzena.com/gavin/bc
[21]: https://gavinhoward.com/2020/04/i-am-moving-away-from-github/
[22]: https://www.deepl.com/translator
-[23]: https://svnweb.freebsd.org/base/head/contrib/bc/
+[23]: https://cgit.freebsd.org/src/tree/contrib/bc
[24]: https://bugs.freebsd.org/
[25]: https://reviews.freebsd.org/
[26]: ./manuals/bcl.3.md
diff --git a/contrib/bc/configure.sh b/contrib/bc/configure.sh
index ae1675cde97d..310c26882906 100755
--- a/contrib/bc/configure.sh
+++ b/contrib/bc/configure.sh
@@ -1,1324 +1,1319 @@
#! /bin/sh
#
# SPDX-License-Identifier: BSD-2-Clause
#
# Copyright (c) 2018-2021 Gavin D. Howard and contributors.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# * Redistributions of source code must retain the above copyright notice, this
# list of conditions and the following disclaimer.
#
# * Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
#
script="$0"
scriptdir=$(dirname "$script")
script=$(basename "$script")
. "$scriptdir/functions.sh"
cd "$scriptdir"
usage() {
if [ $# -gt 0 ]; then
_usage_val=1
printf "%s\n\n" "$1"
else
_usage_val=0
fi
printf 'usage:\n'
printf ' %s -h\n' "$script"
printf ' %s --help\n' "$script"
printf ' %s [-a|-bD|-dB|-c] [-CEfgGHlmMNPtTvz] [-O OPT_LEVEL] [-k KARATSUBA_LEN]\n' "$script"
printf ' %s \\\n' "$script"
printf ' [--library|--bc-only --disable-dc|--dc-only --disable-bc|--coverage]\\\n'
printf ' [--force --debug --disable-extra-math --disable-generated-tests] \\\n'
printf ' [--disable-history --disable-man-pages --disable-nls] \\\n'
printf ' [--disable-prompt --disable-strip] [--install-all-locales] \\\n'
printf ' [--opt=OPT_LEVEL] [--karatsuba-len=KARATSUBA_LEN] \\\n'
printf ' [--prefix=PREFIX] [--bindir=BINDIR] [--datarootdir=DATAROOTDIR] \\\n'
printf ' [--datadir=DATADIR] [--mandir=MANDIR] [--man1dir=MAN1DIR] \\\n'
printf '\n'
printf ' -a, --library\n'
printf ' Build the libbc instead of the programs. This is meant to be used with\n'
printf ' Other software like programming languages that want to make use of the\n'
printf ' parsing and math capabilities. This option will install headers using\n'
printf ' `make install`.\n'
printf ' -b, --bc-only\n'
printf ' Build bc only. It is an error if "-d", "--dc-only", "-B", or\n'
printf ' "--disable-bc" are specified too.\n'
printf ' -B, --disable-bc\n'
printf ' Disable bc. It is an error if "-b", "--bc-only", "-D", or "--disable-dc"\n'
printf ' are specified too.\n'
printf ' -c, --coverage\n'
printf ' Generate test coverage code. Requires gcov and regcovr.\n'
printf ' It is an error if either "-b" ("-D") or "-d" ("-B") is specified.\n'
printf ' Requires a compiler that use gcc-compatible coverage options\n'
printf ' -C, --disable-clean\n'
printf ' Disable the clean that configure.sh does before configure.\n'
printf ' -d, --dc-only\n'
printf ' Build dc only. It is an error if "-b", "--bc-only", "-D", or\n'
printf ' "--disable-dc" are specified too.\n'
printf ' -D, --disable-dc\n'
printf ' Disable dc. It is an error if "-d", "--dc-only", "-B", or "--disable-bc"\n'
printf ' are specified too.\n'
printf ' -E, --disable-extra-math\n'
printf ' Disable extra math. This includes: "$" operator (truncate to integer),\n'
printf ' "@" operator (set number of decimal places), and r(x, p) (rounding\n'
printf ' function). Additionally, this option disables the extra printing\n'
printf ' functions in the math library.\n'
printf ' -f, --force\n'
printf ' Force use of all enabled options, even if they do not work. This\n'
printf ' option is to allow the maintainer a way to test that certain options\n'
printf ' are not failing invisibly. (Development only.)'
printf ' -g, --debug\n'
printf ' Build in debug mode. Adds the "-g" flag, and if there are no\n'
printf ' other CFLAGS, and "-O" was not given, this also adds the "-O0"\n'
printf ' flag. If this flag is *not* given, "-DNDEBUG" is added to CPPFLAGS\n'
printf ' and a strip flag is added to the link stage.\n'
printf ' -G, --disable-generated-tests\n'
printf ' Disable generating tests. This is for platforms that do not have a\n'
printf ' GNU bc-compatible bc to generate tests.\n'
printf ' -h, --help\n'
printf ' Print this help message and exit.\n'
printf ' -H, --disable-history\n'
printf ' Disable history.\n'
printf ' -k KARATSUBA_LEN, --karatsuba-len KARATSUBA_LEN\n'
printf ' Set the karatsuba length to KARATSUBA_LEN (default is 64).\n'
printf ' It is an error if KARATSUBA_LEN is not a number or is less than 16.\n'
printf ' -l, --install-all-locales\n'
printf ' Installs all locales, regardless of how many are on the system. This\n'
printf ' option is useful for package maintainers who want to make sure that\n'
printf ' a package contains all of the locales that end users might need.\n'
printf ' -m, --enable-memcheck\n'
printf ' Enable memcheck mode, to ensure no memory leaks. For development only.\n'
printf ' -M, --disable-man-pages\n'
printf ' Disable installing manpages.\n'
printf ' -N, --disable-nls\n'
printf ' Disable POSIX locale (NLS) support.\n'
printf ' -O OPT_LEVEL, --opt OPT_LEVEL\n'
printf ' Set the optimization level. This can also be included in the CFLAGS,\n'
printf ' but it is provided, so maintainers can build optimized debug builds.\n'
printf ' This is passed through to the compiler, so it must be supported.\n'
printf ' -P, --disable-prompt\n'
printf ' Disables the prompt in the built bc. The prompt will never show up,\n'
printf ' or in other words, it will be permanently disabled and cannot be\n'
printf ' enabled.\n'
printf ' -t, --enable-test-timing\n'
printf ' Enable the timing of tests. This is for development only.\n'
printf ' -T, --disable-strip\n'
printf ' Disable stripping symbols from the compiled binary or binaries.\n'
printf ' Stripping symbols only happens when debug mode is off.\n'
printf ' -v, --enable-valgrind\n'
printf ' Enable a build appropriate for valgrind. For development only.\n'
printf ' -z, --enable-fuzz-mode\n'
printf ' Enable fuzzing mode. THIS IS FOR DEVELOPMENT ONLY.\n'
printf ' --prefix PREFIX\n'
printf ' The prefix to install to. Overrides "$PREFIX" if it exists.\n'
printf ' If PREFIX is "/usr", install path will be "/usr/bin".\n'
printf ' Default is "/usr/local".\n'
printf ' --bindir BINDIR\n'
printf ' The directory to install binaries in. Overrides "$BINDIR" if it exists.\n'
printf ' Default is "$PREFIX/bin".\n'
printf ' --includedir INCLUDEDIR\n'
printf ' The directory to install headers in. Overrides "$INCLUDEDIR" if it\n'
printf ' exists. Default is "$PREFIX/include".\n'
printf ' --libdir LIBDIR\n'
printf ' The directory to install libraries in. Overrides "$LIBDIR" if it exists.\n'
printf ' Default is "$PREFIX/lib".\n'
printf ' --datarootdir DATAROOTDIR\n'
printf ' The root location for data files. Overrides "$DATAROOTDIR" if it exists.\n'
printf ' Default is "$PREFIX/share".\n'
printf ' --datadir DATADIR\n'
printf ' The location for data files. Overrides "$DATADIR" if it exists.\n'
printf ' Default is "$DATAROOTDIR".\n'
printf ' --mandir MANDIR\n'
printf ' The location to install manpages to. Overrides "$MANDIR" if it exists.\n'
printf ' Default is "$DATADIR/man".\n'
printf ' --man1dir MAN1DIR\n'
printf ' The location to install Section 1 manpages to. Overrides "$MAN1DIR" if\n'
printf ' it exists. Default is "$MANDIR/man1".\n'
printf ' --man3dir MAN3DIR\n'
printf ' The location to install Section 3 manpages to. Overrides "$MAN3DIR" if\n'
printf ' it exists. Default is "$MANDIR/man3".\n'
printf '\n'
printf 'In addition, the following environment variables are used:\n'
printf '\n'
printf ' CC C compiler. Must be compatible with POSIX c99. If there is a\n'
printf ' space in the basename of the compiler, the items after the\n'
printf ' first space are assumed to be compiler flags, and in that case,\n'
printf ' the flags are automatically moved into CFLAGS. Default is\n'
printf ' "c99".\n'
printf ' HOSTCC Host C compiler. Must be compatible with POSIX c99. If there is\n'
printf ' a space in the basename of the compiler, the items after the\n'
printf ' first space are assumed to be compiler flags, and in the case,\n'
printf ' the flags are automatically moved into HOSTCFLAGS. Default is\n'
printf ' "$CC".\n'
printf ' HOST_CC Same as HOSTCC. If HOSTCC also exists, it is used.\n'
printf ' CFLAGS C compiler flags.\n'
printf ' HOSTCFLAGS CFLAGS for HOSTCC. Default is "$CFLAGS".\n'
printf ' HOST_CFLAGS Same as HOST_CFLAGS. If HOST_CFLAGS also exists, it is used.\n'
printf ' CPPFLAGS C preprocessor flags. Default is "".\n'
printf ' LDFLAGS Linker flags. Default is "".\n'
printf ' PREFIX The prefix to install to. Default is "/usr/local".\n'
printf ' If PREFIX is "/usr", install path will be "/usr/bin".\n'
printf ' BINDIR The directory to install binaries in. Default is "$PREFIX/bin".\n'
printf ' INCLUDEDIR The directory to install header files in. Default is\n'
printf ' "$PREFIX/include".\n'
printf ' LIBDIR The directory to install libraries in. Default is\n'
printf ' "$PREFIX/lib".\n'
printf ' DATAROOTDIR The root location for data files. Default is "$PREFIX/share".\n'
printf ' DATADIR The location for data files. Default is "$DATAROOTDIR".\n'
printf ' MANDIR The location to install manpages to. Default is "$DATADIR/man".\n'
printf ' MAN1DIR The location to install Section 1 manpages to. Default is\n'
printf ' "$MANDIR/man1".\n'
printf ' MAN3DIR The location to install Section 3 manpages to. Default is\n'
printf ' "$MANDIR/man3".\n'
printf ' NLSPATH The location to install locale catalogs to. Must be an absolute\n'
printf ' path (or contain one). This is treated the same as the POSIX\n'
printf ' definition of $NLSPATH (see POSIX environment variables for\n'
printf ' more information). Default is "/usr/share/locale/%%L/%%N".\n'
printf ' EXECSUFFIX The suffix to append to the executable names, used to not\n'
printf ' interfere with other installed bc executables. Default is "".\n'
printf ' EXECPREFIX The prefix to append to the executable names, used to not\n'
printf ' interfere with other installed bc executables. Default is "".\n'
printf ' DESTDIR For package creation. Default is "". If it is empty when\n'
printf ' `%s` is run, it can also be passed to `make install`\n' "$script"
printf ' later as an environment variable. If both are specified,\n'
printf ' the one given to `%s` takes precedence.\n' "$script"
printf ' LONG_BIT The number of bits in a C `long` type. This is mostly for the\n'
printf ' embedded space since this `bc` uses `long`s internally for\n'
printf ' overflow checking. In C99, a `long` is required to be 32 bits.\n'
printf ' For most normal desktop systems, setting this is unnecessary,\n'
printf ' except that 32-bit platforms with 64-bit longs may want to set\n'
printf ' it to `32`. Default is the default of `LONG_BIT` for the target\n'
printf ' platform. Minimum allowed is `32`. It is a build time error if\n'
printf ' the specified value of `LONG_BIT` is greater than the default\n'
printf ' value of `LONG_BIT` for the target platform.\n'
printf ' GEN_HOST Whether to use `gen/strgen.c`, instead of `gen/strgen.sh`, to\n'
printf ' produce the C files that contain the help texts as well as the\n'
printf ' math libraries. By default, `gen/strgen.c` is used, compiled by\n'
printf ' "$HOSTCC" and run on the host machine. Using `gen/strgen.sh`\n'
printf ' removes the need to compile and run an executable on the host\n'
printf ' machine since `gen/strgen.sh` is a POSIX shell script. However,\n'
printf ' `gen/lib2.bc` is perilously close to 4095 characters, the max\n'
printf ' supported length of a string literal in C99 (and it could be\n'
printf ' added to in the future), and `gen/strgen.sh` generates a string\n'
printf ' literal instead of an array, as `gen/strgen.c` does. For most\n'
printf ' production-ready compilers, this limit probably is not\n'
printf ' enforced, but it could be. Both options are still available for\n'
printf ' this reason. If you are sure your compiler does not have the\n'
printf ' limit and do not want to compile and run a binary on the host\n'
printf ' machine, set this variable to "0". Any other value, or a\n'
printf ' non-existent value, will cause the build system to compile and\n'
printf ' run `gen/strgen.c`. Default is "".\n'
printf ' GEN_EMU Emulator to run string generator code under (leave empty if not\n'
printf ' necessary). This is not necessary when using `gen/strgen.sh`.\n'
printf ' Default is "".\n'
printf '\n'
printf 'WARNING: even though `configure.sh` supports both option types, short and\n'
printf 'long, it does not support handling both at the same time. Use only one type.\n'
exit "$_usage_val"
}
replace_ext() {
if [ "$#" -ne 3 ]; then
err_exit "Invalid number of args to $0"
fi
_replace_ext_file="$1"
_replace_ext_ext1="$2"
_replace_ext_ext2="$3"
- _replace_ext_result=${_replace_ext_file%.$_replace_ext_ext1}.$_replace_ext_ext2
+ _replace_ext_result="${_replace_ext_file%.$_replace_ext_ext1}.$_replace_ext_ext2"
printf '%s\n' "$_replace_ext_result"
}
replace_exts() {
if [ "$#" -ne 3 ]; then
err_exit "Invalid number of args to $0"
fi
_replace_exts_files="$1"
_replace_exts_ext1="$2"
_replace_exts_ext2="$3"
for _replace_exts_file in $_replace_exts_files; do
_replace_exts_new_name=$(replace_ext "$_replace_exts_file" "$_replace_exts_ext1" "$_replace_exts_ext2")
_replace_exts_result="$_replace_exts_result $_replace_exts_new_name"
done
printf '%s\n' "$_replace_exts_result"
}
replace() {
if [ "$#" -ne 3 ]; then
err_exit "Invalid number of args to $0"
fi
_replace_str="$1"
_replace_needle="$2"
_replace_replacement="$3"
substring_replace "$_replace_str" "%%$_replace_needle%%" "$_replace_replacement"
}
find_src_files() {
if [ "$#" -ge 1 ] && [ "$1" != "" ]; then
while [ "$#" -ge 1 ]; do
_find_src_files_a="${1## }"
shift
_find_src_files_args="$_find_src_files_args ! -path src/${_find_src_files_a}"
done
else
_find_src_files_args="-print"
fi
printf '%s\n' $(find src/ -depth -name "*.c" $_find_src_files_args)
}
gen_file_list() {
if [ "$#" -lt 1 ]; then
err_exit "Invalid number of args to $0"
fi
_gen_file_list_contents="$1"
shift
p=$(pwd)
cd "$scriptdir"
if [ "$#" -ge 1 ]; then
_gen_file_list_unneeded="$@"
else
_gen_file_list_unneeded=""
fi
_gen_file_list_needle_src="SRC"
_gen_file_list_needle_obj="OBJ"
_gen_file_list_needle_gcda="GCDA"
_gen_file_list_needle_gcno="GCNO"
_gen_file_list_replacement=$(find_src_files $_gen_file_list_unneeded | tr '\n' ' ')
_gen_file_list_contents=$(replace "$_gen_file_list_contents" \
"$_gen_file_list_needle_src" "$_gen_file_list_replacement")
_gen_file_list_replacement=$(replace_exts "$_gen_file_list_replacement" "c" "o")
_gen_file_list_contents=$(replace "$_gen_file_list_contents" \
"$_gen_file_list_needle_obj" "$_gen_file_list_replacement")
_gen_file_list_replacement=$(replace_exts "$_gen_file_list_replacement" "o" "gcda")
_gen_file_list_contents=$(replace "$_gen_file_list_contents" \
"$_gen_file_list_needle_gcda" "$_gen_file_list_replacement")
_gen_file_list_replacement=$(replace_exts "$_gen_file_list_replacement" "gcda" "gcno")
_gen_file_list_contents=$(replace "$_gen_file_list_contents" \
"$_gen_file_list_needle_gcno" "$_gen_file_list_replacement")
cd "$p"
printf '%s\n' "$_gen_file_list_contents"
}
gen_tests() {
_gen_tests_name="$1"
shift
_gen_tests_uname="$1"
shift
_gen_tests_extra_math="$1"
shift
_gen_tests_time_tests="$1"
shift
_gen_tests_extra_required=$(cat tests/extra_required.txt)
for _gen_tests_t in $(cat "$scriptdir/tests/$_gen_tests_name/all.txt"); do
if [ "$_gen_tests_extra_math" -eq 0 ]; then
if [ -z "${_gen_tests_extra_required##*$_gen_tests_t*}" ]; then
printf 'test_%s_%s:\n\t@printf "Skipping %s %s\\n"\n\n' \
"$_gen_tests_name" "$_gen_tests_t" "$_gen_tests_name" \
"$_gen_tests_t" >> "$scriptdir/Makefile"
continue
fi
fi
printf 'test_%s_%s:\n\t@sh tests/test.sh %s %s %s %s %s\n\n' \
"$_gen_tests_name" "$_gen_tests_t" "$_gen_tests_name" \
"$_gen_tests_t" "$generate_tests" "$time_tests" \
"$*" >> "$scriptdir/Makefile"
done
}
gen_test_targets() {
_gen_test_targets_name="$1"
shift
_gen_test_targets_tests=$(cat "$scriptdir/tests/${_gen_test_targets_name}/all.txt")
for _gen_test_targets_t in $_gen_test_targets_tests; do
printf ' test_%s_%s' "$_gen_test_targets_name" "$_gen_test_targets_t"
done
printf '\n'
}
gen_script_tests() {
_gen_script_tests_name="$1"
shift
_gen_script_tests_extra_math="$1"
shift
_gen_script_tests_generate="$1"
shift
_gen_script_tests_time="$1"
shift
_gen_script_tests_tests=$(cat "$scriptdir/tests/$_gen_script_tests_name/scripts/all.txt")
for _gen_script_tests_f in $_gen_script_tests_tests; do
_gen_script_tests_b=$(basename "$_gen_script_tests_f" ".${_gen_script_tests_name}")
printf 'test_%s_script_%s:\n\t@sh tests/script.sh %s %s %s 1 %s %s %s\n\n' \
"$_gen_script_tests_name" "$_gen_script_tests_b" "$_gen_script_tests_name" \
"$_gen_script_tests_f" "$_gen_script_tests_extra_math" "$_gen_script_tests_generate" \
"$_gen_script_tests_time" "$*" >> "$scriptdir/Makefile"
done
}
gen_script_test_targets() {
_gen_script_test_targets_name="$1"
shift
_gen_script_test_targets_tests=$(cat "$scriptdir/tests/$_gen_script_test_targets_name/scripts/all.txt")
for _gen_script_test_targets_f in $_gen_script_test_targets_tests; do
_gen_script_test_targets_b=$(basename "$_gen_script_test_targets_f" \
".$_gen_script_test_targets_name")
printf ' test_%s_script_%s' "$_gen_script_test_targets_name" \
"$_gen_script_test_targets_b"
done
printf '\n'
}
bc_only=0
dc_only=0
coverage=0
karatsuba_len=32
debug=0
hist=1
extra_math=1
optimization=""
generate_tests=1
install_manpages=1
nls=1
prompt=1
force=0
strip_bin=1
all_locales=0
library=0
fuzz=0
time_tests=0
vg=0
memcheck=0
clean=1
while getopts "abBcdDEfgGhHk:lMmNO:PStTvz-" opt; do
case "$opt" in
a) library=1 ;;
b) bc_only=1 ;;
B) dc_only=1 ;;
c) coverage=1 ;;
C) clean=0 ;;
d) dc_only=1 ;;
D) bc_only=1 ;;
E) extra_math=0 ;;
f) force=1 ;;
g) debug=1 ;;
G) generate_tests=0 ;;
h) usage ;;
H) hist=0 ;;
k) karatsuba_len="$OPTARG" ;;
l) all_locales=1 ;;
m) memcheck=1 ;;
M) install_manpages=0 ;;
N) nls=0 ;;
O) optimization="$OPTARG" ;;
P) prompt=0 ;;
t) time_tests=1 ;;
T) strip_bin=0 ;;
v) vg=1 ;;
z) fuzz=1 ;;
-)
arg="$1"
arg="${arg#--}"
LONG_OPTARG="${arg#*=}"
case $arg in
help) usage ;;
library) library=1 ;;
bc-only) bc_only=1 ;;
dc-only) dc_only=1 ;;
coverage) coverage=1 ;;
debug) debug=1 ;;
force) force=1 ;;
prefix=?*) PREFIX="$LONG_OPTARG" ;;
prefix)
if [ "$#" -lt 2 ]; then
usage "No argument given for '--$arg' option"
fi
PREFIX="$2"
shift ;;
bindir=?*) BINDIR="$LONG_OPTARG" ;;
bindir)
if [ "$#" -lt 2 ]; then
usage "No argument given for '--$arg' option"
fi
BINDIR="$2"
shift ;;
includedir=?*) INCLUDEDIR="$LONG_OPTARG" ;;
includedir)
if [ "$#" -lt 2 ]; then
usage "No argument given for '--$arg' option"
fi
INCLUDEDIR="$2"
shift ;;
libdir=?*) LIBDIR="$LONG_OPTARG" ;;
libdir)
if [ "$#" -lt 2 ]; then
usage "No argument given for '--$arg' option"
fi
LIBDIR="$2"
shift ;;
datarootdir=?*) DATAROOTDIR="$LONG_OPTARG" ;;
datarootdir)
if [ "$#" -lt 2 ]; then
usage "No argument given for '--$arg' option"
fi
DATAROOTDIR="$2"
shift ;;
datadir=?*) DATADIR="$LONG_OPTARG" ;;
datadir)
if [ "$#" -lt 2 ]; then
usage "No argument given for '--$arg' option"
fi
DATADIR="$2"
shift ;;
mandir=?*) MANDIR="$LONG_OPTARG" ;;
mandir)
if [ "$#" -lt 2 ]; then
usage "No argument given for '--$arg' option"
fi
MANDIR="$2"
shift ;;
man1dir=?*) MAN1DIR="$LONG_OPTARG" ;;
man1dir)
if [ "$#" -lt 2 ]; then
usage "No argument given for '--$arg' option"
fi
MAN1DIR="$2"
shift ;;
man3dir=?*) MAN3DIR="$LONG_OPTARG" ;;
man3dir)
if [ "$#" -lt 2 ]; then
usage "No argument given for '--$arg' option"
fi
MAN3DIR="$2"
shift ;;
localedir=?*) LOCALEDIR="$LONG_OPTARG" ;;
localedir)
if [ "$#" -lt 2 ]; then
usage "No argument given for '--$arg' option"
fi
LOCALEDIR="$2"
shift ;;
karatsuba-len=?*) karatsuba_len="$LONG_OPTARG" ;;
karatsuba-len)
if [ "$#" -lt 2 ]; then
usage "No argument given for '--$arg' option"
fi
karatsuba_len="$1"
shift ;;
opt=?*) optimization="$LONG_OPTARG" ;;
opt)
if [ "$#" -lt 2 ]; then
usage "No argument given for '--$arg' option"
fi
optimization="$1"
shift ;;
disable-bc) dc_only=1 ;;
disable-dc) bc_only=1 ;;
disable-clean) clean=0 ;;
disable-extra-math) extra_math=0 ;;
disable-generated-tests) generate_tests=0 ;;
disable-history) hist=0 ;;
disable-man-pages) install_manpages=0 ;;
disable-nls) nls=0 ;;
disable-prompt) prompt=0 ;;
disable-strip) strip_bin=0 ;;
enable-test-timing) time_tests=1 ;;
enable-valgrind) vg=1 ;;
enable-fuzz-mode) fuzz=1 ;;
enable-memcheck) memcheck=1 ;;
install-all-locales) all_locales=1 ;;
help* | bc-only* | dc-only* | coverage* | debug*)
usage "No arg allowed for --$arg option" ;;
disable-bc* | disable-dc* | disable-clean*)
usage "No arg allowed for --$arg option" ;;
disable-extra-math*)
usage "No arg allowed for --$arg option" ;;
disable-generated-tests* | disable-history*)
usage "No arg allowed for --$arg option" ;;
disable-man-pages* | disable-nls* | disable-strip*)
usage "No arg allowed for --$arg option" ;;
enable-fuzz-mode* | enable-test-timing* | enable-valgrind*)
usage "No arg allowed for --$arg option" ;;
enable-memcheck* | install-all-locales*)
usage "No arg allowed for --$arg option" ;;
'') break ;; # "--" terminates argument processing
* ) usage "Invalid option $LONG_OPTARG" ;;
esac
shift
OPTIND=1 ;;
?) usage "Invalid option $opt" ;;
esac
done
if [ "$clean" -ne 0 ]; then
if [ -f ./Makefile ]; then
make clean_config > /dev/null
fi
fi
if [ "$bc_only" -eq 1 ] && [ "$dc_only" -eq 1 ]; then
usage "Can only specify one of -b(-D) or -d(-B)"
fi
if [ "$library" -ne 0 ]; then
if [ "$bc_only" -eq 1 ] || [ "$dc_only" -eq 1 ]; then
usage "Must not specify -b(-D) or -d(-B) when building the library"
fi
fi
case $karatsuba_len in
(*[!0-9]*|'') usage "KARATSUBA_LEN is not a number" ;;
(*) ;;
esac
if [ "$karatsuba_len" -lt 16 ]; then
usage "KARATSUBA_LEN is less than 16"
fi
set -e
if [ -z "${LONG_BIT+set}" ]; then
LONG_BIT_DEFINE=""
elif [ "$LONG_BIT" -lt 32 ]; then
usage "LONG_BIT is less than 32"
else
LONG_BIT_DEFINE="-DBC_LONG_BIT=\$(BC_LONG_BIT)"
fi
if [ -z "$CC" ]; then
CC="c99"
else
ccbase=$(basename "$CC")
suffix=" *"
prefix="* "
if [ "${ccbase%%$suffix}" != "$ccbase" ]; then
ccflags="${ccbase#$prefix}"
cc="${ccbase%%$suffix}"
ccdir=$(dirname "$CC")
if [ "$ccdir" = "." ] && [ "${CC#.}" = "$CC" ]; then
ccdir=""
else
ccdir="$ccdir/"
fi
CC="${ccdir}${cc}"
CFLAGS="$CFLAGS $ccflags"
fi
fi
if [ -z "$HOSTCC" ] && [ -z "$HOST_CC" ]; then
HOSTCC="$CC"
elif [ -z "$HOSTCC" ]; then
HOSTCC="$HOST_CC"
fi
if [ "$HOSTCC" != "$CC" ]; then
ccbase=$(basename "$HOSTCC")
suffix=" *"
prefix="* "
if [ "${ccbase%%$suffix}" != "$ccbase" ]; then
ccflags="${ccbase#$prefix}"
cc="${ccbase%%$suffix}"
ccdir=$(dirname "$HOSTCC")
if [ "$ccdir" = "." ] && [ "${HOSTCC#.}" = "$HOSTCC" ]; then
ccdir=""
else
ccdir="$ccdir/"
fi
HOSTCC="${ccdir}${cc}"
HOSTCFLAGS="$HOSTCFLAGS $ccflags"
fi
fi
if [ -z "${HOSTCFLAGS+set}" ] && [ -z "${HOST_CFLAGS+set}" ]; then
HOSTCFLAGS="$CFLAGS"
elif [ -z "${HOSTCFLAGS+set}" ]; then
HOSTCFLAGS="$HOST_CFLAGS"
fi
link="@printf 'No link necessary\\\\n'"
main_exec="BC"
executable="BC_EXEC"
tests="test_bc timeconst test_dc"
bc_test="@tests/all.sh bc $extra_math 1 $generate_tests 0 \$(BC_EXEC)"
dc_test="@tests/all.sh dc $extra_math 1 $generate_tests 0 \$(DC_EXEC)"
timeconst="@tests/bc/timeconst.sh tests/bc/scripts/timeconst.bc \$(BC_EXEC)"
# In order to have cleanup at exit, we need to be in
# debug mode, so don't run valgrind without that.
if [ "$vg" -ne 0 ]; then
debug=1
bc_test_exec='valgrind $(VALGRIND_ARGS) $(BC_EXEC)'
dc_test_exec='valgrind $(VALGRIND_ARGS) $(DC_EXEC)'
else
bc_test_exec='$(BC_EXEC)'
dc_test_exec='$(DC_EXEC)'
fi
karatsuba="@printf 'karatsuba cannot be run because one of bc or dc is not built\\\\n'"
karatsuba_test="@printf 'karatsuba cannot be run because one of bc or dc is not built\\\\n'"
bc_lib="\$(GEN_DIR)/lib.o"
bc_help="\$(GEN_DIR)/bc_help.o"
dc_help="\$(GEN_DIR)/dc_help.o"
default_target_prereqs="\$(BIN) \$(OBJS)"
default_target_cmd="\$(CC) \$(CFLAGS) \$(OBJS) \$(LDFLAGS) -o \$(EXEC)"
default_target="\$(DC_EXEC)"
second_target_prereqs=""
second_target_cmd="$default_target_cmd"
second_target="\$(BC_EXEC)"
if [ "$library" -ne 0 ]; then
extra_math=1
nls=0
hist=0
prompt=0
bc=1
dc=1
default_target_prereqs="\$(BIN) \$(OBJ)"
default_target_cmd="ar -r -cu \$(LIBBC) \$(OBJ)"
default_target="\$(LIBBC)"
tests="test_library"
elif [ "$bc_only" -eq 1 ]; then
bc=1
dc=0
dc_help=""
executables="bc"
dc_test="@printf 'No dc tests to run\\\\n'"
install_prereqs=" install_execs"
install_man_prereqs=" install_bc_manpage"
uninstall_prereqs=" uninstall_bc"
uninstall_man_prereqs=" uninstall_bc_manpage"
default_target="\$(BC_EXEC)"
second_target="\$(DC_EXEC)"
tests="test_bc timeconst"
elif [ "$dc_only" -eq 1 ]; then
bc=0
dc=1
bc_lib=""
bc_help=""
executables="dc"
main_exec="DC"
executable="DC_EXEC"
bc_test="@printf 'No bc tests to run\\\\n'"
timeconst="@printf 'timeconst cannot be run because bc is not built\\\\n'"
install_prereqs=" install_execs"
install_man_prereqs=" install_dc_manpage"
uninstall_prereqs=" uninstall_dc"
uninstall_man_prereqs=" uninstall_dc_manpage"
tests="test_dc"
else
bc=1
dc=1
executables="bc and dc"
karatsuba="@\$(KARATSUBA) 30 0 \$(BC_EXEC)"
karatsuba_test="@\$(KARATSUBA) 1 100 \$(BC_EXEC)"
if [ "$library" -eq 0 ]; then
install_prereqs=" install_execs"
install_man_prereqs=" install_bc_manpage install_dc_manpage"
uninstall_prereqs=" uninstall_bc uninstall_dc"
uninstall_man_prereqs=" uninstall_bc_manpage uninstall_dc_manpage"
else
install_prereqs=" install_library install_bcl_header"
install_man_prereqs=" install_bcl_manpage"
uninstall_prereqs=" uninstall_library uninstall_bcl_header"
uninstall_man_prereqs=" uninstall_bcl_manpage"
tests="test_library"
fi
second_target_prereqs="$default_target_prereqs"
default_target_prereqs="$second_target"
default_target_cmd="\$(LINK) \$(BIN) \$(EXEC_PREFIX)\$(DC)"
fi
if [ "$fuzz" -ne 0 ]; then
debug=1
hist=0
prompt=0
nls=0
optimization="3"
fi
if [ "$debug" -eq 1 ]; then
if [ -z "$CFLAGS" ] && [ -z "$optimization" ]; then
CFLAGS="-O0"
fi
CFLAGS="-g $CFLAGS"
else
CPPFLAGS="-DNDEBUG $CPPFLAGS"
if [ "$strip_bin" -ne 0 ]; then
LDFLAGS="-s $LDFLAGS"
fi
fi
if [ -n "$optimization" ]; then
CFLAGS="-O$optimization $CFLAGS"
fi
if [ "$coverage" -eq 1 ]; then
if [ "$bc_only" -eq 1 ] || [ "$dc_only" -eq 1 ]; then
usage "Can only specify -c without -b or -d"
fi
CFLAGS="-fprofile-arcs -ftest-coverage -g -O0 $CFLAGS"
CPPFLAGS="-DNDEBUG $CPPFLAGS"
COVERAGE_OUTPUT="@gcov -pabcdf \$(GCDA) \$(BC_GCDA) \$(DC_GCDA) \$(HISTORY_GCDA) \$(RAND_GCDA)"
COVERAGE_OUTPUT="$COVERAGE_OUTPUT;\$(RM) -f \$(GEN)*.gc*"
COVERAGE_OUTPUT="$COVERAGE_OUTPUT;gcovr --html-details --output index.html"
COVERAGE_PREREQS=" test coverage_output"
else
COVERAGE_OUTPUT="@printf 'Coverage not generated\\\\n'"
COVERAGE_PREREQS=""
fi
if [ -z "${DESTDIR+set}" ]; then
destdir=""
else
destdir="DESTDIR = $DESTDIR"
fi
if [ -z "${PREFIX+set}" ]; then
PREFIX="/usr/local"
fi
if [ -z "${BINDIR+set}" ]; then
BINDIR="$PREFIX/bin"
fi
if [ -z "${INCLUDEDIR+set}" ]; then
INCLUDEDIR="$PREFIX/include"
fi
if [ -z "${LIBDIR+set}" ]; then
LIBDIR="$PREFIX/lib"
fi
if [ "$install_manpages" -ne 0 ] || [ "$nls" -ne 0 ]; then
if [ -z "${DATAROOTDIR+set}" ]; then
DATAROOTDIR="$PREFIX/share"
fi
fi
if [ "$install_manpages" -ne 0 ]; then
if [ -z "${DATADIR+set}" ]; then
DATADIR="$DATAROOTDIR"
fi
if [ -z "${MANDIR+set}" ]; then
MANDIR="$DATADIR/man"
fi
if [ -z "${MAN1DIR+set}" ]; then
MAN1DIR="$MANDIR/man1"
fi
if [ -z "${MAN3DIR+set}" ]; then
MAN3DIR="$MANDIR/man3"
fi
else
install_man_prereqs=""
uninstall_man_prereqs=""
fi
if [ "$nls" -ne 0 ]; then
set +e
printf 'Testing NLS...\n'
flags="-DBC_ENABLE_NLS=1 -DBC_ENABLED=$bc -DDC_ENABLED=$dc"
flags="$flags -DBC_ENABLE_HISTORY=$hist"
flags="$flags -DBC_ENABLE_EXTRA_MATH=$extra_math -I./include/"
flags="$flags -D_POSIX_C_SOURCE=200809L -D_XOPEN_SOURCE=700"
"$CC" $CPPFLAGS $CFLAGS $flags -c "src/vm.c" -o "$scriptdir/vm.o" > /dev/null 2>&1
err="$?"
rm -rf "$scriptdir/vm.o"
# If this errors, it is probably because of building on Windows,
# and NLS is not supported on Windows, so disable it.
if [ "$err" -ne 0 ]; then
printf 'NLS does not work.\n'
if [ $force -eq 0 ]; then
printf 'Disabling NLS...\n\n'
nls=0
else
printf 'Forcing NLS...\n\n'
fi
else
printf 'NLS works.\n\n'
printf 'Testing gencat...\n'
gencat "$scriptdir/en_US.cat" "$scriptdir/locales/en_US.msg" > /dev/null 2>&1
err="$?"
rm -rf "$scriptdir/en_US.cat"
if [ "$err" -ne 0 ]; then
printf 'gencat does not work.\n'
if [ $force -eq 0 ]; then
printf 'Disabling NLS...\n\n'
nls=0
else
printf 'Forcing NLS...\n\n'
fi
else
printf 'gencat works.\n\n'
if [ "$HOSTCC" != "$CC" ]; then
printf 'Cross-compile detected.\n\n'
printf 'WARNING: Catalog files generated with gencat may not be portable\n'
printf ' across different architectures.\n\n'
fi
if [ -z "$NLSPATH" ]; then
NLSPATH="/usr/share/locale/%L/%N"
fi
install_locales_prereqs=" install_locales"
uninstall_locales_prereqs=" uninstall_locales"
fi
fi
set -e
else
install_locales_prereqs=""
uninstall_locales_prereqs=""
all_locales=0
fi
if [ "$nls" -ne 0 ] && [ "$all_locales" -ne 0 ]; then
install_locales="\$(LOCALE_INSTALL) -l \$(NLSPATH) \$(MAIN_EXEC) \$(DESTDIR)"
else
install_locales="\$(LOCALE_INSTALL) \$(NLSPATH) \$(MAIN_EXEC) \$(DESTDIR)"
fi
if [ "$hist" -eq 1 ]; then
set +e
printf 'Testing history...\n'
flags="-DBC_ENABLE_HISTORY=1 -DBC_ENABLED=$bc -DDC_ENABLED=$dc"
flags="$flags -DBC_ENABLE_NLS=$nls -DBC_ENABLE_LIBRARY=0"
flags="$flags -DBC_ENABLE_EXTRA_MATH=$extra_math -I./include/"
flags="$flags -D_POSIX_C_SOURCE=200809L -D_XOPEN_SOURCE=700"
"$CC" $CPPFLAGS $CFLAGS $flags -c "src/history.c" -o "$scriptdir/history.o" > /dev/null 2>&1
err="$?"
rm -rf "$scriptdir/history.o"
# If this errors, it is probably because of building on Windows,
# and history is not supported on Windows, so disable it.
if [ "$err" -ne 0 ]; then
printf 'History does not work.\n'
if [ $force -eq 0 ]; then
printf 'Disabling history...\n\n'
hist=0
else
printf 'Forcing history...\n\n'
fi
else
printf 'History works.\n\n'
fi
set -e
fi
if [ "$library" -eq 1 ]; then
bc_lib=""
fi
if [ "$extra_math" -eq 1 ] && [ "$bc" -ne 0 ] && [ "$library" -eq 0 ]; then
BC_LIB2_O="\$(GEN_DIR)/lib2.o"
else
BC_LIB2_O=""
fi
GEN="strgen"
GEN_EXEC_TARGET="\$(HOSTCC) \$(HOSTCFLAGS) -o \$(GEN_EXEC) \$(GEN_C)"
CLEAN_PREREQS=" clean_gen"
if [ -z "${GEN_HOST+set}" ]; then
GEN_HOST=1
else
if [ "$GEN_HOST" -eq 0 ]; then
GEN="strgen.sh"
GEN_EXEC_TARGET="@printf 'Do not need to build gen/strgen.c\\\\n'"
CLEAN_PREREQS=""
fi
fi
manpage_args=""
unneeded=""
headers="\$(HEADERS)"
if [ "$extra_math" -eq 0 ]; then
manpage_args="E"
unneeded="$unneeded rand.c"
else
headers="$headers \$(EXTRA_MATH_HEADERS)"
fi
if [ "$hist" -eq 0 ]; then
manpage_args="${manpage_args}H"
unneeded="$unneeded history.c"
else
headers="$headers \$(HISTORY_HEADERS)"
fi
if [ "$nls" -eq 0 ]; then
manpage_args="${manpage_args}N"
fi
if [ "$prompt" -eq 0 ]; then
manpage_args="${manpage_args}P"
fi
if [ "$bc" -eq 0 ]; then
unneeded="$unneeded bc.c bc_lex.c bc_parse.c"
else
headers="$headers \$(BC_HEADERS)"
fi
if [ "$dc" -eq 0 ]; then
unneeded="$unneeded dc.c dc_lex.c dc_parse.c"
else
headers="$headers \$(DC_HEADERS)"
fi
if [ "$library" -ne 0 ]; then
unneeded="$unneeded args.c opt.c read.c file.c main.c"
unneeded="$unneeded lang.c lex.c parse.c program.c"
unneeded="$unneeded bc.c bc_lex.c bc_parse.c"
unneeded="$unneeded dc.c dc_lex.c dc_parse.c"
headers="$headers \$(LIBRARY_HEADERS)"
else
unneeded="$unneeded library.c"
fi
if [ "$manpage_args" = "" ]; then
manpage_args="A"
fi
if [ "$vg" -ne 0 ]; then
memcheck=1
fi
bc_tests=$(gen_test_targets bc)
bc_script_tests=$(gen_script_test_targets bc)
dc_tests=$(gen_test_targets dc)
dc_script_tests=$(gen_script_test_targets dc)
# Print out the values; this is for debugging.
if [ "$bc" -ne 0 ]; then
printf 'Building bc\n'
else
printf 'Not building bc\n'
fi
if [ "$dc" -ne 0 ]; then
printf 'Building dc\n'
else
printf 'Not building dc\n'
fi
printf '\n'
printf 'BC_ENABLE_LIBRARY=%s\n\n' "$library"
printf 'BC_ENABLE_HISTORY=%s\n' "$hist"
printf 'BC_ENABLE_EXTRA_MATH=%s\n' "$extra_math"
printf 'BC_ENABLE_NLS=%s\n' "$nls"
printf 'BC_ENABLE_PROMPT=%s\n' "$prompt"
printf 'BC_ENABLE_AFL=%s\n' "$fuzz"
printf '\n'
printf 'BC_NUM_KARATSUBA_LEN=%s\n' "$karatsuba_len"
printf '\n'
printf 'CC=%s\n' "$CC"
printf 'CFLAGS=%s\n' "$CFLAGS"
printf 'HOSTCC=%s\n' "$HOSTCC"
printf 'HOSTCFLAGS=%s\n' "$HOSTCFLAGS"
printf 'CPPFLAGS=%s\n' "$CPPFLAGS"
printf 'LDFLAGS=%s\n' "$LDFLAGS"
printf 'PREFIX=%s\n' "$PREFIX"
printf 'BINDIR=%s\n' "$BINDIR"
printf 'INCLUDEDIR=%s\n' "$INCLUDEDIR"
printf 'LIBDIR=%s\n' "$LIBDIR"
printf 'DATAROOTDIR=%s\n' "$DATAROOTDIR"
printf 'DATADIR=%s\n' "$DATADIR"
printf 'MANDIR=%s\n' "$MANDIR"
printf 'MAN1DIR=%s\n' "$MAN1DIR"
printf 'MAN3DIR=%s\n' "$MAN3DIR"
printf 'NLSPATH=%s\n' "$NLSPATH"
printf 'EXECSUFFIX=%s\n' "$EXECSUFFIX"
printf 'EXECPREFIX=%s\n' "$EXECPREFIX"
printf 'DESTDIR=%s\n' "$DESTDIR"
printf 'LONG_BIT=%s\n' "$LONG_BIT"
printf 'GEN_HOST=%s\n' "$GEN_HOST"
printf 'GEN_EMU=%s\n' "$GEN_EMU"
contents=$(cat "$scriptdir/Makefile.in")
needle="WARNING"
replacement='*** WARNING: Autogenerated from Makefile.in. DO NOT MODIFY ***'
contents=$(replace "$contents" "$needle" "$replacement")
if [ "$unneeded" = "" ]; then
unneeded="library.c"
fi
contents=$(gen_file_list "$contents" $unneeded)
SRC_TARGETS=""
src_files=$(find_src_files $unneeded)
-temp_ifs="$IFS"
-IFS=$'\n'
-
for f in $src_files; do
o=$(replace_ext "$f" "c" "o")
SRC_TARGETS=$(printf '%s\n\n%s: %s %s\n\t$(CC) $(CFLAGS) -o %s -c %s\n' \
"$SRC_TARGETS" "$o" "$headers" "$f" "$o" "$f")
done
-IFS="$temp_ifs"
-
contents=$(replace "$contents" "HEADERS" "$headers")
contents=$(replace "$contents" "BC_ENABLED" "$bc")
contents=$(replace "$contents" "DC_ENABLED" "$dc")
contents=$(replace "$contents" "BC_ALL_TESTS" "$bc_test")
contents=$(replace "$contents" "BC_TESTS" "$bc_tests")
contents=$(replace "$contents" "BC_SCRIPT_TESTS" "$bc_script_tests")
contents=$(replace "$contents" "BC_TEST_EXEC" "$bc_test_exec")
contents=$(replace "$contents" "TIMECONST_ALL_TESTS" "$timeconst")
contents=$(replace "$contents" "DC_ALL_TESTS" "$dc_test")
contents=$(replace "$contents" "DC_TESTS" "$dc_tests")
contents=$(replace "$contents" "DC_SCRIPT_TESTS" "$dc_script_tests")
contents=$(replace "$contents" "DC_TEST_EXEC" "$dc_test_exec")
contents=$(replace "$contents" "LIBRARY" "$library")
contents=$(replace "$contents" "HISTORY" "$hist")
contents=$(replace "$contents" "EXTRA_MATH" "$extra_math")
contents=$(replace "$contents" "NLS" "$nls")
contents=$(replace "$contents" "PROMPT" "$prompt")
contents=$(replace "$contents" "FUZZ" "$fuzz")
contents=$(replace "$contents" "MEMCHECK" "$memcheck")
contents=$(replace "$contents" "BC_LIB_O" "$bc_lib")
contents=$(replace "$contents" "BC_HELP_O" "$bc_help")
contents=$(replace "$contents" "DC_HELP_O" "$dc_help")
contents=$(replace "$contents" "BC_LIB2_O" "$BC_LIB2_O")
contents=$(replace "$contents" "KARATSUBA_LEN" "$karatsuba_len")
contents=$(replace "$contents" "NLSPATH" "$NLSPATH")
contents=$(replace "$contents" "DESTDIR" "$destdir")
contents=$(replace "$contents" "EXECSUFFIX" "$EXECSUFFIX")
contents=$(replace "$contents" "EXECPREFIX" "$EXECPREFIX")
contents=$(replace "$contents" "BINDIR" "$BINDIR")
contents=$(replace "$contents" "INCLUDEDIR" "$INCLUDEDIR")
contents=$(replace "$contents" "LIBDIR" "$LIBDIR")
contents=$(replace "$contents" "MAN1DIR" "$MAN1DIR")
contents=$(replace "$contents" "MAN3DIR" "$MAN3DIR")
contents=$(replace "$contents" "CFLAGS" "$CFLAGS")
contents=$(replace "$contents" "HOSTCFLAGS" "$HOSTCFLAGS")
contents=$(replace "$contents" "CPPFLAGS" "$CPPFLAGS")
contents=$(replace "$contents" "LDFLAGS" "$LDFLAGS")
contents=$(replace "$contents" "CC" "$CC")
contents=$(replace "$contents" "HOSTCC" "$HOSTCC")
contents=$(replace "$contents" "COVERAGE_OUTPUT" "$COVERAGE_OUTPUT")
contents=$(replace "$contents" "COVERAGE_PREREQS" "$COVERAGE_PREREQS")
contents=$(replace "$contents" "INSTALL_PREREQS" "$install_prereqs")
contents=$(replace "$contents" "INSTALL_MAN_PREREQS" "$install_man_prereqs")
contents=$(replace "$contents" "INSTALL_LOCALES" "$install_locales")
contents=$(replace "$contents" "INSTALL_LOCALES_PREREQS" "$install_locales_prereqs")
contents=$(replace "$contents" "UNINSTALL_MAN_PREREQS" "$uninstall_man_prereqs")
contents=$(replace "$contents" "UNINSTALL_PREREQS" "$uninstall_prereqs")
contents=$(replace "$contents" "UNINSTALL_LOCALES_PREREQS" "$uninstall_locales_prereqs")
contents=$(replace "$contents" "DEFAULT_TARGET" "$default_target")
contents=$(replace "$contents" "DEFAULT_TARGET_PREREQS" "$default_target_prereqs")
contents=$(replace "$contents" "DEFAULT_TARGET_CMD" "$default_target_cmd")
contents=$(replace "$contents" "SECOND_TARGET" "$second_target")
contents=$(replace "$contents" "SECOND_TARGET_PREREQS" "$second_target_prereqs")
contents=$(replace "$contents" "SECOND_TARGET_CMD" "$second_target_cmd")
contents=$(replace "$contents" "ALL_PREREQ" "$ALL_PREREQ")
contents=$(replace "$contents" "BC_EXEC_PREREQ" "$bc_exec_prereq")
contents=$(replace "$contents" "BC_EXEC_CMD" "$bc_exec_cmd")
contents=$(replace "$contents" "DC_EXEC_PREREQ" "$dc_exec_prereq")
contents=$(replace "$contents" "DC_EXEC_CMD" "$dc_exec_cmd")
contents=$(replace "$contents" "EXECUTABLES" "$executables")
contents=$(replace "$contents" "MAIN_EXEC" "$main_exec")
contents=$(replace "$contents" "EXEC" "$executable")
contents=$(replace "$contents" "TESTS" "$tests")
contents=$(replace "$contents" "BC_TEST" "$bc_test")
contents=$(replace "$contents" "DC_TEST" "$dc_test")
contents=$(replace "$contents" "VG_BC_TEST" "$vg_bc_test")
contents=$(replace "$contents" "VG_DC_TEST" "$vg_dc_test")
contents=$(replace "$contents" "TIMECONST" "$timeconst")
contents=$(replace "$contents" "KARATSUBA" "$karatsuba")
contents=$(replace "$contents" "KARATSUBA_TEST" "$karatsuba_test")
contents=$(replace "$contents" "LONG_BIT" "$LONG_BIT")
contents=$(replace "$contents" "LONG_BIT_DEFINE" "$LONG_BIT_DEFINE")
contents=$(replace "$contents" "GEN" "$GEN")
contents=$(replace "$contents" "GEN_EXEC_TARGET" "$GEN_EXEC_TARGET")
contents=$(replace "$contents" "CLEAN_PREREQS" "$CLEAN_PREREQS")
contents=$(replace "$contents" "GEN_EMU" "$GEN_EMU")
printf '%s\n%s\n\n' "$contents" "$SRC_TARGETS" > "$scriptdir/Makefile"
if [ "$bc" -ne 0 ]; then
gen_tests bc BC "$extra_math" "$time_tests" $bc_test_exec
gen_script_tests bc "$extra_math" "$generate_tests" "$time_tests" $bc_test_exec
fi
if [ "$dc" -ne 0 ]; then
gen_tests dc DC "$extra_math" "$time_tests" $dc_test_exec
gen_script_tests dc "$extra_math" "$generate_tests" "$time_tests" $dc_test_exec
fi
cd "$scriptdir"
cp -f manuals/bc/$manpage_args.1.md manuals/bc.1.md
cp -f manuals/bc/$manpage_args.1 manuals/bc.1
cp -f manuals/dc/$manpage_args.1.md manuals/dc.1.md
cp -f manuals/dc/$manpage_args.1 manuals/dc.1
make clean > /dev/null
diff --git a/contrib/bc/include/args.h b/contrib/bc/include/args.h
index 6b68ed300440..d53785067237 100644
--- a/contrib/bc/include/args.h
+++ b/contrib/bc/include/args.h
@@ -1,46 +1,46 @@
/*
* *****************************************************************************
*
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (c) 2018-2021 Gavin D. Howard and contributors.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* *****************************************************************************
*
* Definitions for processing command-line arguments.
*
*/
#ifndef BC_ARGS_H
#define BC_ARGS_H
#include <status.h>
#include <vm.h>
-void bc_args(int argc, char *argv[]);
+void bc_args(int argc, char *argv[], bool exit_exprs);
extern const char* const bc_args_env_name;
#endif // BC_ARGS_H
diff --git a/contrib/bc/include/status.h b/contrib/bc/include/status.h
index 3fa844485690..cf41a3ce4670 100644
--- a/contrib/bc/include/status.h
+++ b/contrib/bc/include/status.h
@@ -1,208 +1,212 @@
/*
* *****************************************************************************
*
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (c) 2018-2021 Gavin D. Howard and contributors.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* *****************************************************************************
*
* All bc status codes.
*
*/
#ifndef BC_STATUS_H
#define BC_STATUS_H
#include <stdint.h>
#ifndef BC_ENABLED
#define BC_ENABLED (1)
#endif // BC_ENABLED
#ifndef DC_ENABLED
#define DC_ENABLED (1)
#endif // DC_ENABLED
#if BC_ENABLE_AFL
#ifndef __AFL_HAVE_MANUAL_CONTROL
#error Must compile with afl-clang-fast for fuzzing
#endif // __AFL_HAVE_MANUAL_CONTROL
#endif // BC_ENABLE_AFL
#ifndef BC_ENABLE_MEMCHECK
#define BC_ENABLE_MEMCHECK (0)
#endif // BC_ENABLE_MEMCHECK
#include <bcl.h>
typedef enum BcStatus {
BC_STATUS_SUCCESS = 0,
BC_STATUS_ERROR_MATH,
BC_STATUS_ERROR_PARSE,
BC_STATUS_ERROR_EXEC,
BC_STATUS_ERROR_FATAL,
BC_STATUS_EOF,
BC_STATUS_QUIT,
} BcStatus;
typedef enum BcErr {
BC_ERR_MATH_NEGATIVE,
BC_ERR_MATH_NON_INTEGER,
BC_ERR_MATH_OVERFLOW,
BC_ERR_MATH_DIVIDE_BY_ZERO,
BC_ERR_FATAL_ALLOC_ERR,
BC_ERR_FATAL_IO_ERR,
BC_ERR_FATAL_FILE_ERR,
BC_ERR_FATAL_BIN_FILE,
BC_ERR_FATAL_PATH_DIR,
BC_ERR_FATAL_OPTION,
BC_ERR_FATAL_OPTION_NO_ARG,
BC_ERR_FATAL_OPTION_ARG,
BC_ERR_EXEC_IBASE,
BC_ERR_EXEC_OBASE,
BC_ERR_EXEC_SCALE,
BC_ERR_EXEC_READ_EXPR,
BC_ERR_EXEC_REC_READ,
BC_ERR_EXEC_TYPE,
BC_ERR_EXEC_STACK,
BC_ERR_EXEC_PARAMS,
BC_ERR_EXEC_UNDEF_FUNC,
BC_ERR_EXEC_VOID_VAL,
BC_ERR_PARSE_EOF,
BC_ERR_PARSE_CHAR,
BC_ERR_PARSE_STRING,
BC_ERR_PARSE_COMMENT,
BC_ERR_PARSE_TOKEN,
#if BC_ENABLED
BC_ERR_PARSE_EXPR,
BC_ERR_PARSE_EMPTY_EXPR,
BC_ERR_PARSE_PRINT,
BC_ERR_PARSE_FUNC,
BC_ERR_PARSE_ASSIGN,
BC_ERR_PARSE_NO_AUTO,
BC_ERR_PARSE_DUP_LOCAL,
BC_ERR_PARSE_BLOCK,
BC_ERR_PARSE_RET_VOID,
BC_ERR_PARSE_REF_VAR,
BC_ERR_POSIX_NAME_LEN,
BC_ERR_POSIX_COMMENT,
BC_ERR_POSIX_KW,
BC_ERR_POSIX_DOT,
BC_ERR_POSIX_RET,
BC_ERR_POSIX_BOOL,
BC_ERR_POSIX_REL_POS,
BC_ERR_POSIX_MULTIREL,
BC_ERR_POSIX_FOR,
BC_ERR_POSIX_EXP_NUM,
BC_ERR_POSIX_REF,
BC_ERR_POSIX_VOID,
BC_ERR_POSIX_BRACE,
#endif // BC_ENABLED
BC_ERR_NELEMS,
#if BC_ENABLED
BC_ERR_POSIX_START = BC_ERR_POSIX_NAME_LEN,
BC_ERR_POSIX_END = BC_ERR_POSIX_BRACE,
#endif // BC_ENABLED
} BcErr;
#define BC_ERR_IDX_MATH (0)
#define BC_ERR_IDX_PARSE (1)
#define BC_ERR_IDX_EXEC (2)
#define BC_ERR_IDX_FATAL (3)
#define BC_ERR_IDX_NELEMS (4)
#if BC_ENABLED
#define BC_ERR_IDX_WARN (BC_ERR_IDX_NELEMS)
#endif // BC_ENABLED
#define BC_UNUSED(e) ((void) (e))
#ifndef BC_LIKELY
#define BC_LIKELY(e) (e)
#endif // BC_LIKELY
#ifndef BC_UNLIKELY
#define BC_UNLIKELY(e) (e)
#endif // BC_UNLIKELY
#define BC_ERR(e) BC_UNLIKELY(e)
#define BC_NO_ERR(s) BC_LIKELY(s)
#ifndef BC_DEBUG_CODE
#define BC_DEBUG_CODE (0)
#endif // BC_DEBUG_CODE
#if __STDC_VERSION__ >= 201100L
#include <stdnoreturn.h>
#define BC_NORETURN _Noreturn
#else // __STDC_VERSION__
#define BC_NORETURN
#define BC_MUST_RETURN
#endif // __STDC_VERSION__
#if defined(__clang__) || defined(__GNUC__)
-#if defined(__has_attribute) && __has_attribute(fallthrough)
+#if defined(__has_attribute)
+#if __has_attribute(fallthrough)
#define BC_FALLTHROUGH __attribute__((fallthrough));
-#else // defined(__has_attribute) && __has_attribute(fallthrough)
+#else // __has_attribute(fallthrough)
#define BC_FALLTHROUGH
-#endif // defined(__has_attribute) && __has_attribute(fallthrough)
+#endif // __has_attribute(fallthrough)
+#else // defined(__has_attribute)
+#define BC_FALLTHROUGH
+#endif // defined(__has_attribute)
#else // defined(__clang__) || defined(__GNUC__)
#define BC_FALLTHROUGH
#endif // defined(__clang__) || defined(__GNUC__)
// Workarounds for AIX's POSIX incompatibility.
#ifndef SIZE_MAX
#define SIZE_MAX __SIZE_MAX__
#endif // SIZE_MAX
#ifndef UINTMAX_C
#define UINTMAX_C __UINTMAX_C
#endif // UINTMAX_C
#ifndef UINT32_C
#define UINT32_C __UINT32_C
#endif // UINT32_C
#ifndef UINT_FAST32_MAX
#define UINT_FAST32_MAX __UINT_FAST32_MAX__
#endif // UINT_FAST32_MAX
#ifndef UINT16_MAX
#define UINT16_MAX __UINT16_MAX__
#endif // UINT16_MAX
#ifndef SIG_ATOMIC_MAX
#define SIG_ATOMIC_MAX __SIG_ATOMIC_MAX__
#endif // SIG_ATOMIC_MAX
#endif // BC_STATUS_H
diff --git a/contrib/bc/include/vm.h b/contrib/bc/include/vm.h
index 8b0babff4d81..80a060edd42f 100644
--- a/contrib/bc/include/vm.h
+++ b/contrib/bc/include/vm.h
@@ -1,460 +1,461 @@
/*
* *****************************************************************************
*
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (c) 2018-2021 Gavin D. Howard and contributors.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* *****************************************************************************
*
* Definitions for bc's VM.
*
*/
#ifndef BC_VM_H
#define BC_VM_H
#include <assert.h>
#include <stddef.h>
#include <limits.h>
#include <signal.h>
#if BC_ENABLE_NLS
# ifdef _WIN32
# error NLS is not supported on Windows.
# endif // _WIN32
#include <nl_types.h>
#endif // BC_ENABLE_NLS
#include <status.h>
#include <num.h>
#include <parse.h>
#include <program.h>
#include <history.h>
#if !BC_ENABLE_LIBRARY
#include <file.h>
#endif // !BC_ENABLE_LIBRARY
#if !BC_ENABLED && !DC_ENABLED
#error Must define BC_ENABLED, DC_ENABLED, or both
#endif
// CHAR_BIT must be at least 6.
#if CHAR_BIT < 6
#error CHAR_BIT must be at least 6.
#endif
#ifndef BC_ENABLE_NLS
#define BC_ENABLE_NLS (0)
#endif // BC_ENABLE_NLS
#ifndef MAINEXEC
#define MAINEXEC bc
#endif
#ifndef EXECPREFIX
#define EXECPREFIX
#endif
#define GEN_STR(V) #V
#define GEN_STR2(V) GEN_STR(V)
#define BC_VERSION GEN_STR2(VERSION)
#define BC_EXECPREFIX GEN_STR2(EXECPREFIX)
#define BC_MAINEXEC GEN_STR2(MAINEXEC)
// Windows has deprecated isatty().
#ifdef _WIN32
#define isatty _isatty
#endif // _WIN32
#if !BC_ENABLE_LIBRARY
#if DC_ENABLED
#define DC_FLAG_X (UINTMAX_C(1)<<0)
#endif // DC_ENABLED
#if BC_ENABLED
#define BC_FLAG_W (UINTMAX_C(1)<<1)
#define BC_FLAG_S (UINTMAX_C(1)<<2)
#define BC_FLAG_L (UINTMAX_C(1)<<3)
#define BC_FLAG_G (UINTMAX_C(1)<<4)
#endif // BC_ENABLED
#define BC_FLAG_I (UINTMAX_C(1)<<5)
#define BC_FLAG_P (UINTMAX_C(1)<<6)
#define BC_FLAG_TTYIN (UINTMAX_C(1)<<7)
#define BC_FLAG_TTY (UINTMAX_C(1)<<8)
#define BC_TTYIN (vm.flags & BC_FLAG_TTYIN)
#define BC_TTY (vm.flags & BC_FLAG_TTY)
#if BC_ENABLED
#define BC_S (vm.flags & BC_FLAG_S)
#define BC_W (vm.flags & BC_FLAG_W)
#define BC_L (vm.flags & BC_FLAG_L)
#define BC_G (vm.flags & BC_FLAG_G)
#endif // BC_ENABLED
#if DC_ENABLED
#define DC_X (vm.flags & DC_FLAG_X)
#endif // DC_ENABLED
#define BC_I (vm.flags & BC_FLAG_I)
#define BC_P (vm.flags & BC_FLAG_P)
#if BC_ENABLED
#define BC_IS_POSIX (BC_S || BC_W)
#if DC_ENABLED
#define BC_IS_BC (vm.name[0] != 'd')
#define BC_IS_DC (vm.name[0] == 'd')
#else // DC_ENABLED
#define BC_IS_BC (1)
#define BC_IS_DC (0)
#endif // DC_ENABLED
#else // BC_ENABLED
#define BC_IS_POSIX (0)
#define BC_IS_BC (0)
#define BC_IS_DC (1)
#endif // BC_ENABLED
#if BC_ENABLED
#define BC_USE_PROMPT (!BC_P && BC_TTY && !BC_IS_POSIX)
#else // BC_ENABLED
#define BC_USE_PROMPT (!BC_P && BC_TTY)
#endif // BC_ENABLED
#endif // !BC_ENABLE_LIBRARY
#define BC_MAX(a, b) ((a) > (b) ? (a) : (b))
#define BC_MIN(a, b) ((a) < (b) ? (a) : (b))
#define BC_MAX_OBASE ((BcBigDig) (BC_BASE_POW))
#define BC_MAX_DIM ((BcBigDig) (SIZE_MAX - 1))
#define BC_MAX_SCALE ((BcBigDig) (BC_NUM_BIGDIG_MAX - 1))
#define BC_MAX_STRING ((BcBigDig) (BC_NUM_BIGDIG_MAX - 1))
#define BC_MAX_NAME BC_MAX_STRING
#define BC_MAX_NUM BC_MAX_SCALE
#if BC_ENABLE_EXTRA_MATH
#define BC_MAX_RAND ((BcBigDig) (((BcRand) 0) - 1))
#endif // BC_ENABLE_EXTRA_MATH
#define BC_MAX_EXP ((ulong) (BC_NUM_BIGDIG_MAX))
#define BC_MAX_VARS ((ulong) (SIZE_MAX - 1))
#if BC_DEBUG_CODE
#define BC_VM_JMP bc_vm_jmp(__func__)
#else // BC_DEBUG_CODE
#define BC_VM_JMP bc_vm_jmp()
#endif // BC_DEBUG_CODE
#define BC_SIG_EXC \
BC_UNLIKELY(vm.status != (sig_atomic_t) BC_STATUS_SUCCESS || vm.sig)
#define BC_NO_SIG_EXC \
BC_LIKELY(vm.status == (sig_atomic_t) BC_STATUS_SUCCESS && !vm.sig)
#ifndef NDEBUG
#define BC_SIG_ASSERT_LOCKED do { assert(vm.sig_lock); } while (0)
#define BC_SIG_ASSERT_NOT_LOCKED do { assert(vm.sig_lock == 0); } while (0)
#else // NDEBUG
#define BC_SIG_ASSERT_LOCKED
#define BC_SIG_ASSERT_NOT_LOCKED
#endif // NDEBUG
#define BC_SIG_LOCK \
do { \
BC_SIG_ASSERT_NOT_LOCKED; \
vm.sig_lock = 1; \
} while (0)
#define BC_SIG_UNLOCK \
do { \
BC_SIG_ASSERT_LOCKED; \
vm.sig_lock = 0; \
if (BC_SIG_EXC) BC_VM_JMP; \
} while (0)
#define BC_SIG_MAYLOCK \
do { \
vm.sig_lock = 1; \
} while (0)
#define BC_SIG_MAYUNLOCK \
do { \
vm.sig_lock = 0; \
if (BC_SIG_EXC) BC_VM_JMP; \
} while (0)
#define BC_SIG_TRYLOCK(v) \
do { \
v = vm.sig_lock; \
vm.sig_lock = 1; \
} while (0)
#define BC_SIG_TRYUNLOCK(v) \
do { \
vm.sig_lock = (v); \
if (!(v) && BC_SIG_EXC) BC_VM_JMP; \
} while (0)
#define BC_SETJMP(l) \
do { \
sigjmp_buf sjb; \
BC_SIG_LOCK; \
if (sigsetjmp(sjb, 0)) { \
assert(BC_SIG_EXC); \
goto l; \
} \
bc_vec_push(&vm.jmp_bufs, &sjb); \
BC_SIG_UNLOCK; \
} while (0)
#define BC_SETJMP_LOCKED(l) \
do { \
sigjmp_buf sjb; \
BC_SIG_ASSERT_LOCKED; \
if (sigsetjmp(sjb, 0)) { \
assert(BC_SIG_EXC); \
goto l; \
} \
bc_vec_push(&vm.jmp_bufs, &sjb); \
} while (0)
#define BC_LONGJMP_CONT \
do { \
BC_SIG_ASSERT_LOCKED; \
if (!vm.sig_pop) bc_vec_pop(&vm.jmp_bufs); \
BC_SIG_UNLOCK; \
} while (0)
#define BC_UNSETJMP \
do { \
BC_SIG_ASSERT_LOCKED; \
bc_vec_pop(&vm.jmp_bufs); \
} while (0)
#define BC_LONGJMP_STOP \
do { \
vm.sig_pop = 0; \
vm.sig = 0; \
} while (0)
#define BC_VM_BUF_SIZE (1<<12)
#define BC_VM_STDOUT_BUF_SIZE (1<<11)
#define BC_VM_STDERR_BUF_SIZE (1<<10)
#define BC_VM_STDIN_BUF_SIZE (BC_VM_STDERR_BUF_SIZE - 1)
#define BC_VM_SAFE_RESULT(r) ((r)->t >= BC_RESULT_TEMP)
#if BC_ENABLE_LIBRARY
#define bc_vm_error(e, l, ...) (bc_vm_handleError((e)))
#define bc_vm_err(e) (bc_vm_handleError((e)))
#define bc_vm_verr(e, ...) (bc_vm_handleError((e)))
#else // BC_ENABLE_LIBRARY
#define bc_vm_error(e, l, ...) (bc_vm_handleError((e), (l), __VA_ARGS__))
#define bc_vm_err(e) (bc_vm_handleError((e), 0))
#define bc_vm_verr(e, ...) (bc_vm_handleError((e), 0, __VA_ARGS__))
#endif // BC_ENABLE_LIBRARY
#define BC_STATUS_IS_ERROR(s) \
((s) >= BC_STATUS_ERROR_MATH && (s) <= BC_STATUS_ERROR_FATAL)
#define BC_VM_INVALID_CATALOG ((nl_catd) -1)
#if BC_DEBUG_CODE
#define BC_VM_FUNC_ENTER \
do { \
bc_file_printf(&vm.ferr, "Entering %s\n", __func__); \
bc_file_flush(&vm.ferr); \
} while (0);
#define BC_VM_FUNC_EXIT \
do { \
bc_file_printf(&vm.ferr, "Leaving %s\n", __func__); \
bc_file_flush(&vm.ferr); \
} while (0);
#else // BC_DEBUG_CODE
#define BC_VM_FUNC_ENTER
#define BC_VM_FUNC_EXIT
#endif // BC_DEBUG_CODE
typedef struct BcVm {
volatile sig_atomic_t status;
volatile sig_atomic_t sig_pop;
#if !BC_ENABLE_LIBRARY
BcParse prs;
BcProgram prog;
#endif // !BC_ENABLE_LIBRARY
BcVec jmp_bufs;
BcVec temps;
#if BC_ENABLE_LIBRARY
BcVec ctxts;
BcVec out;
BcRNG rng;
BclError err;
bool abrt;
unsigned int refs;
volatile sig_atomic_t running;
#endif // BC_ENABLE_LIBRARY
#if !BC_ENABLE_LIBRARY
const char* file;
const char *sigmsg;
#endif // !BC_ENABLE_LIBRARY
volatile sig_atomic_t sig_lock;
volatile sig_atomic_t sig;
#if !BC_ENABLE_LIBRARY
uchar siglen;
uchar read_ret;
uint16_t flags;
uint16_t nchars;
uint16_t line_len;
bool no_exit_exprs;
+ bool exit_exprs;
bool eof;
#endif // !BC_ENABLE_LIBRARY
BcBigDig maxes[BC_PROG_GLOBALS_LEN + BC_ENABLE_EXTRA_MATH];
#if !BC_ENABLE_LIBRARY
BcVec files;
BcVec exprs;
const char *name;
const char *help;
#if BC_ENABLE_HISTORY
BcHistory history;
#endif // BC_ENABLE_HISTORY
BcLexNext next;
BcParseParse parse;
BcParseExpr expr;
const char *func_header;
const char *err_ids[BC_ERR_IDX_NELEMS + BC_ENABLED];
const char *err_msgs[BC_ERR_NELEMS];
const char *locale;
#endif // !BC_ENABLE_LIBRARY
BcBigDig last_base;
BcBigDig last_pow;
BcBigDig last_exp;
BcBigDig last_rem;
#if !BC_ENABLE_LIBRARY
char *env_args_buffer;
BcVec env_args;
#endif // !BC_ENABLE_LIBRARY
BcNum max;
BcNum max2;
BcDig max_num[BC_NUM_BIGDIG_LOG10];
BcDig max2_num[BC_NUM_BIGDIG_LOG10];
#if !BC_ENABLE_LIBRARY
BcFile fout;
BcFile ferr;
#if BC_ENABLE_NLS
nl_catd catalog;
#endif // BC_ENABLE_NLS
char *buf;
size_t buf_len;
#endif // !BC_ENABLE_LIBRARY
} BcVm;
void bc_vm_info(const char* const help);
void bc_vm_boot(int argc, char *argv[], const char *env_len,
const char* const env_args);
void bc_vm_init(void);
void bc_vm_shutdown(void);
void bc_vm_freeTemps(void);
void bc_vm_printf(const char *fmt, ...);
void bc_vm_putchar(int c);
size_t bc_vm_arraySize(size_t n, size_t size);
size_t bc_vm_growSize(size_t a, size_t b);
void* bc_vm_malloc(size_t n);
void* bc_vm_realloc(void *ptr, size_t n);
char* bc_vm_strdup(const char *str);
#if BC_DEBUG_CODE
void bc_vm_jmp(const char *f);
#else // BC_DEBUG_CODE
void bc_vm_jmp(void);
#endif // BC_DEBUG_CODE
#if BC_ENABLE_LIBRARY
void bc_vm_handleError(BcErr e);
void bc_vm_fatalError(BcErr e);
void bc_vm_atexit(void);
#else // BC_ENABLE_LIBRARY
void bc_vm_handleError(BcErr e, size_t line, ...);
#if !BC_ENABLE_LIBRARY && !BC_ENABLE_MEMCHECK
BC_NORETURN
#endif // !BC_ENABLE_LIBRARY && !BC_ENABLE_MEMCHECK
void bc_vm_fatalError(BcErr e);
int bc_vm_atexit(int status);
#endif // BC_ENABLE_LIBRARY
extern const char bc_copyright[];
extern const char* const bc_err_line;
extern const char* const bc_err_func_header;
extern const char *bc_errs[];
extern const uchar bc_err_ids[];
extern const char* const bc_err_msgs[];
extern BcVm vm;
extern char output_bufs[BC_VM_BUF_SIZE];
#endif // BC_VM_H
diff --git a/contrib/bc/manuals/bc.1.md.in b/contrib/bc/manuals/bc.1.md.in
index 624ea3fb54ab..1ce83b8237cd 100644
--- a/contrib/bc/manuals/bc.1.md.in
+++ b/contrib/bc/manuals/bc.1.md.in
@@ -1,1813 +1,1822 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# NAME
bc - arbitrary-precision decimal arithmetic language and calculator
# SYNOPSIS
**bc** [**-ghilPqsvVw**] [**--global-stacks**] [**--help**] [**--interactive**] [**--mathlib**] [**--no-prompt**] [**--quiet**] [**--standard**] [**--warn**] [**--version**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...]
[*file*...]
# DESCRIPTION
bc(1) is an interactive processor for a language first standardized in 1991 by
POSIX. (The current standard is [here][1].) The language provides unlimited
precision decimal arithmetic and is somewhat C-like, but there are differences.
Such differences will be noted in this document.
After parsing and handling options, this bc(1) reads any files given on the
command line and executes them before reading from **stdin**.
{{ A N P NP }}
This bc(1) is a drop-in replacement for *any* bc(1), including (and
especially) the GNU bc(1). It also has many extensions and extra features beyond
other implementations.
{{ end }}
{{ E EN EP ENP }}
This bc(1) is a drop-in replacement for *any* bc(1), including (and
especially) the GNU bc(1).
{{ end }}
# OPTIONS
The following are the options that bc(1) accepts.
**-g**, **--global-stacks**
{{ A H N P HN HP NP HNP }}
: Turns the globals **ibase**, **obase**, **scale**, and **seed** into stacks.
This has the effect that a copy of the current value of all four are pushed
{{ end }}
{{ E EH EN EP EHN EHP ENP EHNP }}
Turns the globals **ibase**, **obase**, and **scale** into stacks.
This has the effect that a copy of the current value of all three are pushed
{{ end }}
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
{{ A H N P HN HP NP HNP }}
(**Note**: the function **output(x,b)** exists in the extended math library.
See the **LIBRARY** section.)
However, since using this flag means that functions cannot set **ibase**,
**obase**, **scale**, or **seed** globally, functions that are made to do so
cannot work anymore. There are two possible use cases for that, and each has
a solution.
{{ end }}
{{ E EH EN EP EHN EHP ENP EHNP }}
However, since using this flag means that functions cannot set **ibase**,
**obase**, or **scale** globally, functions that are made to do so cannot
work anymore. There are two possible use cases for that, and each has a
solution.
{{ end }}
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o="bc -e ibase=A -e obase=8"
alias h2b="bc -e ibase=G -e obase=2"
{{ A H N P HN HP NP HNP }}
Second, if the purpose of a function is to set **ibase**, **obase**,
**scale**, or **seed** globally for any other purpose, it could be split
into one to four functions (based on how many globals it sets) and each of
those functions could return the desired value for a global.
For functions that set **seed**, the value assigned to **seed** is not
propagated to parent functions. This means that the sequence of
pseudo-random numbers that they see will not be the same sequence of
pseudo-random numbers that any parent sees. This is only the case once
**seed** has been set.
If a function desires to not affect the sequence of pseudo-random numbers
of its parents, but wants to use the same **seed**, it can use the following
line:
seed = seed
{{ end }}
{{ E EH EN EP EHN EHP ENP EHNP }}
Second, if the purpose of a function is to set **ibase**, **obase**, or
**scale** globally for any other purpose, it could be split into one to
three functions (based on how many globals it sets) and each of those
functions could return the desired value for a global.
{{ end }}
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
**-h**, **--help**
: Prints a usage message and quits.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-l**, **--mathlib**
: Sets **scale** (see the **SYNTAX** section) to **20** and loads the included
{{ A H N P HN HP NP HNP }}
math library and the extended math library before running any code,
including any expressions or files specified on the command line.
To learn what is in the libraries, see the **LIBRARY** section.
{{ end }}
{{ E EH EN EP EHN EHP ENP EHNP }}
math library before running any code, including any expressions or files
specified on the command line.
To learn what is in the library, see the **LIBRARY** section.
{{ end }}
**-P**, **--no-prompt**
{{ A E H N EH EN HN EHN }}
: Disables the prompt in TTY mode. (The prompt is only enabled in TTY mode.
See the **TTY MODE** section) This is mostly for those users that do not
want a prompt or are not used to having them in bc(1). Most of those users
would want to put this option in **BC_ENV_ARGS** (see the
**ENVIRONMENT VARIABLES** section).
{{ end }}
{{ P EP HP NP EHP ENP HNP EHNP }}
: This option is a no-op.
{{ end }}
This is a **non-portable extension**.
**-q**, **--quiet**
: This option is for compatibility with the [GNU bc(1)][2]; it is a no-op.
Without this option, GNU bc(1) prints a copyright header. This bc(1) only
prints the copyright header if one or more of the **-v**, **-V**, or
**--version** options are given.
This is a **non-portable extension**.
**-s**, **--standard**
: Process exactly the language defined by the [standard][1] and error if any
extensions are used.
This is a **non-portable extension**.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
This is a **non-portable extension**.
**-w**, **--warn**
: Like **-s** and **--standard**, except that warnings (and not errors) are
printed for non-standard extensions and execution continues normally.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **BC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **bc <file> >&-**, it will quit with an error. This
is done so that bc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **bc <file> 2>&-**, it will quit with an error. This
is done so that bc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
The syntax for bc(1) programs is mostly C-like, with some differences. This
bc(1) follows the [POSIX standard][1], which is a much more thorough resource
for the language this bc(1) accepts. This section is meant to be a summary and a
listing of all the extensions to the standard.
In the sections below, **E** means expression, **S** means statement, and **I**
means identifier.
Identifiers (**I**) start with a lowercase letter and can be followed by any
number (up to **BC_NAME_MAX-1**) of lowercase letters (**a-z**), digits
(**0-9**), and underscores (**\_**). The regex is **\[a-z\]\[a-z0-9\_\]\***.
Identifiers with more than one character (letter) are a
**non-portable extension**.
**ibase** is a global variable determining how to interpret constant numbers. It
is the "input" base, or the number base used for interpreting input numbers.
**ibase** is initially **10**. If the **-s** (**--standard**) and **-w**
(**--warn**) flags were not given on the command line, the max allowable value
for **ibase** is **36**. Otherwise, it is **16**. The min allowable value for
**ibase** is **2**. The max allowable value for **ibase** can be queried in
bc(1) programs with the **maxibase()** built-in function.
**obase** is a global variable determining how to output results. It is the
"output" base, or the number base used for outputting numbers. **obase** is
initially **10**. The max allowable value for **obase** is **BC_BASE_MAX** and
can be queried in bc(1) programs with the **maxobase()** built-in function. The
{{ A H N P HN HP NP HNP }}
min allowable value for **obase** is **0**. If **obase** is **0**, values are
output in scientific notation, and if **obase** is **1**, values are output in
engineering notation. Otherwise, values are output in the specified base.
Outputting in scientific and engineering notations are **non-portable
extensions**.
{{ end }}
{{ E EH EN EP EHN EHP ENP EHNP }}
min allowable value for **obase** is **2**. Values are output in the specified
base.
{{ end }}
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a global variable that
sets the precision of any operations, with exceptions. **scale** is initially
**0**. **scale** cannot be negative. The max allowable value for **scale** is
**BC_SCALE_MAX** and can be queried in bc(1) programs with the **maxscale()**
built-in function.
bc(1) has both *global* variables and *local* variables. All *local*
variables are local to the function; they are parameters or are introduced in
the **auto** list of a function (see the **FUNCTIONS** section). If a variable
is accessed which is not a parameter or in the **auto** list, it is assumed to
be *global*. If a parent function has a *local* variable version of a variable
that a child function considers *global*, the value of that *global* variable in
the child function is the value of the variable in the parent function, not the
value of the actual *global* variable.
All of the above applies to arrays as well.
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence operator is an
assignment operator *and* the expression is notsurrounded by parentheses.
The value that is printed is also assigned to the special variable **last**. A
single dot (**.**) may also be used as a synonym for **last**. These are
**non-portable extensions**.
Either semicolons or newlines may separate statements.
## Comments
There are two kinds of comments:
1. Block comments are enclosed in **/\*** and **\*/**.
2. Line comments go from **#** until, and not including, the next newline. This
is a **non-portable extension**.
## Named Expressions
The following are named expressions in bc(1):
1. Variables: **I**
2. Array Elements: **I[E]**
3. **ibase**
4. **obase**
5. **scale**
{{ A H N P HN HP NP HNP }}
6. **seed**
7. **last** or a single dot (**.**)
Numbers 6 and 7 are **non-portable extensions**.
The meaning of **seed** is dependent on the current pseudo-random number
generator but is guaranteed to not change except for new major versions.
The *scale* and sign of the value may be significant.
If a previously used **seed** value is assigned to **seed** and used again, the
pseudo-random number generator is guaranteed to produce the same sequence of
pseudo-random numbers as it did when the **seed** value was previously used.
The exact value assigned to **seed** is not guaranteed to be returned if
**seed** is queried again immediately. However, if **seed** *does* return a
different value, both values, when assigned to **seed**, are guaranteed to
produce the same sequence of pseudo-random numbers. This means that certain
values assigned to **seed** will *not* produce unique sequences of pseudo-random
numbers. The value of **seed** will change after any use of the **rand()** and
**irand(E)** operands (see the *Operands* subsection below), except if the
parameter passed to **irand(E)** is **0**, **1**, or negative.
There is no limit to the length (number of significant decimal digits) or
*scale* of the value that can be assigned to **seed**.
{{ end }}
{{ E EH EN EP EHN EHP ENP EHNP }}
6. **last** or a single dot (**.**)
Number 6 is a **non-portable extension**.
{{ end }}
Variables and arrays do not interfere; users can have arrays named the same as
variables. This also applies to functions (see the **FUNCTIONS** section), so a
user can have a variable, array, and function that all have the same name, and
they will not shadow each other, whether inside of functions or not.
Named expressions are required as the operand of **increment**/**decrement**
operators and as the left side of **assignment** operators (see the *Operators*
subsection).
## Operands
The following are valid operands in bc(1):
1. Numbers (see the *Numbers* subsection below).
2. Array indices (**I[E]**).
3. **(E)**: The value of **E** (used to change precedence).
4. **sqrt(E)**: The square root of **E**. **E** must be non-negative.
5. **length(E)**: The number of significant decimal digits in **E**.
6. **length(I[])**: The number of elements in the array **I**. This is a
**non-portable extension**.
7. **scale(E)**: The *scale* of **E**.
8. **abs(E)**: The absolute value of **E**. This is a **non-portable
extension**.
9. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a non-**void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
10. **read()**: Reads a line from **stdin** and uses that as an expression. The
result of that expression is the result of the **read()** operand. This is a
**non-portable extension**.
11. **maxibase()**: The max allowable **ibase**. This is a **non-portable
extension**.
12. **maxobase()**: The max allowable **obase**. This is a **non-portable
extension**.
13. **maxscale()**: The max allowable **scale**. This is a **non-portable
extension**.
{{ A H N P HN HP NP HNP }}
14. **rand()**: A pseudo-random integer between **0** (inclusive) and
**BC_RAND_MAX** (inclusive). Using this operand will change the value of
**seed**. This is a **non-portable extension**.
15. **irand(E)**: A pseudo-random integer between **0** (inclusive) and the
value of **E** (exclusive). If **E** is negative or is a non-integer
(**E**'s *scale* is not **0**), an error is raised, and bc(1) resets (see
the **RESET** section) while **seed** remains unchanged. If **E** is larger
than **BC_RAND_MAX**, the higher bound is honored by generating several
pseudo-random integers, multiplying them by appropriate powers of
**BC_RAND_MAX+1**, and adding them together. Thus, the size of integer that
can be generated with this operand is unbounded. Using this operand will
change the value of **seed**, unless the value of **E** is **0** or **1**.
In that case, **0** is returned, and **seed** is *not* changed. This is a
**non-portable extension**.
16. **maxrand()**: The max integer returned by **rand()**. This is a
**non-portable extension**.
The integers generated by **rand()** and **irand(E)** are guaranteed to be as
unbiased as possible, subject to the limitations of the pseudo-random number
generator.
**Note**: The values returned by the pseudo-random number generator with
**rand()** and **irand(E)** are guaranteed to *NOT* be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator. However,
they *are* guaranteed to be reproducible with identical **seed** values. This
means that the pseudo-random values from bc(1) should only be used where a
reproducible stream of pseudo-random numbers is *ESSENTIAL*. In any other case,
use a non-seeded pseudo-random number generator.
{{ end }}
## Numbers
Numbers are strings made up of digits, uppercase letters, and at most **1**
period for a radix. Numbers can have up to **BC_NUM_MAX** digits. Uppercase
letters are equal to **9** + their position in the alphabet (i.e., **A** equals
**10**, or **9+1**). If a digit or letter makes no sense with the current value
of **ibase**, they are set to the value of the highest valid digit in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **Z** alone always equals decimal
**35**.
{{ A H N P HN HP NP HNP }}
In addition, bc(1) accepts numbers in scientific notation. These have the form
**\<number\>e\<integer\>**. The exponent (the portion after the **e**) must be
an integer. An example is **1.89237e9**, which is equal to **1892370000**.
Negative exponents are also allowed, so **4.2890e-3** is equal to **0.0042890**.
Using scientific notation is an error or warning if the **-s** or **-w**,
respectively, command-line options (or equivalents) are given.
**WARNING**: Both the number and the exponent in scientific notation are
interpreted according to the current **ibase**, but the number is still
multiplied by **10\^exponent** regardless of the current **ibase**. For example,
if **ibase** is **16** and bc(1) is given the number string **FFeA**, the
resulting decimal number will be **2550000000000**, and if bc(1) is given the
number string **10e-4**, the resulting decimal number will be **0.0016**.
Accepting input as scientific notation is a **non-portable extension**.
{{ end }}
## Operators
The following arithmetic and logical operators can be used. They are listed in
order of decreasing precedence. Operators in the same group have the same
precedence.
**++** **--**
: Type: Prefix and Postfix
Associativity: None
Description: **increment**, **decrement**
**-** **!**
: Type: Prefix
Associativity: None
Description: **negation**, **boolean not**
{{ A H N P HN HP NP HNP }}
**\$**
: Type: Postfix
Associativity: None
Description: **truncation**
**\@**
: Type: Binary
Associativity: Right
Description: **set precision**
{{ end }}
**\^**
: Type: Binary
Associativity: Right
Description: **power**
**\*** **/** **%**
: Type: Binary
Associativity: Left
Description: **multiply**, **divide**, **modulus**
**+** **-**
: Type: Binary
Associativity: Left
Description: **add**, **subtract**
{{ A H N P HN HP NP HNP }}
**\<\<** **\>\>**
: Type: Binary
Associativity: Left
Description: **shift left**, **shift right**
**=** **\<\<=** **\>\>=** **+=** **-=** **\*=** **/=** **%=** **\^=** **\@=**
{{ end }}
{{ E EH EN EP EHN EHP ENP EHNP }}
**=** **+=** **-=** **\*=** **/=** **%=** **\^=**
{{ end }}
: Type: Binary
Associativity: Right
Description: **assignment**
**==** **\<=** **\>=** **!=** **\<** **\>**
: Type: Binary
Associativity: Left
Description: **relational**
**&&**
: Type: Binary
Associativity: Left
Description: **boolean and**
**||**
: Type: Binary
Associativity: Left
Description: **boolean or**
The operators will be described in more detail below.
**++** **--**
: The prefix and postfix **increment** and **decrement** operators behave
exactly like they would in C. They require a named expression (see the
*Named Expressions* subsection) as an operand.
The prefix versions of these operators are more efficient; use them where
possible.
**-**
: The **negation** operator returns **0** if a user attempts to negate any
expression with the value **0**. Otherwise, a copy of the expression with
its sign flipped is returned.
**!**
: The **boolean not** operator returns **1** if the expression is **0**, or
**0** otherwise.
This is a **non-portable extension**.
{{ A H N P HN HP NP HNP }}
**\$**
: The **truncation** operator returns a copy of the given expression with all
of its *scale* removed.
This is a **non-portable extension**.
**\@**
: The **set precision** operator takes two expressions and returns a copy of
the first with its *scale* equal to the value of the second expression. That
could either mean that the number is returned without change (if the
*scale* of the first expression matches the value of the second
expression), extended (if it is less), or truncated (if it is more).
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
{{ end }}
**\^**
: The **power** operator (not the **exclusive or** operator, as it would be in
C) takes two expressions and raises the first to the power of the value of
the second. The *scale* of the result is equal to **scale**.
The second expression must be an integer (no *scale*), and if it is
negative, the first value must be non-zero.
**\***
: The **multiply** operator takes two expressions, multiplies them, and
returns the product. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result is
equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The **divide** operator takes two expressions, divides them, and returns the
quotient. The *scale* of the result shall be the value of **scale**.
The second expression must be non-zero.
**%**
: The **modulus** operator takes two expressions, **a** and **b**, and
evaluates them by 1) Computing **a/b** to current **scale** and 2) Using the
result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The second expression must be non-zero.
**+**
: The **add** operator takes two expressions, **a** and **b**, and returns the
sum, with a *scale* equal to the max of the *scale*s of **a** and **b**.
**-**
: The **subtract** operator takes two expressions, **a** and **b**, and
returns the difference, with a *scale* equal to the max of the *scale*s of
**a** and **b**.
{{ A H N P HN HP NP HNP }}
**\<\<**
: The **left shift** operator takes two expressions, **a** and **b**, and
returns a copy of the value of **a** with its decimal point moved **b**
places to the right.
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**\>\>**
: The **right shift** operator takes two expressions, **a** and **b**, and
returns a copy of the value of **a** with its decimal point moved **b**
places to the left.
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
{{ end }}
{{ A H N P HN HP NP HNP }}
**=** **\<\<=** **\>\>=** **+=** **-=** **\*=** **/=** **%=** **\^=** **\@=**
{{ end }}
{{ E EH EN EP EHN EHP ENP EHNP }}
**=** **+=** **-=** **\*=** **/=** **%=** **\^=**
{{ end }}
: The **assignment** operators take two expressions, **a** and **b** where
**a** is a named expression (see the *Named Expressions* subsection).
For **=**, **b** is copied and the result is assigned to **a**. For all
others, **a** and **b** are applied as operands to the corresponding
arithmetic operator and the result is assigned to **a**.
{{ A H N P HN HP NP HNP }}
The **assignment** operators that correspond to operators that are
extensions are themselves **non-portable extensions**.
{{ end }}
**==** **\<=** **\>=** **!=** **\<** **\>**
: The **relational** operators compare two expressions, **a** and **b**, and
if the relation holds, according to C language semantics, the result is
**1**. Otherwise, it is **0**.
Note that unlike in C, these operators have a lower precedence than the
**assignment** operators, which means that **a=b\>c** is interpreted as
**(a=b)\>c**.
Also, unlike the [standard][1] requires, these operators can appear anywhere
any other expressions can be used. This allowance is a
**non-portable extension**.
**&&**
: The **boolean and** operator takes two expressions and returns **1** if both
expressions are non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
**||**
: The **boolean or** operator takes two expressions and returns **1** if one
of the expressions is non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
## Statements
The following items are statements:
1. **E**
2. **{** **S** **;** ... **;** **S** **}**
3. **if** **(** **E** **)** **S**
4. **if** **(** **E** **)** **S** **else** **S**
5. **while** **(** **E** **)** **S**
6. **for** **(** **E** **;** **E** **;** **E** **)** **S**
7. An empty statement
8. **break**
9. **continue**
10. **quit**
11. **halt**
12. **limits**
13. A string of characters, enclosed in double quotes
14. **print** **E** **,** ... **,** **E**
15. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
Numbers 4, 9, 11, 12, 14, and 15 are **non-portable extensions**.
Also, as a **non-portable extension**, any or all of the expressions in the
header of a for loop may be omitted. If the condition (second expression) is
omitted, it is assumed to be a constant **1**.
The **break** statement causes a loop to stop iterating and resume execution
immediately following a loop. This is only allowed in loops.
The **continue** statement causes a loop iteration to stop early and returns to
the start of the loop, including testing the loop condition. This is only
allowed in loops.
The **if** **else** statement does the same thing as in C.
The **quit** statement causes bc(1) to quit, even if it is on a branch that will
not be executed (it is a compile-time command).
The **halt** statement causes bc(1) to quit, if it is executed. (Unlike **quit**
if it is on a branch of an **if** statement that is not executed, bc(1) does not
quit.)
The **limits** statement prints the limits that this bc(1) is subject to. This
is like the **quit** statement in that it is a compile-time command.
An expression by itself is evaluated and printed, followed by a newline.
{{ A H N P HN HP NP HNP }}
Both scientific notation and engineering notation are available for printing the
results of expressions. Scientific notation is activated by assigning **0** to
**obase**, and engineering notation is activated by assigning **1** to
**obase**. To deactivate them, just assign a different value to **obase**.
Scientific notation and engineering notation are disabled if bc(1) is run with
either the **-s** or **-w** command-line options (or equivalents).
Printing numbers in scientific notation and/or engineering notation is a
**non-portable extension**.
{{ end }}
## Print Statement
The "expressions" in a **print** statement may also be strings. If they are, there
are backslash escape sequences that are interpreted specially. What those
sequences are, and what they cause to be printed, are shown below:
-------- -------
**\\a** **\\a**
**\\b** **\\b**
**\\\\** **\\**
**\\e** **\\**
**\\f** **\\f**
**\\n** **\\n**
**\\q** **"**
**\\r** **\\r**
**\\t** **\\t**
-------- -------
Any other character following a backslash causes the backslash and character to
be printed as-is.
Any non-string expression in a print statement shall be assigned to **last**,
like any other expression that is printed.
## Order of Evaluation
All expressions in a statment are evaluated left to right, except as necessary
to maintain order of operations. This means, for example, assuming that **i** is
equal to **0**, in the expression
a[i++] = i++
the first (or 0th) element of **a** is set to **1**, and **i** is equal to **2**
at the end of the expression.
This includes function arguments. Thus, assuming **i** is equal to **0**, this
means that in the expression
x(i++, i++)
the first argument passed to **x()** is **0**, and the second argument is **1**,
while **i** is equal to **2** before the function starts executing.
# FUNCTIONS
Function definitions are as follows:
```
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
```
Any **I** in the parameter list or **auto** list may be replaced with **I[]** to
make a parameter or **auto** var an array, and any **I** in the parameter list
may be replaced with **\*I[]** to make a parameter an array reference. Callers
of functions that take array references should not put an asterisk in the call;
they must be called with just **I[]** like normal array parameters and will be
automatically converted into references.
As a **non-portable extension**, the opening brace of a **define** statement may
appear on the next line.
As a **non-portable extension**, the return statement may also be in one of the
following forms:
1. **return**
2. **return** **(** **)**
3. **return** **E**
The first two, or not specifying a **return** statement, is equivalent to
**return (0)**, unless the function is a **void** function (see the *Void
Functions* subsection below).
## Void Functions
Functions can also be **void** functions, defined as follows:
```
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
```
They can only be used as standalone expressions, where such an expression would
be printed alone, except in a print statement.
Void functions can only use the first two **return** statements listed above.
They can also omit the return statement entirely.
The word "void" is not treated as a keyword; it is still possible to have
variables, arrays, and functions named **void**. The word "void" is only
treated specially right after the **define** keyword.
This is a **non-portable extension**.
## Array References
For any array in the parameter list, if the array is declared in the form
```
*I[]
```
it is a **reference**. Any changes to the array in the function are reflected,
when the function returns, to the array that was passed in.
Other than this, all function arguments are passed by value.
This is a **non-portable extension**.
# LIBRARY
{{ A H N P HN HP NP HNP }}
All of the functions below, including the functions in the extended math
library (see the *Extended Library* subsection below), are available when the
**-l** or **--mathlib** command-line flags are given, except that the extended
math library is not available when the **-s** option, the **-w** option, or
equivalents are given.
{{ end }}
{{ E EH EN EP EHN EHP ENP EHNP }}
All of the functions below are available when the **-l** or **--mathlib**
command-line flags are given.
{{ end }}
## Standard Library
The [standard][1] defines the following functions for the math library:
**s(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**c(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a(x)**
: Returns the arctangent of **x**, in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l(x)**
: Returns the natural logarithm of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**e(x)**
: Returns the mathematical constant **e** raised to the power of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**j(x, n)**
: Returns the bessel integer order **n** (truncated) of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
{{ A H N P HN HP NP HNP }}
## Extended Library
The extended library is *not* loaded when the **-s**/**--standard** or
**-w**/**--warn** options are given since they are not part of the library
defined by the [standard][1].
The extended library is a **non-portable extension**.
**p(x, y)**
: Calculates **x** to the power of **y**, even if **y** is not an integer, and
returns the result to the current **scale**.
It is an error if **y** is negative and **x** is **0**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**r(x, p)**
: Returns **x** rounded to **p** decimal places according to the rounding mode
[round half away from **0**][3].
**ceil(x, p)**
: Returns **x** rounded to **p** decimal places according to the rounding mode
[round away from **0**][6].
**f(x)**
: Returns the factorial of the truncated absolute value of **x**.
**perm(n, k)**
: Returns the permutation of the truncated absolute value of **n** of the
truncated absolute value of **k**, if **k \<= n**. If not, it returns **0**.
**comb(n, k)**
: Returns the combination of the truncated absolute value of **n** of the
truncated absolute value of **k**, if **k \<= n**. If not, it returns **0**.
**l2(x)**
: Returns the logarithm base **2** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l10(x)**
: Returns the logarithm base **10** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**log(x, b)**
: Returns the logarithm base **b** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**cbrt(x)**
: Returns the cube root of **x**.
**root(x, n)**
: Calculates the truncated value of **n**, **r**, and returns the **r**th root
of **x** to the current **scale**.
If **r** is **0** or negative, this raises an error and causes bc(1) to
reset (see the **RESET** section). It also raises an error and causes bc(1)
to reset if **r** is even and **x** is negative.
**pi(p)**
: Returns **pi** to **p** decimal places.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**t(x)**
: Returns the tangent of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a2(y, x)**
: Returns the arctangent of **y/x**, in radians. If both **y** and **x** are
equal to **0**, it raises an error and causes bc(1) to reset (see the
**RESET** section). Otherwise, if **x** is greater than **0**, it returns
**a(y/x)**. If **x** is less than **0**, and **y** is greater than or equal
to **0**, it returns **a(y/x)+pi**. If **x** is less than **0**, and **y**
is less than **0**, it returns **a(y/x)-pi**. If **x** is equal to **0**,
and **y** is greater than **0**, it returns **pi/2**. If **x** is equal to
**0**, and **y** is less than **0**, it returns **-pi/2**.
This function is the same as the **atan2()** function in many programming
languages.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**sin(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is an alias of **s(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**cos(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is an alias of **c(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**tan(x)**
: Returns the tangent of **x**, which is assumed to be in radians.
If **x** is equal to **1** or **-1**, this raises an error and causes bc(1)
to reset (see the **RESET** section).
This is an alias of **t(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**atan(x)**
: Returns the arctangent of **x**, in radians.
This is an alias of **a(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**atan2(y, x)**
: Returns the arctangent of **y/x**, in radians. If both **y** and **x** are
equal to **0**, it raises an error and causes bc(1) to reset (see the
**RESET** section). Otherwise, if **x** is greater than **0**, it returns
**a(y/x)**. If **x** is less than **0**, and **y** is greater than or equal
to **0**, it returns **a(y/x)+pi**. If **x** is less than **0**, and **y**
is less than **0**, it returns **a(y/x)-pi**. If **x** is equal to **0**,
and **y** is greater than **0**, it returns **pi/2**. If **x** is equal to
**0**, and **y** is less than **0**, it returns **-pi/2**.
This function is the same as the **atan2()** function in many programming
languages.
This is an alias of **a2(y, x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**r2d(x)**
: Converts **x** from radians to degrees and returns the result.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**d2r(x)**
: Converts **x** from degrees to radians and returns the result.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**frand(p)**
: Generates a pseudo-random number between **0** (inclusive) and **1**
(exclusive) with the number of decimal digits after the decimal point equal
to the truncated absolute value of **p**. If **p** is not **0**, then
calling this function will change the value of **seed**. If **p** is **0**,
then **0** is returned, and **seed** is *not* changed.
**ifrand(i, p)**
: Generates a pseudo-random number that is between **0** (inclusive) and the
truncated absolute value of **i** (exclusive) with the number of decimal
digits after the decimal point equal to the truncated absolute value of
**p**. If the absolute value of **i** is greater than or equal to **2**, and
**p** is not **0**, then calling this function will change the value of
**seed**; otherwise, **0** is returned and **seed** is not changed.
**srand(x)**
: Returns **x** with its sign flipped with probability **0.5**. In other
words, it randomizes the sign of **x**.
**brand()**
: Returns a random boolean value (either **0** or **1**).
**ubytes(x)**
: Returns the numbers of unsigned integer bytes required to hold the truncated
absolute value of **x**.
**sbytes(x)**
: Returns the numbers of signed, two's-complement integer bytes required to
hold the truncated value of **x**.
**hex(x)**
: Outputs the hexadecimal (base **16**) representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**binary(x)**
: Outputs the binary (base **2**) representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output(x, b)**
: Outputs the base **b** representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in as few power of two bytes as possible. Both outputs are
split into bytes separated by spaces.
If **x** is not an integer or is negative, an error message is printed
instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in as few power of two bytes as possible. Both
outputs are split into bytes separated by spaces.
If **x** is not an integer, an error message is printed instead, but bc(1)
is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uintn(x, n)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **n** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **n** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**intn(x, n)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **n** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **n** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint8(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **1** byte. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **1** byte, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int8(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **1** byte. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **1** byte, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint16(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **2** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **2** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int16(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **2** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **2** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint32(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **4** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **4** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int32(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **4** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **4** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint64(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **8** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **8** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int64(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **8** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **8** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**hex_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in hexadecimal using **n** bytes. Not all of the value will
be output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**binary_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in binary using **n** bytes. Not all of the value will be
output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in the current **obase** (see the **SYNTAX** section) using
**n** bytes. Not all of the value will be output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output_byte(x, i)**
: Outputs byte **i** of the truncated absolute value of **x**, where **0** is
the least significant byte and **number_of_bytes - 1** is the most
significant byte.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
{{ end }}
## Transcendental Functions
All transcendental functions can return slightly inaccurate results (up to 1
[ULP][4]). This is unavoidable, and [this article][5] explains why it is
impossible and unnecessary to calculate exact results for the transcendental
functions.
Because of the possible inaccuracy, I recommend that users call those functions
with the precision (**scale**) set to at least 1 higher than is necessary. If
exact results are *absolutely* required, users can double the precision
(**scale**) and then truncate.
The transcendental functions in the standard math library are:
* **s(x)**
* **c(x)**
* **a(x)**
* **l(x)**
* **e(x)**
* **j(x, n)**
{{ A H N P HN HP NP HNP }}
The transcendental functions in the extended math library are:
* **l2(x)**
* **l10(x)**
* **log(x, b)**
* **pi(p)**
* **t(x)**
* **a2(y, x)**
* **sin(x)**
* **cos(x)**
* **tan(x)**
* **atan(x)**
* **atan2(y, x)**
* **r2d(x)**
* **d2r(x)**
{{ end }}
# RESET
When bc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any functions that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
functions returned) is skipped.
Thus, when bc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
Note that this reset behavior is different from the GNU bc(1), which attempts to
start executing the statement right after the one that caused an error.
# PERFORMANCE
Most bc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This bc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **BC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **BC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**BC_BASE_DIGS**.
The actual values of **BC_LONG_BIT** and **BC_BASE_DIGS** can be queried with
the **limits** statement.
In addition, this bc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **BC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on bc(1):
**BC_LONG_BIT**
: The number of bits in the **long** type in the environment where bc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**BC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **BC_LONG_BIT**.
**BC_BASE_POW**
: The max decimal number that each large integer can store (see
**BC_BASE_DIGS**) plus **1**. Depends on **BC_BASE_DIGS**.
**BC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **BC_LONG_BIT**.
**BC_BASE_MAX**
: The maximum output base. Set at **BC_BASE_POW**.
**BC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**BC_SCALE_MAX**
: The maximum **scale**. Set at **BC_OVERFLOW_MAX-1**.
**BC_STRING_MAX**
: The maximum length of strings. Set at **BC_OVERFLOW_MAX-1**.
**BC_NAME_MAX**
: The maximum length of identifiers. Set at **BC_OVERFLOW_MAX-1**.
**BC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **BC_OVERFLOW_MAX-1**.
{{ A H N P HN HP NP HNP }}
**BC_RAND_MAX**
: The maximum integer (inclusive) returned by the **rand()** operand. Set at
**2\^BC_LONG_BIT-1**.
{{ end }}
Exponent
: The maximum allowable exponent (positive or negative). Set at
**BC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
The actual values can be queried with the **limits** statement.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
bc(1) recognizes the following environment variables:
**POSIXLY_CORRECT**
: If this variable exists (no matter the contents), bc(1) behaves as if
the **-s** option was given.
**BC_ENV_ARGS**
: This is another way to give command-line arguments to bc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **BC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
The code that parses **BC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some bc file.bc"** will be correctly parsed, but the string
**"/home/gavin/some \"bc\" file.bc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **BC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**BC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), bc(1) will output
lines to that length, including the backslash (**\\**). The default line
length is **70**.
# EXIT STATUS
bc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
{{ A H N P HN HP NP HNP }}
Math errors include divide by **0**, taking the square root of a negative
number, using a negative number as a bound for the pseudo-random number
generator, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**), places (**\@**), left shift (**\<\<**), and right shift (**\>\>**)
operators and their corresponding assignment operators.
{{ end }}
{{ E EH EN EP EHN EHP ENP EHNP }}
Math errors include divide by **0**, taking the square root of a negative
number, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**) operator and the corresponding assignment operator.
{{ end }}
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, using a token where it is invalid,
giving an invalid expression, giving an invalid print statement, giving an
invalid function definition, attempting to assign to an expression that is
not a named expression (see the *Named Expressions* subsection of the
**SYNTAX** section), giving an invalid **auto** list, having a duplicate
**auto**/function parameter, failing to find the end of a code block,
attempting to return a value from a **void** function, attempting to use a
variable as a reference, and using any extensions when the option **-s** or
any equivalents were given.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a **void** function call as a value in an expression.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (bc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, bc(1) always exits
and returns **4**, no matter what mode bc(1) is in.
The other statuses will only be returned when bc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since bc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Per the [standard][1], bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, bc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, bc(1) turns
on "TTY mode."
{{ A E N P EN EP NP ENP }}
TTY mode is required for history to be enabled (see the **COMMAND LINE HISTORY**
section). It is also required to enable special handling for **SIGINT** signals.
{{ end }}
{{ A E H N EH EN HN EHN }}
The prompt is enabled in TTY mode.
{{ end }}
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause bc(1) to stop execution of the current input. If
bc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If bc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If bc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to bc(1) as it is executing a file, it
can seem as though bc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause bc(1) to clean up and exit, and it uses the
{{ A E N P EN EP NP ENP }}
default handler for all other signals. The one exception is **SIGHUP**; in that
case, when bc(1) is in TTY mode, a **SIGHUP** will cause bc(1) to clean up and
exit.
{{ end }}
{{ H EH HN HP EHN EHP HNP EHNP }}
default handler for all other signals.
{{ end }}
{{ A E N P EN EP NP ENP }}
# COMMAND LINE HISTORY
bc(1) supports interactive command-line editing. If bc(1) is in TTY mode (see
the **TTY MODE** section), history is enabled. Previous lines can be recalled
and edited with the arrow keys.
**Note**: tabs are converted to 8 spaces.
{{ end }}
{{ A E H P EH EP HP EHP }}
# LOCALES
This bc(1) ships with support for adding error messages for different locales
and thus, supports **LC_MESSAGES**.
{{ end }}
# SEE ALSO
dc(1)
# STANDARDS
bc(1) is compliant with the [IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1]
specification. The flags **-efghiqsvVw**, all long options, and the extensions
noted above are extensions to that specification.
Note that the specification explicitly says that bc(1) only accepts numbers that
use a period (**.**) as a radix point, regardless of the value of
**LC_NUMERIC**.
{{ A E H P EH EP HP EHP }}
This bc(1) supports error messages for different locales, and thus, it supports
**LC_MESSAGES**.
{{ end }}
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHORS
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
[2]: https://www.gnu.org/software/bc/
[3]: https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero
[4]: https://en.wikipedia.org/wiki/Unit_in_the_last_place
[5]: https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT
[6]: https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero
diff --git a/contrib/bc/manuals/bc/A.1 b/contrib/bc/manuals/bc/A.1
index da35e8c7eaee..d1e80769c855 100644
--- a/contrib/bc/manuals/bc/A.1
+++ b/contrib/bc/manuals/bc/A.1
@@ -1,2045 +1,2058 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "BC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "BC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH NAME
.PP
bc - arbitrary-precision decimal arithmetic language and calculator
.SH SYNOPSIS
.PP
\f[B]bc\f[R] [\f[B]-ghilPqsvVw\f[R]] [\f[B]\[en]global-stacks\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]mathlib\f[R]] [\f[B]\[en]no-prompt\f[R]]
[\f[B]\[en]quiet\f[R]] [\f[B]\[en]standard\f[R]] [\f[B]\[en]warn\f[R]]
[\f[B]\[en]version\f[R]] [\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
bc(1) is an interactive processor for a language first standardized in
1991 by POSIX.
(The current standard is
here (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).)
The language provides unlimited precision decimal arithmetic and is
somewhat C-like, but there are differences.
Such differences will be noted in this document.
.PP
After parsing and handling options, this bc(1) reads any files given on
the command line and executes them before reading from \f[B]stdin\f[R].
.PP
This bc(1) is a drop-in replacement for \f[I]any\f[R] bc(1), including
(and especially) the GNU bc(1).
It also has many extensions and extra features beyond other
implementations.
.SH OPTIONS
.PP
The following are the options that bc(1) accepts.
.TP
\f[B]-g\f[R], \f[B]\[en]global-stacks\f[R]
Turns the globals \f[B]ibase\f[R], \f[B]obase\f[R], \f[B]scale\f[R], and
\f[B]seed\f[R] into stacks.
.RS
.PP
This has the effect that a copy of the current value of all four are
pushed onto a stack for every function call, as well as popped when
every function returns.
This means that functions can assign to any and all of those globals
without worrying that the change will affect other functions.
Thus, a hypothetical function named \f[B]output(x,b)\f[R] that simply
printed \f[B]x\f[R] in base \f[B]b\f[R] could be written like this:
.IP
.nf
\f[C]
define void output(x, b) {
obase=b
x
}
\f[R]
.fi
.PP
instead of like this:
.IP
.nf
\f[C]
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
\f[R]
.fi
.PP
This makes writing functions much easier.
.PP
(\f[B]Note\f[R]: the function \f[B]output(x,b)\f[R] exists in the
extended math library.
See the \f[B]LIBRARY\f[R] section.)
.PP
However, since using this flag means that functions cannot set
\f[B]ibase\f[R], \f[B]obase\f[R], \f[B]scale\f[R], or \f[B]seed\f[R]
globally, functions that are made to do so cannot work anymore.
There are two possible use cases for that, and each has a solution.
.PP
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases.
Examples:
.IP
.nf
\f[C]
alias d2o=\[dq]bc -e ibase=A -e obase=8\[dq]
alias h2b=\[dq]bc -e ibase=G -e obase=2\[dq]
\f[R]
.fi
.PP
Second, if the purpose of a function is to set \f[B]ibase\f[R],
\f[B]obase\f[R], \f[B]scale\f[R], or \f[B]seed\f[R] globally for any
other purpose, it could be split into one to four functions (based on
how many globals it sets) and each of those functions could return the
desired value for a global.
.PP
For functions that set \f[B]seed\f[R], the value assigned to
\f[B]seed\f[R] is not propagated to parent functions.
This means that the sequence of pseudo-random numbers that they see will
not be the same sequence of pseudo-random numbers that any parent sees.
This is only the case once \f[B]seed\f[R] has been set.
.PP
If a function desires to not affect the sequence of pseudo-random
numbers of its parents, but wants to use the same \f[B]seed\f[R], it can
use the following line:
.IP
.nf
\f[C]
seed = seed
\f[R]
.fi
.PP
If the behavior of this option is desired for every run of bc(1), then
users could make sure to define \f[B]BC_ENV_ARGS\f[R] and include this
option (see the \f[B]ENVIRONMENT VARIABLES\f[R] section for more
details).
.PP
If \f[B]-s\f[R], \f[B]-w\f[R], or any equivalents are used, this option
is ignored.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-l\f[R], \f[B]\[en]mathlib\f[R]
Sets \f[B]scale\f[R] (see the \f[B]SYNTAX\f[R] section) to \f[B]20\f[R]
and loads the included math library and the extended math library before
running any code, including any expressions or files specified on the
command line.
.RS
.PP
To learn what is in the libraries, see the \f[B]LIBRARY\f[R] section.
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
Disables the prompt in TTY mode.
(The prompt is only enabled in TTY mode.
See the \f[B]TTY MODE\f[R] section) This is mostly for those users that
do not want a prompt or are not used to having them in bc(1).
Most of those users would want to put this option in
\f[B]BC_ENV_ARGS\f[R] (see the \f[B]ENVIRONMENT VARIABLES\f[R] section).
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-q\f[R], \f[B]\[en]quiet\f[R]
This option is for compatibility with the GNU
bc(1) (https://www.gnu.org/software/bc/); it is a no-op.
Without this option, GNU bc(1) prints a copyright header.
This bc(1) only prints the copyright header if one or more of the
\f[B]-v\f[R], \f[B]-V\f[R], or \f[B]\[en]version\f[R] options are given.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-s\f[R], \f[B]\[en]standard\f[R]
Process exactly the language defined by the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
and error if any extensions are used.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-w\f[R], \f[B]\[en]warn\f[R]
Like \f[B]-s\f[R] and \f[B]\[en]standard\f[R], except that warnings (and
not errors) are printed for non-standard extensions and execution
continues normally.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]BC_ENV_ARGS\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]bc >&-\f[R], it will quit with an error.
This is done so that bc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]bc 2>&-\f[R], it will quit with an error.
This is done so that bc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
The syntax for bc(1) programs is mostly C-like, with some differences.
This bc(1) follows the POSIX
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
which is a much more thorough resource for the language this bc(1)
accepts.
This section is meant to be a summary and a listing of all the
extensions to the standard.
.PP
In the sections below, \f[B]E\f[R] means expression, \f[B]S\f[R] means
statement, and \f[B]I\f[R] means identifier.
.PP
Identifiers (\f[B]I\f[R]) start with a lowercase letter and can be
followed by any number (up to \f[B]BC_NAME_MAX-1\f[R]) of lowercase
letters (\f[B]a-z\f[R]), digits (\f[B]0-9\f[R]), and underscores
(\f[B]_\f[R]).
The regex is \f[B][a-z][a-z0-9_]*\f[R].
Identifiers with more than one character (letter) are a
\f[B]non-portable extension\f[R].
.PP
\f[B]ibase\f[R] is a global variable determining how to interpret
constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
If the \f[B]-s\f[R] (\f[B]\[en]standard\f[R]) and \f[B]-w\f[R]
(\f[B]\[en]warn\f[R]) flags were not given on the command line, the max
allowable value for \f[B]ibase\f[R] is \f[B]36\f[R].
Otherwise, it is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in bc(1)
programs with the \f[B]maxibase()\f[R] built-in function.
.PP
\f[B]obase\f[R] is a global variable determining how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]BC_BASE_MAX\f[R] and
can be queried in bc(1) programs with the \f[B]maxobase()\f[R] built-in
function.
The min allowable value for \f[B]obase\f[R] is \f[B]0\f[R].
If \f[B]obase\f[R] is \f[B]0\f[R], values are output in scientific
notation, and if \f[B]obase\f[R] is \f[B]1\f[R], values are output in
engineering notation.
Otherwise, values are output in the specified base.
.PP
Outputting in scientific and engineering notations are \f[B]non-portable
extensions\f[R].
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a global variable that sets the precision of any operations, with
exceptions.
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] is \f[B]BC_SCALE_MAX\f[R]
and can be queried in bc(1) programs with the \f[B]maxscale()\f[R]
built-in function.
.PP
bc(1) has both \f[I]global\f[R] variables and \f[I]local\f[R] variables.
All \f[I]local\f[R] variables are local to the function; they are
parameters or are introduced in the \f[B]auto\f[R] list of a function
(see the \f[B]FUNCTIONS\f[R] section).
If a variable is accessed which is not a parameter or in the
\f[B]auto\f[R] list, it is assumed to be \f[I]global\f[R].
If a parent function has a \f[I]local\f[R] variable version of a
variable that a child function considers \f[I]global\f[R], the value of
that \f[I]global\f[R] variable in the child function is the value of the
variable in the parent function, not the value of the actual
\f[I]global\f[R] variable.
.PP
All of the above applies to arrays as well.
.PP
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence
operator is an assignment operator \f[I]and\f[R] the expression is
notsurrounded by parentheses.
.PP
The value that is printed is also assigned to the special variable
\f[B]last\f[R].
A single dot (\f[B].\f[R]) may also be used as a synonym for
\f[B]last\f[R].
These are \f[B]non-portable extensions\f[R].
.PP
Either semicolons or newlines may separate statements.
.SS Comments
.PP
There are two kinds of comments:
.IP "1." 3
Block comments are enclosed in \f[B]/*\f[R] and \f[B]*/\f[R].
.IP "2." 3
Line comments go from \f[B]#\f[R] until, and not including, the next
newline.
This is a \f[B]non-portable extension\f[R].
.SS Named Expressions
.PP
The following are named expressions in bc(1):
.IP "1." 3
Variables: \f[B]I\f[R]
.IP "2." 3
Array Elements: \f[B]I[E]\f[R]
.IP "3." 3
\f[B]ibase\f[R]
.IP "4." 3
\f[B]obase\f[R]
.IP "5." 3
\f[B]scale\f[R]
.IP "6." 3
\f[B]seed\f[R]
.IP "7." 3
\f[B]last\f[R] or a single dot (\f[B].\f[R])
.PP
Numbers 6 and 7 are \f[B]non-portable extensions\f[R].
.PP
The meaning of \f[B]seed\f[R] is dependent on the current pseudo-random
number generator but is guaranteed to not change except for new major
versions.
.PP
The \f[I]scale\f[R] and sign of the value may be significant.
.PP
If a previously used \f[B]seed\f[R] value is assigned to \f[B]seed\f[R]
and used again, the pseudo-random number generator is guaranteed to
produce the same sequence of pseudo-random numbers as it did when the
\f[B]seed\f[R] value was previously used.
.PP
The exact value assigned to \f[B]seed\f[R] is not guaranteed to be
returned if \f[B]seed\f[R] is queried again immediately.
However, if \f[B]seed\f[R] \f[I]does\f[R] return a different value, both
values, when assigned to \f[B]seed\f[R], are guaranteed to produce the
same sequence of pseudo-random numbers.
This means that certain values assigned to \f[B]seed\f[R] will
\f[I]not\f[R] produce unique sequences of pseudo-random numbers.
The value of \f[B]seed\f[R] will change after any use of the
\f[B]rand()\f[R] and \f[B]irand(E)\f[R] operands (see the
\f[I]Operands\f[R] subsection below), except if the parameter passed to
\f[B]irand(E)\f[R] is \f[B]0\f[R], \f[B]1\f[R], or negative.
.PP
There is no limit to the length (number of significant decimal digits)
or \f[I]scale\f[R] of the value that can be assigned to \f[B]seed\f[R].
.PP
Variables and arrays do not interfere; users can have arrays named the
same as variables.
This also applies to functions (see the \f[B]FUNCTIONS\f[R] section), so
a user can have a variable, array, and function that all have the same
name, and they will not shadow each other, whether inside of functions
or not.
.PP
Named expressions are required as the operand of
\f[B]increment\f[R]/\f[B]decrement\f[R] operators and as the left side
of \f[B]assignment\f[R] operators (see the \f[I]Operators\f[R]
subsection).
.SS Operands
.PP
The following are valid operands in bc(1):
.IP " 1." 4
Numbers (see the \f[I]Numbers\f[R] subsection below).
.IP " 2." 4
Array indices (\f[B]I[E]\f[R]).
.IP " 3." 4
\f[B](E)\f[R]: The value of \f[B]E\f[R] (used to change precedence).
.IP " 4." 4
\f[B]sqrt(E)\f[R]: The square root of \f[B]E\f[R].
\f[B]E\f[R] must be non-negative.
.IP " 5." 4
\f[B]length(E)\f[R]: The number of significant decimal digits in
\f[B]E\f[R].
.IP " 6." 4
\f[B]length(I[])\f[R]: The number of elements in the array \f[B]I\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 7." 4
\f[B]scale(E)\f[R]: The \f[I]scale\f[R] of \f[B]E\f[R].
.IP " 8." 4
\f[B]abs(E)\f[R]: The absolute value of \f[B]E\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 9." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a non-\f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.IP "10." 4
\f[B]read()\f[R]: Reads a line from \f[B]stdin\f[R] and uses that as an
expression.
The result of that expression is the result of the \f[B]read()\f[R]
operand.
This is a \f[B]non-portable extension\f[R].
.IP "11." 4
\f[B]maxibase()\f[R]: The max allowable \f[B]ibase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "12." 4
\f[B]maxobase()\f[R]: The max allowable \f[B]obase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "13." 4
\f[B]maxscale()\f[R]: The max allowable \f[B]scale\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "14." 4
\f[B]rand()\f[R]: A pseudo-random integer between \f[B]0\f[R]
(inclusive) and \f[B]BC_RAND_MAX\f[R] (inclusive).
Using this operand will change the value of \f[B]seed\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "15." 4
\f[B]irand(E)\f[R]: A pseudo-random integer between \f[B]0\f[R]
(inclusive) and the value of \f[B]E\f[R] (exclusive).
If \f[B]E\f[R] is negative or is a non-integer (\f[B]E\f[R]\[cq]s
\f[I]scale\f[R] is not \f[B]0\f[R]), an error is raised, and bc(1)
resets (see the \f[B]RESET\f[R] section) while \f[B]seed\f[R] remains
unchanged.
If \f[B]E\f[R] is larger than \f[B]BC_RAND_MAX\f[R], the higher bound is
honored by generating several pseudo-random integers, multiplying them
by appropriate powers of \f[B]BC_RAND_MAX+1\f[R], and adding them
together.
Thus, the size of integer that can be generated with this operand is
unbounded.
Using this operand will change the value of \f[B]seed\f[R], unless the
value of \f[B]E\f[R] is \f[B]0\f[R] or \f[B]1\f[R].
In that case, \f[B]0\f[R] is returned, and \f[B]seed\f[R] is
\f[I]not\f[R] changed.
This is a \f[B]non-portable extension\f[R].
.IP "16." 4
\f[B]maxrand()\f[R]: The max integer returned by \f[B]rand()\f[R].
This is a \f[B]non-portable extension\f[R].
.PP
The integers generated by \f[B]rand()\f[R] and \f[B]irand(E)\f[R] are
guaranteed to be as unbiased as possible, subject to the limitations of
the pseudo-random number generator.
.PP
\f[B]Note\f[R]: The values returned by the pseudo-random number
generator with \f[B]rand()\f[R] and \f[B]irand(E)\f[R] are guaranteed to
\f[I]NOT\f[R] be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator.
However, they \f[I]are\f[R] guaranteed to be reproducible with identical
\f[B]seed\f[R] values.
This means that the pseudo-random values from bc(1) should only be used
where a reproducible stream of pseudo-random numbers is
\f[I]ESSENTIAL\f[R].
In any other case, use a non-seeded pseudo-random number generator.
.SS Numbers
.PP
Numbers are strings made up of digits, uppercase letters, and at most
\f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]BC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]Z\f[R] alone always equals decimal \f[B]35\f[R].
.PP
In addition, bc(1) accepts numbers in scientific notation.
These have the form \f[B]<number>e<integer>\f[R].
The exponent (the portion after the \f[B]e\f[R]) must be an integer.
An example is \f[B]1.89237e9\f[R], which is equal to
\f[B]1892370000\f[R].
Negative exponents are also allowed, so \f[B]4.2890e-3\f[R] is equal to
\f[B]0.0042890\f[R].
.PP
Using scientific notation is an error or warning if the \f[B]-s\f[R] or
\f[B]-w\f[R], respectively, command-line options (or equivalents) are
given.
.PP
\f[B]WARNING\f[R]: Both the number and the exponent in scientific
notation are interpreted according to the current \f[B]ibase\f[R], but
the number is still multiplied by \f[B]10\[ha]exponent\f[R] regardless
of the current \f[B]ibase\f[R].
For example, if \f[B]ibase\f[R] is \f[B]16\f[R] and bc(1) is given the
number string \f[B]FFeA\f[R], the resulting decimal number will be
\f[B]2550000000000\f[R], and if bc(1) is given the number string
\f[B]10e-4\f[R], the resulting decimal number will be \f[B]0.0016\f[R].
.PP
Accepting input as scientific notation is a \f[B]non-portable
extension\f[R].
.SS Operators
.PP
The following arithmetic and logical operators can be used.
They are listed in order of decreasing precedence.
Operators in the same group have the same precedence.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
Type: Prefix and Postfix
.RS
.PP
Associativity: None
.PP
Description: \f[B]increment\f[R], \f[B]decrement\f[R]
.RE
.TP
\f[B]-\f[R] \f[B]!\f[R]
Type: Prefix
.RS
.PP
Associativity: None
.PP
Description: \f[B]negation\f[R], \f[B]boolean not\f[R]
.RE
.TP
\f[B]$\f[R]
Type: Postfix
.RS
.PP
Associativity: None
.PP
Description: \f[B]truncation\f[R]
.RE
.TP
\f[B]\[at]\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]set precision\f[R]
.RE
.TP
\f[B]\[ha]\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]power\f[R]
.RE
.TP
\f[B]*\f[R] \f[B]/\f[R] \f[B]%\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]multiply\f[R], \f[B]divide\f[R], \f[B]modulus\f[R]
.RE
.TP
\f[B]+\f[R] \f[B]-\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]add\f[R], \f[B]subtract\f[R]
.RE
.TP
\f[B]<<\f[R] \f[B]>>\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]shift left\f[R], \f[B]shift right\f[R]
.RE
.TP
\f[B]=\f[R] \f[B]<<=\f[R] \f[B]>>=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R] \f[B]\[at]=\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]assignment\f[R]
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]relational\f[R]
.RE
.TP
\f[B]&&\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean and\f[R]
.RE
.TP
\f[B]||\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean or\f[R]
.RE
.PP
The operators will be described in more detail below.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
The prefix and postfix \f[B]increment\f[R] and \f[B]decrement\f[R]
operators behave exactly like they would in C.
They require a named expression (see the \f[I]Named Expressions\f[R]
subsection) as an operand.
.RS
.PP
The prefix versions of these operators are more efficient; use them
where possible.
.RE
.TP
\f[B]-\f[R]
The \f[B]negation\f[R] operator returns \f[B]0\f[R] if a user attempts
to negate any expression with the value \f[B]0\f[R].
Otherwise, a copy of the expression with its sign flipped is returned.
.TP
\f[B]!\f[R]
The \f[B]boolean not\f[R] operator returns \f[B]1\f[R] if the expression
is \f[B]0\f[R], or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]$\f[R]
The \f[B]truncation\f[R] operator returns a copy of the given expression
with all of its \f[I]scale\f[R] removed.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[at]\f[R]
The \f[B]set precision\f[R] operator takes two expressions and returns a
copy of the first with its \f[I]scale\f[R] equal to the value of the
second expression.
That could either mean that the number is returned without change (if
the \f[I]scale\f[R] of the first expression matches the value of the
second expression), extended (if it is less), or truncated (if it is
more).
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]) and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The \f[B]power\f[R] operator (not the \f[B]exclusive or\f[R] operator,
as it would be in C) takes two expressions and raises the first to the
power of the value of the second.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]), and if it
is negative, the first value must be non-zero.
.RE
.TP
\f[B]*\f[R]
The \f[B]multiply\f[R] operator takes two expressions, multiplies them,
and returns the product.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The \f[B]divide\f[R] operator takes two expressions, divides them, and
returns the quotient.
The \f[I]scale\f[R] of the result shall be the value of \f[B]scale\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]%\f[R]
The \f[B]modulus\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and evaluates them by 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R] and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]+\f[R]
The \f[B]add\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the sum, with a \f[I]scale\f[R] equal to the
max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]-\f[R]
The \f[B]subtract\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the difference, with a \f[I]scale\f[R] equal to
the max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]<<\f[R]
The \f[B]left shift\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns a copy of the value of \f[B]a\f[R] with its
decimal point moved \f[B]b\f[R] places to the right.
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]) and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]>>\f[R]
The \f[B]right shift\f[R] operator takes two expressions, \f[B]a\f[R]
and \f[B]b\f[R], and returns a copy of the value of \f[B]a\f[R] with its
decimal point moved \f[B]b\f[R] places to the left.
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]) and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]=\f[R] \f[B]<<=\f[R] \f[B]>>=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R] \f[B]\[at]=\f[R]
The \f[B]assignment\f[R] operators take two expressions, \f[B]a\f[R] and
\f[B]b\f[R] where \f[B]a\f[R] is a named expression (see the \f[I]Named
Expressions\f[R] subsection).
.RS
.PP
For \f[B]=\f[R], \f[B]b\f[R] is copied and the result is assigned to
\f[B]a\f[R].
For all others, \f[B]a\f[R] and \f[B]b\f[R] are applied as operands to
the corresponding arithmetic operator and the result is assigned to
\f[B]a\f[R].
.PP
The \f[B]assignment\f[R] operators that correspond to operators that are
extensions are themselves \f[B]non-portable extensions\f[R].
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
The \f[B]relational\f[R] operators compare two expressions, \f[B]a\f[R]
and \f[B]b\f[R], and if the relation holds, according to C language
semantics, the result is \f[B]1\f[R].
Otherwise, it is \f[B]0\f[R].
.RS
.PP
Note that unlike in C, these operators have a lower precedence than the
\f[B]assignment\f[R] operators, which means that \f[B]a=b>c\f[R] is
interpreted as \f[B](a=b)>c\f[R].
.PP
Also, unlike the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
requires, these operators can appear anywhere any other expressions can
be used.
This allowance is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]&&\f[R]
The \f[B]boolean and\f[R] operator takes two expressions and returns
\f[B]1\f[R] if both expressions are non-zero, \f[B]0\f[R] otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]||\f[R]
The \f[B]boolean or\f[R] operator takes two expressions and returns
\f[B]1\f[R] if one of the expressions is non-zero, \f[B]0\f[R]
otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Statements
.PP
The following items are statements:
.IP " 1." 4
\f[B]E\f[R]
.IP " 2." 4
\f[B]{\f[R] \f[B]S\f[R] \f[B];\f[R] \&... \f[B];\f[R] \f[B]S\f[R]
\f[B]}\f[R]
.IP " 3." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 4." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
\f[B]else\f[R] \f[B]S\f[R]
.IP " 5." 4
\f[B]while\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 6." 4
\f[B]for\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B];\f[R] \f[B]E\f[R]
\f[B];\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 7." 4
An empty statement
.IP " 8." 4
\f[B]break\f[R]
.IP " 9." 4
\f[B]continue\f[R]
.IP "10." 4
\f[B]quit\f[R]
.IP "11." 4
\f[B]halt\f[R]
.IP "12." 4
\f[B]limits\f[R]
.IP "13." 4
A string of characters, enclosed in double quotes
.IP "14." 4
\f[B]print\f[R] \f[B]E\f[R] \f[B],\f[R] \&... \f[B],\f[R] \f[B]E\f[R]
.IP "15." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a \f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.PP
Numbers 4, 9, 11, 12, 14, and 15 are \f[B]non-portable extensions\f[R].
.PP
Also, as a \f[B]non-portable extension\f[R], any or all of the
expressions in the header of a for loop may be omitted.
If the condition (second expression) is omitted, it is assumed to be a
constant \f[B]1\f[R].
.PP
The \f[B]break\f[R] statement causes a loop to stop iterating and resume
execution immediately following a loop.
This is only allowed in loops.
.PP
The \f[B]continue\f[R] statement causes a loop iteration to stop early
and returns to the start of the loop, including testing the loop
condition.
This is only allowed in loops.
.PP
The \f[B]if\f[R] \f[B]else\f[R] statement does the same thing as in C.
.PP
The \f[B]quit\f[R] statement causes bc(1) to quit, even if it is on a
branch that will not be executed (it is a compile-time command).
.PP
The \f[B]halt\f[R] statement causes bc(1) to quit, if it is executed.
(Unlike \f[B]quit\f[R] if it is on a branch of an \f[B]if\f[R] statement
that is not executed, bc(1) does not quit.)
.PP
The \f[B]limits\f[R] statement prints the limits that this bc(1) is
subject to.
This is like the \f[B]quit\f[R] statement in that it is a compile-time
command.
.PP
An expression by itself is evaluated and printed, followed by a newline.
.PP
Both scientific notation and engineering notation are available for
printing the results of expressions.
Scientific notation is activated by assigning \f[B]0\f[R] to
\f[B]obase\f[R], and engineering notation is activated by assigning
\f[B]1\f[R] to \f[B]obase\f[R].
To deactivate them, just assign a different value to \f[B]obase\f[R].
.PP
Scientific notation and engineering notation are disabled if bc(1) is
run with either the \f[B]-s\f[R] or \f[B]-w\f[R] command-line options
(or equivalents).
.PP
Printing numbers in scientific notation and/or engineering notation is a
\f[B]non-portable extension\f[R].
.SS Print Statement
.PP
The \[lq]expressions\[rq] in a \f[B]print\f[R] statement may also be
strings.
If they are, there are backslash escape sequences that are interpreted
specially.
What those sequences are, and what they cause to be printed, are shown
below:
.PP
.TS
tab(@);
l l.
T{
\f[B]\[rs]a\f[R]
T}@T{
\f[B]\[rs]a\f[R]
T}
T{
\f[B]\[rs]b\f[R]
T}@T{
\f[B]\[rs]b\f[R]
T}
T{
\f[B]\[rs]\[rs]\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]e\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]f\f[R]
T}@T{
\f[B]\[rs]f\f[R]
T}
T{
\f[B]\[rs]n\f[R]
T}@T{
\f[B]\[rs]n\f[R]
T}
T{
\f[B]\[rs]q\f[R]
T}@T{
\f[B]\[dq]\f[R]
T}
T{
\f[B]\[rs]r\f[R]
T}@T{
\f[B]\[rs]r\f[R]
T}
T{
\f[B]\[rs]t\f[R]
T}@T{
\f[B]\[rs]t\f[R]
T}
.TE
.PP
Any other character following a backslash causes the backslash and
character to be printed as-is.
.PP
Any non-string expression in a print statement shall be assigned to
\f[B]last\f[R], like any other expression that is printed.
.SS Order of Evaluation
.PP
All expressions in a statment are evaluated left to right, except as
necessary to maintain order of operations.
This means, for example, assuming that \f[B]i\f[R] is equal to
\f[B]0\f[R], in the expression
.IP
.nf
\f[C]
a[i++] = i++
\f[R]
.fi
.PP
the first (or 0th) element of \f[B]a\f[R] is set to \f[B]1\f[R], and
\f[B]i\f[R] is equal to \f[B]2\f[R] at the end of the expression.
.PP
This includes function arguments.
Thus, assuming \f[B]i\f[R] is equal to \f[B]0\f[R], this means that in
the expression
.IP
.nf
\f[C]
x(i++, i++)
\f[R]
.fi
.PP
the first argument passed to \f[B]x()\f[R] is \f[B]0\f[R], and the
second argument is \f[B]1\f[R], while \f[B]i\f[R] is equal to
\f[B]2\f[R] before the function starts executing.
.SH FUNCTIONS
.PP
Function definitions are as follows:
.IP
.nf
\f[C]
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
\f[R]
.fi
.PP
Any \f[B]I\f[R] in the parameter list or \f[B]auto\f[R] list may be
replaced with \f[B]I[]\f[R] to make a parameter or \f[B]auto\f[R] var an
array, and any \f[B]I\f[R] in the parameter list may be replaced with
\f[B]*I[]\f[R] to make a parameter an array reference.
Callers of functions that take array references should not put an
asterisk in the call; they must be called with just \f[B]I[]\f[R] like
normal array parameters and will be automatically converted into
references.
.PP
As a \f[B]non-portable extension\f[R], the opening brace of a
\f[B]define\f[R] statement may appear on the next line.
.PP
As a \f[B]non-portable extension\f[R], the return statement may also be
in one of the following forms:
.IP "1." 3
\f[B]return\f[R]
.IP "2." 3
\f[B]return\f[R] \f[B](\f[R] \f[B])\f[R]
.IP "3." 3
\f[B]return\f[R] \f[B]E\f[R]
.PP
The first two, or not specifying a \f[B]return\f[R] statement, is
equivalent to \f[B]return (0)\f[R], unless the function is a
\f[B]void\f[R] function (see the \f[I]Void Functions\f[R] subsection
below).
.SS Void Functions
.PP
Functions can also be \f[B]void\f[R] functions, defined as follows:
.IP
.nf
\f[C]
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
\f[R]
.fi
.PP
They can only be used as standalone expressions, where such an
expression would be printed alone, except in a print statement.
.PP
Void functions can only use the first two \f[B]return\f[R] statements
listed above.
They can also omit the return statement entirely.
.PP
The word \[lq]void\[rq] is not treated as a keyword; it is still
possible to have variables, arrays, and functions named \f[B]void\f[R].
The word \[lq]void\[rq] is only treated specially right after the
\f[B]define\f[R] keyword.
.PP
This is a \f[B]non-portable extension\f[R].
.SS Array References
.PP
For any array in the parameter list, if the array is declared in the
form
.IP
.nf
\f[C]
*I[]
\f[R]
.fi
.PP
it is a \f[B]reference\f[R].
Any changes to the array in the function are reflected, when the
function returns, to the array that was passed in.
.PP
Other than this, all function arguments are passed by value.
.PP
This is a \f[B]non-portable extension\f[R].
.SH LIBRARY
.PP
All of the functions below, including the functions in the extended math
library (see the \f[I]Extended Library\f[R] subsection below), are
available when the \f[B]-l\f[R] or \f[B]\[en]mathlib\f[R] command-line
flags are given, except that the extended math library is not available
when the \f[B]-s\f[R] option, the \f[B]-w\f[R] option, or equivalents
are given.
.SS Standard Library
.PP
The
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
defines the following functions for the math library:
.TP
\f[B]s(x)\f[R]
Returns the sine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]c(x)\f[R]
Returns the cosine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]a(x)\f[R]
Returns the arctangent of \f[B]x\f[R], in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]l(x)\f[R]
Returns the natural logarithm of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]e(x)\f[R]
Returns the mathematical constant \f[B]e\f[R] raised to the power of
\f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]j(x, n)\f[R]
Returns the bessel integer order \f[B]n\f[R] (truncated) of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.SS Extended Library
.PP
The extended library is \f[I]not\f[R] loaded when the
\f[B]-s\f[R]/\f[B]\[en]standard\f[R] or \f[B]-w\f[R]/\f[B]\[en]warn\f[R]
options are given since they are not part of the library defined by the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).
.PP
The extended library is a \f[B]non-portable extension\f[R].
.TP
\f[B]p(x, y)\f[R]
Calculates \f[B]x\f[R] to the power of \f[B]y\f[R], even if \f[B]y\f[R]
is not an integer, and returns the result to the current
\f[B]scale\f[R].
.RS
.PP
It is an error if \f[B]y\f[R] is negative and \f[B]x\f[R] is
\f[B]0\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]r(x, p)\f[R]
Returns \f[B]x\f[R] rounded to \f[B]p\f[R] decimal places according to
the rounding mode round half away from
\f[B]0\f[R] (https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero).
.TP
\f[B]ceil(x, p)\f[R]
Returns \f[B]x\f[R] rounded to \f[B]p\f[R] decimal places according to
the rounding mode round away from
\f[B]0\f[R] (https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero).
.TP
\f[B]f(x)\f[R]
Returns the factorial of the truncated absolute value of \f[B]x\f[R].
.TP
\f[B]perm(n, k)\f[R]
Returns the permutation of the truncated absolute value of \f[B]n\f[R]
of the truncated absolute value of \f[B]k\f[R], if \f[B]k <= n\f[R].
If not, it returns \f[B]0\f[R].
.TP
\f[B]comb(n, k)\f[R]
Returns the combination of the truncated absolute value of \f[B]n\f[R]
of the truncated absolute value of \f[B]k\f[R], if \f[B]k <= n\f[R].
If not, it returns \f[B]0\f[R].
.TP
\f[B]l2(x)\f[R]
Returns the logarithm base \f[B]2\f[R] of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]l10(x)\f[R]
Returns the logarithm base \f[B]10\f[R] of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]log(x, b)\f[R]
Returns the logarithm base \f[B]b\f[R] of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]cbrt(x)\f[R]
Returns the cube root of \f[B]x\f[R].
.TP
\f[B]root(x, n)\f[R]
Calculates the truncated value of \f[B]n\f[R], \f[B]r\f[R], and returns
the \f[B]r\f[R]th root of \f[B]x\f[R] to the current \f[B]scale\f[R].
.RS
.PP
If \f[B]r\f[R] is \f[B]0\f[R] or negative, this raises an error and
causes bc(1) to reset (see the \f[B]RESET\f[R] section).
It also raises an error and causes bc(1) to reset if \f[B]r\f[R] is even
and \f[B]x\f[R] is negative.
.RE
.TP
\f[B]pi(p)\f[R]
Returns \f[B]pi\f[R] to \f[B]p\f[R] decimal places.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]t(x)\f[R]
Returns the tangent of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]a2(y, x)\f[R]
Returns the arctangent of \f[B]y/x\f[R], in radians.
If both \f[B]y\f[R] and \f[B]x\f[R] are equal to \f[B]0\f[R], it raises
an error and causes bc(1) to reset (see the \f[B]RESET\f[R] section).
Otherwise, if \f[B]x\f[R] is greater than \f[B]0\f[R], it returns
\f[B]a(y/x)\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is greater than
or equal to \f[B]0\f[R], it returns \f[B]a(y/x)+pi\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]a(y/x)-pi\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is greater than
\f[B]0\f[R], it returns \f[B]pi/2\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]-pi/2\f[R].
.RS
.PP
This function is the same as the \f[B]atan2()\f[R] function in many
programming languages.
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]sin(x)\f[R]
Returns the sine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is an alias of \f[B]s(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]cos(x)\f[R]
Returns the cosine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is an alias of \f[B]c(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]tan(x)\f[R]
Returns the tangent of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
If \f[B]x\f[R] is equal to \f[B]1\f[R] or \f[B]-1\f[R], this raises an
error and causes bc(1) to reset (see the \f[B]RESET\f[R] section).
.PP
This is an alias of \f[B]t(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]atan(x)\f[R]
Returns the arctangent of \f[B]x\f[R], in radians.
.RS
.PP
This is an alias of \f[B]a(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]atan2(y, x)\f[R]
Returns the arctangent of \f[B]y/x\f[R], in radians.
If both \f[B]y\f[R] and \f[B]x\f[R] are equal to \f[B]0\f[R], it raises
an error and causes bc(1) to reset (see the \f[B]RESET\f[R] section).
Otherwise, if \f[B]x\f[R] is greater than \f[B]0\f[R], it returns
\f[B]a(y/x)\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is greater than
or equal to \f[B]0\f[R], it returns \f[B]a(y/x)+pi\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]a(y/x)-pi\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is greater than
\f[B]0\f[R], it returns \f[B]pi/2\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]-pi/2\f[R].
.RS
.PP
This function is the same as the \f[B]atan2()\f[R] function in many
programming languages.
.PP
This is an alias of \f[B]a2(y, x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]r2d(x)\f[R]
Converts \f[B]x\f[R] from radians to degrees and returns the result.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]d2r(x)\f[R]
Converts \f[B]x\f[R] from degrees to radians and returns the result.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]frand(p)\f[R]
Generates a pseudo-random number between \f[B]0\f[R] (inclusive) and
\f[B]1\f[R] (exclusive) with the number of decimal digits after the
decimal point equal to the truncated absolute value of \f[B]p\f[R].
If \f[B]p\f[R] is not \f[B]0\f[R], then calling this function will
change the value of \f[B]seed\f[R].
If \f[B]p\f[R] is \f[B]0\f[R], then \f[B]0\f[R] is returned, and
\f[B]seed\f[R] is \f[I]not\f[R] changed.
.TP
\f[B]ifrand(i, p)\f[R]
Generates a pseudo-random number that is between \f[B]0\f[R] (inclusive)
and the truncated absolute value of \f[B]i\f[R] (exclusive) with the
number of decimal digits after the decimal point equal to the truncated
absolute value of \f[B]p\f[R].
If the absolute value of \f[B]i\f[R] is greater than or equal to
\f[B]2\f[R], and \f[B]p\f[R] is not \f[B]0\f[R], then calling this
function will change the value of \f[B]seed\f[R]; otherwise, \f[B]0\f[R]
is returned and \f[B]seed\f[R] is not changed.
.TP
\f[B]srand(x)\f[R]
Returns \f[B]x\f[R] with its sign flipped with probability
\f[B]0.5\f[R].
In other words, it randomizes the sign of \f[B]x\f[R].
.TP
\f[B]brand()\f[R]
Returns a random boolean value (either \f[B]0\f[R] or \f[B]1\f[R]).
.TP
\f[B]ubytes(x)\f[R]
Returns the numbers of unsigned integer bytes required to hold the
truncated absolute value of \f[B]x\f[R].
.TP
\f[B]sbytes(x)\f[R]
Returns the numbers of signed, two\[cq]s-complement integer bytes
required to hold the truncated value of \f[B]x\f[R].
.TP
\f[B]hex(x)\f[R]
Outputs the hexadecimal (base \f[B]16\f[R]) representation of
\f[B]x\f[R].
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]binary(x)\f[R]
Outputs the binary (base \f[B]2\f[R]) representation of \f[B]x\f[R].
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]output(x, b)\f[R]
Outputs the base \f[B]b\f[R] representation of \f[B]x\f[R].
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in as few power of two bytes as possible.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or is negative, an error message is
printed instead, but bc(1) is not reset (see the \f[B]RESET\f[R]
section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in as few power of two bytes as
possible.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, an error message is printed instead,
but bc(1) is not reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uintn(x, n)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]n\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]n\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]intn(x, n)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]n\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]n\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint8(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]1\f[R] byte.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]1\f[R] byte, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int8(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]1\f[R] byte.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]1\f[R] byte, an
error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint16(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]2\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]2\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int16(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]2\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]2\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint32(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]4\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]4\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int32(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]4\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]4\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint64(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]8\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]8\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int64(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]8\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]8\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]hex_uint(x, n)\f[R]
Outputs the representation of the truncated absolute value of
\f[B]x\f[R] as an unsigned integer in hexadecimal using \f[B]n\f[R]
bytes.
Not all of the value will be output if \f[B]n\f[R] is too small.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]binary_uint(x, n)\f[R]
Outputs the representation of the truncated absolute value of
\f[B]x\f[R] as an unsigned integer in binary using \f[B]n\f[R] bytes.
Not all of the value will be output if \f[B]n\f[R] is too small.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]output_uint(x, n)\f[R]
Outputs the representation of the truncated absolute value of
\f[B]x\f[R] as an unsigned integer in the current \f[B]obase\f[R] (see
the \f[B]SYNTAX\f[R] section) using \f[B]n\f[R] bytes.
Not all of the value will be output if \f[B]n\f[R] is too small.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]output_byte(x, i)\f[R]
Outputs byte \f[B]i\f[R] of the truncated absolute value of \f[B]x\f[R],
where \f[B]0\f[R] is the least significant byte and \f[B]number_of_bytes
- 1\f[R] is the most significant byte.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.SS Transcendental Functions
.PP
All transcendental functions can return slightly inaccurate results (up
to 1 ULP (https://en.wikipedia.org/wiki/Unit_in_the_last_place)).
This is unavoidable, and this
article (https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT) explains
why it is impossible and unnecessary to calculate exact results for the
transcendental functions.
.PP
Because of the possible inaccuracy, I recommend that users call those
functions with the precision (\f[B]scale\f[R]) set to at least 1 higher
than is necessary.
If exact results are \f[I]absolutely\f[R] required, users can double the
precision (\f[B]scale\f[R]) and then truncate.
.PP
The transcendental functions in the standard math library are:
.IP \[bu] 2
\f[B]s(x)\f[R]
.IP \[bu] 2
\f[B]c(x)\f[R]
.IP \[bu] 2
\f[B]a(x)\f[R]
.IP \[bu] 2
\f[B]l(x)\f[R]
.IP \[bu] 2
\f[B]e(x)\f[R]
.IP \[bu] 2
\f[B]j(x, n)\f[R]
.PP
The transcendental functions in the extended math library are:
.IP \[bu] 2
\f[B]l2(x)\f[R]
.IP \[bu] 2
\f[B]l10(x)\f[R]
.IP \[bu] 2
\f[B]log(x, b)\f[R]
.IP \[bu] 2
\f[B]pi(p)\f[R]
.IP \[bu] 2
\f[B]t(x)\f[R]
.IP \[bu] 2
\f[B]a2(y, x)\f[R]
.IP \[bu] 2
\f[B]sin(x)\f[R]
.IP \[bu] 2
\f[B]cos(x)\f[R]
.IP \[bu] 2
\f[B]tan(x)\f[R]
.IP \[bu] 2
\f[B]atan(x)\f[R]
.IP \[bu] 2
\f[B]atan2(y, x)\f[R]
.IP \[bu] 2
\f[B]r2d(x)\f[R]
.IP \[bu] 2
\f[B]d2r(x)\f[R]
.SH RESET
.PP
When bc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any functions that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all functions returned) is skipped.
.PP
Thus, when bc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.PP
Note that this reset behavior is different from the GNU bc(1), which
attempts to start executing the statement right after the one that
caused an error.
.SH PERFORMANCE
.PP
Most bc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This bc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]BC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]BC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]BC_BASE_DIGS\f[R].
.PP
The actual values of \f[B]BC_LONG_BIT\f[R] and \f[B]BC_BASE_DIGS\f[R]
can be queried with the \f[B]limits\f[R] statement.
.PP
In addition, this bc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]BC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on bc(1):
.TP
\f[B]BC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
bc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]BC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]BC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]BC_BASE_DIGS\f[R].
.TP
\f[B]BC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]BC_BASE_POW\f[R].
.TP
\f[B]BC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]BC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_RAND_MAX\f[R]
The maximum integer (inclusive) returned by the \f[B]rand()\f[R]
operand.
Set at \f[B]2\[ha]BC_LONG_BIT-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]BC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
The actual values can be queried with the \f[B]limits\f[R] statement.
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
bc(1) recognizes the following environment variables:
.TP
\f[B]POSIXLY_CORRECT\f[R]
If this variable exists (no matter the contents), bc(1) behaves as if
the \f[B]-s\f[R] option was given.
.TP
\f[B]BC_ENV_ARGS\f[R]
This is another way to give command-line arguments to bc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]BC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
.RS
.PP
The code that parses \f[B]BC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some bc file.bc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]bc\[dq] file.bc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]BC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]BC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), bc(1) will output lines to that length,
including the backslash (\f[B]\[rs]\f[R]).
The default line length is \f[B]70\f[R].
.SH EXIT STATUS
.PP
bc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, using a negative number as a bound for the
pseudo-random number generator, attempting to convert a negative number
to a hardware integer, overflow when converting a number to a hardware
integer, and attempting to use a non-integer where an integer is
required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]), places (\f[B]\[at]\f[R]), left shift
(\f[B]<<\f[R]), and right shift (\f[B]>>\f[R]) operators and their
corresponding assignment operators.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, using a token
where it is invalid, giving an invalid expression, giving an invalid
print statement, giving an invalid function definition, attempting to
assign to an expression that is not a named expression (see the
\f[I]Named Expressions\f[R] subsection of the \f[B]SYNTAX\f[R] section),
giving an invalid \f[B]auto\f[R] list, having a duplicate
\f[B]auto\f[R]/function parameter, failing to find the end of a code
block, attempting to return a value from a \f[B]void\f[R] function,
attempting to use a variable as a reference, and using any extensions
when the option \f[B]-s\f[R] or any equivalents were given.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a \f[B]void\f[R] function call as a value in an
expression.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (bc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, bc(1)
always exits and returns \f[B]4\f[R], no matter what mode bc(1) is in.
.PP
The other statuses will only be returned when bc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
bc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Per the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, bc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, bc(1) turns on \[lq]TTY mode.\[rq]
.PP
TTY mode is required for history to be enabled (see the \f[B]COMMAND
LINE HISTORY\f[R] section).
It is also required to enable special handling for \f[B]SIGINT\f[R]
signals.
.PP
The prompt is enabled in TTY mode.
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause bc(1) to stop execution of the
current input.
If bc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If bc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If bc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to bc(1) as it is
executing a file, it can seem as though bc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause bc(1) to clean up and
exit, and it uses the default handler for all other signals.
The one exception is \f[B]SIGHUP\f[R]; in that case, when bc(1) is in
TTY mode, a \f[B]SIGHUP\f[R] will cause bc(1) to clean up and exit.
.SH COMMAND LINE HISTORY
.PP
bc(1) supports interactive command-line editing.
If bc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), history is
enabled.
Previous lines can be recalled and edited with the arrow keys.
.PP
\f[B]Note\f[R]: tabs are converted to 8 spaces.
.SH LOCALES
.PP
This bc(1) ships with support for adding error messages for different
locales and thus, supports \f[B]LC_MESSAGES\f[R].
.SH SEE ALSO
.PP
dc(1)
.SH STANDARDS
.PP
bc(1) is compliant with the IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
The flags \f[B]-efghiqsvVw\f[R], all long options, and the extensions
noted above are extensions to that specification.
.PP
Note that the specification explicitly says that bc(1) only accepts
numbers that use a period (\f[B].\f[R]) as a radix point, regardless of
the value of \f[B]LC_NUMERIC\f[R].
.PP
This bc(1) supports error messages for different locales, and thus, it
supports \f[B]LC_MESSAGES\f[R].
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHORS
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/bc/A.1.md b/contrib/bc/manuals/bc/A.1.md
index 293a21ad0259..0cf7a4a0d70e 100644
--- a/contrib/bc/manuals/bc/A.1.md
+++ b/contrib/bc/manuals/bc/A.1.md
@@ -1,1696 +1,1705 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# NAME
bc - arbitrary-precision decimal arithmetic language and calculator
# SYNOPSIS
**bc** [**-ghilPqsvVw**] [**--global-stacks**] [**--help**] [**--interactive**] [**--mathlib**] [**--no-prompt**] [**--quiet**] [**--standard**] [**--warn**] [**--version**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...]
[*file*...]
# DESCRIPTION
bc(1) is an interactive processor for a language first standardized in 1991 by
POSIX. (The current standard is [here][1].) The language provides unlimited
precision decimal arithmetic and is somewhat C-like, but there are differences.
Such differences will be noted in this document.
After parsing and handling options, this bc(1) reads any files given on the
command line and executes them before reading from **stdin**.
This bc(1) is a drop-in replacement for *any* bc(1), including (and
especially) the GNU bc(1). It also has many extensions and extra features beyond
other implementations.
# OPTIONS
The following are the options that bc(1) accepts.
**-g**, **--global-stacks**
: Turns the globals **ibase**, **obase**, **scale**, and **seed** into stacks.
This has the effect that a copy of the current value of all four are pushed
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
(**Note**: the function **output(x,b)** exists in the extended math library.
See the **LIBRARY** section.)
However, since using this flag means that functions cannot set **ibase**,
**obase**, **scale**, or **seed** globally, functions that are made to do so
cannot work anymore. There are two possible use cases for that, and each has
a solution.
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o="bc -e ibase=A -e obase=8"
alias h2b="bc -e ibase=G -e obase=2"
Second, if the purpose of a function is to set **ibase**, **obase**,
**scale**, or **seed** globally for any other purpose, it could be split
into one to four functions (based on how many globals it sets) and each of
those functions could return the desired value for a global.
For functions that set **seed**, the value assigned to **seed** is not
propagated to parent functions. This means that the sequence of
pseudo-random numbers that they see will not be the same sequence of
pseudo-random numbers that any parent sees. This is only the case once
**seed** has been set.
If a function desires to not affect the sequence of pseudo-random numbers
of its parents, but wants to use the same **seed**, it can use the following
line:
seed = seed
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
**-h**, **--help**
: Prints a usage message and quits.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-l**, **--mathlib**
: Sets **scale** (see the **SYNTAX** section) to **20** and loads the included
math library and the extended math library before running any code,
including any expressions or files specified on the command line.
To learn what is in the libraries, see the **LIBRARY** section.
**-P**, **--no-prompt**
: Disables the prompt in TTY mode. (The prompt is only enabled in TTY mode.
See the **TTY MODE** section) This is mostly for those users that do not
want a prompt or are not used to having them in bc(1). Most of those users
would want to put this option in **BC_ENV_ARGS** (see the
**ENVIRONMENT VARIABLES** section).
This is a **non-portable extension**.
**-q**, **--quiet**
: This option is for compatibility with the [GNU bc(1)][2]; it is a no-op.
Without this option, GNU bc(1) prints a copyright header. This bc(1) only
prints the copyright header if one or more of the **-v**, **-V**, or
**--version** options are given.
This is a **non-portable extension**.
**-s**, **--standard**
: Process exactly the language defined by the [standard][1] and error if any
extensions are used.
This is a **non-portable extension**.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
This is a **non-portable extension**.
**-w**, **--warn**
: Like **-s** and **--standard**, except that warnings (and not errors) are
printed for non-standard extensions and execution continues normally.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **BC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **bc <file> >&-**, it will quit with an error. This
is done so that bc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **bc <file> 2>&-**, it will quit with an error. This
is done so that bc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
The syntax for bc(1) programs is mostly C-like, with some differences. This
bc(1) follows the [POSIX standard][1], which is a much more thorough resource
for the language this bc(1) accepts. This section is meant to be a summary and a
listing of all the extensions to the standard.
In the sections below, **E** means expression, **S** means statement, and **I**
means identifier.
Identifiers (**I**) start with a lowercase letter and can be followed by any
number (up to **BC_NAME_MAX-1**) of lowercase letters (**a-z**), digits
(**0-9**), and underscores (**\_**). The regex is **\[a-z\]\[a-z0-9\_\]\***.
Identifiers with more than one character (letter) are a
**non-portable extension**.
**ibase** is a global variable determining how to interpret constant numbers. It
is the "input" base, or the number base used for interpreting input numbers.
**ibase** is initially **10**. If the **-s** (**--standard**) and **-w**
(**--warn**) flags were not given on the command line, the max allowable value
for **ibase** is **36**. Otherwise, it is **16**. The min allowable value for
**ibase** is **2**. The max allowable value for **ibase** can be queried in
bc(1) programs with the **maxibase()** built-in function.
**obase** is a global variable determining how to output results. It is the
"output" base, or the number base used for outputting numbers. **obase** is
initially **10**. The max allowable value for **obase** is **BC_BASE_MAX** and
can be queried in bc(1) programs with the **maxobase()** built-in function. The
min allowable value for **obase** is **0**. If **obase** is **0**, values are
output in scientific notation, and if **obase** is **1**, values are output in
engineering notation. Otherwise, values are output in the specified base.
Outputting in scientific and engineering notations are **non-portable
extensions**.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a global variable that
sets the precision of any operations, with exceptions. **scale** is initially
**0**. **scale** cannot be negative. The max allowable value for **scale** is
**BC_SCALE_MAX** and can be queried in bc(1) programs with the **maxscale()**
built-in function.
bc(1) has both *global* variables and *local* variables. All *local*
variables are local to the function; they are parameters or are introduced in
the **auto** list of a function (see the **FUNCTIONS** section). If a variable
is accessed which is not a parameter or in the **auto** list, it is assumed to
be *global*. If a parent function has a *local* variable version of a variable
that a child function considers *global*, the value of that *global* variable in
the child function is the value of the variable in the parent function, not the
value of the actual *global* variable.
All of the above applies to arrays as well.
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence operator is an
assignment operator *and* the expression is notsurrounded by parentheses.
The value that is printed is also assigned to the special variable **last**. A
single dot (**.**) may also be used as a synonym for **last**. These are
**non-portable extensions**.
Either semicolons or newlines may separate statements.
## Comments
There are two kinds of comments:
1. Block comments are enclosed in **/\*** and **\*/**.
2. Line comments go from **#** until, and not including, the next newline. This
is a **non-portable extension**.
## Named Expressions
The following are named expressions in bc(1):
1. Variables: **I**
2. Array Elements: **I[E]**
3. **ibase**
4. **obase**
5. **scale**
6. **seed**
7. **last** or a single dot (**.**)
Numbers 6 and 7 are **non-portable extensions**.
The meaning of **seed** is dependent on the current pseudo-random number
generator but is guaranteed to not change except for new major versions.
The *scale* and sign of the value may be significant.
If a previously used **seed** value is assigned to **seed** and used again, the
pseudo-random number generator is guaranteed to produce the same sequence of
pseudo-random numbers as it did when the **seed** value was previously used.
The exact value assigned to **seed** is not guaranteed to be returned if
**seed** is queried again immediately. However, if **seed** *does* return a
different value, both values, when assigned to **seed**, are guaranteed to
produce the same sequence of pseudo-random numbers. This means that certain
values assigned to **seed** will *not* produce unique sequences of pseudo-random
numbers. The value of **seed** will change after any use of the **rand()** and
**irand(E)** operands (see the *Operands* subsection below), except if the
parameter passed to **irand(E)** is **0**, **1**, or negative.
There is no limit to the length (number of significant decimal digits) or
*scale* of the value that can be assigned to **seed**.
Variables and arrays do not interfere; users can have arrays named the same as
variables. This also applies to functions (see the **FUNCTIONS** section), so a
user can have a variable, array, and function that all have the same name, and
they will not shadow each other, whether inside of functions or not.
Named expressions are required as the operand of **increment**/**decrement**
operators and as the left side of **assignment** operators (see the *Operators*
subsection).
## Operands
The following are valid operands in bc(1):
1. Numbers (see the *Numbers* subsection below).
2. Array indices (**I[E]**).
3. **(E)**: The value of **E** (used to change precedence).
4. **sqrt(E)**: The square root of **E**. **E** must be non-negative.
5. **length(E)**: The number of significant decimal digits in **E**.
6. **length(I[])**: The number of elements in the array **I**. This is a
**non-portable extension**.
7. **scale(E)**: The *scale* of **E**.
8. **abs(E)**: The absolute value of **E**. This is a **non-portable
extension**.
9. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a non-**void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
10. **read()**: Reads a line from **stdin** and uses that as an expression. The
result of that expression is the result of the **read()** operand. This is a
**non-portable extension**.
11. **maxibase()**: The max allowable **ibase**. This is a **non-portable
extension**.
12. **maxobase()**: The max allowable **obase**. This is a **non-portable
extension**.
13. **maxscale()**: The max allowable **scale**. This is a **non-portable
extension**.
14. **rand()**: A pseudo-random integer between **0** (inclusive) and
**BC_RAND_MAX** (inclusive). Using this operand will change the value of
**seed**. This is a **non-portable extension**.
15. **irand(E)**: A pseudo-random integer between **0** (inclusive) and the
value of **E** (exclusive). If **E** is negative or is a non-integer
(**E**'s *scale* is not **0**), an error is raised, and bc(1) resets (see
the **RESET** section) while **seed** remains unchanged. If **E** is larger
than **BC_RAND_MAX**, the higher bound is honored by generating several
pseudo-random integers, multiplying them by appropriate powers of
**BC_RAND_MAX+1**, and adding them together. Thus, the size of integer that
can be generated with this operand is unbounded. Using this operand will
change the value of **seed**, unless the value of **E** is **0** or **1**.
In that case, **0** is returned, and **seed** is *not* changed. This is a
**non-portable extension**.
16. **maxrand()**: The max integer returned by **rand()**. This is a
**non-portable extension**.
The integers generated by **rand()** and **irand(E)** are guaranteed to be as
unbiased as possible, subject to the limitations of the pseudo-random number
generator.
**Note**: The values returned by the pseudo-random number generator with
**rand()** and **irand(E)** are guaranteed to *NOT* be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator. However,
they *are* guaranteed to be reproducible with identical **seed** values. This
means that the pseudo-random values from bc(1) should only be used where a
reproducible stream of pseudo-random numbers is *ESSENTIAL*. In any other case,
use a non-seeded pseudo-random number generator.
## Numbers
Numbers are strings made up of digits, uppercase letters, and at most **1**
period for a radix. Numbers can have up to **BC_NUM_MAX** digits. Uppercase
letters are equal to **9** + their position in the alphabet (i.e., **A** equals
**10**, or **9+1**). If a digit or letter makes no sense with the current value
of **ibase**, they are set to the value of the highest valid digit in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **Z** alone always equals decimal
**35**.
In addition, bc(1) accepts numbers in scientific notation. These have the form
**\<number\>e\<integer\>**. The exponent (the portion after the **e**) must be
an integer. An example is **1.89237e9**, which is equal to **1892370000**.
Negative exponents are also allowed, so **4.2890e-3** is equal to **0.0042890**.
Using scientific notation is an error or warning if the **-s** or **-w**,
respectively, command-line options (or equivalents) are given.
**WARNING**: Both the number and the exponent in scientific notation are
interpreted according to the current **ibase**, but the number is still
multiplied by **10\^exponent** regardless of the current **ibase**. For example,
if **ibase** is **16** and bc(1) is given the number string **FFeA**, the
resulting decimal number will be **2550000000000**, and if bc(1) is given the
number string **10e-4**, the resulting decimal number will be **0.0016**.
Accepting input as scientific notation is a **non-portable extension**.
## Operators
The following arithmetic and logical operators can be used. They are listed in
order of decreasing precedence. Operators in the same group have the same
precedence.
**++** **--**
: Type: Prefix and Postfix
Associativity: None
Description: **increment**, **decrement**
**-** **!**
: Type: Prefix
Associativity: None
Description: **negation**, **boolean not**
**\$**
: Type: Postfix
Associativity: None
Description: **truncation**
**\@**
: Type: Binary
Associativity: Right
Description: **set precision**
**\^**
: Type: Binary
Associativity: Right
Description: **power**
**\*** **/** **%**
: Type: Binary
Associativity: Left
Description: **multiply**, **divide**, **modulus**
**+** **-**
: Type: Binary
Associativity: Left
Description: **add**, **subtract**
**\<\<** **\>\>**
: Type: Binary
Associativity: Left
Description: **shift left**, **shift right**
**=** **\<\<=** **\>\>=** **+=** **-=** **\*=** **/=** **%=** **\^=** **\@=**
: Type: Binary
Associativity: Right
Description: **assignment**
**==** **\<=** **\>=** **!=** **\<** **\>**
: Type: Binary
Associativity: Left
Description: **relational**
**&&**
: Type: Binary
Associativity: Left
Description: **boolean and**
**||**
: Type: Binary
Associativity: Left
Description: **boolean or**
The operators will be described in more detail below.
**++** **--**
: The prefix and postfix **increment** and **decrement** operators behave
exactly like they would in C. They require a named expression (see the
*Named Expressions* subsection) as an operand.
The prefix versions of these operators are more efficient; use them where
possible.
**-**
: The **negation** operator returns **0** if a user attempts to negate any
expression with the value **0**. Otherwise, a copy of the expression with
its sign flipped is returned.
**!**
: The **boolean not** operator returns **1** if the expression is **0**, or
**0** otherwise.
This is a **non-portable extension**.
**\$**
: The **truncation** operator returns a copy of the given expression with all
of its *scale* removed.
This is a **non-portable extension**.
**\@**
: The **set precision** operator takes two expressions and returns a copy of
the first with its *scale* equal to the value of the second expression. That
could either mean that the number is returned without change (if the
*scale* of the first expression matches the value of the second
expression), extended (if it is less), or truncated (if it is more).
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**\^**
: The **power** operator (not the **exclusive or** operator, as it would be in
C) takes two expressions and raises the first to the power of the value of
the second. The *scale* of the result is equal to **scale**.
The second expression must be an integer (no *scale*), and if it is
negative, the first value must be non-zero.
**\***
: The **multiply** operator takes two expressions, multiplies them, and
returns the product. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result is
equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The **divide** operator takes two expressions, divides them, and returns the
quotient. The *scale* of the result shall be the value of **scale**.
The second expression must be non-zero.
**%**
: The **modulus** operator takes two expressions, **a** and **b**, and
evaluates them by 1) Computing **a/b** to current **scale** and 2) Using the
result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The second expression must be non-zero.
**+**
: The **add** operator takes two expressions, **a** and **b**, and returns the
sum, with a *scale* equal to the max of the *scale*s of **a** and **b**.
**-**
: The **subtract** operator takes two expressions, **a** and **b**, and
returns the difference, with a *scale* equal to the max of the *scale*s of
**a** and **b**.
**\<\<**
: The **left shift** operator takes two expressions, **a** and **b**, and
returns a copy of the value of **a** with its decimal point moved **b**
places to the right.
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**\>\>**
: The **right shift** operator takes two expressions, **a** and **b**, and
returns a copy of the value of **a** with its decimal point moved **b**
places to the left.
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**=** **\<\<=** **\>\>=** **+=** **-=** **\*=** **/=** **%=** **\^=** **\@=**
: The **assignment** operators take two expressions, **a** and **b** where
**a** is a named expression (see the *Named Expressions* subsection).
For **=**, **b** is copied and the result is assigned to **a**. For all
others, **a** and **b** are applied as operands to the corresponding
arithmetic operator and the result is assigned to **a**.
The **assignment** operators that correspond to operators that are
extensions are themselves **non-portable extensions**.
**==** **\<=** **\>=** **!=** **\<** **\>**
: The **relational** operators compare two expressions, **a** and **b**, and
if the relation holds, according to C language semantics, the result is
**1**. Otherwise, it is **0**.
Note that unlike in C, these operators have a lower precedence than the
**assignment** operators, which means that **a=b\>c** is interpreted as
**(a=b)\>c**.
Also, unlike the [standard][1] requires, these operators can appear anywhere
any other expressions can be used. This allowance is a
**non-portable extension**.
**&&**
: The **boolean and** operator takes two expressions and returns **1** if both
expressions are non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
**||**
: The **boolean or** operator takes two expressions and returns **1** if one
of the expressions is non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
## Statements
The following items are statements:
1. **E**
2. **{** **S** **;** ... **;** **S** **}**
3. **if** **(** **E** **)** **S**
4. **if** **(** **E** **)** **S** **else** **S**
5. **while** **(** **E** **)** **S**
6. **for** **(** **E** **;** **E** **;** **E** **)** **S**
7. An empty statement
8. **break**
9. **continue**
10. **quit**
11. **halt**
12. **limits**
13. A string of characters, enclosed in double quotes
14. **print** **E** **,** ... **,** **E**
15. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
Numbers 4, 9, 11, 12, 14, and 15 are **non-portable extensions**.
Also, as a **non-portable extension**, any or all of the expressions in the
header of a for loop may be omitted. If the condition (second expression) is
omitted, it is assumed to be a constant **1**.
The **break** statement causes a loop to stop iterating and resume execution
immediately following a loop. This is only allowed in loops.
The **continue** statement causes a loop iteration to stop early and returns to
the start of the loop, including testing the loop condition. This is only
allowed in loops.
The **if** **else** statement does the same thing as in C.
The **quit** statement causes bc(1) to quit, even if it is on a branch that will
not be executed (it is a compile-time command).
The **halt** statement causes bc(1) to quit, if it is executed. (Unlike **quit**
if it is on a branch of an **if** statement that is not executed, bc(1) does not
quit.)
The **limits** statement prints the limits that this bc(1) is subject to. This
is like the **quit** statement in that it is a compile-time command.
An expression by itself is evaluated and printed, followed by a newline.
Both scientific notation and engineering notation are available for printing the
results of expressions. Scientific notation is activated by assigning **0** to
**obase**, and engineering notation is activated by assigning **1** to
**obase**. To deactivate them, just assign a different value to **obase**.
Scientific notation and engineering notation are disabled if bc(1) is run with
either the **-s** or **-w** command-line options (or equivalents).
Printing numbers in scientific notation and/or engineering notation is a
**non-portable extension**.
## Print Statement
The "expressions" in a **print** statement may also be strings. If they are, there
are backslash escape sequences that are interpreted specially. What those
sequences are, and what they cause to be printed, are shown below:
-------- -------
**\\a** **\\a**
**\\b** **\\b**
**\\\\** **\\**
**\\e** **\\**
**\\f** **\\f**
**\\n** **\\n**
**\\q** **"**
**\\r** **\\r**
**\\t** **\\t**
-------- -------
Any other character following a backslash causes the backslash and character to
be printed as-is.
Any non-string expression in a print statement shall be assigned to **last**,
like any other expression that is printed.
## Order of Evaluation
All expressions in a statment are evaluated left to right, except as necessary
to maintain order of operations. This means, for example, assuming that **i** is
equal to **0**, in the expression
a[i++] = i++
the first (or 0th) element of **a** is set to **1**, and **i** is equal to **2**
at the end of the expression.
This includes function arguments. Thus, assuming **i** is equal to **0**, this
means that in the expression
x(i++, i++)
the first argument passed to **x()** is **0**, and the second argument is **1**,
while **i** is equal to **2** before the function starts executing.
# FUNCTIONS
Function definitions are as follows:
```
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
```
Any **I** in the parameter list or **auto** list may be replaced with **I[]** to
make a parameter or **auto** var an array, and any **I** in the parameter list
may be replaced with **\*I[]** to make a parameter an array reference. Callers
of functions that take array references should not put an asterisk in the call;
they must be called with just **I[]** like normal array parameters and will be
automatically converted into references.
As a **non-portable extension**, the opening brace of a **define** statement may
appear on the next line.
As a **non-portable extension**, the return statement may also be in one of the
following forms:
1. **return**
2. **return** **(** **)**
3. **return** **E**
The first two, or not specifying a **return** statement, is equivalent to
**return (0)**, unless the function is a **void** function (see the *Void
Functions* subsection below).
## Void Functions
Functions can also be **void** functions, defined as follows:
```
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
```
They can only be used as standalone expressions, where such an expression would
be printed alone, except in a print statement.
Void functions can only use the first two **return** statements listed above.
They can also omit the return statement entirely.
The word "void" is not treated as a keyword; it is still possible to have
variables, arrays, and functions named **void**. The word "void" is only
treated specially right after the **define** keyword.
This is a **non-portable extension**.
## Array References
For any array in the parameter list, if the array is declared in the form
```
*I[]
```
it is a **reference**. Any changes to the array in the function are reflected,
when the function returns, to the array that was passed in.
Other than this, all function arguments are passed by value.
This is a **non-portable extension**.
# LIBRARY
All of the functions below, including the functions in the extended math
library (see the *Extended Library* subsection below), are available when the
**-l** or **--mathlib** command-line flags are given, except that the extended
math library is not available when the **-s** option, the **-w** option, or
equivalents are given.
## Standard Library
The [standard][1] defines the following functions for the math library:
**s(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**c(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a(x)**
: Returns the arctangent of **x**, in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l(x)**
: Returns the natural logarithm of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**e(x)**
: Returns the mathematical constant **e** raised to the power of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**j(x, n)**
: Returns the bessel integer order **n** (truncated) of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
## Extended Library
The extended library is *not* loaded when the **-s**/**--standard** or
**-w**/**--warn** options are given since they are not part of the library
defined by the [standard][1].
The extended library is a **non-portable extension**.
**p(x, y)**
: Calculates **x** to the power of **y**, even if **y** is not an integer, and
returns the result to the current **scale**.
It is an error if **y** is negative and **x** is **0**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**r(x, p)**
: Returns **x** rounded to **p** decimal places according to the rounding mode
[round half away from **0**][3].
**ceil(x, p)**
: Returns **x** rounded to **p** decimal places according to the rounding mode
[round away from **0**][6].
**f(x)**
: Returns the factorial of the truncated absolute value of **x**.
**perm(n, k)**
: Returns the permutation of the truncated absolute value of **n** of the
truncated absolute value of **k**, if **k \<= n**. If not, it returns **0**.
**comb(n, k)**
: Returns the combination of the truncated absolute value of **n** of the
truncated absolute value of **k**, if **k \<= n**. If not, it returns **0**.
**l2(x)**
: Returns the logarithm base **2** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l10(x)**
: Returns the logarithm base **10** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**log(x, b)**
: Returns the logarithm base **b** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**cbrt(x)**
: Returns the cube root of **x**.
**root(x, n)**
: Calculates the truncated value of **n**, **r**, and returns the **r**th root
of **x** to the current **scale**.
If **r** is **0** or negative, this raises an error and causes bc(1) to
reset (see the **RESET** section). It also raises an error and causes bc(1)
to reset if **r** is even and **x** is negative.
**pi(p)**
: Returns **pi** to **p** decimal places.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**t(x)**
: Returns the tangent of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a2(y, x)**
: Returns the arctangent of **y/x**, in radians. If both **y** and **x** are
equal to **0**, it raises an error and causes bc(1) to reset (see the
**RESET** section). Otherwise, if **x** is greater than **0**, it returns
**a(y/x)**. If **x** is less than **0**, and **y** is greater than or equal
to **0**, it returns **a(y/x)+pi**. If **x** is less than **0**, and **y**
is less than **0**, it returns **a(y/x)-pi**. If **x** is equal to **0**,
and **y** is greater than **0**, it returns **pi/2**. If **x** is equal to
**0**, and **y** is less than **0**, it returns **-pi/2**.
This function is the same as the **atan2()** function in many programming
languages.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**sin(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is an alias of **s(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**cos(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is an alias of **c(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**tan(x)**
: Returns the tangent of **x**, which is assumed to be in radians.
If **x** is equal to **1** or **-1**, this raises an error and causes bc(1)
to reset (see the **RESET** section).
This is an alias of **t(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**atan(x)**
: Returns the arctangent of **x**, in radians.
This is an alias of **a(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**atan2(y, x)**
: Returns the arctangent of **y/x**, in radians. If both **y** and **x** are
equal to **0**, it raises an error and causes bc(1) to reset (see the
**RESET** section). Otherwise, if **x** is greater than **0**, it returns
**a(y/x)**. If **x** is less than **0**, and **y** is greater than or equal
to **0**, it returns **a(y/x)+pi**. If **x** is less than **0**, and **y**
is less than **0**, it returns **a(y/x)-pi**. If **x** is equal to **0**,
and **y** is greater than **0**, it returns **pi/2**. If **x** is equal to
**0**, and **y** is less than **0**, it returns **-pi/2**.
This function is the same as the **atan2()** function in many programming
languages.
This is an alias of **a2(y, x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**r2d(x)**
: Converts **x** from radians to degrees and returns the result.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**d2r(x)**
: Converts **x** from degrees to radians and returns the result.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**frand(p)**
: Generates a pseudo-random number between **0** (inclusive) and **1**
(exclusive) with the number of decimal digits after the decimal point equal
to the truncated absolute value of **p**. If **p** is not **0**, then
calling this function will change the value of **seed**. If **p** is **0**,
then **0** is returned, and **seed** is *not* changed.
**ifrand(i, p)**
: Generates a pseudo-random number that is between **0** (inclusive) and the
truncated absolute value of **i** (exclusive) with the number of decimal
digits after the decimal point equal to the truncated absolute value of
**p**. If the absolute value of **i** is greater than or equal to **2**, and
**p** is not **0**, then calling this function will change the value of
**seed**; otherwise, **0** is returned and **seed** is not changed.
**srand(x)**
: Returns **x** with its sign flipped with probability **0.5**. In other
words, it randomizes the sign of **x**.
**brand()**
: Returns a random boolean value (either **0** or **1**).
**ubytes(x)**
: Returns the numbers of unsigned integer bytes required to hold the truncated
absolute value of **x**.
**sbytes(x)**
: Returns the numbers of signed, two's-complement integer bytes required to
hold the truncated value of **x**.
**hex(x)**
: Outputs the hexadecimal (base **16**) representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**binary(x)**
: Outputs the binary (base **2**) representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output(x, b)**
: Outputs the base **b** representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in as few power of two bytes as possible. Both outputs are
split into bytes separated by spaces.
If **x** is not an integer or is negative, an error message is printed
instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in as few power of two bytes as possible. Both
outputs are split into bytes separated by spaces.
If **x** is not an integer, an error message is printed instead, but bc(1)
is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uintn(x, n)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **n** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **n** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**intn(x, n)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **n** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **n** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint8(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **1** byte. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **1** byte, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int8(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **1** byte. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **1** byte, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint16(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **2** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **2** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int16(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **2** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **2** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint32(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **4** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **4** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int32(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **4** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **4** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint64(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **8** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **8** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int64(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **8** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **8** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**hex_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in hexadecimal using **n** bytes. Not all of the value will
be output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**binary_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in binary using **n** bytes. Not all of the value will be
output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in the current **obase** (see the **SYNTAX** section) using
**n** bytes. Not all of the value will be output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output_byte(x, i)**
: Outputs byte **i** of the truncated absolute value of **x**, where **0** is
the least significant byte and **number_of_bytes - 1** is the most
significant byte.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
## Transcendental Functions
All transcendental functions can return slightly inaccurate results (up to 1
[ULP][4]). This is unavoidable, and [this article][5] explains why it is
impossible and unnecessary to calculate exact results for the transcendental
functions.
Because of the possible inaccuracy, I recommend that users call those functions
with the precision (**scale**) set to at least 1 higher than is necessary. If
exact results are *absolutely* required, users can double the precision
(**scale**) and then truncate.
The transcendental functions in the standard math library are:
* **s(x)**
* **c(x)**
* **a(x)**
* **l(x)**
* **e(x)**
* **j(x, n)**
The transcendental functions in the extended math library are:
* **l2(x)**
* **l10(x)**
* **log(x, b)**
* **pi(p)**
* **t(x)**
* **a2(y, x)**
* **sin(x)**
* **cos(x)**
* **tan(x)**
* **atan(x)**
* **atan2(y, x)**
* **r2d(x)**
* **d2r(x)**
# RESET
When bc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any functions that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
functions returned) is skipped.
Thus, when bc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
Note that this reset behavior is different from the GNU bc(1), which attempts to
start executing the statement right after the one that caused an error.
# PERFORMANCE
Most bc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This bc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **BC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **BC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**BC_BASE_DIGS**.
The actual values of **BC_LONG_BIT** and **BC_BASE_DIGS** can be queried with
the **limits** statement.
In addition, this bc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **BC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on bc(1):
**BC_LONG_BIT**
: The number of bits in the **long** type in the environment where bc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**BC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **BC_LONG_BIT**.
**BC_BASE_POW**
: The max decimal number that each large integer can store (see
**BC_BASE_DIGS**) plus **1**. Depends on **BC_BASE_DIGS**.
**BC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **BC_LONG_BIT**.
**BC_BASE_MAX**
: The maximum output base. Set at **BC_BASE_POW**.
**BC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**BC_SCALE_MAX**
: The maximum **scale**. Set at **BC_OVERFLOW_MAX-1**.
**BC_STRING_MAX**
: The maximum length of strings. Set at **BC_OVERFLOW_MAX-1**.
**BC_NAME_MAX**
: The maximum length of identifiers. Set at **BC_OVERFLOW_MAX-1**.
**BC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **BC_OVERFLOW_MAX-1**.
**BC_RAND_MAX**
: The maximum integer (inclusive) returned by the **rand()** operand. Set at
**2\^BC_LONG_BIT-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**BC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
The actual values can be queried with the **limits** statement.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
bc(1) recognizes the following environment variables:
**POSIXLY_CORRECT**
: If this variable exists (no matter the contents), bc(1) behaves as if
the **-s** option was given.
**BC_ENV_ARGS**
: This is another way to give command-line arguments to bc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **BC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
The code that parses **BC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some bc file.bc"** will be correctly parsed, but the string
**"/home/gavin/some \"bc\" file.bc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **BC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**BC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), bc(1) will output
lines to that length, including the backslash (**\\**). The default line
length is **70**.
# EXIT STATUS
bc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, using a negative number as a bound for the pseudo-random number
generator, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**), places (**\@**), left shift (**\<\<**), and right shift (**\>\>**)
operators and their corresponding assignment operators.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, using a token where it is invalid,
giving an invalid expression, giving an invalid print statement, giving an
invalid function definition, attempting to assign to an expression that is
not a named expression (see the *Named Expressions* subsection of the
**SYNTAX** section), giving an invalid **auto** list, having a duplicate
**auto**/function parameter, failing to find the end of a code block,
attempting to return a value from a **void** function, attempting to use a
variable as a reference, and using any extensions when the option **-s** or
any equivalents were given.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a **void** function call as a value in an expression.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (bc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, bc(1) always exits
and returns **4**, no matter what mode bc(1) is in.
The other statuses will only be returned when bc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since bc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Per the [standard][1], bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, bc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, bc(1) turns
on "TTY mode."
TTY mode is required for history to be enabled (see the **COMMAND LINE HISTORY**
section). It is also required to enable special handling for **SIGINT** signals.
The prompt is enabled in TTY mode.
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause bc(1) to stop execution of the current input. If
bc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If bc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If bc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to bc(1) as it is executing a file, it
can seem as though bc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause bc(1) to clean up and exit, and it uses the
default handler for all other signals. The one exception is **SIGHUP**; in that
case, when bc(1) is in TTY mode, a **SIGHUP** will cause bc(1) to clean up and
exit.
# COMMAND LINE HISTORY
bc(1) supports interactive command-line editing. If bc(1) is in TTY mode (see
the **TTY MODE** section), history is enabled. Previous lines can be recalled
and edited with the arrow keys.
**Note**: tabs are converted to 8 spaces.
# LOCALES
This bc(1) ships with support for adding error messages for different locales
and thus, supports **LC_MESSAGES**.
# SEE ALSO
dc(1)
# STANDARDS
bc(1) is compliant with the [IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1]
specification. The flags **-efghiqsvVw**, all long options, and the extensions
noted above are extensions to that specification.
Note that the specification explicitly says that bc(1) only accepts numbers that
use a period (**.**) as a radix point, regardless of the value of
**LC_NUMERIC**.
This bc(1) supports error messages for different locales, and thus, it supports
**LC_MESSAGES**.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHORS
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
[2]: https://www.gnu.org/software/bc/
[3]: https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero
[4]: https://en.wikipedia.org/wiki/Unit_in_the_last_place
[5]: https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT
[6]: https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero
diff --git a/contrib/bc/manuals/bc/E.1 b/contrib/bc/manuals/bc/E.1
index 02a56e6c653c..597cde782788 100644
--- a/contrib/bc/manuals/bc/E.1
+++ b/contrib/bc/manuals/bc/E.1
@@ -1,1301 +1,1314 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "BC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "BC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH NAME
.PP
bc - arbitrary-precision decimal arithmetic language and calculator
.SH SYNOPSIS
.PP
\f[B]bc\f[R] [\f[B]-ghilPqsvVw\f[R]] [\f[B]\[en]global-stacks\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]mathlib\f[R]] [\f[B]\[en]no-prompt\f[R]]
[\f[B]\[en]quiet\f[R]] [\f[B]\[en]standard\f[R]] [\f[B]\[en]warn\f[R]]
[\f[B]\[en]version\f[R]] [\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
bc(1) is an interactive processor for a language first standardized in
1991 by POSIX.
(The current standard is
here (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).)
The language provides unlimited precision decimal arithmetic and is
somewhat C-like, but there are differences.
Such differences will be noted in this document.
.PP
After parsing and handling options, this bc(1) reads any files given on
the command line and executes them before reading from \f[B]stdin\f[R].
.PP
This bc(1) is a drop-in replacement for \f[I]any\f[R] bc(1), including
(and especially) the GNU bc(1).
.SH OPTIONS
.PP
The following are the options that bc(1) accepts.
.PP
\f[B]-g\f[R], \f[B]\[en]global-stacks\f[R]
.IP
.nf
\f[C]
Turns the globals **ibase**, **obase**, and **scale** into stacks.
This has the effect that a copy of the current value of all three are pushed
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
However, since using this flag means that functions cannot set **ibase**,
**obase**, or **scale** globally, functions that are made to do so cannot
work anymore. There are two possible use cases for that, and each has a
solution.
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o=\[dq]bc -e ibase=A -e obase=8\[dq]
alias h2b=\[dq]bc -e ibase=G -e obase=2\[dq]
Second, if the purpose of a function is to set **ibase**, **obase**, or
**scale** globally for any other purpose, it could be split into one to
three functions (based on how many globals it sets) and each of those
functions could return the desired value for a global.
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
\f[R]
.fi
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-l\f[R], \f[B]\[en]mathlib\f[R]
Sets \f[B]scale\f[R] (see the \f[B]SYNTAX\f[R] section) to \f[B]20\f[R]
and loads the included math library before running any code, including
any expressions or files specified on the command line.
.RS
.PP
To learn what is in the library, see the \f[B]LIBRARY\f[R] section.
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
Disables the prompt in TTY mode.
(The prompt is only enabled in TTY mode.
See the \f[B]TTY MODE\f[R] section) This is mostly for those users that
do not want a prompt or are not used to having them in bc(1).
Most of those users would want to put this option in
\f[B]BC_ENV_ARGS\f[R] (see the \f[B]ENVIRONMENT VARIABLES\f[R] section).
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-q\f[R], \f[B]\[en]quiet\f[R]
This option is for compatibility with the GNU
bc(1) (https://www.gnu.org/software/bc/); it is a no-op.
Without this option, GNU bc(1) prints a copyright header.
This bc(1) only prints the copyright header if one or more of the
\f[B]-v\f[R], \f[B]-V\f[R], or \f[B]\[en]version\f[R] options are given.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-s\f[R], \f[B]\[en]standard\f[R]
Process exactly the language defined by the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
and error if any extensions are used.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-w\f[R], \f[B]\[en]warn\f[R]
Like \f[B]-s\f[R] and \f[B]\[en]standard\f[R], except that warnings (and
not errors) are printed for non-standard extensions and execution
continues normally.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]BC_ENV_ARGS\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]bc >&-\f[R], it will quit with an error.
This is done so that bc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]bc 2>&-\f[R], it will quit with an error.
This is done so that bc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
The syntax for bc(1) programs is mostly C-like, with some differences.
This bc(1) follows the POSIX
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
which is a much more thorough resource for the language this bc(1)
accepts.
This section is meant to be a summary and a listing of all the
extensions to the standard.
.PP
In the sections below, \f[B]E\f[R] means expression, \f[B]S\f[R] means
statement, and \f[B]I\f[R] means identifier.
.PP
Identifiers (\f[B]I\f[R]) start with a lowercase letter and can be
followed by any number (up to \f[B]BC_NAME_MAX-1\f[R]) of lowercase
letters (\f[B]a-z\f[R]), digits (\f[B]0-9\f[R]), and underscores
(\f[B]_\f[R]).
The regex is \f[B][a-z][a-z0-9_]*\f[R].
Identifiers with more than one character (letter) are a
\f[B]non-portable extension\f[R].
.PP
\f[B]ibase\f[R] is a global variable determining how to interpret
constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
If the \f[B]-s\f[R] (\f[B]\[en]standard\f[R]) and \f[B]-w\f[R]
(\f[B]\[en]warn\f[R]) flags were not given on the command line, the max
allowable value for \f[B]ibase\f[R] is \f[B]36\f[R].
Otherwise, it is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in bc(1)
programs with the \f[B]maxibase()\f[R] built-in function.
.PP
\f[B]obase\f[R] is a global variable determining how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]BC_BASE_MAX\f[R] and
can be queried in bc(1) programs with the \f[B]maxobase()\f[R] built-in
function.
The min allowable value for \f[B]obase\f[R] is \f[B]2\f[R].
Values are output in the specified base.
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a global variable that sets the precision of any operations, with
exceptions.
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] is \f[B]BC_SCALE_MAX\f[R]
and can be queried in bc(1) programs with the \f[B]maxscale()\f[R]
built-in function.
.PP
bc(1) has both \f[I]global\f[R] variables and \f[I]local\f[R] variables.
All \f[I]local\f[R] variables are local to the function; they are
parameters or are introduced in the \f[B]auto\f[R] list of a function
(see the \f[B]FUNCTIONS\f[R] section).
If a variable is accessed which is not a parameter or in the
\f[B]auto\f[R] list, it is assumed to be \f[I]global\f[R].
If a parent function has a \f[I]local\f[R] variable version of a
variable that a child function considers \f[I]global\f[R], the value of
that \f[I]global\f[R] variable in the child function is the value of the
variable in the parent function, not the value of the actual
\f[I]global\f[R] variable.
.PP
All of the above applies to arrays as well.
.PP
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence
operator is an assignment operator \f[I]and\f[R] the expression is
notsurrounded by parentheses.
.PP
The value that is printed is also assigned to the special variable
\f[B]last\f[R].
A single dot (\f[B].\f[R]) may also be used as a synonym for
\f[B]last\f[R].
These are \f[B]non-portable extensions\f[R].
.PP
Either semicolons or newlines may separate statements.
.SS Comments
.PP
There are two kinds of comments:
.IP "1." 3
Block comments are enclosed in \f[B]/*\f[R] and \f[B]*/\f[R].
.IP "2." 3
Line comments go from \f[B]#\f[R] until, and not including, the next
newline.
This is a \f[B]non-portable extension\f[R].
.SS Named Expressions
.PP
The following are named expressions in bc(1):
.IP "1." 3
Variables: \f[B]I\f[R]
.IP "2." 3
Array Elements: \f[B]I[E]\f[R]
.IP "3." 3
\f[B]ibase\f[R]
.IP "4." 3
\f[B]obase\f[R]
.IP "5." 3
\f[B]scale\f[R]
.IP "6." 3
\f[B]last\f[R] or a single dot (\f[B].\f[R])
.PP
Number 6 is a \f[B]non-portable extension\f[R].
.PP
Variables and arrays do not interfere; users can have arrays named the
same as variables.
This also applies to functions (see the \f[B]FUNCTIONS\f[R] section), so
a user can have a variable, array, and function that all have the same
name, and they will not shadow each other, whether inside of functions
or not.
.PP
Named expressions are required as the operand of
\f[B]increment\f[R]/\f[B]decrement\f[R] operators and as the left side
of \f[B]assignment\f[R] operators (see the \f[I]Operators\f[R]
subsection).
.SS Operands
.PP
The following are valid operands in bc(1):
.IP " 1." 4
Numbers (see the \f[I]Numbers\f[R] subsection below).
.IP " 2." 4
Array indices (\f[B]I[E]\f[R]).
.IP " 3." 4
\f[B](E)\f[R]: The value of \f[B]E\f[R] (used to change precedence).
.IP " 4." 4
\f[B]sqrt(E)\f[R]: The square root of \f[B]E\f[R].
\f[B]E\f[R] must be non-negative.
.IP " 5." 4
\f[B]length(E)\f[R]: The number of significant decimal digits in
\f[B]E\f[R].
.IP " 6." 4
\f[B]length(I[])\f[R]: The number of elements in the array \f[B]I\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 7." 4
\f[B]scale(E)\f[R]: The \f[I]scale\f[R] of \f[B]E\f[R].
.IP " 8." 4
\f[B]abs(E)\f[R]: The absolute value of \f[B]E\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 9." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a non-\f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.IP "10." 4
\f[B]read()\f[R]: Reads a line from \f[B]stdin\f[R] and uses that as an
expression.
The result of that expression is the result of the \f[B]read()\f[R]
operand.
This is a \f[B]non-portable extension\f[R].
.IP "11." 4
\f[B]maxibase()\f[R]: The max allowable \f[B]ibase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "12." 4
\f[B]maxobase()\f[R]: The max allowable \f[B]obase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "13." 4
\f[B]maxscale()\f[R]: The max allowable \f[B]scale\f[R].
This is a \f[B]non-portable extension\f[R].
.SS Numbers
.PP
Numbers are strings made up of digits, uppercase letters, and at most
\f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]BC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]Z\f[R] alone always equals decimal \f[B]35\f[R].
.SS Operators
.PP
The following arithmetic and logical operators can be used.
They are listed in order of decreasing precedence.
Operators in the same group have the same precedence.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
Type: Prefix and Postfix
.RS
.PP
Associativity: None
.PP
Description: \f[B]increment\f[R], \f[B]decrement\f[R]
.RE
.TP
\f[B]-\f[R] \f[B]!\f[R]
Type: Prefix
.RS
.PP
Associativity: None
.PP
Description: \f[B]negation\f[R], \f[B]boolean not\f[R]
.RE
.TP
\f[B]\[ha]\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]power\f[R]
.RE
.TP
\f[B]*\f[R] \f[B]/\f[R] \f[B]%\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]multiply\f[R], \f[B]divide\f[R], \f[B]modulus\f[R]
.RE
.TP
\f[B]+\f[R] \f[B]-\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]add\f[R], \f[B]subtract\f[R]
.RE
.TP
\f[B]=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]assignment\f[R]
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]relational\f[R]
.RE
.TP
\f[B]&&\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean and\f[R]
.RE
.TP
\f[B]||\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean or\f[R]
.RE
.PP
The operators will be described in more detail below.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
The prefix and postfix \f[B]increment\f[R] and \f[B]decrement\f[R]
operators behave exactly like they would in C.
They require a named expression (see the \f[I]Named Expressions\f[R]
subsection) as an operand.
.RS
.PP
The prefix versions of these operators are more efficient; use them
where possible.
.RE
.TP
\f[B]-\f[R]
The \f[B]negation\f[R] operator returns \f[B]0\f[R] if a user attempts
to negate any expression with the value \f[B]0\f[R].
Otherwise, a copy of the expression with its sign flipped is returned.
.TP
\f[B]!\f[R]
The \f[B]boolean not\f[R] operator returns \f[B]1\f[R] if the expression
is \f[B]0\f[R], or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The \f[B]power\f[R] operator (not the \f[B]exclusive or\f[R] operator,
as it would be in C) takes two expressions and raises the first to the
power of the value of the second.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]), and if it
is negative, the first value must be non-zero.
.RE
.TP
\f[B]*\f[R]
The \f[B]multiply\f[R] operator takes two expressions, multiplies them,
and returns the product.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The \f[B]divide\f[R] operator takes two expressions, divides them, and
returns the quotient.
The \f[I]scale\f[R] of the result shall be the value of \f[B]scale\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]%\f[R]
The \f[B]modulus\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and evaluates them by 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R] and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]+\f[R]
The \f[B]add\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the sum, with a \f[I]scale\f[R] equal to the
max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]-\f[R]
The \f[B]subtract\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the difference, with a \f[I]scale\f[R] equal to
the max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R]
The \f[B]assignment\f[R] operators take two expressions, \f[B]a\f[R] and
\f[B]b\f[R] where \f[B]a\f[R] is a named expression (see the \f[I]Named
Expressions\f[R] subsection).
.RS
.PP
For \f[B]=\f[R], \f[B]b\f[R] is copied and the result is assigned to
\f[B]a\f[R].
For all others, \f[B]a\f[R] and \f[B]b\f[R] are applied as operands to
the corresponding arithmetic operator and the result is assigned to
\f[B]a\f[R].
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
The \f[B]relational\f[R] operators compare two expressions, \f[B]a\f[R]
and \f[B]b\f[R], and if the relation holds, according to C language
semantics, the result is \f[B]1\f[R].
Otherwise, it is \f[B]0\f[R].
.RS
.PP
Note that unlike in C, these operators have a lower precedence than the
\f[B]assignment\f[R] operators, which means that \f[B]a=b>c\f[R] is
interpreted as \f[B](a=b)>c\f[R].
.PP
Also, unlike the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
requires, these operators can appear anywhere any other expressions can
be used.
This allowance is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]&&\f[R]
The \f[B]boolean and\f[R] operator takes two expressions and returns
\f[B]1\f[R] if both expressions are non-zero, \f[B]0\f[R] otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]||\f[R]
The \f[B]boolean or\f[R] operator takes two expressions and returns
\f[B]1\f[R] if one of the expressions is non-zero, \f[B]0\f[R]
otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Statements
.PP
The following items are statements:
.IP " 1." 4
\f[B]E\f[R]
.IP " 2." 4
\f[B]{\f[R] \f[B]S\f[R] \f[B];\f[R] \&... \f[B];\f[R] \f[B]S\f[R]
\f[B]}\f[R]
.IP " 3." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 4." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
\f[B]else\f[R] \f[B]S\f[R]
.IP " 5." 4
\f[B]while\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 6." 4
\f[B]for\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B];\f[R] \f[B]E\f[R]
\f[B];\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 7." 4
An empty statement
.IP " 8." 4
\f[B]break\f[R]
.IP " 9." 4
\f[B]continue\f[R]
.IP "10." 4
\f[B]quit\f[R]
.IP "11." 4
\f[B]halt\f[R]
.IP "12." 4
\f[B]limits\f[R]
.IP "13." 4
A string of characters, enclosed in double quotes
.IP "14." 4
\f[B]print\f[R] \f[B]E\f[R] \f[B],\f[R] \&... \f[B],\f[R] \f[B]E\f[R]
.IP "15." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a \f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.PP
Numbers 4, 9, 11, 12, 14, and 15 are \f[B]non-portable extensions\f[R].
.PP
Also, as a \f[B]non-portable extension\f[R], any or all of the
expressions in the header of a for loop may be omitted.
If the condition (second expression) is omitted, it is assumed to be a
constant \f[B]1\f[R].
.PP
The \f[B]break\f[R] statement causes a loop to stop iterating and resume
execution immediately following a loop.
This is only allowed in loops.
.PP
The \f[B]continue\f[R] statement causes a loop iteration to stop early
and returns to the start of the loop, including testing the loop
condition.
This is only allowed in loops.
.PP
The \f[B]if\f[R] \f[B]else\f[R] statement does the same thing as in C.
.PP
The \f[B]quit\f[R] statement causes bc(1) to quit, even if it is on a
branch that will not be executed (it is a compile-time command).
.PP
The \f[B]halt\f[R] statement causes bc(1) to quit, if it is executed.
(Unlike \f[B]quit\f[R] if it is on a branch of an \f[B]if\f[R] statement
that is not executed, bc(1) does not quit.)
.PP
The \f[B]limits\f[R] statement prints the limits that this bc(1) is
subject to.
This is like the \f[B]quit\f[R] statement in that it is a compile-time
command.
.PP
An expression by itself is evaluated and printed, followed by a newline.
.SS Print Statement
.PP
The \[lq]expressions\[rq] in a \f[B]print\f[R] statement may also be
strings.
If they are, there are backslash escape sequences that are interpreted
specially.
What those sequences are, and what they cause to be printed, are shown
below:
.PP
.TS
tab(@);
l l.
T{
\f[B]\[rs]a\f[R]
T}@T{
\f[B]\[rs]a\f[R]
T}
T{
\f[B]\[rs]b\f[R]
T}@T{
\f[B]\[rs]b\f[R]
T}
T{
\f[B]\[rs]\[rs]\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]e\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]f\f[R]
T}@T{
\f[B]\[rs]f\f[R]
T}
T{
\f[B]\[rs]n\f[R]
T}@T{
\f[B]\[rs]n\f[R]
T}
T{
\f[B]\[rs]q\f[R]
T}@T{
\f[B]\[dq]\f[R]
T}
T{
\f[B]\[rs]r\f[R]
T}@T{
\f[B]\[rs]r\f[R]
T}
T{
\f[B]\[rs]t\f[R]
T}@T{
\f[B]\[rs]t\f[R]
T}
.TE
.PP
Any other character following a backslash causes the backslash and
character to be printed as-is.
.PP
Any non-string expression in a print statement shall be assigned to
\f[B]last\f[R], like any other expression that is printed.
.SS Order of Evaluation
.PP
All expressions in a statment are evaluated left to right, except as
necessary to maintain order of operations.
This means, for example, assuming that \f[B]i\f[R] is equal to
\f[B]0\f[R], in the expression
.IP
.nf
\f[C]
a[i++] = i++
\f[R]
.fi
.PP
the first (or 0th) element of \f[B]a\f[R] is set to \f[B]1\f[R], and
\f[B]i\f[R] is equal to \f[B]2\f[R] at the end of the expression.
.PP
This includes function arguments.
Thus, assuming \f[B]i\f[R] is equal to \f[B]0\f[R], this means that in
the expression
.IP
.nf
\f[C]
x(i++, i++)
\f[R]
.fi
.PP
the first argument passed to \f[B]x()\f[R] is \f[B]0\f[R], and the
second argument is \f[B]1\f[R], while \f[B]i\f[R] is equal to
\f[B]2\f[R] before the function starts executing.
.SH FUNCTIONS
.PP
Function definitions are as follows:
.IP
.nf
\f[C]
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
\f[R]
.fi
.PP
Any \f[B]I\f[R] in the parameter list or \f[B]auto\f[R] list may be
replaced with \f[B]I[]\f[R] to make a parameter or \f[B]auto\f[R] var an
array, and any \f[B]I\f[R] in the parameter list may be replaced with
\f[B]*I[]\f[R] to make a parameter an array reference.
Callers of functions that take array references should not put an
asterisk in the call; they must be called with just \f[B]I[]\f[R] like
normal array parameters and will be automatically converted into
references.
.PP
As a \f[B]non-portable extension\f[R], the opening brace of a
\f[B]define\f[R] statement may appear on the next line.
.PP
As a \f[B]non-portable extension\f[R], the return statement may also be
in one of the following forms:
.IP "1." 3
\f[B]return\f[R]
.IP "2." 3
\f[B]return\f[R] \f[B](\f[R] \f[B])\f[R]
.IP "3." 3
\f[B]return\f[R] \f[B]E\f[R]
.PP
The first two, or not specifying a \f[B]return\f[R] statement, is
equivalent to \f[B]return (0)\f[R], unless the function is a
\f[B]void\f[R] function (see the \f[I]Void Functions\f[R] subsection
below).
.SS Void Functions
.PP
Functions can also be \f[B]void\f[R] functions, defined as follows:
.IP
.nf
\f[C]
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
\f[R]
.fi
.PP
They can only be used as standalone expressions, where such an
expression would be printed alone, except in a print statement.
.PP
Void functions can only use the first two \f[B]return\f[R] statements
listed above.
They can also omit the return statement entirely.
.PP
The word \[lq]void\[rq] is not treated as a keyword; it is still
possible to have variables, arrays, and functions named \f[B]void\f[R].
The word \[lq]void\[rq] is only treated specially right after the
\f[B]define\f[R] keyword.
.PP
This is a \f[B]non-portable extension\f[R].
.SS Array References
.PP
For any array in the parameter list, if the array is declared in the
form
.IP
.nf
\f[C]
*I[]
\f[R]
.fi
.PP
it is a \f[B]reference\f[R].
Any changes to the array in the function are reflected, when the
function returns, to the array that was passed in.
.PP
Other than this, all function arguments are passed by value.
.PP
This is a \f[B]non-portable extension\f[R].
.SH LIBRARY
.PP
All of the functions below are available when the \f[B]-l\f[R] or
\f[B]\[en]mathlib\f[R] command-line flags are given.
.SS Standard Library
.PP
The
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
defines the following functions for the math library:
.TP
\f[B]s(x)\f[R]
Returns the sine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]c(x)\f[R]
Returns the cosine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]a(x)\f[R]
Returns the arctangent of \f[B]x\f[R], in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]l(x)\f[R]
Returns the natural logarithm of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]e(x)\f[R]
Returns the mathematical constant \f[B]e\f[R] raised to the power of
\f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]j(x, n)\f[R]
Returns the bessel integer order \f[B]n\f[R] (truncated) of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.SS Transcendental Functions
.PP
All transcendental functions can return slightly inaccurate results (up
to 1 ULP (https://en.wikipedia.org/wiki/Unit_in_the_last_place)).
This is unavoidable, and this
article (https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT) explains
why it is impossible and unnecessary to calculate exact results for the
transcendental functions.
.PP
Because of the possible inaccuracy, I recommend that users call those
functions with the precision (\f[B]scale\f[R]) set to at least 1 higher
than is necessary.
If exact results are \f[I]absolutely\f[R] required, users can double the
precision (\f[B]scale\f[R]) and then truncate.
.PP
The transcendental functions in the standard math library are:
.IP \[bu] 2
\f[B]s(x)\f[R]
.IP \[bu] 2
\f[B]c(x)\f[R]
.IP \[bu] 2
\f[B]a(x)\f[R]
.IP \[bu] 2
\f[B]l(x)\f[R]
.IP \[bu] 2
\f[B]e(x)\f[R]
.IP \[bu] 2
\f[B]j(x, n)\f[R]
.SH RESET
.PP
When bc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any functions that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all functions returned) is skipped.
.PP
Thus, when bc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.PP
Note that this reset behavior is different from the GNU bc(1), which
attempts to start executing the statement right after the one that
caused an error.
.SH PERFORMANCE
.PP
Most bc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This bc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]BC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]BC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]BC_BASE_DIGS\f[R].
.PP
The actual values of \f[B]BC_LONG_BIT\f[R] and \f[B]BC_BASE_DIGS\f[R]
can be queried with the \f[B]limits\f[R] statement.
.PP
In addition, this bc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]BC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on bc(1):
.TP
\f[B]BC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
bc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]BC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]BC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]BC_BASE_DIGS\f[R].
.TP
\f[B]BC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]BC_BASE_POW\f[R].
.TP
\f[B]BC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]BC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]BC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
The actual values can be queried with the \f[B]limits\f[R] statement.
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
bc(1) recognizes the following environment variables:
.TP
\f[B]POSIXLY_CORRECT\f[R]
If this variable exists (no matter the contents), bc(1) behaves as if
the \f[B]-s\f[R] option was given.
.TP
\f[B]BC_ENV_ARGS\f[R]
This is another way to give command-line arguments to bc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]BC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
.RS
.PP
The code that parses \f[B]BC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some bc file.bc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]bc\[dq] file.bc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]BC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]BC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), bc(1) will output lines to that length,
including the backslash (\f[B]\[rs]\f[R]).
The default line length is \f[B]70\f[R].
.SH EXIT STATUS
.PP
bc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, attempting to convert a negative number to a hardware
integer, overflow when converting a number to a hardware integer, and
attempting to use a non-integer where an integer is required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]) operator and the corresponding assignment
operator.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, using a token
where it is invalid, giving an invalid expression, giving an invalid
print statement, giving an invalid function definition, attempting to
assign to an expression that is not a named expression (see the
\f[I]Named Expressions\f[R] subsection of the \f[B]SYNTAX\f[R] section),
giving an invalid \f[B]auto\f[R] list, having a duplicate
\f[B]auto\f[R]/function parameter, failing to find the end of a code
block, attempting to return a value from a \f[B]void\f[R] function,
attempting to use a variable as a reference, and using any extensions
when the option \f[B]-s\f[R] or any equivalents were given.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a \f[B]void\f[R] function call as a value in an
expression.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (bc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, bc(1)
always exits and returns \f[B]4\f[R], no matter what mode bc(1) is in.
.PP
The other statuses will only be returned when bc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
bc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Per the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, bc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, bc(1) turns on \[lq]TTY mode.\[rq]
.PP
TTY mode is required for history to be enabled (see the \f[B]COMMAND
LINE HISTORY\f[R] section).
It is also required to enable special handling for \f[B]SIGINT\f[R]
signals.
.PP
The prompt is enabled in TTY mode.
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause bc(1) to stop execution of the
current input.
If bc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If bc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If bc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to bc(1) as it is
executing a file, it can seem as though bc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause bc(1) to clean up and
exit, and it uses the default handler for all other signals.
The one exception is \f[B]SIGHUP\f[R]; in that case, when bc(1) is in
TTY mode, a \f[B]SIGHUP\f[R] will cause bc(1) to clean up and exit.
.SH COMMAND LINE HISTORY
.PP
bc(1) supports interactive command-line editing.
If bc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), history is
enabled.
Previous lines can be recalled and edited with the arrow keys.
.PP
\f[B]Note\f[R]: tabs are converted to 8 spaces.
.SH LOCALES
.PP
This bc(1) ships with support for adding error messages for different
locales and thus, supports \f[B]LC_MESSAGES\f[R].
.SH SEE ALSO
.PP
dc(1)
.SH STANDARDS
.PP
bc(1) is compliant with the IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
The flags \f[B]-efghiqsvVw\f[R], all long options, and the extensions
noted above are extensions to that specification.
.PP
Note that the specification explicitly says that bc(1) only accepts
numbers that use a period (\f[B].\f[R]) as a radix point, regardless of
the value of \f[B]LC_NUMERIC\f[R].
.PP
This bc(1) supports error messages for different locales, and thus, it
supports \f[B]LC_MESSAGES\f[R].
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHORS
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/bc/E.1.md b/contrib/bc/manuals/bc/E.1.md
index 7cbc1a56548a..864cf32068bf 100644
--- a/contrib/bc/manuals/bc/E.1.md
+++ b/contrib/bc/manuals/bc/E.1.md
@@ -1,1085 +1,1094 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# NAME
bc - arbitrary-precision decimal arithmetic language and calculator
# SYNOPSIS
**bc** [**-ghilPqsvVw**] [**--global-stacks**] [**--help**] [**--interactive**] [**--mathlib**] [**--no-prompt**] [**--quiet**] [**--standard**] [**--warn**] [**--version**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...]
[*file*...]
# DESCRIPTION
bc(1) is an interactive processor for a language first standardized in 1991 by
POSIX. (The current standard is [here][1].) The language provides unlimited
precision decimal arithmetic and is somewhat C-like, but there are differences.
Such differences will be noted in this document.
After parsing and handling options, this bc(1) reads any files given on the
command line and executes them before reading from **stdin**.
This bc(1) is a drop-in replacement for *any* bc(1), including (and
especially) the GNU bc(1).
# OPTIONS
The following are the options that bc(1) accepts.
**-g**, **--global-stacks**
Turns the globals **ibase**, **obase**, and **scale** into stacks.
This has the effect that a copy of the current value of all three are pushed
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
However, since using this flag means that functions cannot set **ibase**,
**obase**, or **scale** globally, functions that are made to do so cannot
work anymore. There are two possible use cases for that, and each has a
solution.
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o="bc -e ibase=A -e obase=8"
alias h2b="bc -e ibase=G -e obase=2"
Second, if the purpose of a function is to set **ibase**, **obase**, or
**scale** globally for any other purpose, it could be split into one to
three functions (based on how many globals it sets) and each of those
functions could return the desired value for a global.
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
**-h**, **--help**
: Prints a usage message and quits.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-l**, **--mathlib**
: Sets **scale** (see the **SYNTAX** section) to **20** and loads the included
math library before running any code, including any expressions or files
specified on the command line.
To learn what is in the library, see the **LIBRARY** section.
**-P**, **--no-prompt**
: Disables the prompt in TTY mode. (The prompt is only enabled in TTY mode.
See the **TTY MODE** section) This is mostly for those users that do not
want a prompt or are not used to having them in bc(1). Most of those users
would want to put this option in **BC_ENV_ARGS** (see the
**ENVIRONMENT VARIABLES** section).
This is a **non-portable extension**.
**-q**, **--quiet**
: This option is for compatibility with the [GNU bc(1)][2]; it is a no-op.
Without this option, GNU bc(1) prints a copyright header. This bc(1) only
prints the copyright header if one or more of the **-v**, **-V**, or
**--version** options are given.
This is a **non-portable extension**.
**-s**, **--standard**
: Process exactly the language defined by the [standard][1] and error if any
extensions are used.
This is a **non-portable extension**.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
This is a **non-portable extension**.
**-w**, **--warn**
: Like **-s** and **--standard**, except that warnings (and not errors) are
printed for non-standard extensions and execution continues normally.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **BC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **bc <file> >&-**, it will quit with an error. This
is done so that bc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **bc <file> 2>&-**, it will quit with an error. This
is done so that bc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
The syntax for bc(1) programs is mostly C-like, with some differences. This
bc(1) follows the [POSIX standard][1], which is a much more thorough resource
for the language this bc(1) accepts. This section is meant to be a summary and a
listing of all the extensions to the standard.
In the sections below, **E** means expression, **S** means statement, and **I**
means identifier.
Identifiers (**I**) start with a lowercase letter and can be followed by any
number (up to **BC_NAME_MAX-1**) of lowercase letters (**a-z**), digits
(**0-9**), and underscores (**\_**). The regex is **\[a-z\]\[a-z0-9\_\]\***.
Identifiers with more than one character (letter) are a
**non-portable extension**.
**ibase** is a global variable determining how to interpret constant numbers. It
is the "input" base, or the number base used for interpreting input numbers.
**ibase** is initially **10**. If the **-s** (**--standard**) and **-w**
(**--warn**) flags were not given on the command line, the max allowable value
for **ibase** is **36**. Otherwise, it is **16**. The min allowable value for
**ibase** is **2**. The max allowable value for **ibase** can be queried in
bc(1) programs with the **maxibase()** built-in function.
**obase** is a global variable determining how to output results. It is the
"output" base, or the number base used for outputting numbers. **obase** is
initially **10**. The max allowable value for **obase** is **BC_BASE_MAX** and
can be queried in bc(1) programs with the **maxobase()** built-in function. The
min allowable value for **obase** is **2**. Values are output in the specified
base.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a global variable that
sets the precision of any operations, with exceptions. **scale** is initially
**0**. **scale** cannot be negative. The max allowable value for **scale** is
**BC_SCALE_MAX** and can be queried in bc(1) programs with the **maxscale()**
built-in function.
bc(1) has both *global* variables and *local* variables. All *local*
variables are local to the function; they are parameters or are introduced in
the **auto** list of a function (see the **FUNCTIONS** section). If a variable
is accessed which is not a parameter or in the **auto** list, it is assumed to
be *global*. If a parent function has a *local* variable version of a variable
that a child function considers *global*, the value of that *global* variable in
the child function is the value of the variable in the parent function, not the
value of the actual *global* variable.
All of the above applies to arrays as well.
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence operator is an
assignment operator *and* the expression is notsurrounded by parentheses.
The value that is printed is also assigned to the special variable **last**. A
single dot (**.**) may also be used as a synonym for **last**. These are
**non-portable extensions**.
Either semicolons or newlines may separate statements.
## Comments
There are two kinds of comments:
1. Block comments are enclosed in **/\*** and **\*/**.
2. Line comments go from **#** until, and not including, the next newline. This
is a **non-portable extension**.
## Named Expressions
The following are named expressions in bc(1):
1. Variables: **I**
2. Array Elements: **I[E]**
3. **ibase**
4. **obase**
5. **scale**
6. **last** or a single dot (**.**)
Number 6 is a **non-portable extension**.
Variables and arrays do not interfere; users can have arrays named the same as
variables. This also applies to functions (see the **FUNCTIONS** section), so a
user can have a variable, array, and function that all have the same name, and
they will not shadow each other, whether inside of functions or not.
Named expressions are required as the operand of **increment**/**decrement**
operators and as the left side of **assignment** operators (see the *Operators*
subsection).
## Operands
The following are valid operands in bc(1):
1. Numbers (see the *Numbers* subsection below).
2. Array indices (**I[E]**).
3. **(E)**: The value of **E** (used to change precedence).
4. **sqrt(E)**: The square root of **E**. **E** must be non-negative.
5. **length(E)**: The number of significant decimal digits in **E**.
6. **length(I[])**: The number of elements in the array **I**. This is a
**non-portable extension**.
7. **scale(E)**: The *scale* of **E**.
8. **abs(E)**: The absolute value of **E**. This is a **non-portable
extension**.
9. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a non-**void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
10. **read()**: Reads a line from **stdin** and uses that as an expression. The
result of that expression is the result of the **read()** operand. This is a
**non-portable extension**.
11. **maxibase()**: The max allowable **ibase**. This is a **non-portable
extension**.
12. **maxobase()**: The max allowable **obase**. This is a **non-portable
extension**.
13. **maxscale()**: The max allowable **scale**. This is a **non-portable
extension**.
## Numbers
Numbers are strings made up of digits, uppercase letters, and at most **1**
period for a radix. Numbers can have up to **BC_NUM_MAX** digits. Uppercase
letters are equal to **9** + their position in the alphabet (i.e., **A** equals
**10**, or **9+1**). If a digit or letter makes no sense with the current value
of **ibase**, they are set to the value of the highest valid digit in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **Z** alone always equals decimal
**35**.
## Operators
The following arithmetic and logical operators can be used. They are listed in
order of decreasing precedence. Operators in the same group have the same
precedence.
**++** **--**
: Type: Prefix and Postfix
Associativity: None
Description: **increment**, **decrement**
**-** **!**
: Type: Prefix
Associativity: None
Description: **negation**, **boolean not**
**\^**
: Type: Binary
Associativity: Right
Description: **power**
**\*** **/** **%**
: Type: Binary
Associativity: Left
Description: **multiply**, **divide**, **modulus**
**+** **-**
: Type: Binary
Associativity: Left
Description: **add**, **subtract**
**=** **+=** **-=** **\*=** **/=** **%=** **\^=**
: Type: Binary
Associativity: Right
Description: **assignment**
**==** **\<=** **\>=** **!=** **\<** **\>**
: Type: Binary
Associativity: Left
Description: **relational**
**&&**
: Type: Binary
Associativity: Left
Description: **boolean and**
**||**
: Type: Binary
Associativity: Left
Description: **boolean or**
The operators will be described in more detail below.
**++** **--**
: The prefix and postfix **increment** and **decrement** operators behave
exactly like they would in C. They require a named expression (see the
*Named Expressions* subsection) as an operand.
The prefix versions of these operators are more efficient; use them where
possible.
**-**
: The **negation** operator returns **0** if a user attempts to negate any
expression with the value **0**. Otherwise, a copy of the expression with
its sign flipped is returned.
**!**
: The **boolean not** operator returns **1** if the expression is **0**, or
**0** otherwise.
This is a **non-portable extension**.
**\^**
: The **power** operator (not the **exclusive or** operator, as it would be in
C) takes two expressions and raises the first to the power of the value of
the second. The *scale* of the result is equal to **scale**.
The second expression must be an integer (no *scale*), and if it is
negative, the first value must be non-zero.
**\***
: The **multiply** operator takes two expressions, multiplies them, and
returns the product. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result is
equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The **divide** operator takes two expressions, divides them, and returns the
quotient. The *scale* of the result shall be the value of **scale**.
The second expression must be non-zero.
**%**
: The **modulus** operator takes two expressions, **a** and **b**, and
evaluates them by 1) Computing **a/b** to current **scale** and 2) Using the
result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The second expression must be non-zero.
**+**
: The **add** operator takes two expressions, **a** and **b**, and returns the
sum, with a *scale* equal to the max of the *scale*s of **a** and **b**.
**-**
: The **subtract** operator takes two expressions, **a** and **b**, and
returns the difference, with a *scale* equal to the max of the *scale*s of
**a** and **b**.
**=** **+=** **-=** **\*=** **/=** **%=** **\^=**
: The **assignment** operators take two expressions, **a** and **b** where
**a** is a named expression (see the *Named Expressions* subsection).
For **=**, **b** is copied and the result is assigned to **a**. For all
others, **a** and **b** are applied as operands to the corresponding
arithmetic operator and the result is assigned to **a**.
**==** **\<=** **\>=** **!=** **\<** **\>**
: The **relational** operators compare two expressions, **a** and **b**, and
if the relation holds, according to C language semantics, the result is
**1**. Otherwise, it is **0**.
Note that unlike in C, these operators have a lower precedence than the
**assignment** operators, which means that **a=b\>c** is interpreted as
**(a=b)\>c**.
Also, unlike the [standard][1] requires, these operators can appear anywhere
any other expressions can be used. This allowance is a
**non-portable extension**.
**&&**
: The **boolean and** operator takes two expressions and returns **1** if both
expressions are non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
**||**
: The **boolean or** operator takes two expressions and returns **1** if one
of the expressions is non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
## Statements
The following items are statements:
1. **E**
2. **{** **S** **;** ... **;** **S** **}**
3. **if** **(** **E** **)** **S**
4. **if** **(** **E** **)** **S** **else** **S**
5. **while** **(** **E** **)** **S**
6. **for** **(** **E** **;** **E** **;** **E** **)** **S**
7. An empty statement
8. **break**
9. **continue**
10. **quit**
11. **halt**
12. **limits**
13. A string of characters, enclosed in double quotes
14. **print** **E** **,** ... **,** **E**
15. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
Numbers 4, 9, 11, 12, 14, and 15 are **non-portable extensions**.
Also, as a **non-portable extension**, any or all of the expressions in the
header of a for loop may be omitted. If the condition (second expression) is
omitted, it is assumed to be a constant **1**.
The **break** statement causes a loop to stop iterating and resume execution
immediately following a loop. This is only allowed in loops.
The **continue** statement causes a loop iteration to stop early and returns to
the start of the loop, including testing the loop condition. This is only
allowed in loops.
The **if** **else** statement does the same thing as in C.
The **quit** statement causes bc(1) to quit, even if it is on a branch that will
not be executed (it is a compile-time command).
The **halt** statement causes bc(1) to quit, if it is executed. (Unlike **quit**
if it is on a branch of an **if** statement that is not executed, bc(1) does not
quit.)
The **limits** statement prints the limits that this bc(1) is subject to. This
is like the **quit** statement in that it is a compile-time command.
An expression by itself is evaluated and printed, followed by a newline.
## Print Statement
The "expressions" in a **print** statement may also be strings. If they are, there
are backslash escape sequences that are interpreted specially. What those
sequences are, and what they cause to be printed, are shown below:
-------- -------
**\\a** **\\a**
**\\b** **\\b**
**\\\\** **\\**
**\\e** **\\**
**\\f** **\\f**
**\\n** **\\n**
**\\q** **"**
**\\r** **\\r**
**\\t** **\\t**
-------- -------
Any other character following a backslash causes the backslash and character to
be printed as-is.
Any non-string expression in a print statement shall be assigned to **last**,
like any other expression that is printed.
## Order of Evaluation
All expressions in a statment are evaluated left to right, except as necessary
to maintain order of operations. This means, for example, assuming that **i** is
equal to **0**, in the expression
a[i++] = i++
the first (or 0th) element of **a** is set to **1**, and **i** is equal to **2**
at the end of the expression.
This includes function arguments. Thus, assuming **i** is equal to **0**, this
means that in the expression
x(i++, i++)
the first argument passed to **x()** is **0**, and the second argument is **1**,
while **i** is equal to **2** before the function starts executing.
# FUNCTIONS
Function definitions are as follows:
```
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
```
Any **I** in the parameter list or **auto** list may be replaced with **I[]** to
make a parameter or **auto** var an array, and any **I** in the parameter list
may be replaced with **\*I[]** to make a parameter an array reference. Callers
of functions that take array references should not put an asterisk in the call;
they must be called with just **I[]** like normal array parameters and will be
automatically converted into references.
As a **non-portable extension**, the opening brace of a **define** statement may
appear on the next line.
As a **non-portable extension**, the return statement may also be in one of the
following forms:
1. **return**
2. **return** **(** **)**
3. **return** **E**
The first two, or not specifying a **return** statement, is equivalent to
**return (0)**, unless the function is a **void** function (see the *Void
Functions* subsection below).
## Void Functions
Functions can also be **void** functions, defined as follows:
```
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
```
They can only be used as standalone expressions, where such an expression would
be printed alone, except in a print statement.
Void functions can only use the first two **return** statements listed above.
They can also omit the return statement entirely.
The word "void" is not treated as a keyword; it is still possible to have
variables, arrays, and functions named **void**. The word "void" is only
treated specially right after the **define** keyword.
This is a **non-portable extension**.
## Array References
For any array in the parameter list, if the array is declared in the form
```
*I[]
```
it is a **reference**. Any changes to the array in the function are reflected,
when the function returns, to the array that was passed in.
Other than this, all function arguments are passed by value.
This is a **non-portable extension**.
# LIBRARY
All of the functions below are available when the **-l** or **--mathlib**
command-line flags are given.
## Standard Library
The [standard][1] defines the following functions for the math library:
**s(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**c(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a(x)**
: Returns the arctangent of **x**, in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l(x)**
: Returns the natural logarithm of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**e(x)**
: Returns the mathematical constant **e** raised to the power of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**j(x, n)**
: Returns the bessel integer order **n** (truncated) of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
## Transcendental Functions
All transcendental functions can return slightly inaccurate results (up to 1
[ULP][4]). This is unavoidable, and [this article][5] explains why it is
impossible and unnecessary to calculate exact results for the transcendental
functions.
Because of the possible inaccuracy, I recommend that users call those functions
with the precision (**scale**) set to at least 1 higher than is necessary. If
exact results are *absolutely* required, users can double the precision
(**scale**) and then truncate.
The transcendental functions in the standard math library are:
* **s(x)**
* **c(x)**
* **a(x)**
* **l(x)**
* **e(x)**
* **j(x, n)**
# RESET
When bc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any functions that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
functions returned) is skipped.
Thus, when bc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
Note that this reset behavior is different from the GNU bc(1), which attempts to
start executing the statement right after the one that caused an error.
# PERFORMANCE
Most bc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This bc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **BC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **BC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**BC_BASE_DIGS**.
The actual values of **BC_LONG_BIT** and **BC_BASE_DIGS** can be queried with
the **limits** statement.
In addition, this bc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **BC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on bc(1):
**BC_LONG_BIT**
: The number of bits in the **long** type in the environment where bc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**BC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **BC_LONG_BIT**.
**BC_BASE_POW**
: The max decimal number that each large integer can store (see
**BC_BASE_DIGS**) plus **1**. Depends on **BC_BASE_DIGS**.
**BC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **BC_LONG_BIT**.
**BC_BASE_MAX**
: The maximum output base. Set at **BC_BASE_POW**.
**BC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**BC_SCALE_MAX**
: The maximum **scale**. Set at **BC_OVERFLOW_MAX-1**.
**BC_STRING_MAX**
: The maximum length of strings. Set at **BC_OVERFLOW_MAX-1**.
**BC_NAME_MAX**
: The maximum length of identifiers. Set at **BC_OVERFLOW_MAX-1**.
**BC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **BC_OVERFLOW_MAX-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**BC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
The actual values can be queried with the **limits** statement.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
bc(1) recognizes the following environment variables:
**POSIXLY_CORRECT**
: If this variable exists (no matter the contents), bc(1) behaves as if
the **-s** option was given.
**BC_ENV_ARGS**
: This is another way to give command-line arguments to bc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **BC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
The code that parses **BC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some bc file.bc"** will be correctly parsed, but the string
**"/home/gavin/some \"bc\" file.bc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **BC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**BC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), bc(1) will output
lines to that length, including the backslash (**\\**). The default line
length is **70**.
# EXIT STATUS
bc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**) operator and the corresponding assignment operator.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, using a token where it is invalid,
giving an invalid expression, giving an invalid print statement, giving an
invalid function definition, attempting to assign to an expression that is
not a named expression (see the *Named Expressions* subsection of the
**SYNTAX** section), giving an invalid **auto** list, having a duplicate
**auto**/function parameter, failing to find the end of a code block,
attempting to return a value from a **void** function, attempting to use a
variable as a reference, and using any extensions when the option **-s** or
any equivalents were given.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a **void** function call as a value in an expression.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (bc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, bc(1) always exits
and returns **4**, no matter what mode bc(1) is in.
The other statuses will only be returned when bc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since bc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Per the [standard][1], bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, bc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, bc(1) turns
on "TTY mode."
TTY mode is required for history to be enabled (see the **COMMAND LINE HISTORY**
section). It is also required to enable special handling for **SIGINT** signals.
The prompt is enabled in TTY mode.
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause bc(1) to stop execution of the current input. If
bc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If bc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If bc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to bc(1) as it is executing a file, it
can seem as though bc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause bc(1) to clean up and exit, and it uses the
default handler for all other signals. The one exception is **SIGHUP**; in that
case, when bc(1) is in TTY mode, a **SIGHUP** will cause bc(1) to clean up and
exit.
# COMMAND LINE HISTORY
bc(1) supports interactive command-line editing. If bc(1) is in TTY mode (see
the **TTY MODE** section), history is enabled. Previous lines can be recalled
and edited with the arrow keys.
**Note**: tabs are converted to 8 spaces.
# LOCALES
This bc(1) ships with support for adding error messages for different locales
and thus, supports **LC_MESSAGES**.
# SEE ALSO
dc(1)
# STANDARDS
bc(1) is compliant with the [IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1]
specification. The flags **-efghiqsvVw**, all long options, and the extensions
noted above are extensions to that specification.
Note that the specification explicitly says that bc(1) only accepts numbers that
use a period (**.**) as a radix point, regardless of the value of
**LC_NUMERIC**.
This bc(1) supports error messages for different locales, and thus, it supports
**LC_MESSAGES**.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHORS
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
[2]: https://www.gnu.org/software/bc/
[3]: https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero
[4]: https://en.wikipedia.org/wiki/Unit_in_the_last_place
[5]: https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT
[6]: https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero
diff --git a/contrib/bc/manuals/bc/EH.1 b/contrib/bc/manuals/bc/EH.1
index 8cb2a3bc8335..dca77a99162e 100644
--- a/contrib/bc/manuals/bc/EH.1
+++ b/contrib/bc/manuals/bc/EH.1
@@ -1,1283 +1,1296 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "BC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "BC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH NAME
.PP
bc - arbitrary-precision decimal arithmetic language and calculator
.SH SYNOPSIS
.PP
\f[B]bc\f[R] [\f[B]-ghilPqsvVw\f[R]] [\f[B]\[en]global-stacks\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]mathlib\f[R]] [\f[B]\[en]no-prompt\f[R]]
[\f[B]\[en]quiet\f[R]] [\f[B]\[en]standard\f[R]] [\f[B]\[en]warn\f[R]]
[\f[B]\[en]version\f[R]] [\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
bc(1) is an interactive processor for a language first standardized in
1991 by POSIX.
(The current standard is
here (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).)
The language provides unlimited precision decimal arithmetic and is
somewhat C-like, but there are differences.
Such differences will be noted in this document.
.PP
After parsing and handling options, this bc(1) reads any files given on
the command line and executes them before reading from \f[B]stdin\f[R].
.SH OPTIONS
.PP
The following are the options that bc(1) accepts.
.PP
\f[B]-g\f[R], \f[B]\[en]global-stacks\f[R]
.IP
.nf
\f[C]
Turns the globals **ibase**, **obase**, and **scale** into stacks.
This has the effect that a copy of the current value of all three are pushed
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
However, since using this flag means that functions cannot set **ibase**,
**obase**, or **scale** globally, functions that are made to do so cannot
work anymore. There are two possible use cases for that, and each has a
solution.
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o=\[dq]bc -e ibase=A -e obase=8\[dq]
alias h2b=\[dq]bc -e ibase=G -e obase=2\[dq]
Second, if the purpose of a function is to set **ibase**, **obase**, or
**scale** globally for any other purpose, it could be split into one to
three functions (based on how many globals it sets) and each of those
functions could return the desired value for a global.
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
\f[R]
.fi
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-l\f[R], \f[B]\[en]mathlib\f[R]
Sets \f[B]scale\f[R] (see the \f[B]SYNTAX\f[R] section) to \f[B]20\f[R]
and loads the included math library before running any code, including
any expressions or files specified on the command line.
.RS
.PP
To learn what is in the library, see the \f[B]LIBRARY\f[R] section.
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
Disables the prompt in TTY mode.
(The prompt is only enabled in TTY mode.
See the \f[B]TTY MODE\f[R] section) This is mostly for those users that
do not want a prompt or are not used to having them in bc(1).
Most of those users would want to put this option in
\f[B]BC_ENV_ARGS\f[R] (see the \f[B]ENVIRONMENT VARIABLES\f[R] section).
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-q\f[R], \f[B]\[en]quiet\f[R]
This option is for compatibility with the GNU
bc(1) (https://www.gnu.org/software/bc/); it is a no-op.
Without this option, GNU bc(1) prints a copyright header.
This bc(1) only prints the copyright header if one or more of the
\f[B]-v\f[R], \f[B]-V\f[R], or \f[B]\[en]version\f[R] options are given.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-s\f[R], \f[B]\[en]standard\f[R]
Process exactly the language defined by the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
and error if any extensions are used.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-w\f[R], \f[B]\[en]warn\f[R]
Like \f[B]-s\f[R] and \f[B]\[en]standard\f[R], except that warnings (and
not errors) are printed for non-standard extensions and execution
continues normally.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]BC_ENV_ARGS\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]bc >&-\f[R], it will quit with an error.
This is done so that bc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]bc 2>&-\f[R], it will quit with an error.
This is done so that bc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
The syntax for bc(1) programs is mostly C-like, with some differences.
This bc(1) follows the POSIX
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
which is a much more thorough resource for the language this bc(1)
accepts.
This section is meant to be a summary and a listing of all the
extensions to the standard.
.PP
In the sections below, \f[B]E\f[R] means expression, \f[B]S\f[R] means
statement, and \f[B]I\f[R] means identifier.
.PP
Identifiers (\f[B]I\f[R]) start with a lowercase letter and can be
followed by any number (up to \f[B]BC_NAME_MAX-1\f[R]) of lowercase
letters (\f[B]a-z\f[R]), digits (\f[B]0-9\f[R]), and underscores
(\f[B]_\f[R]).
The regex is \f[B][a-z][a-z0-9_]*\f[R].
Identifiers with more than one character (letter) are a
\f[B]non-portable extension\f[R].
.PP
\f[B]ibase\f[R] is a global variable determining how to interpret
constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
If the \f[B]-s\f[R] (\f[B]\[en]standard\f[R]) and \f[B]-w\f[R]
(\f[B]\[en]warn\f[R]) flags were not given on the command line, the max
allowable value for \f[B]ibase\f[R] is \f[B]36\f[R].
Otherwise, it is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in bc(1)
programs with the \f[B]maxibase()\f[R] built-in function.
.PP
\f[B]obase\f[R] is a global variable determining how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]BC_BASE_MAX\f[R] and
can be queried in bc(1) programs with the \f[B]maxobase()\f[R] built-in
function.
The min allowable value for \f[B]obase\f[R] is \f[B]2\f[R].
Values are output in the specified base.
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a global variable that sets the precision of any operations, with
exceptions.
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] is \f[B]BC_SCALE_MAX\f[R]
and can be queried in bc(1) programs with the \f[B]maxscale()\f[R]
built-in function.
.PP
bc(1) has both \f[I]global\f[R] variables and \f[I]local\f[R] variables.
All \f[I]local\f[R] variables are local to the function; they are
parameters or are introduced in the \f[B]auto\f[R] list of a function
(see the \f[B]FUNCTIONS\f[R] section).
If a variable is accessed which is not a parameter or in the
\f[B]auto\f[R] list, it is assumed to be \f[I]global\f[R].
If a parent function has a \f[I]local\f[R] variable version of a
variable that a child function considers \f[I]global\f[R], the value of
that \f[I]global\f[R] variable in the child function is the value of the
variable in the parent function, not the value of the actual
\f[I]global\f[R] variable.
.PP
All of the above applies to arrays as well.
.PP
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence
operator is an assignment operator \f[I]and\f[R] the expression is
notsurrounded by parentheses.
.PP
The value that is printed is also assigned to the special variable
\f[B]last\f[R].
A single dot (\f[B].\f[R]) may also be used as a synonym for
\f[B]last\f[R].
These are \f[B]non-portable extensions\f[R].
.PP
Either semicolons or newlines may separate statements.
.SS Comments
.PP
There are two kinds of comments:
.IP "1." 3
Block comments are enclosed in \f[B]/*\f[R] and \f[B]*/\f[R].
.IP "2." 3
Line comments go from \f[B]#\f[R] until, and not including, the next
newline.
This is a \f[B]non-portable extension\f[R].
.SS Named Expressions
.PP
The following are named expressions in bc(1):
.IP "1." 3
Variables: \f[B]I\f[R]
.IP "2." 3
Array Elements: \f[B]I[E]\f[R]
.IP "3." 3
\f[B]ibase\f[R]
.IP "4." 3
\f[B]obase\f[R]
.IP "5." 3
\f[B]scale\f[R]
.IP "6." 3
\f[B]last\f[R] or a single dot (\f[B].\f[R])
.PP
Number 6 is a \f[B]non-portable extension\f[R].
.PP
Variables and arrays do not interfere; users can have arrays named the
same as variables.
This also applies to functions (see the \f[B]FUNCTIONS\f[R] section), so
a user can have a variable, array, and function that all have the same
name, and they will not shadow each other, whether inside of functions
or not.
.PP
Named expressions are required as the operand of
\f[B]increment\f[R]/\f[B]decrement\f[R] operators and as the left side
of \f[B]assignment\f[R] operators (see the \f[I]Operators\f[R]
subsection).
.SS Operands
.PP
The following are valid operands in bc(1):
.IP " 1." 4
Numbers (see the \f[I]Numbers\f[R] subsection below).
.IP " 2." 4
Array indices (\f[B]I[E]\f[R]).
.IP " 3." 4
\f[B](E)\f[R]: The value of \f[B]E\f[R] (used to change precedence).
.IP " 4." 4
\f[B]sqrt(E)\f[R]: The square root of \f[B]E\f[R].
\f[B]E\f[R] must be non-negative.
.IP " 5." 4
\f[B]length(E)\f[R]: The number of significant decimal digits in
\f[B]E\f[R].
.IP " 6." 4
\f[B]length(I[])\f[R]: The number of elements in the array \f[B]I\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 7." 4
\f[B]scale(E)\f[R]: The \f[I]scale\f[R] of \f[B]E\f[R].
.IP " 8." 4
\f[B]abs(E)\f[R]: The absolute value of \f[B]E\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 9." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a non-\f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.IP "10." 4
\f[B]read()\f[R]: Reads a line from \f[B]stdin\f[R] and uses that as an
expression.
The result of that expression is the result of the \f[B]read()\f[R]
operand.
This is a \f[B]non-portable extension\f[R].
.IP "11." 4
\f[B]maxibase()\f[R]: The max allowable \f[B]ibase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "12." 4
\f[B]maxobase()\f[R]: The max allowable \f[B]obase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "13." 4
\f[B]maxscale()\f[R]: The max allowable \f[B]scale\f[R].
This is a \f[B]non-portable extension\f[R].
.SS Numbers
.PP
Numbers are strings made up of digits, uppercase letters, and at most
\f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]BC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]Z\f[R] alone always equals decimal \f[B]35\f[R].
.SS Operators
.PP
The following arithmetic and logical operators can be used.
They are listed in order of decreasing precedence.
Operators in the same group have the same precedence.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
Type: Prefix and Postfix
.RS
.PP
Associativity: None
.PP
Description: \f[B]increment\f[R], \f[B]decrement\f[R]
.RE
.TP
\f[B]-\f[R] \f[B]!\f[R]
Type: Prefix
.RS
.PP
Associativity: None
.PP
Description: \f[B]negation\f[R], \f[B]boolean not\f[R]
.RE
.TP
\f[B]\[ha]\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]power\f[R]
.RE
.TP
\f[B]*\f[R] \f[B]/\f[R] \f[B]%\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]multiply\f[R], \f[B]divide\f[R], \f[B]modulus\f[R]
.RE
.TP
\f[B]+\f[R] \f[B]-\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]add\f[R], \f[B]subtract\f[R]
.RE
.TP
\f[B]=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]assignment\f[R]
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]relational\f[R]
.RE
.TP
\f[B]&&\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean and\f[R]
.RE
.TP
\f[B]||\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean or\f[R]
.RE
.PP
The operators will be described in more detail below.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
The prefix and postfix \f[B]increment\f[R] and \f[B]decrement\f[R]
operators behave exactly like they would in C.
They require a named expression (see the \f[I]Named Expressions\f[R]
subsection) as an operand.
.RS
.PP
The prefix versions of these operators are more efficient; use them
where possible.
.RE
.TP
\f[B]-\f[R]
The \f[B]negation\f[R] operator returns \f[B]0\f[R] if a user attempts
to negate any expression with the value \f[B]0\f[R].
Otherwise, a copy of the expression with its sign flipped is returned.
.TP
\f[B]!\f[R]
The \f[B]boolean not\f[R] operator returns \f[B]1\f[R] if the expression
is \f[B]0\f[R], or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The \f[B]power\f[R] operator (not the \f[B]exclusive or\f[R] operator,
as it would be in C) takes two expressions and raises the first to the
power of the value of the second.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]), and if it
is negative, the first value must be non-zero.
.RE
.TP
\f[B]*\f[R]
The \f[B]multiply\f[R] operator takes two expressions, multiplies them,
and returns the product.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The \f[B]divide\f[R] operator takes two expressions, divides them, and
returns the quotient.
The \f[I]scale\f[R] of the result shall be the value of \f[B]scale\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]%\f[R]
The \f[B]modulus\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and evaluates them by 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R] and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]+\f[R]
The \f[B]add\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the sum, with a \f[I]scale\f[R] equal to the
max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]-\f[R]
The \f[B]subtract\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the difference, with a \f[I]scale\f[R] equal to
the max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R]
The \f[B]assignment\f[R] operators take two expressions, \f[B]a\f[R] and
\f[B]b\f[R] where \f[B]a\f[R] is a named expression (see the \f[I]Named
Expressions\f[R] subsection).
.RS
.PP
For \f[B]=\f[R], \f[B]b\f[R] is copied and the result is assigned to
\f[B]a\f[R].
For all others, \f[B]a\f[R] and \f[B]b\f[R] are applied as operands to
the corresponding arithmetic operator and the result is assigned to
\f[B]a\f[R].
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
The \f[B]relational\f[R] operators compare two expressions, \f[B]a\f[R]
and \f[B]b\f[R], and if the relation holds, according to C language
semantics, the result is \f[B]1\f[R].
Otherwise, it is \f[B]0\f[R].
.RS
.PP
Note that unlike in C, these operators have a lower precedence than the
\f[B]assignment\f[R] operators, which means that \f[B]a=b>c\f[R] is
interpreted as \f[B](a=b)>c\f[R].
.PP
Also, unlike the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
requires, these operators can appear anywhere any other expressions can
be used.
This allowance is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]&&\f[R]
The \f[B]boolean and\f[R] operator takes two expressions and returns
\f[B]1\f[R] if both expressions are non-zero, \f[B]0\f[R] otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]||\f[R]
The \f[B]boolean or\f[R] operator takes two expressions and returns
\f[B]1\f[R] if one of the expressions is non-zero, \f[B]0\f[R]
otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Statements
.PP
The following items are statements:
.IP " 1." 4
\f[B]E\f[R]
.IP " 2." 4
\f[B]{\f[R] \f[B]S\f[R] \f[B];\f[R] \&... \f[B];\f[R] \f[B]S\f[R]
\f[B]}\f[R]
.IP " 3." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 4." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
\f[B]else\f[R] \f[B]S\f[R]
.IP " 5." 4
\f[B]while\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 6." 4
\f[B]for\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B];\f[R] \f[B]E\f[R]
\f[B];\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 7." 4
An empty statement
.IP " 8." 4
\f[B]break\f[R]
.IP " 9." 4
\f[B]continue\f[R]
.IP "10." 4
\f[B]quit\f[R]
.IP "11." 4
\f[B]halt\f[R]
.IP "12." 4
\f[B]limits\f[R]
.IP "13." 4
A string of characters, enclosed in double quotes
.IP "14." 4
\f[B]print\f[R] \f[B]E\f[R] \f[B],\f[R] \&... \f[B],\f[R] \f[B]E\f[R]
.IP "15." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a \f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.PP
Numbers 4, 9, 11, 12, 14, and 15 are \f[B]non-portable extensions\f[R].
.PP
Also, as a \f[B]non-portable extension\f[R], any or all of the
expressions in the header of a for loop may be omitted.
If the condition (second expression) is omitted, it is assumed to be a
constant \f[B]1\f[R].
.PP
The \f[B]break\f[R] statement causes a loop to stop iterating and resume
execution immediately following a loop.
This is only allowed in loops.
.PP
The \f[B]continue\f[R] statement causes a loop iteration to stop early
and returns to the start of the loop, including testing the loop
condition.
This is only allowed in loops.
.PP
The \f[B]if\f[R] \f[B]else\f[R] statement does the same thing as in C.
.PP
The \f[B]quit\f[R] statement causes bc(1) to quit, even if it is on a
branch that will not be executed (it is a compile-time command).
.PP
The \f[B]halt\f[R] statement causes bc(1) to quit, if it is executed.
(Unlike \f[B]quit\f[R] if it is on a branch of an \f[B]if\f[R] statement
that is not executed, bc(1) does not quit.)
.PP
The \f[B]limits\f[R] statement prints the limits that this bc(1) is
subject to.
This is like the \f[B]quit\f[R] statement in that it is a compile-time
command.
.PP
An expression by itself is evaluated and printed, followed by a newline.
.SS Print Statement
.PP
The \[lq]expressions\[rq] in a \f[B]print\f[R] statement may also be
strings.
If they are, there are backslash escape sequences that are interpreted
specially.
What those sequences are, and what they cause to be printed, are shown
below:
.PP
.TS
tab(@);
l l.
T{
\f[B]\[rs]a\f[R]
T}@T{
\f[B]\[rs]a\f[R]
T}
T{
\f[B]\[rs]b\f[R]
T}@T{
\f[B]\[rs]b\f[R]
T}
T{
\f[B]\[rs]\[rs]\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]e\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]f\f[R]
T}@T{
\f[B]\[rs]f\f[R]
T}
T{
\f[B]\[rs]n\f[R]
T}@T{
\f[B]\[rs]n\f[R]
T}
T{
\f[B]\[rs]q\f[R]
T}@T{
\f[B]\[dq]\f[R]
T}
T{
\f[B]\[rs]r\f[R]
T}@T{
\f[B]\[rs]r\f[R]
T}
T{
\f[B]\[rs]t\f[R]
T}@T{
\f[B]\[rs]t\f[R]
T}
.TE
.PP
Any other character following a backslash causes the backslash and
character to be printed as-is.
.PP
Any non-string expression in a print statement shall be assigned to
\f[B]last\f[R], like any other expression that is printed.
.SS Order of Evaluation
.PP
All expressions in a statment are evaluated left to right, except as
necessary to maintain order of operations.
This means, for example, assuming that \f[B]i\f[R] is equal to
\f[B]0\f[R], in the expression
.IP
.nf
\f[C]
a[i++] = i++
\f[R]
.fi
.PP
the first (or 0th) element of \f[B]a\f[R] is set to \f[B]1\f[R], and
\f[B]i\f[R] is equal to \f[B]2\f[R] at the end of the expression.
.PP
This includes function arguments.
Thus, assuming \f[B]i\f[R] is equal to \f[B]0\f[R], this means that in
the expression
.IP
.nf
\f[C]
x(i++, i++)
\f[R]
.fi
.PP
the first argument passed to \f[B]x()\f[R] is \f[B]0\f[R], and the
second argument is \f[B]1\f[R], while \f[B]i\f[R] is equal to
\f[B]2\f[R] before the function starts executing.
.SH FUNCTIONS
.PP
Function definitions are as follows:
.IP
.nf
\f[C]
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
\f[R]
.fi
.PP
Any \f[B]I\f[R] in the parameter list or \f[B]auto\f[R] list may be
replaced with \f[B]I[]\f[R] to make a parameter or \f[B]auto\f[R] var an
array, and any \f[B]I\f[R] in the parameter list may be replaced with
\f[B]*I[]\f[R] to make a parameter an array reference.
Callers of functions that take array references should not put an
asterisk in the call; they must be called with just \f[B]I[]\f[R] like
normal array parameters and will be automatically converted into
references.
.PP
As a \f[B]non-portable extension\f[R], the opening brace of a
\f[B]define\f[R] statement may appear on the next line.
.PP
As a \f[B]non-portable extension\f[R], the return statement may also be
in one of the following forms:
.IP "1." 3
\f[B]return\f[R]
.IP "2." 3
\f[B]return\f[R] \f[B](\f[R] \f[B])\f[R]
.IP "3." 3
\f[B]return\f[R] \f[B]E\f[R]
.PP
The first two, or not specifying a \f[B]return\f[R] statement, is
equivalent to \f[B]return (0)\f[R], unless the function is a
\f[B]void\f[R] function (see the \f[I]Void Functions\f[R] subsection
below).
.SS Void Functions
.PP
Functions can also be \f[B]void\f[R] functions, defined as follows:
.IP
.nf
\f[C]
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
\f[R]
.fi
.PP
They can only be used as standalone expressions, where such an
expression would be printed alone, except in a print statement.
.PP
Void functions can only use the first two \f[B]return\f[R] statements
listed above.
They can also omit the return statement entirely.
.PP
The word \[lq]void\[rq] is not treated as a keyword; it is still
possible to have variables, arrays, and functions named \f[B]void\f[R].
The word \[lq]void\[rq] is only treated specially right after the
\f[B]define\f[R] keyword.
.PP
This is a \f[B]non-portable extension\f[R].
.SS Array References
.PP
For any array in the parameter list, if the array is declared in the
form
.IP
.nf
\f[C]
*I[]
\f[R]
.fi
.PP
it is a \f[B]reference\f[R].
Any changes to the array in the function are reflected, when the
function returns, to the array that was passed in.
.PP
Other than this, all function arguments are passed by value.
.PP
This is a \f[B]non-portable extension\f[R].
.SH LIBRARY
.PP
All of the functions below are available when the \f[B]-l\f[R] or
\f[B]\[en]mathlib\f[R] command-line flags are given.
.SS Standard Library
.PP
The
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
defines the following functions for the math library:
.TP
\f[B]s(x)\f[R]
Returns the sine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]c(x)\f[R]
Returns the cosine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]a(x)\f[R]
Returns the arctangent of \f[B]x\f[R], in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]l(x)\f[R]
Returns the natural logarithm of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]e(x)\f[R]
Returns the mathematical constant \f[B]e\f[R] raised to the power of
\f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]j(x, n)\f[R]
Returns the bessel integer order \f[B]n\f[R] (truncated) of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.SS Transcendental Functions
.PP
All transcendental functions can return slightly inaccurate results (up
to 1 ULP (https://en.wikipedia.org/wiki/Unit_in_the_last_place)).
This is unavoidable, and this
article (https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT) explains
why it is impossible and unnecessary to calculate exact results for the
transcendental functions.
.PP
Because of the possible inaccuracy, I recommend that users call those
functions with the precision (\f[B]scale\f[R]) set to at least 1 higher
than is necessary.
If exact results are \f[I]absolutely\f[R] required, users can double the
precision (\f[B]scale\f[R]) and then truncate.
.PP
The transcendental functions in the standard math library are:
.IP \[bu] 2
\f[B]s(x)\f[R]
.IP \[bu] 2
\f[B]c(x)\f[R]
.IP \[bu] 2
\f[B]a(x)\f[R]
.IP \[bu] 2
\f[B]l(x)\f[R]
.IP \[bu] 2
\f[B]e(x)\f[R]
.IP \[bu] 2
\f[B]j(x, n)\f[R]
.SH RESET
.PP
When bc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any functions that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all functions returned) is skipped.
.PP
Thus, when bc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.PP
Note that this reset behavior is different from the GNU bc(1), which
attempts to start executing the statement right after the one that
caused an error.
.SH PERFORMANCE
.PP
Most bc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This bc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]BC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]BC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]BC_BASE_DIGS\f[R].
.PP
The actual values of \f[B]BC_LONG_BIT\f[R] and \f[B]BC_BASE_DIGS\f[R]
can be queried with the \f[B]limits\f[R] statement.
.PP
In addition, this bc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]BC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on bc(1):
.TP
\f[B]BC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
bc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]BC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]BC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]BC_BASE_DIGS\f[R].
.TP
\f[B]BC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]BC_BASE_POW\f[R].
.TP
\f[B]BC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]BC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]BC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
The actual values can be queried with the \f[B]limits\f[R] statement.
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
bc(1) recognizes the following environment variables:
.TP
\f[B]POSIXLY_CORRECT\f[R]
If this variable exists (no matter the contents), bc(1) behaves as if
the \f[B]-s\f[R] option was given.
.TP
\f[B]BC_ENV_ARGS\f[R]
This is another way to give command-line arguments to bc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]BC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
.RS
.PP
The code that parses \f[B]BC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some bc file.bc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]bc\[dq] file.bc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]BC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]BC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), bc(1) will output lines to that length,
including the backslash (\f[B]\[rs]\f[R]).
The default line length is \f[B]70\f[R].
.SH EXIT STATUS
.PP
bc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, attempting to convert a negative number to a hardware
integer, overflow when converting a number to a hardware integer, and
attempting to use a non-integer where an integer is required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]) operator and the corresponding assignment
operator.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, using a token
where it is invalid, giving an invalid expression, giving an invalid
print statement, giving an invalid function definition, attempting to
assign to an expression that is not a named expression (see the
\f[I]Named Expressions\f[R] subsection of the \f[B]SYNTAX\f[R] section),
giving an invalid \f[B]auto\f[R] list, having a duplicate
\f[B]auto\f[R]/function parameter, failing to find the end of a code
block, attempting to return a value from a \f[B]void\f[R] function,
attempting to use a variable as a reference, and using any extensions
when the option \f[B]-s\f[R] or any equivalents were given.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a \f[B]void\f[R] function call as a value in an
expression.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (bc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, bc(1)
always exits and returns \f[B]4\f[R], no matter what mode bc(1) is in.
.PP
The other statuses will only be returned when bc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
bc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Per the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, bc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, bc(1) turns on \[lq]TTY mode.\[rq]
.PP
The prompt is enabled in TTY mode.
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause bc(1) to stop execution of the
current input.
If bc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If bc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If bc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to bc(1) as it is
executing a file, it can seem as though bc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause bc(1) to clean up and
exit, and it uses the default handler for all other signals.
.SH LOCALES
.PP
This bc(1) ships with support for adding error messages for different
locales and thus, supports \f[B]LC_MESSAGES\f[R].
.SH SEE ALSO
.PP
dc(1)
.SH STANDARDS
.PP
bc(1) is compliant with the IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
The flags \f[B]-efghiqsvVw\f[R], all long options, and the extensions
noted above are extensions to that specification.
.PP
Note that the specification explicitly says that bc(1) only accepts
numbers that use a period (\f[B].\f[R]) as a radix point, regardless of
the value of \f[B]LC_NUMERIC\f[R].
.PP
This bc(1) supports error messages for different locales, and thus, it
supports \f[B]LC_MESSAGES\f[R].
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHORS
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/bc/EH.1.md b/contrib/bc/manuals/bc/EH.1.md
index 351882878cd3..c1e324ab6ebc 100644
--- a/contrib/bc/manuals/bc/EH.1.md
+++ b/contrib/bc/manuals/bc/EH.1.md
@@ -1,1069 +1,1078 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# NAME
bc - arbitrary-precision decimal arithmetic language and calculator
# SYNOPSIS
**bc** [**-ghilPqsvVw**] [**--global-stacks**] [**--help**] [**--interactive**] [**--mathlib**] [**--no-prompt**] [**--quiet**] [**--standard**] [**--warn**] [**--version**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...]
[*file*...]
# DESCRIPTION
bc(1) is an interactive processor for a language first standardized in 1991 by
POSIX. (The current standard is [here][1].) The language provides unlimited
precision decimal arithmetic and is somewhat C-like, but there are differences.
Such differences will be noted in this document.
After parsing and handling options, this bc(1) reads any files given on the
command line and executes them before reading from **stdin**.
# OPTIONS
The following are the options that bc(1) accepts.
**-g**, **--global-stacks**
Turns the globals **ibase**, **obase**, and **scale** into stacks.
This has the effect that a copy of the current value of all three are pushed
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
However, since using this flag means that functions cannot set **ibase**,
**obase**, or **scale** globally, functions that are made to do so cannot
work anymore. There are two possible use cases for that, and each has a
solution.
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o="bc -e ibase=A -e obase=8"
alias h2b="bc -e ibase=G -e obase=2"
Second, if the purpose of a function is to set **ibase**, **obase**, or
**scale** globally for any other purpose, it could be split into one to
three functions (based on how many globals it sets) and each of those
functions could return the desired value for a global.
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
**-h**, **--help**
: Prints a usage message and quits.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-l**, **--mathlib**
: Sets **scale** (see the **SYNTAX** section) to **20** and loads the included
math library before running any code, including any expressions or files
specified on the command line.
To learn what is in the library, see the **LIBRARY** section.
**-P**, **--no-prompt**
: Disables the prompt in TTY mode. (The prompt is only enabled in TTY mode.
See the **TTY MODE** section) This is mostly for those users that do not
want a prompt or are not used to having them in bc(1). Most of those users
would want to put this option in **BC_ENV_ARGS** (see the
**ENVIRONMENT VARIABLES** section).
This is a **non-portable extension**.
**-q**, **--quiet**
: This option is for compatibility with the [GNU bc(1)][2]; it is a no-op.
Without this option, GNU bc(1) prints a copyright header. This bc(1) only
prints the copyright header if one or more of the **-v**, **-V**, or
**--version** options are given.
This is a **non-portable extension**.
**-s**, **--standard**
: Process exactly the language defined by the [standard][1] and error if any
extensions are used.
This is a **non-portable extension**.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
This is a **non-portable extension**.
**-w**, **--warn**
: Like **-s** and **--standard**, except that warnings (and not errors) are
printed for non-standard extensions and execution continues normally.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **BC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **bc <file> >&-**, it will quit with an error. This
is done so that bc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **bc <file> 2>&-**, it will quit with an error. This
is done so that bc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
The syntax for bc(1) programs is mostly C-like, with some differences. This
bc(1) follows the [POSIX standard][1], which is a much more thorough resource
for the language this bc(1) accepts. This section is meant to be a summary and a
listing of all the extensions to the standard.
In the sections below, **E** means expression, **S** means statement, and **I**
means identifier.
Identifiers (**I**) start with a lowercase letter and can be followed by any
number (up to **BC_NAME_MAX-1**) of lowercase letters (**a-z**), digits
(**0-9**), and underscores (**\_**). The regex is **\[a-z\]\[a-z0-9\_\]\***.
Identifiers with more than one character (letter) are a
**non-portable extension**.
**ibase** is a global variable determining how to interpret constant numbers. It
is the "input" base, or the number base used for interpreting input numbers.
**ibase** is initially **10**. If the **-s** (**--standard**) and **-w**
(**--warn**) flags were not given on the command line, the max allowable value
for **ibase** is **36**. Otherwise, it is **16**. The min allowable value for
**ibase** is **2**. The max allowable value for **ibase** can be queried in
bc(1) programs with the **maxibase()** built-in function.
**obase** is a global variable determining how to output results. It is the
"output" base, or the number base used for outputting numbers. **obase** is
initially **10**. The max allowable value for **obase** is **BC_BASE_MAX** and
can be queried in bc(1) programs with the **maxobase()** built-in function. The
min allowable value for **obase** is **2**. Values are output in the specified
base.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a global variable that
sets the precision of any operations, with exceptions. **scale** is initially
**0**. **scale** cannot be negative. The max allowable value for **scale** is
**BC_SCALE_MAX** and can be queried in bc(1) programs with the **maxscale()**
built-in function.
bc(1) has both *global* variables and *local* variables. All *local*
variables are local to the function; they are parameters or are introduced in
the **auto** list of a function (see the **FUNCTIONS** section). If a variable
is accessed which is not a parameter or in the **auto** list, it is assumed to
be *global*. If a parent function has a *local* variable version of a variable
that a child function considers *global*, the value of that *global* variable in
the child function is the value of the variable in the parent function, not the
value of the actual *global* variable.
All of the above applies to arrays as well.
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence operator is an
assignment operator *and* the expression is notsurrounded by parentheses.
The value that is printed is also assigned to the special variable **last**. A
single dot (**.**) may also be used as a synonym for **last**. These are
**non-portable extensions**.
Either semicolons or newlines may separate statements.
## Comments
There are two kinds of comments:
1. Block comments are enclosed in **/\*** and **\*/**.
2. Line comments go from **#** until, and not including, the next newline. This
is a **non-portable extension**.
## Named Expressions
The following are named expressions in bc(1):
1. Variables: **I**
2. Array Elements: **I[E]**
3. **ibase**
4. **obase**
5. **scale**
6. **last** or a single dot (**.**)
Number 6 is a **non-portable extension**.
Variables and arrays do not interfere; users can have arrays named the same as
variables. This also applies to functions (see the **FUNCTIONS** section), so a
user can have a variable, array, and function that all have the same name, and
they will not shadow each other, whether inside of functions or not.
Named expressions are required as the operand of **increment**/**decrement**
operators and as the left side of **assignment** operators (see the *Operators*
subsection).
## Operands
The following are valid operands in bc(1):
1. Numbers (see the *Numbers* subsection below).
2. Array indices (**I[E]**).
3. **(E)**: The value of **E** (used to change precedence).
4. **sqrt(E)**: The square root of **E**. **E** must be non-negative.
5. **length(E)**: The number of significant decimal digits in **E**.
6. **length(I[])**: The number of elements in the array **I**. This is a
**non-portable extension**.
7. **scale(E)**: The *scale* of **E**.
8. **abs(E)**: The absolute value of **E**. This is a **non-portable
extension**.
9. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a non-**void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
10. **read()**: Reads a line from **stdin** and uses that as an expression. The
result of that expression is the result of the **read()** operand. This is a
**non-portable extension**.
11. **maxibase()**: The max allowable **ibase**. This is a **non-portable
extension**.
12. **maxobase()**: The max allowable **obase**. This is a **non-portable
extension**.
13. **maxscale()**: The max allowable **scale**. This is a **non-portable
extension**.
## Numbers
Numbers are strings made up of digits, uppercase letters, and at most **1**
period for a radix. Numbers can have up to **BC_NUM_MAX** digits. Uppercase
letters are equal to **9** + their position in the alphabet (i.e., **A** equals
**10**, or **9+1**). If a digit or letter makes no sense with the current value
of **ibase**, they are set to the value of the highest valid digit in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **Z** alone always equals decimal
**35**.
## Operators
The following arithmetic and logical operators can be used. They are listed in
order of decreasing precedence. Operators in the same group have the same
precedence.
**++** **--**
: Type: Prefix and Postfix
Associativity: None
Description: **increment**, **decrement**
**-** **!**
: Type: Prefix
Associativity: None
Description: **negation**, **boolean not**
**\^**
: Type: Binary
Associativity: Right
Description: **power**
**\*** **/** **%**
: Type: Binary
Associativity: Left
Description: **multiply**, **divide**, **modulus**
**+** **-**
: Type: Binary
Associativity: Left
Description: **add**, **subtract**
**=** **+=** **-=** **\*=** **/=** **%=** **\^=**
: Type: Binary
Associativity: Right
Description: **assignment**
**==** **\<=** **\>=** **!=** **\<** **\>**
: Type: Binary
Associativity: Left
Description: **relational**
**&&**
: Type: Binary
Associativity: Left
Description: **boolean and**
**||**
: Type: Binary
Associativity: Left
Description: **boolean or**
The operators will be described in more detail below.
**++** **--**
: The prefix and postfix **increment** and **decrement** operators behave
exactly like they would in C. They require a named expression (see the
*Named Expressions* subsection) as an operand.
The prefix versions of these operators are more efficient; use them where
possible.
**-**
: The **negation** operator returns **0** if a user attempts to negate any
expression with the value **0**. Otherwise, a copy of the expression with
its sign flipped is returned.
**!**
: The **boolean not** operator returns **1** if the expression is **0**, or
**0** otherwise.
This is a **non-portable extension**.
**\^**
: The **power** operator (not the **exclusive or** operator, as it would be in
C) takes two expressions and raises the first to the power of the value of
the second. The *scale* of the result is equal to **scale**.
The second expression must be an integer (no *scale*), and if it is
negative, the first value must be non-zero.
**\***
: The **multiply** operator takes two expressions, multiplies them, and
returns the product. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result is
equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The **divide** operator takes two expressions, divides them, and returns the
quotient. The *scale* of the result shall be the value of **scale**.
The second expression must be non-zero.
**%**
: The **modulus** operator takes two expressions, **a** and **b**, and
evaluates them by 1) Computing **a/b** to current **scale** and 2) Using the
result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The second expression must be non-zero.
**+**
: The **add** operator takes two expressions, **a** and **b**, and returns the
sum, with a *scale* equal to the max of the *scale*s of **a** and **b**.
**-**
: The **subtract** operator takes two expressions, **a** and **b**, and
returns the difference, with a *scale* equal to the max of the *scale*s of
**a** and **b**.
**=** **+=** **-=** **\*=** **/=** **%=** **\^=**
: The **assignment** operators take two expressions, **a** and **b** where
**a** is a named expression (see the *Named Expressions* subsection).
For **=**, **b** is copied and the result is assigned to **a**. For all
others, **a** and **b** are applied as operands to the corresponding
arithmetic operator and the result is assigned to **a**.
**==** **\<=** **\>=** **!=** **\<** **\>**
: The **relational** operators compare two expressions, **a** and **b**, and
if the relation holds, according to C language semantics, the result is
**1**. Otherwise, it is **0**.
Note that unlike in C, these operators have a lower precedence than the
**assignment** operators, which means that **a=b\>c** is interpreted as
**(a=b)\>c**.
Also, unlike the [standard][1] requires, these operators can appear anywhere
any other expressions can be used. This allowance is a
**non-portable extension**.
**&&**
: The **boolean and** operator takes two expressions and returns **1** if both
expressions are non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
**||**
: The **boolean or** operator takes two expressions and returns **1** if one
of the expressions is non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
## Statements
The following items are statements:
1. **E**
2. **{** **S** **;** ... **;** **S** **}**
3. **if** **(** **E** **)** **S**
4. **if** **(** **E** **)** **S** **else** **S**
5. **while** **(** **E** **)** **S**
6. **for** **(** **E** **;** **E** **;** **E** **)** **S**
7. An empty statement
8. **break**
9. **continue**
10. **quit**
11. **halt**
12. **limits**
13. A string of characters, enclosed in double quotes
14. **print** **E** **,** ... **,** **E**
15. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
Numbers 4, 9, 11, 12, 14, and 15 are **non-portable extensions**.
Also, as a **non-portable extension**, any or all of the expressions in the
header of a for loop may be omitted. If the condition (second expression) is
omitted, it is assumed to be a constant **1**.
The **break** statement causes a loop to stop iterating and resume execution
immediately following a loop. This is only allowed in loops.
The **continue** statement causes a loop iteration to stop early and returns to
the start of the loop, including testing the loop condition. This is only
allowed in loops.
The **if** **else** statement does the same thing as in C.
The **quit** statement causes bc(1) to quit, even if it is on a branch that will
not be executed (it is a compile-time command).
The **halt** statement causes bc(1) to quit, if it is executed. (Unlike **quit**
if it is on a branch of an **if** statement that is not executed, bc(1) does not
quit.)
The **limits** statement prints the limits that this bc(1) is subject to. This
is like the **quit** statement in that it is a compile-time command.
An expression by itself is evaluated and printed, followed by a newline.
## Print Statement
The "expressions" in a **print** statement may also be strings. If they are, there
are backslash escape sequences that are interpreted specially. What those
sequences are, and what they cause to be printed, are shown below:
-------- -------
**\\a** **\\a**
**\\b** **\\b**
**\\\\** **\\**
**\\e** **\\**
**\\f** **\\f**
**\\n** **\\n**
**\\q** **"**
**\\r** **\\r**
**\\t** **\\t**
-------- -------
Any other character following a backslash causes the backslash and character to
be printed as-is.
Any non-string expression in a print statement shall be assigned to **last**,
like any other expression that is printed.
## Order of Evaluation
All expressions in a statment are evaluated left to right, except as necessary
to maintain order of operations. This means, for example, assuming that **i** is
equal to **0**, in the expression
a[i++] = i++
the first (or 0th) element of **a** is set to **1**, and **i** is equal to **2**
at the end of the expression.
This includes function arguments. Thus, assuming **i** is equal to **0**, this
means that in the expression
x(i++, i++)
the first argument passed to **x()** is **0**, and the second argument is **1**,
while **i** is equal to **2** before the function starts executing.
# FUNCTIONS
Function definitions are as follows:
```
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
```
Any **I** in the parameter list or **auto** list may be replaced with **I[]** to
make a parameter or **auto** var an array, and any **I** in the parameter list
may be replaced with **\*I[]** to make a parameter an array reference. Callers
of functions that take array references should not put an asterisk in the call;
they must be called with just **I[]** like normal array parameters and will be
automatically converted into references.
As a **non-portable extension**, the opening brace of a **define** statement may
appear on the next line.
As a **non-portable extension**, the return statement may also be in one of the
following forms:
1. **return**
2. **return** **(** **)**
3. **return** **E**
The first two, or not specifying a **return** statement, is equivalent to
**return (0)**, unless the function is a **void** function (see the *Void
Functions* subsection below).
## Void Functions
Functions can also be **void** functions, defined as follows:
```
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
```
They can only be used as standalone expressions, where such an expression would
be printed alone, except in a print statement.
Void functions can only use the first two **return** statements listed above.
They can also omit the return statement entirely.
The word "void" is not treated as a keyword; it is still possible to have
variables, arrays, and functions named **void**. The word "void" is only
treated specially right after the **define** keyword.
This is a **non-portable extension**.
## Array References
For any array in the parameter list, if the array is declared in the form
```
*I[]
```
it is a **reference**. Any changes to the array in the function are reflected,
when the function returns, to the array that was passed in.
Other than this, all function arguments are passed by value.
This is a **non-portable extension**.
# LIBRARY
All of the functions below are available when the **-l** or **--mathlib**
command-line flags are given.
## Standard Library
The [standard][1] defines the following functions for the math library:
**s(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**c(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a(x)**
: Returns the arctangent of **x**, in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l(x)**
: Returns the natural logarithm of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**e(x)**
: Returns the mathematical constant **e** raised to the power of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**j(x, n)**
: Returns the bessel integer order **n** (truncated) of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
## Transcendental Functions
All transcendental functions can return slightly inaccurate results (up to 1
[ULP][4]). This is unavoidable, and [this article][5] explains why it is
impossible and unnecessary to calculate exact results for the transcendental
functions.
Because of the possible inaccuracy, I recommend that users call those functions
with the precision (**scale**) set to at least 1 higher than is necessary. If
exact results are *absolutely* required, users can double the precision
(**scale**) and then truncate.
The transcendental functions in the standard math library are:
* **s(x)**
* **c(x)**
* **a(x)**
* **l(x)**
* **e(x)**
* **j(x, n)**
# RESET
When bc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any functions that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
functions returned) is skipped.
Thus, when bc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
Note that this reset behavior is different from the GNU bc(1), which attempts to
start executing the statement right after the one that caused an error.
# PERFORMANCE
Most bc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This bc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **BC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **BC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**BC_BASE_DIGS**.
The actual values of **BC_LONG_BIT** and **BC_BASE_DIGS** can be queried with
the **limits** statement.
In addition, this bc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **BC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on bc(1):
**BC_LONG_BIT**
: The number of bits in the **long** type in the environment where bc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**BC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **BC_LONG_BIT**.
**BC_BASE_POW**
: The max decimal number that each large integer can store (see
**BC_BASE_DIGS**) plus **1**. Depends on **BC_BASE_DIGS**.
**BC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **BC_LONG_BIT**.
**BC_BASE_MAX**
: The maximum output base. Set at **BC_BASE_POW**.
**BC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**BC_SCALE_MAX**
: The maximum **scale**. Set at **BC_OVERFLOW_MAX-1**.
**BC_STRING_MAX**
: The maximum length of strings. Set at **BC_OVERFLOW_MAX-1**.
**BC_NAME_MAX**
: The maximum length of identifiers. Set at **BC_OVERFLOW_MAX-1**.
**BC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **BC_OVERFLOW_MAX-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**BC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
The actual values can be queried with the **limits** statement.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
bc(1) recognizes the following environment variables:
**POSIXLY_CORRECT**
: If this variable exists (no matter the contents), bc(1) behaves as if
the **-s** option was given.
**BC_ENV_ARGS**
: This is another way to give command-line arguments to bc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **BC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
The code that parses **BC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some bc file.bc"** will be correctly parsed, but the string
**"/home/gavin/some \"bc\" file.bc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **BC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**BC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), bc(1) will output
lines to that length, including the backslash (**\\**). The default line
length is **70**.
# EXIT STATUS
bc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**) operator and the corresponding assignment operator.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, using a token where it is invalid,
giving an invalid expression, giving an invalid print statement, giving an
invalid function definition, attempting to assign to an expression that is
not a named expression (see the *Named Expressions* subsection of the
**SYNTAX** section), giving an invalid **auto** list, having a duplicate
**auto**/function parameter, failing to find the end of a code block,
attempting to return a value from a **void** function, attempting to use a
variable as a reference, and using any extensions when the option **-s** or
any equivalents were given.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a **void** function call as a value in an expression.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (bc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, bc(1) always exits
and returns **4**, no matter what mode bc(1) is in.
The other statuses will only be returned when bc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since bc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Per the [standard][1], bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, bc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, bc(1) turns
on "TTY mode."
The prompt is enabled in TTY mode.
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause bc(1) to stop execution of the current input. If
bc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If bc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If bc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to bc(1) as it is executing a file, it
can seem as though bc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause bc(1) to clean up and exit, and it uses the
default handler for all other signals.
# LOCALES
This bc(1) ships with support for adding error messages for different locales
and thus, supports **LC_MESSAGES**.
# SEE ALSO
dc(1)
# STANDARDS
bc(1) is compliant with the [IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1]
specification. The flags **-efghiqsvVw**, all long options, and the extensions
noted above are extensions to that specification.
Note that the specification explicitly says that bc(1) only accepts numbers that
use a period (**.**) as a radix point, regardless of the value of
**LC_NUMERIC**.
This bc(1) supports error messages for different locales, and thus, it supports
**LC_MESSAGES**.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHORS
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
[2]: https://www.gnu.org/software/bc/
[3]: https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero
[4]: https://en.wikipedia.org/wiki/Unit_in_the_last_place
[5]: https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT
[6]: https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero
diff --git a/contrib/bc/manuals/bc/EHN.1 b/contrib/bc/manuals/bc/EHN.1
index f751f9d31beb..6b208ade85fd 100644
--- a/contrib/bc/manuals/bc/EHN.1
+++ b/contrib/bc/manuals/bc/EHN.1
@@ -1,1276 +1,1289 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "BC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "BC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH NAME
.PP
bc - arbitrary-precision decimal arithmetic language and calculator
.SH SYNOPSIS
.PP
\f[B]bc\f[R] [\f[B]-ghilPqsvVw\f[R]] [\f[B]\[en]global-stacks\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]mathlib\f[R]] [\f[B]\[en]no-prompt\f[R]]
[\f[B]\[en]quiet\f[R]] [\f[B]\[en]standard\f[R]] [\f[B]\[en]warn\f[R]]
[\f[B]\[en]version\f[R]] [\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
bc(1) is an interactive processor for a language first standardized in
1991 by POSIX.
(The current standard is
here (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).)
The language provides unlimited precision decimal arithmetic and is
somewhat C-like, but there are differences.
Such differences will be noted in this document.
.PP
After parsing and handling options, this bc(1) reads any files given on
the command line and executes them before reading from \f[B]stdin\f[R].
.SH OPTIONS
.PP
The following are the options that bc(1) accepts.
.PP
\f[B]-g\f[R], \f[B]\[en]global-stacks\f[R]
.IP
.nf
\f[C]
Turns the globals **ibase**, **obase**, and **scale** into stacks.
This has the effect that a copy of the current value of all three are pushed
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
However, since using this flag means that functions cannot set **ibase**,
**obase**, or **scale** globally, functions that are made to do so cannot
work anymore. There are two possible use cases for that, and each has a
solution.
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o=\[dq]bc -e ibase=A -e obase=8\[dq]
alias h2b=\[dq]bc -e ibase=G -e obase=2\[dq]
Second, if the purpose of a function is to set **ibase**, **obase**, or
**scale** globally for any other purpose, it could be split into one to
three functions (based on how many globals it sets) and each of those
functions could return the desired value for a global.
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
\f[R]
.fi
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-l\f[R], \f[B]\[en]mathlib\f[R]
Sets \f[B]scale\f[R] (see the \f[B]SYNTAX\f[R] section) to \f[B]20\f[R]
and loads the included math library before running any code, including
any expressions or files specified on the command line.
.RS
.PP
To learn what is in the library, see the \f[B]LIBRARY\f[R] section.
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
Disables the prompt in TTY mode.
(The prompt is only enabled in TTY mode.
See the \f[B]TTY MODE\f[R] section) This is mostly for those users that
do not want a prompt or are not used to having them in bc(1).
Most of those users would want to put this option in
\f[B]BC_ENV_ARGS\f[R] (see the \f[B]ENVIRONMENT VARIABLES\f[R] section).
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-q\f[R], \f[B]\[en]quiet\f[R]
This option is for compatibility with the GNU
bc(1) (https://www.gnu.org/software/bc/); it is a no-op.
Without this option, GNU bc(1) prints a copyright header.
This bc(1) only prints the copyright header if one or more of the
\f[B]-v\f[R], \f[B]-V\f[R], or \f[B]\[en]version\f[R] options are given.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-s\f[R], \f[B]\[en]standard\f[R]
Process exactly the language defined by the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
and error if any extensions are used.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-w\f[R], \f[B]\[en]warn\f[R]
Like \f[B]-s\f[R] and \f[B]\[en]standard\f[R], except that warnings (and
not errors) are printed for non-standard extensions and execution
continues normally.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]BC_ENV_ARGS\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]bc >&-\f[R], it will quit with an error.
This is done so that bc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]bc 2>&-\f[R], it will quit with an error.
This is done so that bc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
The syntax for bc(1) programs is mostly C-like, with some differences.
This bc(1) follows the POSIX
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
which is a much more thorough resource for the language this bc(1)
accepts.
This section is meant to be a summary and a listing of all the
extensions to the standard.
.PP
In the sections below, \f[B]E\f[R] means expression, \f[B]S\f[R] means
statement, and \f[B]I\f[R] means identifier.
.PP
Identifiers (\f[B]I\f[R]) start with a lowercase letter and can be
followed by any number (up to \f[B]BC_NAME_MAX-1\f[R]) of lowercase
letters (\f[B]a-z\f[R]), digits (\f[B]0-9\f[R]), and underscores
(\f[B]_\f[R]).
The regex is \f[B][a-z][a-z0-9_]*\f[R].
Identifiers with more than one character (letter) are a
\f[B]non-portable extension\f[R].
.PP
\f[B]ibase\f[R] is a global variable determining how to interpret
constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
If the \f[B]-s\f[R] (\f[B]\[en]standard\f[R]) and \f[B]-w\f[R]
(\f[B]\[en]warn\f[R]) flags were not given on the command line, the max
allowable value for \f[B]ibase\f[R] is \f[B]36\f[R].
Otherwise, it is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in bc(1)
programs with the \f[B]maxibase()\f[R] built-in function.
.PP
\f[B]obase\f[R] is a global variable determining how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]BC_BASE_MAX\f[R] and
can be queried in bc(1) programs with the \f[B]maxobase()\f[R] built-in
function.
The min allowable value for \f[B]obase\f[R] is \f[B]2\f[R].
Values are output in the specified base.
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a global variable that sets the precision of any operations, with
exceptions.
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] is \f[B]BC_SCALE_MAX\f[R]
and can be queried in bc(1) programs with the \f[B]maxscale()\f[R]
built-in function.
.PP
bc(1) has both \f[I]global\f[R] variables and \f[I]local\f[R] variables.
All \f[I]local\f[R] variables are local to the function; they are
parameters or are introduced in the \f[B]auto\f[R] list of a function
(see the \f[B]FUNCTIONS\f[R] section).
If a variable is accessed which is not a parameter or in the
\f[B]auto\f[R] list, it is assumed to be \f[I]global\f[R].
If a parent function has a \f[I]local\f[R] variable version of a
variable that a child function considers \f[I]global\f[R], the value of
that \f[I]global\f[R] variable in the child function is the value of the
variable in the parent function, not the value of the actual
\f[I]global\f[R] variable.
.PP
All of the above applies to arrays as well.
.PP
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence
operator is an assignment operator \f[I]and\f[R] the expression is
notsurrounded by parentheses.
.PP
The value that is printed is also assigned to the special variable
\f[B]last\f[R].
A single dot (\f[B].\f[R]) may also be used as a synonym for
\f[B]last\f[R].
These are \f[B]non-portable extensions\f[R].
.PP
Either semicolons or newlines may separate statements.
.SS Comments
.PP
There are two kinds of comments:
.IP "1." 3
Block comments are enclosed in \f[B]/*\f[R] and \f[B]*/\f[R].
.IP "2." 3
Line comments go from \f[B]#\f[R] until, and not including, the next
newline.
This is a \f[B]non-portable extension\f[R].
.SS Named Expressions
.PP
The following are named expressions in bc(1):
.IP "1." 3
Variables: \f[B]I\f[R]
.IP "2." 3
Array Elements: \f[B]I[E]\f[R]
.IP "3." 3
\f[B]ibase\f[R]
.IP "4." 3
\f[B]obase\f[R]
.IP "5." 3
\f[B]scale\f[R]
.IP "6." 3
\f[B]last\f[R] or a single dot (\f[B].\f[R])
.PP
Number 6 is a \f[B]non-portable extension\f[R].
.PP
Variables and arrays do not interfere; users can have arrays named the
same as variables.
This also applies to functions (see the \f[B]FUNCTIONS\f[R] section), so
a user can have a variable, array, and function that all have the same
name, and they will not shadow each other, whether inside of functions
or not.
.PP
Named expressions are required as the operand of
\f[B]increment\f[R]/\f[B]decrement\f[R] operators and as the left side
of \f[B]assignment\f[R] operators (see the \f[I]Operators\f[R]
subsection).
.SS Operands
.PP
The following are valid operands in bc(1):
.IP " 1." 4
Numbers (see the \f[I]Numbers\f[R] subsection below).
.IP " 2." 4
Array indices (\f[B]I[E]\f[R]).
.IP " 3." 4
\f[B](E)\f[R]: The value of \f[B]E\f[R] (used to change precedence).
.IP " 4." 4
\f[B]sqrt(E)\f[R]: The square root of \f[B]E\f[R].
\f[B]E\f[R] must be non-negative.
.IP " 5." 4
\f[B]length(E)\f[R]: The number of significant decimal digits in
\f[B]E\f[R].
.IP " 6." 4
\f[B]length(I[])\f[R]: The number of elements in the array \f[B]I\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 7." 4
\f[B]scale(E)\f[R]: The \f[I]scale\f[R] of \f[B]E\f[R].
.IP " 8." 4
\f[B]abs(E)\f[R]: The absolute value of \f[B]E\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 9." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a non-\f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.IP "10." 4
\f[B]read()\f[R]: Reads a line from \f[B]stdin\f[R] and uses that as an
expression.
The result of that expression is the result of the \f[B]read()\f[R]
operand.
This is a \f[B]non-portable extension\f[R].
.IP "11." 4
\f[B]maxibase()\f[R]: The max allowable \f[B]ibase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "12." 4
\f[B]maxobase()\f[R]: The max allowable \f[B]obase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "13." 4
\f[B]maxscale()\f[R]: The max allowable \f[B]scale\f[R].
This is a \f[B]non-portable extension\f[R].
.SS Numbers
.PP
Numbers are strings made up of digits, uppercase letters, and at most
\f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]BC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]Z\f[R] alone always equals decimal \f[B]35\f[R].
.SS Operators
.PP
The following arithmetic and logical operators can be used.
They are listed in order of decreasing precedence.
Operators in the same group have the same precedence.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
Type: Prefix and Postfix
.RS
.PP
Associativity: None
.PP
Description: \f[B]increment\f[R], \f[B]decrement\f[R]
.RE
.TP
\f[B]-\f[R] \f[B]!\f[R]
Type: Prefix
.RS
.PP
Associativity: None
.PP
Description: \f[B]negation\f[R], \f[B]boolean not\f[R]
.RE
.TP
\f[B]\[ha]\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]power\f[R]
.RE
.TP
\f[B]*\f[R] \f[B]/\f[R] \f[B]%\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]multiply\f[R], \f[B]divide\f[R], \f[B]modulus\f[R]
.RE
.TP
\f[B]+\f[R] \f[B]-\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]add\f[R], \f[B]subtract\f[R]
.RE
.TP
\f[B]=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]assignment\f[R]
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]relational\f[R]
.RE
.TP
\f[B]&&\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean and\f[R]
.RE
.TP
\f[B]||\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean or\f[R]
.RE
.PP
The operators will be described in more detail below.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
The prefix and postfix \f[B]increment\f[R] and \f[B]decrement\f[R]
operators behave exactly like they would in C.
They require a named expression (see the \f[I]Named Expressions\f[R]
subsection) as an operand.
.RS
.PP
The prefix versions of these operators are more efficient; use them
where possible.
.RE
.TP
\f[B]-\f[R]
The \f[B]negation\f[R] operator returns \f[B]0\f[R] if a user attempts
to negate any expression with the value \f[B]0\f[R].
Otherwise, a copy of the expression with its sign flipped is returned.
.TP
\f[B]!\f[R]
The \f[B]boolean not\f[R] operator returns \f[B]1\f[R] if the expression
is \f[B]0\f[R], or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The \f[B]power\f[R] operator (not the \f[B]exclusive or\f[R] operator,
as it would be in C) takes two expressions and raises the first to the
power of the value of the second.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]), and if it
is negative, the first value must be non-zero.
.RE
.TP
\f[B]*\f[R]
The \f[B]multiply\f[R] operator takes two expressions, multiplies them,
and returns the product.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The \f[B]divide\f[R] operator takes two expressions, divides them, and
returns the quotient.
The \f[I]scale\f[R] of the result shall be the value of \f[B]scale\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]%\f[R]
The \f[B]modulus\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and evaluates them by 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R] and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]+\f[R]
The \f[B]add\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the sum, with a \f[I]scale\f[R] equal to the
max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]-\f[R]
The \f[B]subtract\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the difference, with a \f[I]scale\f[R] equal to
the max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R]
The \f[B]assignment\f[R] operators take two expressions, \f[B]a\f[R] and
\f[B]b\f[R] where \f[B]a\f[R] is a named expression (see the \f[I]Named
Expressions\f[R] subsection).
.RS
.PP
For \f[B]=\f[R], \f[B]b\f[R] is copied and the result is assigned to
\f[B]a\f[R].
For all others, \f[B]a\f[R] and \f[B]b\f[R] are applied as operands to
the corresponding arithmetic operator and the result is assigned to
\f[B]a\f[R].
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
The \f[B]relational\f[R] operators compare two expressions, \f[B]a\f[R]
and \f[B]b\f[R], and if the relation holds, according to C language
semantics, the result is \f[B]1\f[R].
Otherwise, it is \f[B]0\f[R].
.RS
.PP
Note that unlike in C, these operators have a lower precedence than the
\f[B]assignment\f[R] operators, which means that \f[B]a=b>c\f[R] is
interpreted as \f[B](a=b)>c\f[R].
.PP
Also, unlike the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
requires, these operators can appear anywhere any other expressions can
be used.
This allowance is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]&&\f[R]
The \f[B]boolean and\f[R] operator takes two expressions and returns
\f[B]1\f[R] if both expressions are non-zero, \f[B]0\f[R] otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]||\f[R]
The \f[B]boolean or\f[R] operator takes two expressions and returns
\f[B]1\f[R] if one of the expressions is non-zero, \f[B]0\f[R]
otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Statements
.PP
The following items are statements:
.IP " 1." 4
\f[B]E\f[R]
.IP " 2." 4
\f[B]{\f[R] \f[B]S\f[R] \f[B];\f[R] \&... \f[B];\f[R] \f[B]S\f[R]
\f[B]}\f[R]
.IP " 3." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 4." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
\f[B]else\f[R] \f[B]S\f[R]
.IP " 5." 4
\f[B]while\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 6." 4
\f[B]for\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B];\f[R] \f[B]E\f[R]
\f[B];\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 7." 4
An empty statement
.IP " 8." 4
\f[B]break\f[R]
.IP " 9." 4
\f[B]continue\f[R]
.IP "10." 4
\f[B]quit\f[R]
.IP "11." 4
\f[B]halt\f[R]
.IP "12." 4
\f[B]limits\f[R]
.IP "13." 4
A string of characters, enclosed in double quotes
.IP "14." 4
\f[B]print\f[R] \f[B]E\f[R] \f[B],\f[R] \&... \f[B],\f[R] \f[B]E\f[R]
.IP "15." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a \f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.PP
Numbers 4, 9, 11, 12, 14, and 15 are \f[B]non-portable extensions\f[R].
.PP
Also, as a \f[B]non-portable extension\f[R], any or all of the
expressions in the header of a for loop may be omitted.
If the condition (second expression) is omitted, it is assumed to be a
constant \f[B]1\f[R].
.PP
The \f[B]break\f[R] statement causes a loop to stop iterating and resume
execution immediately following a loop.
This is only allowed in loops.
.PP
The \f[B]continue\f[R] statement causes a loop iteration to stop early
and returns to the start of the loop, including testing the loop
condition.
This is only allowed in loops.
.PP
The \f[B]if\f[R] \f[B]else\f[R] statement does the same thing as in C.
.PP
The \f[B]quit\f[R] statement causes bc(1) to quit, even if it is on a
branch that will not be executed (it is a compile-time command).
.PP
The \f[B]halt\f[R] statement causes bc(1) to quit, if it is executed.
(Unlike \f[B]quit\f[R] if it is on a branch of an \f[B]if\f[R] statement
that is not executed, bc(1) does not quit.)
.PP
The \f[B]limits\f[R] statement prints the limits that this bc(1) is
subject to.
This is like the \f[B]quit\f[R] statement in that it is a compile-time
command.
.PP
An expression by itself is evaluated and printed, followed by a newline.
.SS Print Statement
.PP
The \[lq]expressions\[rq] in a \f[B]print\f[R] statement may also be
strings.
If they are, there are backslash escape sequences that are interpreted
specially.
What those sequences are, and what they cause to be printed, are shown
below:
.PP
.TS
tab(@);
l l.
T{
\f[B]\[rs]a\f[R]
T}@T{
\f[B]\[rs]a\f[R]
T}
T{
\f[B]\[rs]b\f[R]
T}@T{
\f[B]\[rs]b\f[R]
T}
T{
\f[B]\[rs]\[rs]\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]e\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]f\f[R]
T}@T{
\f[B]\[rs]f\f[R]
T}
T{
\f[B]\[rs]n\f[R]
T}@T{
\f[B]\[rs]n\f[R]
T}
T{
\f[B]\[rs]q\f[R]
T}@T{
\f[B]\[dq]\f[R]
T}
T{
\f[B]\[rs]r\f[R]
T}@T{
\f[B]\[rs]r\f[R]
T}
T{
\f[B]\[rs]t\f[R]
T}@T{
\f[B]\[rs]t\f[R]
T}
.TE
.PP
Any other character following a backslash causes the backslash and
character to be printed as-is.
.PP
Any non-string expression in a print statement shall be assigned to
\f[B]last\f[R], like any other expression that is printed.
.SS Order of Evaluation
.PP
All expressions in a statment are evaluated left to right, except as
necessary to maintain order of operations.
This means, for example, assuming that \f[B]i\f[R] is equal to
\f[B]0\f[R], in the expression
.IP
.nf
\f[C]
a[i++] = i++
\f[R]
.fi
.PP
the first (or 0th) element of \f[B]a\f[R] is set to \f[B]1\f[R], and
\f[B]i\f[R] is equal to \f[B]2\f[R] at the end of the expression.
.PP
This includes function arguments.
Thus, assuming \f[B]i\f[R] is equal to \f[B]0\f[R], this means that in
the expression
.IP
.nf
\f[C]
x(i++, i++)
\f[R]
.fi
.PP
the first argument passed to \f[B]x()\f[R] is \f[B]0\f[R], and the
second argument is \f[B]1\f[R], while \f[B]i\f[R] is equal to
\f[B]2\f[R] before the function starts executing.
.SH FUNCTIONS
.PP
Function definitions are as follows:
.IP
.nf
\f[C]
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
\f[R]
.fi
.PP
Any \f[B]I\f[R] in the parameter list or \f[B]auto\f[R] list may be
replaced with \f[B]I[]\f[R] to make a parameter or \f[B]auto\f[R] var an
array, and any \f[B]I\f[R] in the parameter list may be replaced with
\f[B]*I[]\f[R] to make a parameter an array reference.
Callers of functions that take array references should not put an
asterisk in the call; they must be called with just \f[B]I[]\f[R] like
normal array parameters and will be automatically converted into
references.
.PP
As a \f[B]non-portable extension\f[R], the opening brace of a
\f[B]define\f[R] statement may appear on the next line.
.PP
As a \f[B]non-portable extension\f[R], the return statement may also be
in one of the following forms:
.IP "1." 3
\f[B]return\f[R]
.IP "2." 3
\f[B]return\f[R] \f[B](\f[R] \f[B])\f[R]
.IP "3." 3
\f[B]return\f[R] \f[B]E\f[R]
.PP
The first two, or not specifying a \f[B]return\f[R] statement, is
equivalent to \f[B]return (0)\f[R], unless the function is a
\f[B]void\f[R] function (see the \f[I]Void Functions\f[R] subsection
below).
.SS Void Functions
.PP
Functions can also be \f[B]void\f[R] functions, defined as follows:
.IP
.nf
\f[C]
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
\f[R]
.fi
.PP
They can only be used as standalone expressions, where such an
expression would be printed alone, except in a print statement.
.PP
Void functions can only use the first two \f[B]return\f[R] statements
listed above.
They can also omit the return statement entirely.
.PP
The word \[lq]void\[rq] is not treated as a keyword; it is still
possible to have variables, arrays, and functions named \f[B]void\f[R].
The word \[lq]void\[rq] is only treated specially right after the
\f[B]define\f[R] keyword.
.PP
This is a \f[B]non-portable extension\f[R].
.SS Array References
.PP
For any array in the parameter list, if the array is declared in the
form
.IP
.nf
\f[C]
*I[]
\f[R]
.fi
.PP
it is a \f[B]reference\f[R].
Any changes to the array in the function are reflected, when the
function returns, to the array that was passed in.
.PP
Other than this, all function arguments are passed by value.
.PP
This is a \f[B]non-portable extension\f[R].
.SH LIBRARY
.PP
All of the functions below are available when the \f[B]-l\f[R] or
\f[B]\[en]mathlib\f[R] command-line flags are given.
.SS Standard Library
.PP
The
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
defines the following functions for the math library:
.TP
\f[B]s(x)\f[R]
Returns the sine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]c(x)\f[R]
Returns the cosine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]a(x)\f[R]
Returns the arctangent of \f[B]x\f[R], in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]l(x)\f[R]
Returns the natural logarithm of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]e(x)\f[R]
Returns the mathematical constant \f[B]e\f[R] raised to the power of
\f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]j(x, n)\f[R]
Returns the bessel integer order \f[B]n\f[R] (truncated) of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.SS Transcendental Functions
.PP
All transcendental functions can return slightly inaccurate results (up
to 1 ULP (https://en.wikipedia.org/wiki/Unit_in_the_last_place)).
This is unavoidable, and this
article (https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT) explains
why it is impossible and unnecessary to calculate exact results for the
transcendental functions.
.PP
Because of the possible inaccuracy, I recommend that users call those
functions with the precision (\f[B]scale\f[R]) set to at least 1 higher
than is necessary.
If exact results are \f[I]absolutely\f[R] required, users can double the
precision (\f[B]scale\f[R]) and then truncate.
.PP
The transcendental functions in the standard math library are:
.IP \[bu] 2
\f[B]s(x)\f[R]
.IP \[bu] 2
\f[B]c(x)\f[R]
.IP \[bu] 2
\f[B]a(x)\f[R]
.IP \[bu] 2
\f[B]l(x)\f[R]
.IP \[bu] 2
\f[B]e(x)\f[R]
.IP \[bu] 2
\f[B]j(x, n)\f[R]
.SH RESET
.PP
When bc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any functions that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all functions returned) is skipped.
.PP
Thus, when bc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.PP
Note that this reset behavior is different from the GNU bc(1), which
attempts to start executing the statement right after the one that
caused an error.
.SH PERFORMANCE
.PP
Most bc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This bc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]BC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]BC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]BC_BASE_DIGS\f[R].
.PP
The actual values of \f[B]BC_LONG_BIT\f[R] and \f[B]BC_BASE_DIGS\f[R]
can be queried with the \f[B]limits\f[R] statement.
.PP
In addition, this bc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]BC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on bc(1):
.TP
\f[B]BC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
bc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]BC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]BC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]BC_BASE_DIGS\f[R].
.TP
\f[B]BC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]BC_BASE_POW\f[R].
.TP
\f[B]BC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]BC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]BC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
The actual values can be queried with the \f[B]limits\f[R] statement.
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
bc(1) recognizes the following environment variables:
.TP
\f[B]POSIXLY_CORRECT\f[R]
If this variable exists (no matter the contents), bc(1) behaves as if
the \f[B]-s\f[R] option was given.
.TP
\f[B]BC_ENV_ARGS\f[R]
This is another way to give command-line arguments to bc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]BC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
.RS
.PP
The code that parses \f[B]BC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some bc file.bc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]bc\[dq] file.bc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]BC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]BC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), bc(1) will output lines to that length,
including the backslash (\f[B]\[rs]\f[R]).
The default line length is \f[B]70\f[R].
.SH EXIT STATUS
.PP
bc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, attempting to convert a negative number to a hardware
integer, overflow when converting a number to a hardware integer, and
attempting to use a non-integer where an integer is required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]) operator and the corresponding assignment
operator.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, using a token
where it is invalid, giving an invalid expression, giving an invalid
print statement, giving an invalid function definition, attempting to
assign to an expression that is not a named expression (see the
\f[I]Named Expressions\f[R] subsection of the \f[B]SYNTAX\f[R] section),
giving an invalid \f[B]auto\f[R] list, having a duplicate
\f[B]auto\f[R]/function parameter, failing to find the end of a code
block, attempting to return a value from a \f[B]void\f[R] function,
attempting to use a variable as a reference, and using any extensions
when the option \f[B]-s\f[R] or any equivalents were given.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a \f[B]void\f[R] function call as a value in an
expression.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (bc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, bc(1)
always exits and returns \f[B]4\f[R], no matter what mode bc(1) is in.
.PP
The other statuses will only be returned when bc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
bc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Per the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, bc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, bc(1) turns on \[lq]TTY mode.\[rq]
.PP
The prompt is enabled in TTY mode.
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause bc(1) to stop execution of the
current input.
If bc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If bc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If bc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to bc(1) as it is
executing a file, it can seem as though bc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause bc(1) to clean up and
exit, and it uses the default handler for all other signals.
.SH SEE ALSO
.PP
dc(1)
.SH STANDARDS
.PP
bc(1) is compliant with the IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
The flags \f[B]-efghiqsvVw\f[R], all long options, and the extensions
noted above are extensions to that specification.
.PP
Note that the specification explicitly says that bc(1) only accepts
numbers that use a period (\f[B].\f[R]) as a radix point, regardless of
the value of \f[B]LC_NUMERIC\f[R].
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHORS
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/bc/EHN.1.md b/contrib/bc/manuals/bc/EHN.1.md
index dfe1c401970f..4ee01a4bbcc8 100644
--- a/contrib/bc/manuals/bc/EHN.1.md
+++ b/contrib/bc/manuals/bc/EHN.1.md
@@ -1,1061 +1,1070 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# NAME
bc - arbitrary-precision decimal arithmetic language and calculator
# SYNOPSIS
**bc** [**-ghilPqsvVw**] [**--global-stacks**] [**--help**] [**--interactive**] [**--mathlib**] [**--no-prompt**] [**--quiet**] [**--standard**] [**--warn**] [**--version**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...]
[*file*...]
# DESCRIPTION
bc(1) is an interactive processor for a language first standardized in 1991 by
POSIX. (The current standard is [here][1].) The language provides unlimited
precision decimal arithmetic and is somewhat C-like, but there are differences.
Such differences will be noted in this document.
After parsing and handling options, this bc(1) reads any files given on the
command line and executes them before reading from **stdin**.
# OPTIONS
The following are the options that bc(1) accepts.
**-g**, **--global-stacks**
Turns the globals **ibase**, **obase**, and **scale** into stacks.
This has the effect that a copy of the current value of all three are pushed
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
However, since using this flag means that functions cannot set **ibase**,
**obase**, or **scale** globally, functions that are made to do so cannot
work anymore. There are two possible use cases for that, and each has a
solution.
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o="bc -e ibase=A -e obase=8"
alias h2b="bc -e ibase=G -e obase=2"
Second, if the purpose of a function is to set **ibase**, **obase**, or
**scale** globally for any other purpose, it could be split into one to
three functions (based on how many globals it sets) and each of those
functions could return the desired value for a global.
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
**-h**, **--help**
: Prints a usage message and quits.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-l**, **--mathlib**
: Sets **scale** (see the **SYNTAX** section) to **20** and loads the included
math library before running any code, including any expressions or files
specified on the command line.
To learn what is in the library, see the **LIBRARY** section.
**-P**, **--no-prompt**
: Disables the prompt in TTY mode. (The prompt is only enabled in TTY mode.
See the **TTY MODE** section) This is mostly for those users that do not
want a prompt or are not used to having them in bc(1). Most of those users
would want to put this option in **BC_ENV_ARGS** (see the
**ENVIRONMENT VARIABLES** section).
This is a **non-portable extension**.
**-q**, **--quiet**
: This option is for compatibility with the [GNU bc(1)][2]; it is a no-op.
Without this option, GNU bc(1) prints a copyright header. This bc(1) only
prints the copyright header if one or more of the **-v**, **-V**, or
**--version** options are given.
This is a **non-portable extension**.
**-s**, **--standard**
: Process exactly the language defined by the [standard][1] and error if any
extensions are used.
This is a **non-portable extension**.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
This is a **non-portable extension**.
**-w**, **--warn**
: Like **-s** and **--standard**, except that warnings (and not errors) are
printed for non-standard extensions and execution continues normally.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **BC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **bc <file> >&-**, it will quit with an error. This
is done so that bc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **bc <file> 2>&-**, it will quit with an error. This
is done so that bc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
The syntax for bc(1) programs is mostly C-like, with some differences. This
bc(1) follows the [POSIX standard][1], which is a much more thorough resource
for the language this bc(1) accepts. This section is meant to be a summary and a
listing of all the extensions to the standard.
In the sections below, **E** means expression, **S** means statement, and **I**
means identifier.
Identifiers (**I**) start with a lowercase letter and can be followed by any
number (up to **BC_NAME_MAX-1**) of lowercase letters (**a-z**), digits
(**0-9**), and underscores (**\_**). The regex is **\[a-z\]\[a-z0-9\_\]\***.
Identifiers with more than one character (letter) are a
**non-portable extension**.
**ibase** is a global variable determining how to interpret constant numbers. It
is the "input" base, or the number base used for interpreting input numbers.
**ibase** is initially **10**. If the **-s** (**--standard**) and **-w**
(**--warn**) flags were not given on the command line, the max allowable value
for **ibase** is **36**. Otherwise, it is **16**. The min allowable value for
**ibase** is **2**. The max allowable value for **ibase** can be queried in
bc(1) programs with the **maxibase()** built-in function.
**obase** is a global variable determining how to output results. It is the
"output" base, or the number base used for outputting numbers. **obase** is
initially **10**. The max allowable value for **obase** is **BC_BASE_MAX** and
can be queried in bc(1) programs with the **maxobase()** built-in function. The
min allowable value for **obase** is **2**. Values are output in the specified
base.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a global variable that
sets the precision of any operations, with exceptions. **scale** is initially
**0**. **scale** cannot be negative. The max allowable value for **scale** is
**BC_SCALE_MAX** and can be queried in bc(1) programs with the **maxscale()**
built-in function.
bc(1) has both *global* variables and *local* variables. All *local*
variables are local to the function; they are parameters or are introduced in
the **auto** list of a function (see the **FUNCTIONS** section). If a variable
is accessed which is not a parameter or in the **auto** list, it is assumed to
be *global*. If a parent function has a *local* variable version of a variable
that a child function considers *global*, the value of that *global* variable in
the child function is the value of the variable in the parent function, not the
value of the actual *global* variable.
All of the above applies to arrays as well.
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence operator is an
assignment operator *and* the expression is notsurrounded by parentheses.
The value that is printed is also assigned to the special variable **last**. A
single dot (**.**) may also be used as a synonym for **last**. These are
**non-portable extensions**.
Either semicolons or newlines may separate statements.
## Comments
There are two kinds of comments:
1. Block comments are enclosed in **/\*** and **\*/**.
2. Line comments go from **#** until, and not including, the next newline. This
is a **non-portable extension**.
## Named Expressions
The following are named expressions in bc(1):
1. Variables: **I**
2. Array Elements: **I[E]**
3. **ibase**
4. **obase**
5. **scale**
6. **last** or a single dot (**.**)
Number 6 is a **non-portable extension**.
Variables and arrays do not interfere; users can have arrays named the same as
variables. This also applies to functions (see the **FUNCTIONS** section), so a
user can have a variable, array, and function that all have the same name, and
they will not shadow each other, whether inside of functions or not.
Named expressions are required as the operand of **increment**/**decrement**
operators and as the left side of **assignment** operators (see the *Operators*
subsection).
## Operands
The following are valid operands in bc(1):
1. Numbers (see the *Numbers* subsection below).
2. Array indices (**I[E]**).
3. **(E)**: The value of **E** (used to change precedence).
4. **sqrt(E)**: The square root of **E**. **E** must be non-negative.
5. **length(E)**: The number of significant decimal digits in **E**.
6. **length(I[])**: The number of elements in the array **I**. This is a
**non-portable extension**.
7. **scale(E)**: The *scale* of **E**.
8. **abs(E)**: The absolute value of **E**. This is a **non-portable
extension**.
9. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a non-**void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
10. **read()**: Reads a line from **stdin** and uses that as an expression. The
result of that expression is the result of the **read()** operand. This is a
**non-portable extension**.
11. **maxibase()**: The max allowable **ibase**. This is a **non-portable
extension**.
12. **maxobase()**: The max allowable **obase**. This is a **non-portable
extension**.
13. **maxscale()**: The max allowable **scale**. This is a **non-portable
extension**.
## Numbers
Numbers are strings made up of digits, uppercase letters, and at most **1**
period for a radix. Numbers can have up to **BC_NUM_MAX** digits. Uppercase
letters are equal to **9** + their position in the alphabet (i.e., **A** equals
**10**, or **9+1**). If a digit or letter makes no sense with the current value
of **ibase**, they are set to the value of the highest valid digit in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **Z** alone always equals decimal
**35**.
## Operators
The following arithmetic and logical operators can be used. They are listed in
order of decreasing precedence. Operators in the same group have the same
precedence.
**++** **--**
: Type: Prefix and Postfix
Associativity: None
Description: **increment**, **decrement**
**-** **!**
: Type: Prefix
Associativity: None
Description: **negation**, **boolean not**
**\^**
: Type: Binary
Associativity: Right
Description: **power**
**\*** **/** **%**
: Type: Binary
Associativity: Left
Description: **multiply**, **divide**, **modulus**
**+** **-**
: Type: Binary
Associativity: Left
Description: **add**, **subtract**
**=** **+=** **-=** **\*=** **/=** **%=** **\^=**
: Type: Binary
Associativity: Right
Description: **assignment**
**==** **\<=** **\>=** **!=** **\<** **\>**
: Type: Binary
Associativity: Left
Description: **relational**
**&&**
: Type: Binary
Associativity: Left
Description: **boolean and**
**||**
: Type: Binary
Associativity: Left
Description: **boolean or**
The operators will be described in more detail below.
**++** **--**
: The prefix and postfix **increment** and **decrement** operators behave
exactly like they would in C. They require a named expression (see the
*Named Expressions* subsection) as an operand.
The prefix versions of these operators are more efficient; use them where
possible.
**-**
: The **negation** operator returns **0** if a user attempts to negate any
expression with the value **0**. Otherwise, a copy of the expression with
its sign flipped is returned.
**!**
: The **boolean not** operator returns **1** if the expression is **0**, or
**0** otherwise.
This is a **non-portable extension**.
**\^**
: The **power** operator (not the **exclusive or** operator, as it would be in
C) takes two expressions and raises the first to the power of the value of
the second. The *scale* of the result is equal to **scale**.
The second expression must be an integer (no *scale*), and if it is
negative, the first value must be non-zero.
**\***
: The **multiply** operator takes two expressions, multiplies them, and
returns the product. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result is
equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The **divide** operator takes two expressions, divides them, and returns the
quotient. The *scale* of the result shall be the value of **scale**.
The second expression must be non-zero.
**%**
: The **modulus** operator takes two expressions, **a** and **b**, and
evaluates them by 1) Computing **a/b** to current **scale** and 2) Using the
result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The second expression must be non-zero.
**+**
: The **add** operator takes two expressions, **a** and **b**, and returns the
sum, with a *scale* equal to the max of the *scale*s of **a** and **b**.
**-**
: The **subtract** operator takes two expressions, **a** and **b**, and
returns the difference, with a *scale* equal to the max of the *scale*s of
**a** and **b**.
**=** **+=** **-=** **\*=** **/=** **%=** **\^=**
: The **assignment** operators take two expressions, **a** and **b** where
**a** is a named expression (see the *Named Expressions* subsection).
For **=**, **b** is copied and the result is assigned to **a**. For all
others, **a** and **b** are applied as operands to the corresponding
arithmetic operator and the result is assigned to **a**.
**==** **\<=** **\>=** **!=** **\<** **\>**
: The **relational** operators compare two expressions, **a** and **b**, and
if the relation holds, according to C language semantics, the result is
**1**. Otherwise, it is **0**.
Note that unlike in C, these operators have a lower precedence than the
**assignment** operators, which means that **a=b\>c** is interpreted as
**(a=b)\>c**.
Also, unlike the [standard][1] requires, these operators can appear anywhere
any other expressions can be used. This allowance is a
**non-portable extension**.
**&&**
: The **boolean and** operator takes two expressions and returns **1** if both
expressions are non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
**||**
: The **boolean or** operator takes two expressions and returns **1** if one
of the expressions is non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
## Statements
The following items are statements:
1. **E**
2. **{** **S** **;** ... **;** **S** **}**
3. **if** **(** **E** **)** **S**
4. **if** **(** **E** **)** **S** **else** **S**
5. **while** **(** **E** **)** **S**
6. **for** **(** **E** **;** **E** **;** **E** **)** **S**
7. An empty statement
8. **break**
9. **continue**
10. **quit**
11. **halt**
12. **limits**
13. A string of characters, enclosed in double quotes
14. **print** **E** **,** ... **,** **E**
15. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
Numbers 4, 9, 11, 12, 14, and 15 are **non-portable extensions**.
Also, as a **non-portable extension**, any or all of the expressions in the
header of a for loop may be omitted. If the condition (second expression) is
omitted, it is assumed to be a constant **1**.
The **break** statement causes a loop to stop iterating and resume execution
immediately following a loop. This is only allowed in loops.
The **continue** statement causes a loop iteration to stop early and returns to
the start of the loop, including testing the loop condition. This is only
allowed in loops.
The **if** **else** statement does the same thing as in C.
The **quit** statement causes bc(1) to quit, even if it is on a branch that will
not be executed (it is a compile-time command).
The **halt** statement causes bc(1) to quit, if it is executed. (Unlike **quit**
if it is on a branch of an **if** statement that is not executed, bc(1) does not
quit.)
The **limits** statement prints the limits that this bc(1) is subject to. This
is like the **quit** statement in that it is a compile-time command.
An expression by itself is evaluated and printed, followed by a newline.
## Print Statement
The "expressions" in a **print** statement may also be strings. If they are, there
are backslash escape sequences that are interpreted specially. What those
sequences are, and what they cause to be printed, are shown below:
-------- -------
**\\a** **\\a**
**\\b** **\\b**
**\\\\** **\\**
**\\e** **\\**
**\\f** **\\f**
**\\n** **\\n**
**\\q** **"**
**\\r** **\\r**
**\\t** **\\t**
-------- -------
Any other character following a backslash causes the backslash and character to
be printed as-is.
Any non-string expression in a print statement shall be assigned to **last**,
like any other expression that is printed.
## Order of Evaluation
All expressions in a statment are evaluated left to right, except as necessary
to maintain order of operations. This means, for example, assuming that **i** is
equal to **0**, in the expression
a[i++] = i++
the first (or 0th) element of **a** is set to **1**, and **i** is equal to **2**
at the end of the expression.
This includes function arguments. Thus, assuming **i** is equal to **0**, this
means that in the expression
x(i++, i++)
the first argument passed to **x()** is **0**, and the second argument is **1**,
while **i** is equal to **2** before the function starts executing.
# FUNCTIONS
Function definitions are as follows:
```
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
```
Any **I** in the parameter list or **auto** list may be replaced with **I[]** to
make a parameter or **auto** var an array, and any **I** in the parameter list
may be replaced with **\*I[]** to make a parameter an array reference. Callers
of functions that take array references should not put an asterisk in the call;
they must be called with just **I[]** like normal array parameters and will be
automatically converted into references.
As a **non-portable extension**, the opening brace of a **define** statement may
appear on the next line.
As a **non-portable extension**, the return statement may also be in one of the
following forms:
1. **return**
2. **return** **(** **)**
3. **return** **E**
The first two, or not specifying a **return** statement, is equivalent to
**return (0)**, unless the function is a **void** function (see the *Void
Functions* subsection below).
## Void Functions
Functions can also be **void** functions, defined as follows:
```
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
```
They can only be used as standalone expressions, where such an expression would
be printed alone, except in a print statement.
Void functions can only use the first two **return** statements listed above.
They can also omit the return statement entirely.
The word "void" is not treated as a keyword; it is still possible to have
variables, arrays, and functions named **void**. The word "void" is only
treated specially right after the **define** keyword.
This is a **non-portable extension**.
## Array References
For any array in the parameter list, if the array is declared in the form
```
*I[]
```
it is a **reference**. Any changes to the array in the function are reflected,
when the function returns, to the array that was passed in.
Other than this, all function arguments are passed by value.
This is a **non-portable extension**.
# LIBRARY
All of the functions below are available when the **-l** or **--mathlib**
command-line flags are given.
## Standard Library
The [standard][1] defines the following functions for the math library:
**s(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**c(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a(x)**
: Returns the arctangent of **x**, in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l(x)**
: Returns the natural logarithm of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**e(x)**
: Returns the mathematical constant **e** raised to the power of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**j(x, n)**
: Returns the bessel integer order **n** (truncated) of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
## Transcendental Functions
All transcendental functions can return slightly inaccurate results (up to 1
[ULP][4]). This is unavoidable, and [this article][5] explains why it is
impossible and unnecessary to calculate exact results for the transcendental
functions.
Because of the possible inaccuracy, I recommend that users call those functions
with the precision (**scale**) set to at least 1 higher than is necessary. If
exact results are *absolutely* required, users can double the precision
(**scale**) and then truncate.
The transcendental functions in the standard math library are:
* **s(x)**
* **c(x)**
* **a(x)**
* **l(x)**
* **e(x)**
* **j(x, n)**
# RESET
When bc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any functions that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
functions returned) is skipped.
Thus, when bc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
Note that this reset behavior is different from the GNU bc(1), which attempts to
start executing the statement right after the one that caused an error.
# PERFORMANCE
Most bc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This bc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **BC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **BC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**BC_BASE_DIGS**.
The actual values of **BC_LONG_BIT** and **BC_BASE_DIGS** can be queried with
the **limits** statement.
In addition, this bc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **BC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on bc(1):
**BC_LONG_BIT**
: The number of bits in the **long** type in the environment where bc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**BC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **BC_LONG_BIT**.
**BC_BASE_POW**
: The max decimal number that each large integer can store (see
**BC_BASE_DIGS**) plus **1**. Depends on **BC_BASE_DIGS**.
**BC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **BC_LONG_BIT**.
**BC_BASE_MAX**
: The maximum output base. Set at **BC_BASE_POW**.
**BC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**BC_SCALE_MAX**
: The maximum **scale**. Set at **BC_OVERFLOW_MAX-1**.
**BC_STRING_MAX**
: The maximum length of strings. Set at **BC_OVERFLOW_MAX-1**.
**BC_NAME_MAX**
: The maximum length of identifiers. Set at **BC_OVERFLOW_MAX-1**.
**BC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **BC_OVERFLOW_MAX-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**BC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
The actual values can be queried with the **limits** statement.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
bc(1) recognizes the following environment variables:
**POSIXLY_CORRECT**
: If this variable exists (no matter the contents), bc(1) behaves as if
the **-s** option was given.
**BC_ENV_ARGS**
: This is another way to give command-line arguments to bc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **BC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
The code that parses **BC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some bc file.bc"** will be correctly parsed, but the string
**"/home/gavin/some \"bc\" file.bc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **BC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**BC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), bc(1) will output
lines to that length, including the backslash (**\\**). The default line
length is **70**.
# EXIT STATUS
bc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**) operator and the corresponding assignment operator.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, using a token where it is invalid,
giving an invalid expression, giving an invalid print statement, giving an
invalid function definition, attempting to assign to an expression that is
not a named expression (see the *Named Expressions* subsection of the
**SYNTAX** section), giving an invalid **auto** list, having a duplicate
**auto**/function parameter, failing to find the end of a code block,
attempting to return a value from a **void** function, attempting to use a
variable as a reference, and using any extensions when the option **-s** or
any equivalents were given.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a **void** function call as a value in an expression.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (bc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, bc(1) always exits
and returns **4**, no matter what mode bc(1) is in.
The other statuses will only be returned when bc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since bc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Per the [standard][1], bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, bc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, bc(1) turns
on "TTY mode."
The prompt is enabled in TTY mode.
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause bc(1) to stop execution of the current input. If
bc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If bc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If bc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to bc(1) as it is executing a file, it
can seem as though bc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause bc(1) to clean up and exit, and it uses the
default handler for all other signals.
# SEE ALSO
dc(1)
# STANDARDS
bc(1) is compliant with the [IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1]
specification. The flags **-efghiqsvVw**, all long options, and the extensions
noted above are extensions to that specification.
Note that the specification explicitly says that bc(1) only accepts numbers that
use a period (**.**) as a radix point, regardless of the value of
**LC_NUMERIC**.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHORS
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
[2]: https://www.gnu.org/software/bc/
[3]: https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero
[4]: https://en.wikipedia.org/wiki/Unit_in_the_last_place
[5]: https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT
[6]: https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero
diff --git a/contrib/bc/manuals/bc/EHNP.1 b/contrib/bc/manuals/bc/EHNP.1
index e25cd1a7da42..7bd46f38e104 100644
--- a/contrib/bc/manuals/bc/EHNP.1
+++ b/contrib/bc/manuals/bc/EHNP.1
@@ -1,1269 +1,1282 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "BC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "BC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH NAME
.PP
bc - arbitrary-precision decimal arithmetic language and calculator
.SH SYNOPSIS
.PP
\f[B]bc\f[R] [\f[B]-ghilPqsvVw\f[R]] [\f[B]\[en]global-stacks\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]mathlib\f[R]] [\f[B]\[en]no-prompt\f[R]]
[\f[B]\[en]quiet\f[R]] [\f[B]\[en]standard\f[R]] [\f[B]\[en]warn\f[R]]
[\f[B]\[en]version\f[R]] [\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
bc(1) is an interactive processor for a language first standardized in
1991 by POSIX.
(The current standard is
here (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).)
The language provides unlimited precision decimal arithmetic and is
somewhat C-like, but there are differences.
Such differences will be noted in this document.
.PP
After parsing and handling options, this bc(1) reads any files given on
the command line and executes them before reading from \f[B]stdin\f[R].
.SH OPTIONS
.PP
The following are the options that bc(1) accepts.
.PP
\f[B]-g\f[R], \f[B]\[en]global-stacks\f[R]
.IP
.nf
\f[C]
Turns the globals **ibase**, **obase**, and **scale** into stacks.
This has the effect that a copy of the current value of all three are pushed
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
However, since using this flag means that functions cannot set **ibase**,
**obase**, or **scale** globally, functions that are made to do so cannot
work anymore. There are two possible use cases for that, and each has a
solution.
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o=\[dq]bc -e ibase=A -e obase=8\[dq]
alias h2b=\[dq]bc -e ibase=G -e obase=2\[dq]
Second, if the purpose of a function is to set **ibase**, **obase**, or
**scale** globally for any other purpose, it could be split into one to
three functions (based on how many globals it sets) and each of those
functions could return the desired value for a global.
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
\f[R]
.fi
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-l\f[R], \f[B]\[en]mathlib\f[R]
Sets \f[B]scale\f[R] (see the \f[B]SYNTAX\f[R] section) to \f[B]20\f[R]
and loads the included math library before running any code, including
any expressions or files specified on the command line.
.RS
.PP
To learn what is in the library, see the \f[B]LIBRARY\f[R] section.
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
This option is a no-op.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-q\f[R], \f[B]\[en]quiet\f[R]
This option is for compatibility with the GNU
bc(1) (https://www.gnu.org/software/bc/); it is a no-op.
Without this option, GNU bc(1) prints a copyright header.
This bc(1) only prints the copyright header if one or more of the
\f[B]-v\f[R], \f[B]-V\f[R], or \f[B]\[en]version\f[R] options are given.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-s\f[R], \f[B]\[en]standard\f[R]
Process exactly the language defined by the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
and error if any extensions are used.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-w\f[R], \f[B]\[en]warn\f[R]
Like \f[B]-s\f[R] and \f[B]\[en]standard\f[R], except that warnings (and
not errors) are printed for non-standard extensions and execution
continues normally.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]BC_ENV_ARGS\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]bc >&-\f[R], it will quit with an error.
This is done so that bc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]bc 2>&-\f[R], it will quit with an error.
This is done so that bc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
The syntax for bc(1) programs is mostly C-like, with some differences.
This bc(1) follows the POSIX
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
which is a much more thorough resource for the language this bc(1)
accepts.
This section is meant to be a summary and a listing of all the
extensions to the standard.
.PP
In the sections below, \f[B]E\f[R] means expression, \f[B]S\f[R] means
statement, and \f[B]I\f[R] means identifier.
.PP
Identifiers (\f[B]I\f[R]) start with a lowercase letter and can be
followed by any number (up to \f[B]BC_NAME_MAX-1\f[R]) of lowercase
letters (\f[B]a-z\f[R]), digits (\f[B]0-9\f[R]), and underscores
(\f[B]_\f[R]).
The regex is \f[B][a-z][a-z0-9_]*\f[R].
Identifiers with more than one character (letter) are a
\f[B]non-portable extension\f[R].
.PP
\f[B]ibase\f[R] is a global variable determining how to interpret
constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
If the \f[B]-s\f[R] (\f[B]\[en]standard\f[R]) and \f[B]-w\f[R]
(\f[B]\[en]warn\f[R]) flags were not given on the command line, the max
allowable value for \f[B]ibase\f[R] is \f[B]36\f[R].
Otherwise, it is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in bc(1)
programs with the \f[B]maxibase()\f[R] built-in function.
.PP
\f[B]obase\f[R] is a global variable determining how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]BC_BASE_MAX\f[R] and
can be queried in bc(1) programs with the \f[B]maxobase()\f[R] built-in
function.
The min allowable value for \f[B]obase\f[R] is \f[B]2\f[R].
Values are output in the specified base.
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a global variable that sets the precision of any operations, with
exceptions.
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] is \f[B]BC_SCALE_MAX\f[R]
and can be queried in bc(1) programs with the \f[B]maxscale()\f[R]
built-in function.
.PP
bc(1) has both \f[I]global\f[R] variables and \f[I]local\f[R] variables.
All \f[I]local\f[R] variables are local to the function; they are
parameters or are introduced in the \f[B]auto\f[R] list of a function
(see the \f[B]FUNCTIONS\f[R] section).
If a variable is accessed which is not a parameter or in the
\f[B]auto\f[R] list, it is assumed to be \f[I]global\f[R].
If a parent function has a \f[I]local\f[R] variable version of a
variable that a child function considers \f[I]global\f[R], the value of
that \f[I]global\f[R] variable in the child function is the value of the
variable in the parent function, not the value of the actual
\f[I]global\f[R] variable.
.PP
All of the above applies to arrays as well.
.PP
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence
operator is an assignment operator \f[I]and\f[R] the expression is
notsurrounded by parentheses.
.PP
The value that is printed is also assigned to the special variable
\f[B]last\f[R].
A single dot (\f[B].\f[R]) may also be used as a synonym for
\f[B]last\f[R].
These are \f[B]non-portable extensions\f[R].
.PP
Either semicolons or newlines may separate statements.
.SS Comments
.PP
There are two kinds of comments:
.IP "1." 3
Block comments are enclosed in \f[B]/*\f[R] and \f[B]*/\f[R].
.IP "2." 3
Line comments go from \f[B]#\f[R] until, and not including, the next
newline.
This is a \f[B]non-portable extension\f[R].
.SS Named Expressions
.PP
The following are named expressions in bc(1):
.IP "1." 3
Variables: \f[B]I\f[R]
.IP "2." 3
Array Elements: \f[B]I[E]\f[R]
.IP "3." 3
\f[B]ibase\f[R]
.IP "4." 3
\f[B]obase\f[R]
.IP "5." 3
\f[B]scale\f[R]
.IP "6." 3
\f[B]last\f[R] or a single dot (\f[B].\f[R])
.PP
Number 6 is a \f[B]non-portable extension\f[R].
.PP
Variables and arrays do not interfere; users can have arrays named the
same as variables.
This also applies to functions (see the \f[B]FUNCTIONS\f[R] section), so
a user can have a variable, array, and function that all have the same
name, and they will not shadow each other, whether inside of functions
or not.
.PP
Named expressions are required as the operand of
\f[B]increment\f[R]/\f[B]decrement\f[R] operators and as the left side
of \f[B]assignment\f[R] operators (see the \f[I]Operators\f[R]
subsection).
.SS Operands
.PP
The following are valid operands in bc(1):
.IP " 1." 4
Numbers (see the \f[I]Numbers\f[R] subsection below).
.IP " 2." 4
Array indices (\f[B]I[E]\f[R]).
.IP " 3." 4
\f[B](E)\f[R]: The value of \f[B]E\f[R] (used to change precedence).
.IP " 4." 4
\f[B]sqrt(E)\f[R]: The square root of \f[B]E\f[R].
\f[B]E\f[R] must be non-negative.
.IP " 5." 4
\f[B]length(E)\f[R]: The number of significant decimal digits in
\f[B]E\f[R].
.IP " 6." 4
\f[B]length(I[])\f[R]: The number of elements in the array \f[B]I\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 7." 4
\f[B]scale(E)\f[R]: The \f[I]scale\f[R] of \f[B]E\f[R].
.IP " 8." 4
\f[B]abs(E)\f[R]: The absolute value of \f[B]E\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 9." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a non-\f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.IP "10." 4
\f[B]read()\f[R]: Reads a line from \f[B]stdin\f[R] and uses that as an
expression.
The result of that expression is the result of the \f[B]read()\f[R]
operand.
This is a \f[B]non-portable extension\f[R].
.IP "11." 4
\f[B]maxibase()\f[R]: The max allowable \f[B]ibase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "12." 4
\f[B]maxobase()\f[R]: The max allowable \f[B]obase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "13." 4
\f[B]maxscale()\f[R]: The max allowable \f[B]scale\f[R].
This is a \f[B]non-portable extension\f[R].
.SS Numbers
.PP
Numbers are strings made up of digits, uppercase letters, and at most
\f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]BC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]Z\f[R] alone always equals decimal \f[B]35\f[R].
.SS Operators
.PP
The following arithmetic and logical operators can be used.
They are listed in order of decreasing precedence.
Operators in the same group have the same precedence.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
Type: Prefix and Postfix
.RS
.PP
Associativity: None
.PP
Description: \f[B]increment\f[R], \f[B]decrement\f[R]
.RE
.TP
\f[B]-\f[R] \f[B]!\f[R]
Type: Prefix
.RS
.PP
Associativity: None
.PP
Description: \f[B]negation\f[R], \f[B]boolean not\f[R]
.RE
.TP
\f[B]\[ha]\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]power\f[R]
.RE
.TP
\f[B]*\f[R] \f[B]/\f[R] \f[B]%\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]multiply\f[R], \f[B]divide\f[R], \f[B]modulus\f[R]
.RE
.TP
\f[B]+\f[R] \f[B]-\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]add\f[R], \f[B]subtract\f[R]
.RE
.TP
\f[B]=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]assignment\f[R]
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]relational\f[R]
.RE
.TP
\f[B]&&\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean and\f[R]
.RE
.TP
\f[B]||\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean or\f[R]
.RE
.PP
The operators will be described in more detail below.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
The prefix and postfix \f[B]increment\f[R] and \f[B]decrement\f[R]
operators behave exactly like they would in C.
They require a named expression (see the \f[I]Named Expressions\f[R]
subsection) as an operand.
.RS
.PP
The prefix versions of these operators are more efficient; use them
where possible.
.RE
.TP
\f[B]-\f[R]
The \f[B]negation\f[R] operator returns \f[B]0\f[R] if a user attempts
to negate any expression with the value \f[B]0\f[R].
Otherwise, a copy of the expression with its sign flipped is returned.
.TP
\f[B]!\f[R]
The \f[B]boolean not\f[R] operator returns \f[B]1\f[R] if the expression
is \f[B]0\f[R], or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The \f[B]power\f[R] operator (not the \f[B]exclusive or\f[R] operator,
as it would be in C) takes two expressions and raises the first to the
power of the value of the second.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]), and if it
is negative, the first value must be non-zero.
.RE
.TP
\f[B]*\f[R]
The \f[B]multiply\f[R] operator takes two expressions, multiplies them,
and returns the product.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The \f[B]divide\f[R] operator takes two expressions, divides them, and
returns the quotient.
The \f[I]scale\f[R] of the result shall be the value of \f[B]scale\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]%\f[R]
The \f[B]modulus\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and evaluates them by 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R] and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]+\f[R]
The \f[B]add\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the sum, with a \f[I]scale\f[R] equal to the
max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]-\f[R]
The \f[B]subtract\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the difference, with a \f[I]scale\f[R] equal to
the max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R]
The \f[B]assignment\f[R] operators take two expressions, \f[B]a\f[R] and
\f[B]b\f[R] where \f[B]a\f[R] is a named expression (see the \f[I]Named
Expressions\f[R] subsection).
.RS
.PP
For \f[B]=\f[R], \f[B]b\f[R] is copied and the result is assigned to
\f[B]a\f[R].
For all others, \f[B]a\f[R] and \f[B]b\f[R] are applied as operands to
the corresponding arithmetic operator and the result is assigned to
\f[B]a\f[R].
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
The \f[B]relational\f[R] operators compare two expressions, \f[B]a\f[R]
and \f[B]b\f[R], and if the relation holds, according to C language
semantics, the result is \f[B]1\f[R].
Otherwise, it is \f[B]0\f[R].
.RS
.PP
Note that unlike in C, these operators have a lower precedence than the
\f[B]assignment\f[R] operators, which means that \f[B]a=b>c\f[R] is
interpreted as \f[B](a=b)>c\f[R].
.PP
Also, unlike the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
requires, these operators can appear anywhere any other expressions can
be used.
This allowance is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]&&\f[R]
The \f[B]boolean and\f[R] operator takes two expressions and returns
\f[B]1\f[R] if both expressions are non-zero, \f[B]0\f[R] otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]||\f[R]
The \f[B]boolean or\f[R] operator takes two expressions and returns
\f[B]1\f[R] if one of the expressions is non-zero, \f[B]0\f[R]
otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Statements
.PP
The following items are statements:
.IP " 1." 4
\f[B]E\f[R]
.IP " 2." 4
\f[B]{\f[R] \f[B]S\f[R] \f[B];\f[R] \&... \f[B];\f[R] \f[B]S\f[R]
\f[B]}\f[R]
.IP " 3." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 4." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
\f[B]else\f[R] \f[B]S\f[R]
.IP " 5." 4
\f[B]while\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 6." 4
\f[B]for\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B];\f[R] \f[B]E\f[R]
\f[B];\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 7." 4
An empty statement
.IP " 8." 4
\f[B]break\f[R]
.IP " 9." 4
\f[B]continue\f[R]
.IP "10." 4
\f[B]quit\f[R]
.IP "11." 4
\f[B]halt\f[R]
.IP "12." 4
\f[B]limits\f[R]
.IP "13." 4
A string of characters, enclosed in double quotes
.IP "14." 4
\f[B]print\f[R] \f[B]E\f[R] \f[B],\f[R] \&... \f[B],\f[R] \f[B]E\f[R]
.IP "15." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a \f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.PP
Numbers 4, 9, 11, 12, 14, and 15 are \f[B]non-portable extensions\f[R].
.PP
Also, as a \f[B]non-portable extension\f[R], any or all of the
expressions in the header of a for loop may be omitted.
If the condition (second expression) is omitted, it is assumed to be a
constant \f[B]1\f[R].
.PP
The \f[B]break\f[R] statement causes a loop to stop iterating and resume
execution immediately following a loop.
This is only allowed in loops.
.PP
The \f[B]continue\f[R] statement causes a loop iteration to stop early
and returns to the start of the loop, including testing the loop
condition.
This is only allowed in loops.
.PP
The \f[B]if\f[R] \f[B]else\f[R] statement does the same thing as in C.
.PP
The \f[B]quit\f[R] statement causes bc(1) to quit, even if it is on a
branch that will not be executed (it is a compile-time command).
.PP
The \f[B]halt\f[R] statement causes bc(1) to quit, if it is executed.
(Unlike \f[B]quit\f[R] if it is on a branch of an \f[B]if\f[R] statement
that is not executed, bc(1) does not quit.)
.PP
The \f[B]limits\f[R] statement prints the limits that this bc(1) is
subject to.
This is like the \f[B]quit\f[R] statement in that it is a compile-time
command.
.PP
An expression by itself is evaluated and printed, followed by a newline.
.SS Print Statement
.PP
The \[lq]expressions\[rq] in a \f[B]print\f[R] statement may also be
strings.
If they are, there are backslash escape sequences that are interpreted
specially.
What those sequences are, and what they cause to be printed, are shown
below:
.PP
.TS
tab(@);
l l.
T{
\f[B]\[rs]a\f[R]
T}@T{
\f[B]\[rs]a\f[R]
T}
T{
\f[B]\[rs]b\f[R]
T}@T{
\f[B]\[rs]b\f[R]
T}
T{
\f[B]\[rs]\[rs]\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]e\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]f\f[R]
T}@T{
\f[B]\[rs]f\f[R]
T}
T{
\f[B]\[rs]n\f[R]
T}@T{
\f[B]\[rs]n\f[R]
T}
T{
\f[B]\[rs]q\f[R]
T}@T{
\f[B]\[dq]\f[R]
T}
T{
\f[B]\[rs]r\f[R]
T}@T{
\f[B]\[rs]r\f[R]
T}
T{
\f[B]\[rs]t\f[R]
T}@T{
\f[B]\[rs]t\f[R]
T}
.TE
.PP
Any other character following a backslash causes the backslash and
character to be printed as-is.
.PP
Any non-string expression in a print statement shall be assigned to
\f[B]last\f[R], like any other expression that is printed.
.SS Order of Evaluation
.PP
All expressions in a statment are evaluated left to right, except as
necessary to maintain order of operations.
This means, for example, assuming that \f[B]i\f[R] is equal to
\f[B]0\f[R], in the expression
.IP
.nf
\f[C]
a[i++] = i++
\f[R]
.fi
.PP
the first (or 0th) element of \f[B]a\f[R] is set to \f[B]1\f[R], and
\f[B]i\f[R] is equal to \f[B]2\f[R] at the end of the expression.
.PP
This includes function arguments.
Thus, assuming \f[B]i\f[R] is equal to \f[B]0\f[R], this means that in
the expression
.IP
.nf
\f[C]
x(i++, i++)
\f[R]
.fi
.PP
the first argument passed to \f[B]x()\f[R] is \f[B]0\f[R], and the
second argument is \f[B]1\f[R], while \f[B]i\f[R] is equal to
\f[B]2\f[R] before the function starts executing.
.SH FUNCTIONS
.PP
Function definitions are as follows:
.IP
.nf
\f[C]
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
\f[R]
.fi
.PP
Any \f[B]I\f[R] in the parameter list or \f[B]auto\f[R] list may be
replaced with \f[B]I[]\f[R] to make a parameter or \f[B]auto\f[R] var an
array, and any \f[B]I\f[R] in the parameter list may be replaced with
\f[B]*I[]\f[R] to make a parameter an array reference.
Callers of functions that take array references should not put an
asterisk in the call; they must be called with just \f[B]I[]\f[R] like
normal array parameters and will be automatically converted into
references.
.PP
As a \f[B]non-portable extension\f[R], the opening brace of a
\f[B]define\f[R] statement may appear on the next line.
.PP
As a \f[B]non-portable extension\f[R], the return statement may also be
in one of the following forms:
.IP "1." 3
\f[B]return\f[R]
.IP "2." 3
\f[B]return\f[R] \f[B](\f[R] \f[B])\f[R]
.IP "3." 3
\f[B]return\f[R] \f[B]E\f[R]
.PP
The first two, or not specifying a \f[B]return\f[R] statement, is
equivalent to \f[B]return (0)\f[R], unless the function is a
\f[B]void\f[R] function (see the \f[I]Void Functions\f[R] subsection
below).
.SS Void Functions
.PP
Functions can also be \f[B]void\f[R] functions, defined as follows:
.IP
.nf
\f[C]
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
\f[R]
.fi
.PP
They can only be used as standalone expressions, where such an
expression would be printed alone, except in a print statement.
.PP
Void functions can only use the first two \f[B]return\f[R] statements
listed above.
They can also omit the return statement entirely.
.PP
The word \[lq]void\[rq] is not treated as a keyword; it is still
possible to have variables, arrays, and functions named \f[B]void\f[R].
The word \[lq]void\[rq] is only treated specially right after the
\f[B]define\f[R] keyword.
.PP
This is a \f[B]non-portable extension\f[R].
.SS Array References
.PP
For any array in the parameter list, if the array is declared in the
form
.IP
.nf
\f[C]
*I[]
\f[R]
.fi
.PP
it is a \f[B]reference\f[R].
Any changes to the array in the function are reflected, when the
function returns, to the array that was passed in.
.PP
Other than this, all function arguments are passed by value.
.PP
This is a \f[B]non-portable extension\f[R].
.SH LIBRARY
.PP
All of the functions below are available when the \f[B]-l\f[R] or
\f[B]\[en]mathlib\f[R] command-line flags are given.
.SS Standard Library
.PP
The
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
defines the following functions for the math library:
.TP
\f[B]s(x)\f[R]
Returns the sine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]c(x)\f[R]
Returns the cosine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]a(x)\f[R]
Returns the arctangent of \f[B]x\f[R], in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]l(x)\f[R]
Returns the natural logarithm of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]e(x)\f[R]
Returns the mathematical constant \f[B]e\f[R] raised to the power of
\f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]j(x, n)\f[R]
Returns the bessel integer order \f[B]n\f[R] (truncated) of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.SS Transcendental Functions
.PP
All transcendental functions can return slightly inaccurate results (up
to 1 ULP (https://en.wikipedia.org/wiki/Unit_in_the_last_place)).
This is unavoidable, and this
article (https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT) explains
why it is impossible and unnecessary to calculate exact results for the
transcendental functions.
.PP
Because of the possible inaccuracy, I recommend that users call those
functions with the precision (\f[B]scale\f[R]) set to at least 1 higher
than is necessary.
If exact results are \f[I]absolutely\f[R] required, users can double the
precision (\f[B]scale\f[R]) and then truncate.
.PP
The transcendental functions in the standard math library are:
.IP \[bu] 2
\f[B]s(x)\f[R]
.IP \[bu] 2
\f[B]c(x)\f[R]
.IP \[bu] 2
\f[B]a(x)\f[R]
.IP \[bu] 2
\f[B]l(x)\f[R]
.IP \[bu] 2
\f[B]e(x)\f[R]
.IP \[bu] 2
\f[B]j(x, n)\f[R]
.SH RESET
.PP
When bc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any functions that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all functions returned) is skipped.
.PP
Thus, when bc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.PP
Note that this reset behavior is different from the GNU bc(1), which
attempts to start executing the statement right after the one that
caused an error.
.SH PERFORMANCE
.PP
Most bc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This bc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]BC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]BC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]BC_BASE_DIGS\f[R].
.PP
The actual values of \f[B]BC_LONG_BIT\f[R] and \f[B]BC_BASE_DIGS\f[R]
can be queried with the \f[B]limits\f[R] statement.
.PP
In addition, this bc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]BC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on bc(1):
.TP
\f[B]BC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
bc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]BC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]BC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]BC_BASE_DIGS\f[R].
.TP
\f[B]BC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]BC_BASE_POW\f[R].
.TP
\f[B]BC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]BC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]BC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
The actual values can be queried with the \f[B]limits\f[R] statement.
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
bc(1) recognizes the following environment variables:
.TP
\f[B]POSIXLY_CORRECT\f[R]
If this variable exists (no matter the contents), bc(1) behaves as if
the \f[B]-s\f[R] option was given.
.TP
\f[B]BC_ENV_ARGS\f[R]
This is another way to give command-line arguments to bc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]BC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
.RS
.PP
The code that parses \f[B]BC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some bc file.bc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]bc\[dq] file.bc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]BC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]BC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), bc(1) will output lines to that length,
including the backslash (\f[B]\[rs]\f[R]).
The default line length is \f[B]70\f[R].
.SH EXIT STATUS
.PP
bc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, attempting to convert a negative number to a hardware
integer, overflow when converting a number to a hardware integer, and
attempting to use a non-integer where an integer is required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]) operator and the corresponding assignment
operator.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, using a token
where it is invalid, giving an invalid expression, giving an invalid
print statement, giving an invalid function definition, attempting to
assign to an expression that is not a named expression (see the
\f[I]Named Expressions\f[R] subsection of the \f[B]SYNTAX\f[R] section),
giving an invalid \f[B]auto\f[R] list, having a duplicate
\f[B]auto\f[R]/function parameter, failing to find the end of a code
block, attempting to return a value from a \f[B]void\f[R] function,
attempting to use a variable as a reference, and using any extensions
when the option \f[B]-s\f[R] or any equivalents were given.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a \f[B]void\f[R] function call as a value in an
expression.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (bc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, bc(1)
always exits and returns \f[B]4\f[R], no matter what mode bc(1) is in.
.PP
The other statuses will only be returned when bc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
bc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Per the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, bc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, bc(1) turns on \[lq]TTY mode.\[rq]
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause bc(1) to stop execution of the
current input.
If bc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If bc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If bc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to bc(1) as it is
executing a file, it can seem as though bc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause bc(1) to clean up and
exit, and it uses the default handler for all other signals.
.SH SEE ALSO
.PP
dc(1)
.SH STANDARDS
.PP
bc(1) is compliant with the IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
The flags \f[B]-efghiqsvVw\f[R], all long options, and the extensions
noted above are extensions to that specification.
.PP
Note that the specification explicitly says that bc(1) only accepts
numbers that use a period (\f[B].\f[R]) as a radix point, regardless of
the value of \f[B]LC_NUMERIC\f[R].
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHORS
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/bc/EHNP.1.md b/contrib/bc/manuals/bc/EHNP.1.md
index e55673769736..8aca89e6f7b0 100644
--- a/contrib/bc/manuals/bc/EHNP.1.md
+++ b/contrib/bc/manuals/bc/EHNP.1.md
@@ -1,1055 +1,1064 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# NAME
bc - arbitrary-precision decimal arithmetic language and calculator
# SYNOPSIS
**bc** [**-ghilPqsvVw**] [**--global-stacks**] [**--help**] [**--interactive**] [**--mathlib**] [**--no-prompt**] [**--quiet**] [**--standard**] [**--warn**] [**--version**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...]
[*file*...]
# DESCRIPTION
bc(1) is an interactive processor for a language first standardized in 1991 by
POSIX. (The current standard is [here][1].) The language provides unlimited
precision decimal arithmetic and is somewhat C-like, but there are differences.
Such differences will be noted in this document.
After parsing and handling options, this bc(1) reads any files given on the
command line and executes them before reading from **stdin**.
# OPTIONS
The following are the options that bc(1) accepts.
**-g**, **--global-stacks**
Turns the globals **ibase**, **obase**, and **scale** into stacks.
This has the effect that a copy of the current value of all three are pushed
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
However, since using this flag means that functions cannot set **ibase**,
**obase**, or **scale** globally, functions that are made to do so cannot
work anymore. There are two possible use cases for that, and each has a
solution.
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o="bc -e ibase=A -e obase=8"
alias h2b="bc -e ibase=G -e obase=2"
Second, if the purpose of a function is to set **ibase**, **obase**, or
**scale** globally for any other purpose, it could be split into one to
three functions (based on how many globals it sets) and each of those
functions could return the desired value for a global.
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
**-h**, **--help**
: Prints a usage message and quits.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-l**, **--mathlib**
: Sets **scale** (see the **SYNTAX** section) to **20** and loads the included
math library before running any code, including any expressions or files
specified on the command line.
To learn what is in the library, see the **LIBRARY** section.
**-P**, **--no-prompt**
: This option is a no-op.
This is a **non-portable extension**.
**-q**, **--quiet**
: This option is for compatibility with the [GNU bc(1)][2]; it is a no-op.
Without this option, GNU bc(1) prints a copyright header. This bc(1) only
prints the copyright header if one or more of the **-v**, **-V**, or
**--version** options are given.
This is a **non-portable extension**.
**-s**, **--standard**
: Process exactly the language defined by the [standard][1] and error if any
extensions are used.
This is a **non-portable extension**.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
This is a **non-portable extension**.
**-w**, **--warn**
: Like **-s** and **--standard**, except that warnings (and not errors) are
printed for non-standard extensions and execution continues normally.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **BC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **bc <file> >&-**, it will quit with an error. This
is done so that bc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **bc <file> 2>&-**, it will quit with an error. This
is done so that bc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
The syntax for bc(1) programs is mostly C-like, with some differences. This
bc(1) follows the [POSIX standard][1], which is a much more thorough resource
for the language this bc(1) accepts. This section is meant to be a summary and a
listing of all the extensions to the standard.
In the sections below, **E** means expression, **S** means statement, and **I**
means identifier.
Identifiers (**I**) start with a lowercase letter and can be followed by any
number (up to **BC_NAME_MAX-1**) of lowercase letters (**a-z**), digits
(**0-9**), and underscores (**\_**). The regex is **\[a-z\]\[a-z0-9\_\]\***.
Identifiers with more than one character (letter) are a
**non-portable extension**.
**ibase** is a global variable determining how to interpret constant numbers. It
is the "input" base, or the number base used for interpreting input numbers.
**ibase** is initially **10**. If the **-s** (**--standard**) and **-w**
(**--warn**) flags were not given on the command line, the max allowable value
for **ibase** is **36**. Otherwise, it is **16**. The min allowable value for
**ibase** is **2**. The max allowable value for **ibase** can be queried in
bc(1) programs with the **maxibase()** built-in function.
**obase** is a global variable determining how to output results. It is the
"output" base, or the number base used for outputting numbers. **obase** is
initially **10**. The max allowable value for **obase** is **BC_BASE_MAX** and
can be queried in bc(1) programs with the **maxobase()** built-in function. The
min allowable value for **obase** is **2**. Values are output in the specified
base.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a global variable that
sets the precision of any operations, with exceptions. **scale** is initially
**0**. **scale** cannot be negative. The max allowable value for **scale** is
**BC_SCALE_MAX** and can be queried in bc(1) programs with the **maxscale()**
built-in function.
bc(1) has both *global* variables and *local* variables. All *local*
variables are local to the function; they are parameters or are introduced in
the **auto** list of a function (see the **FUNCTIONS** section). If a variable
is accessed which is not a parameter or in the **auto** list, it is assumed to
be *global*. If a parent function has a *local* variable version of a variable
that a child function considers *global*, the value of that *global* variable in
the child function is the value of the variable in the parent function, not the
value of the actual *global* variable.
All of the above applies to arrays as well.
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence operator is an
assignment operator *and* the expression is notsurrounded by parentheses.
The value that is printed is also assigned to the special variable **last**. A
single dot (**.**) may also be used as a synonym for **last**. These are
**non-portable extensions**.
Either semicolons or newlines may separate statements.
## Comments
There are two kinds of comments:
1. Block comments are enclosed in **/\*** and **\*/**.
2. Line comments go from **#** until, and not including, the next newline. This
is a **non-portable extension**.
## Named Expressions
The following are named expressions in bc(1):
1. Variables: **I**
2. Array Elements: **I[E]**
3. **ibase**
4. **obase**
5. **scale**
6. **last** or a single dot (**.**)
Number 6 is a **non-portable extension**.
Variables and arrays do not interfere; users can have arrays named the same as
variables. This also applies to functions (see the **FUNCTIONS** section), so a
user can have a variable, array, and function that all have the same name, and
they will not shadow each other, whether inside of functions or not.
Named expressions are required as the operand of **increment**/**decrement**
operators and as the left side of **assignment** operators (see the *Operators*
subsection).
## Operands
The following are valid operands in bc(1):
1. Numbers (see the *Numbers* subsection below).
2. Array indices (**I[E]**).
3. **(E)**: The value of **E** (used to change precedence).
4. **sqrt(E)**: The square root of **E**. **E** must be non-negative.
5. **length(E)**: The number of significant decimal digits in **E**.
6. **length(I[])**: The number of elements in the array **I**. This is a
**non-portable extension**.
7. **scale(E)**: The *scale* of **E**.
8. **abs(E)**: The absolute value of **E**. This is a **non-portable
extension**.
9. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a non-**void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
10. **read()**: Reads a line from **stdin** and uses that as an expression. The
result of that expression is the result of the **read()** operand. This is a
**non-portable extension**.
11. **maxibase()**: The max allowable **ibase**. This is a **non-portable
extension**.
12. **maxobase()**: The max allowable **obase**. This is a **non-portable
extension**.
13. **maxscale()**: The max allowable **scale**. This is a **non-portable
extension**.
## Numbers
Numbers are strings made up of digits, uppercase letters, and at most **1**
period for a radix. Numbers can have up to **BC_NUM_MAX** digits. Uppercase
letters are equal to **9** + their position in the alphabet (i.e., **A** equals
**10**, or **9+1**). If a digit or letter makes no sense with the current value
of **ibase**, they are set to the value of the highest valid digit in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **Z** alone always equals decimal
**35**.
## Operators
The following arithmetic and logical operators can be used. They are listed in
order of decreasing precedence. Operators in the same group have the same
precedence.
**++** **--**
: Type: Prefix and Postfix
Associativity: None
Description: **increment**, **decrement**
**-** **!**
: Type: Prefix
Associativity: None
Description: **negation**, **boolean not**
**\^**
: Type: Binary
Associativity: Right
Description: **power**
**\*** **/** **%**
: Type: Binary
Associativity: Left
Description: **multiply**, **divide**, **modulus**
**+** **-**
: Type: Binary
Associativity: Left
Description: **add**, **subtract**
**=** **+=** **-=** **\*=** **/=** **%=** **\^=**
: Type: Binary
Associativity: Right
Description: **assignment**
**==** **\<=** **\>=** **!=** **\<** **\>**
: Type: Binary
Associativity: Left
Description: **relational**
**&&**
: Type: Binary
Associativity: Left
Description: **boolean and**
**||**
: Type: Binary
Associativity: Left
Description: **boolean or**
The operators will be described in more detail below.
**++** **--**
: The prefix and postfix **increment** and **decrement** operators behave
exactly like they would in C. They require a named expression (see the
*Named Expressions* subsection) as an operand.
The prefix versions of these operators are more efficient; use them where
possible.
**-**
: The **negation** operator returns **0** if a user attempts to negate any
expression with the value **0**. Otherwise, a copy of the expression with
its sign flipped is returned.
**!**
: The **boolean not** operator returns **1** if the expression is **0**, or
**0** otherwise.
This is a **non-portable extension**.
**\^**
: The **power** operator (not the **exclusive or** operator, as it would be in
C) takes two expressions and raises the first to the power of the value of
the second. The *scale* of the result is equal to **scale**.
The second expression must be an integer (no *scale*), and if it is
negative, the first value must be non-zero.
**\***
: The **multiply** operator takes two expressions, multiplies them, and
returns the product. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result is
equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The **divide** operator takes two expressions, divides them, and returns the
quotient. The *scale* of the result shall be the value of **scale**.
The second expression must be non-zero.
**%**
: The **modulus** operator takes two expressions, **a** and **b**, and
evaluates them by 1) Computing **a/b** to current **scale** and 2) Using the
result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The second expression must be non-zero.
**+**
: The **add** operator takes two expressions, **a** and **b**, and returns the
sum, with a *scale* equal to the max of the *scale*s of **a** and **b**.
**-**
: The **subtract** operator takes two expressions, **a** and **b**, and
returns the difference, with a *scale* equal to the max of the *scale*s of
**a** and **b**.
**=** **+=** **-=** **\*=** **/=** **%=** **\^=**
: The **assignment** operators take two expressions, **a** and **b** where
**a** is a named expression (see the *Named Expressions* subsection).
For **=**, **b** is copied and the result is assigned to **a**. For all
others, **a** and **b** are applied as operands to the corresponding
arithmetic operator and the result is assigned to **a**.
**==** **\<=** **\>=** **!=** **\<** **\>**
: The **relational** operators compare two expressions, **a** and **b**, and
if the relation holds, according to C language semantics, the result is
**1**. Otherwise, it is **0**.
Note that unlike in C, these operators have a lower precedence than the
**assignment** operators, which means that **a=b\>c** is interpreted as
**(a=b)\>c**.
Also, unlike the [standard][1] requires, these operators can appear anywhere
any other expressions can be used. This allowance is a
**non-portable extension**.
**&&**
: The **boolean and** operator takes two expressions and returns **1** if both
expressions are non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
**||**
: The **boolean or** operator takes two expressions and returns **1** if one
of the expressions is non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
## Statements
The following items are statements:
1. **E**
2. **{** **S** **;** ... **;** **S** **}**
3. **if** **(** **E** **)** **S**
4. **if** **(** **E** **)** **S** **else** **S**
5. **while** **(** **E** **)** **S**
6. **for** **(** **E** **;** **E** **;** **E** **)** **S**
7. An empty statement
8. **break**
9. **continue**
10. **quit**
11. **halt**
12. **limits**
13. A string of characters, enclosed in double quotes
14. **print** **E** **,** ... **,** **E**
15. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
Numbers 4, 9, 11, 12, 14, and 15 are **non-portable extensions**.
Also, as a **non-portable extension**, any or all of the expressions in the
header of a for loop may be omitted. If the condition (second expression) is
omitted, it is assumed to be a constant **1**.
The **break** statement causes a loop to stop iterating and resume execution
immediately following a loop. This is only allowed in loops.
The **continue** statement causes a loop iteration to stop early and returns to
the start of the loop, including testing the loop condition. This is only
allowed in loops.
The **if** **else** statement does the same thing as in C.
The **quit** statement causes bc(1) to quit, even if it is on a branch that will
not be executed (it is a compile-time command).
The **halt** statement causes bc(1) to quit, if it is executed. (Unlike **quit**
if it is on a branch of an **if** statement that is not executed, bc(1) does not
quit.)
The **limits** statement prints the limits that this bc(1) is subject to. This
is like the **quit** statement in that it is a compile-time command.
An expression by itself is evaluated and printed, followed by a newline.
## Print Statement
The "expressions" in a **print** statement may also be strings. If they are, there
are backslash escape sequences that are interpreted specially. What those
sequences are, and what they cause to be printed, are shown below:
-------- -------
**\\a** **\\a**
**\\b** **\\b**
**\\\\** **\\**
**\\e** **\\**
**\\f** **\\f**
**\\n** **\\n**
**\\q** **"**
**\\r** **\\r**
**\\t** **\\t**
-------- -------
Any other character following a backslash causes the backslash and character to
be printed as-is.
Any non-string expression in a print statement shall be assigned to **last**,
like any other expression that is printed.
## Order of Evaluation
All expressions in a statment are evaluated left to right, except as necessary
to maintain order of operations. This means, for example, assuming that **i** is
equal to **0**, in the expression
a[i++] = i++
the first (or 0th) element of **a** is set to **1**, and **i** is equal to **2**
at the end of the expression.
This includes function arguments. Thus, assuming **i** is equal to **0**, this
means that in the expression
x(i++, i++)
the first argument passed to **x()** is **0**, and the second argument is **1**,
while **i** is equal to **2** before the function starts executing.
# FUNCTIONS
Function definitions are as follows:
```
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
```
Any **I** in the parameter list or **auto** list may be replaced with **I[]** to
make a parameter or **auto** var an array, and any **I** in the parameter list
may be replaced with **\*I[]** to make a parameter an array reference. Callers
of functions that take array references should not put an asterisk in the call;
they must be called with just **I[]** like normal array parameters and will be
automatically converted into references.
As a **non-portable extension**, the opening brace of a **define** statement may
appear on the next line.
As a **non-portable extension**, the return statement may also be in one of the
following forms:
1. **return**
2. **return** **(** **)**
3. **return** **E**
The first two, or not specifying a **return** statement, is equivalent to
**return (0)**, unless the function is a **void** function (see the *Void
Functions* subsection below).
## Void Functions
Functions can also be **void** functions, defined as follows:
```
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
```
They can only be used as standalone expressions, where such an expression would
be printed alone, except in a print statement.
Void functions can only use the first two **return** statements listed above.
They can also omit the return statement entirely.
The word "void" is not treated as a keyword; it is still possible to have
variables, arrays, and functions named **void**. The word "void" is only
treated specially right after the **define** keyword.
This is a **non-portable extension**.
## Array References
For any array in the parameter list, if the array is declared in the form
```
*I[]
```
it is a **reference**. Any changes to the array in the function are reflected,
when the function returns, to the array that was passed in.
Other than this, all function arguments are passed by value.
This is a **non-portable extension**.
# LIBRARY
All of the functions below are available when the **-l** or **--mathlib**
command-line flags are given.
## Standard Library
The [standard][1] defines the following functions for the math library:
**s(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**c(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a(x)**
: Returns the arctangent of **x**, in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l(x)**
: Returns the natural logarithm of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**e(x)**
: Returns the mathematical constant **e** raised to the power of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**j(x, n)**
: Returns the bessel integer order **n** (truncated) of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
## Transcendental Functions
All transcendental functions can return slightly inaccurate results (up to 1
[ULP][4]). This is unavoidable, and [this article][5] explains why it is
impossible and unnecessary to calculate exact results for the transcendental
functions.
Because of the possible inaccuracy, I recommend that users call those functions
with the precision (**scale**) set to at least 1 higher than is necessary. If
exact results are *absolutely* required, users can double the precision
(**scale**) and then truncate.
The transcendental functions in the standard math library are:
* **s(x)**
* **c(x)**
* **a(x)**
* **l(x)**
* **e(x)**
* **j(x, n)**
# RESET
When bc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any functions that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
functions returned) is skipped.
Thus, when bc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
Note that this reset behavior is different from the GNU bc(1), which attempts to
start executing the statement right after the one that caused an error.
# PERFORMANCE
Most bc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This bc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **BC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **BC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**BC_BASE_DIGS**.
The actual values of **BC_LONG_BIT** and **BC_BASE_DIGS** can be queried with
the **limits** statement.
In addition, this bc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **BC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on bc(1):
**BC_LONG_BIT**
: The number of bits in the **long** type in the environment where bc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**BC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **BC_LONG_BIT**.
**BC_BASE_POW**
: The max decimal number that each large integer can store (see
**BC_BASE_DIGS**) plus **1**. Depends on **BC_BASE_DIGS**.
**BC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **BC_LONG_BIT**.
**BC_BASE_MAX**
: The maximum output base. Set at **BC_BASE_POW**.
**BC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**BC_SCALE_MAX**
: The maximum **scale**. Set at **BC_OVERFLOW_MAX-1**.
**BC_STRING_MAX**
: The maximum length of strings. Set at **BC_OVERFLOW_MAX-1**.
**BC_NAME_MAX**
: The maximum length of identifiers. Set at **BC_OVERFLOW_MAX-1**.
**BC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **BC_OVERFLOW_MAX-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**BC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
The actual values can be queried with the **limits** statement.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
bc(1) recognizes the following environment variables:
**POSIXLY_CORRECT**
: If this variable exists (no matter the contents), bc(1) behaves as if
the **-s** option was given.
**BC_ENV_ARGS**
: This is another way to give command-line arguments to bc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **BC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
The code that parses **BC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some bc file.bc"** will be correctly parsed, but the string
**"/home/gavin/some \"bc\" file.bc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **BC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**BC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), bc(1) will output
lines to that length, including the backslash (**\\**). The default line
length is **70**.
# EXIT STATUS
bc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**) operator and the corresponding assignment operator.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, using a token where it is invalid,
giving an invalid expression, giving an invalid print statement, giving an
invalid function definition, attempting to assign to an expression that is
not a named expression (see the *Named Expressions* subsection of the
**SYNTAX** section), giving an invalid **auto** list, having a duplicate
**auto**/function parameter, failing to find the end of a code block,
attempting to return a value from a **void** function, attempting to use a
variable as a reference, and using any extensions when the option **-s** or
any equivalents were given.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a **void** function call as a value in an expression.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (bc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, bc(1) always exits
and returns **4**, no matter what mode bc(1) is in.
The other statuses will only be returned when bc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since bc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Per the [standard][1], bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, bc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, bc(1) turns
on "TTY mode."
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause bc(1) to stop execution of the current input. If
bc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If bc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If bc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to bc(1) as it is executing a file, it
can seem as though bc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause bc(1) to clean up and exit, and it uses the
default handler for all other signals.
# SEE ALSO
dc(1)
# STANDARDS
bc(1) is compliant with the [IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1]
specification. The flags **-efghiqsvVw**, all long options, and the extensions
noted above are extensions to that specification.
Note that the specification explicitly says that bc(1) only accepts numbers that
use a period (**.**) as a radix point, regardless of the value of
**LC_NUMERIC**.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHORS
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
[2]: https://www.gnu.org/software/bc/
[3]: https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero
[4]: https://en.wikipedia.org/wiki/Unit_in_the_last_place
[5]: https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT
[6]: https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero
diff --git a/contrib/bc/manuals/bc/EHP.1 b/contrib/bc/manuals/bc/EHP.1
index 7f35d1a1be7f..31c02f1b9591 100644
--- a/contrib/bc/manuals/bc/EHP.1
+++ b/contrib/bc/manuals/bc/EHP.1
@@ -1,1276 +1,1289 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "BC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "BC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH NAME
.PP
bc - arbitrary-precision decimal arithmetic language and calculator
.SH SYNOPSIS
.PP
\f[B]bc\f[R] [\f[B]-ghilPqsvVw\f[R]] [\f[B]\[en]global-stacks\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]mathlib\f[R]] [\f[B]\[en]no-prompt\f[R]]
[\f[B]\[en]quiet\f[R]] [\f[B]\[en]standard\f[R]] [\f[B]\[en]warn\f[R]]
[\f[B]\[en]version\f[R]] [\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
bc(1) is an interactive processor for a language first standardized in
1991 by POSIX.
(The current standard is
here (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).)
The language provides unlimited precision decimal arithmetic and is
somewhat C-like, but there are differences.
Such differences will be noted in this document.
.PP
After parsing and handling options, this bc(1) reads any files given on
the command line and executes them before reading from \f[B]stdin\f[R].
.SH OPTIONS
.PP
The following are the options that bc(1) accepts.
.PP
\f[B]-g\f[R], \f[B]\[en]global-stacks\f[R]
.IP
.nf
\f[C]
Turns the globals **ibase**, **obase**, and **scale** into stacks.
This has the effect that a copy of the current value of all three are pushed
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
However, since using this flag means that functions cannot set **ibase**,
**obase**, or **scale** globally, functions that are made to do so cannot
work anymore. There are two possible use cases for that, and each has a
solution.
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o=\[dq]bc -e ibase=A -e obase=8\[dq]
alias h2b=\[dq]bc -e ibase=G -e obase=2\[dq]
Second, if the purpose of a function is to set **ibase**, **obase**, or
**scale** globally for any other purpose, it could be split into one to
three functions (based on how many globals it sets) and each of those
functions could return the desired value for a global.
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
\f[R]
.fi
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-l\f[R], \f[B]\[en]mathlib\f[R]
Sets \f[B]scale\f[R] (see the \f[B]SYNTAX\f[R] section) to \f[B]20\f[R]
and loads the included math library before running any code, including
any expressions or files specified on the command line.
.RS
.PP
To learn what is in the library, see the \f[B]LIBRARY\f[R] section.
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
This option is a no-op.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-q\f[R], \f[B]\[en]quiet\f[R]
This option is for compatibility with the GNU
bc(1) (https://www.gnu.org/software/bc/); it is a no-op.
Without this option, GNU bc(1) prints a copyright header.
This bc(1) only prints the copyright header if one or more of the
\f[B]-v\f[R], \f[B]-V\f[R], or \f[B]\[en]version\f[R] options are given.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-s\f[R], \f[B]\[en]standard\f[R]
Process exactly the language defined by the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
and error if any extensions are used.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-w\f[R], \f[B]\[en]warn\f[R]
Like \f[B]-s\f[R] and \f[B]\[en]standard\f[R], except that warnings (and
not errors) are printed for non-standard extensions and execution
continues normally.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]BC_ENV_ARGS\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]bc >&-\f[R], it will quit with an error.
This is done so that bc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]bc 2>&-\f[R], it will quit with an error.
This is done so that bc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
The syntax for bc(1) programs is mostly C-like, with some differences.
This bc(1) follows the POSIX
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
which is a much more thorough resource for the language this bc(1)
accepts.
This section is meant to be a summary and a listing of all the
extensions to the standard.
.PP
In the sections below, \f[B]E\f[R] means expression, \f[B]S\f[R] means
statement, and \f[B]I\f[R] means identifier.
.PP
Identifiers (\f[B]I\f[R]) start with a lowercase letter and can be
followed by any number (up to \f[B]BC_NAME_MAX-1\f[R]) of lowercase
letters (\f[B]a-z\f[R]), digits (\f[B]0-9\f[R]), and underscores
(\f[B]_\f[R]).
The regex is \f[B][a-z][a-z0-9_]*\f[R].
Identifiers with more than one character (letter) are a
\f[B]non-portable extension\f[R].
.PP
\f[B]ibase\f[R] is a global variable determining how to interpret
constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
If the \f[B]-s\f[R] (\f[B]\[en]standard\f[R]) and \f[B]-w\f[R]
(\f[B]\[en]warn\f[R]) flags were not given on the command line, the max
allowable value for \f[B]ibase\f[R] is \f[B]36\f[R].
Otherwise, it is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in bc(1)
programs with the \f[B]maxibase()\f[R] built-in function.
.PP
\f[B]obase\f[R] is a global variable determining how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]BC_BASE_MAX\f[R] and
can be queried in bc(1) programs with the \f[B]maxobase()\f[R] built-in
function.
The min allowable value for \f[B]obase\f[R] is \f[B]2\f[R].
Values are output in the specified base.
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a global variable that sets the precision of any operations, with
exceptions.
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] is \f[B]BC_SCALE_MAX\f[R]
and can be queried in bc(1) programs with the \f[B]maxscale()\f[R]
built-in function.
.PP
bc(1) has both \f[I]global\f[R] variables and \f[I]local\f[R] variables.
All \f[I]local\f[R] variables are local to the function; they are
parameters or are introduced in the \f[B]auto\f[R] list of a function
(see the \f[B]FUNCTIONS\f[R] section).
If a variable is accessed which is not a parameter or in the
\f[B]auto\f[R] list, it is assumed to be \f[I]global\f[R].
If a parent function has a \f[I]local\f[R] variable version of a
variable that a child function considers \f[I]global\f[R], the value of
that \f[I]global\f[R] variable in the child function is the value of the
variable in the parent function, not the value of the actual
\f[I]global\f[R] variable.
.PP
All of the above applies to arrays as well.
.PP
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence
operator is an assignment operator \f[I]and\f[R] the expression is
notsurrounded by parentheses.
.PP
The value that is printed is also assigned to the special variable
\f[B]last\f[R].
A single dot (\f[B].\f[R]) may also be used as a synonym for
\f[B]last\f[R].
These are \f[B]non-portable extensions\f[R].
.PP
Either semicolons or newlines may separate statements.
.SS Comments
.PP
There are two kinds of comments:
.IP "1." 3
Block comments are enclosed in \f[B]/*\f[R] and \f[B]*/\f[R].
.IP "2." 3
Line comments go from \f[B]#\f[R] until, and not including, the next
newline.
This is a \f[B]non-portable extension\f[R].
.SS Named Expressions
.PP
The following are named expressions in bc(1):
.IP "1." 3
Variables: \f[B]I\f[R]
.IP "2." 3
Array Elements: \f[B]I[E]\f[R]
.IP "3." 3
\f[B]ibase\f[R]
.IP "4." 3
\f[B]obase\f[R]
.IP "5." 3
\f[B]scale\f[R]
.IP "6." 3
\f[B]last\f[R] or a single dot (\f[B].\f[R])
.PP
Number 6 is a \f[B]non-portable extension\f[R].
.PP
Variables and arrays do not interfere; users can have arrays named the
same as variables.
This also applies to functions (see the \f[B]FUNCTIONS\f[R] section), so
a user can have a variable, array, and function that all have the same
name, and they will not shadow each other, whether inside of functions
or not.
.PP
Named expressions are required as the operand of
\f[B]increment\f[R]/\f[B]decrement\f[R] operators and as the left side
of \f[B]assignment\f[R] operators (see the \f[I]Operators\f[R]
subsection).
.SS Operands
.PP
The following are valid operands in bc(1):
.IP " 1." 4
Numbers (see the \f[I]Numbers\f[R] subsection below).
.IP " 2." 4
Array indices (\f[B]I[E]\f[R]).
.IP " 3." 4
\f[B](E)\f[R]: The value of \f[B]E\f[R] (used to change precedence).
.IP " 4." 4
\f[B]sqrt(E)\f[R]: The square root of \f[B]E\f[R].
\f[B]E\f[R] must be non-negative.
.IP " 5." 4
\f[B]length(E)\f[R]: The number of significant decimal digits in
\f[B]E\f[R].
.IP " 6." 4
\f[B]length(I[])\f[R]: The number of elements in the array \f[B]I\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 7." 4
\f[B]scale(E)\f[R]: The \f[I]scale\f[R] of \f[B]E\f[R].
.IP " 8." 4
\f[B]abs(E)\f[R]: The absolute value of \f[B]E\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 9." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a non-\f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.IP "10." 4
\f[B]read()\f[R]: Reads a line from \f[B]stdin\f[R] and uses that as an
expression.
The result of that expression is the result of the \f[B]read()\f[R]
operand.
This is a \f[B]non-portable extension\f[R].
.IP "11." 4
\f[B]maxibase()\f[R]: The max allowable \f[B]ibase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "12." 4
\f[B]maxobase()\f[R]: The max allowable \f[B]obase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "13." 4
\f[B]maxscale()\f[R]: The max allowable \f[B]scale\f[R].
This is a \f[B]non-portable extension\f[R].
.SS Numbers
.PP
Numbers are strings made up of digits, uppercase letters, and at most
\f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]BC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]Z\f[R] alone always equals decimal \f[B]35\f[R].
.SS Operators
.PP
The following arithmetic and logical operators can be used.
They are listed in order of decreasing precedence.
Operators in the same group have the same precedence.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
Type: Prefix and Postfix
.RS
.PP
Associativity: None
.PP
Description: \f[B]increment\f[R], \f[B]decrement\f[R]
.RE
.TP
\f[B]-\f[R] \f[B]!\f[R]
Type: Prefix
.RS
.PP
Associativity: None
.PP
Description: \f[B]negation\f[R], \f[B]boolean not\f[R]
.RE
.TP
\f[B]\[ha]\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]power\f[R]
.RE
.TP
\f[B]*\f[R] \f[B]/\f[R] \f[B]%\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]multiply\f[R], \f[B]divide\f[R], \f[B]modulus\f[R]
.RE
.TP
\f[B]+\f[R] \f[B]-\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]add\f[R], \f[B]subtract\f[R]
.RE
.TP
\f[B]=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]assignment\f[R]
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]relational\f[R]
.RE
.TP
\f[B]&&\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean and\f[R]
.RE
.TP
\f[B]||\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean or\f[R]
.RE
.PP
The operators will be described in more detail below.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
The prefix and postfix \f[B]increment\f[R] and \f[B]decrement\f[R]
operators behave exactly like they would in C.
They require a named expression (see the \f[I]Named Expressions\f[R]
subsection) as an operand.
.RS
.PP
The prefix versions of these operators are more efficient; use them
where possible.
.RE
.TP
\f[B]-\f[R]
The \f[B]negation\f[R] operator returns \f[B]0\f[R] if a user attempts
to negate any expression with the value \f[B]0\f[R].
Otherwise, a copy of the expression with its sign flipped is returned.
.TP
\f[B]!\f[R]
The \f[B]boolean not\f[R] operator returns \f[B]1\f[R] if the expression
is \f[B]0\f[R], or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The \f[B]power\f[R] operator (not the \f[B]exclusive or\f[R] operator,
as it would be in C) takes two expressions and raises the first to the
power of the value of the second.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]), and if it
is negative, the first value must be non-zero.
.RE
.TP
\f[B]*\f[R]
The \f[B]multiply\f[R] operator takes two expressions, multiplies them,
and returns the product.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The \f[B]divide\f[R] operator takes two expressions, divides them, and
returns the quotient.
The \f[I]scale\f[R] of the result shall be the value of \f[B]scale\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]%\f[R]
The \f[B]modulus\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and evaluates them by 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R] and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]+\f[R]
The \f[B]add\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the sum, with a \f[I]scale\f[R] equal to the
max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]-\f[R]
The \f[B]subtract\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the difference, with a \f[I]scale\f[R] equal to
the max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R]
The \f[B]assignment\f[R] operators take two expressions, \f[B]a\f[R] and
\f[B]b\f[R] where \f[B]a\f[R] is a named expression (see the \f[I]Named
Expressions\f[R] subsection).
.RS
.PP
For \f[B]=\f[R], \f[B]b\f[R] is copied and the result is assigned to
\f[B]a\f[R].
For all others, \f[B]a\f[R] and \f[B]b\f[R] are applied as operands to
the corresponding arithmetic operator and the result is assigned to
\f[B]a\f[R].
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
The \f[B]relational\f[R] operators compare two expressions, \f[B]a\f[R]
and \f[B]b\f[R], and if the relation holds, according to C language
semantics, the result is \f[B]1\f[R].
Otherwise, it is \f[B]0\f[R].
.RS
.PP
Note that unlike in C, these operators have a lower precedence than the
\f[B]assignment\f[R] operators, which means that \f[B]a=b>c\f[R] is
interpreted as \f[B](a=b)>c\f[R].
.PP
Also, unlike the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
requires, these operators can appear anywhere any other expressions can
be used.
This allowance is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]&&\f[R]
The \f[B]boolean and\f[R] operator takes two expressions and returns
\f[B]1\f[R] if both expressions are non-zero, \f[B]0\f[R] otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]||\f[R]
The \f[B]boolean or\f[R] operator takes two expressions and returns
\f[B]1\f[R] if one of the expressions is non-zero, \f[B]0\f[R]
otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Statements
.PP
The following items are statements:
.IP " 1." 4
\f[B]E\f[R]
.IP " 2." 4
\f[B]{\f[R] \f[B]S\f[R] \f[B];\f[R] \&... \f[B];\f[R] \f[B]S\f[R]
\f[B]}\f[R]
.IP " 3." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 4." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
\f[B]else\f[R] \f[B]S\f[R]
.IP " 5." 4
\f[B]while\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 6." 4
\f[B]for\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B];\f[R] \f[B]E\f[R]
\f[B];\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 7." 4
An empty statement
.IP " 8." 4
\f[B]break\f[R]
.IP " 9." 4
\f[B]continue\f[R]
.IP "10." 4
\f[B]quit\f[R]
.IP "11." 4
\f[B]halt\f[R]
.IP "12." 4
\f[B]limits\f[R]
.IP "13." 4
A string of characters, enclosed in double quotes
.IP "14." 4
\f[B]print\f[R] \f[B]E\f[R] \f[B],\f[R] \&... \f[B],\f[R] \f[B]E\f[R]
.IP "15." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a \f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.PP
Numbers 4, 9, 11, 12, 14, and 15 are \f[B]non-portable extensions\f[R].
.PP
Also, as a \f[B]non-portable extension\f[R], any or all of the
expressions in the header of a for loop may be omitted.
If the condition (second expression) is omitted, it is assumed to be a
constant \f[B]1\f[R].
.PP
The \f[B]break\f[R] statement causes a loop to stop iterating and resume
execution immediately following a loop.
This is only allowed in loops.
.PP
The \f[B]continue\f[R] statement causes a loop iteration to stop early
and returns to the start of the loop, including testing the loop
condition.
This is only allowed in loops.
.PP
The \f[B]if\f[R] \f[B]else\f[R] statement does the same thing as in C.
.PP
The \f[B]quit\f[R] statement causes bc(1) to quit, even if it is on a
branch that will not be executed (it is a compile-time command).
.PP
The \f[B]halt\f[R] statement causes bc(1) to quit, if it is executed.
(Unlike \f[B]quit\f[R] if it is on a branch of an \f[B]if\f[R] statement
that is not executed, bc(1) does not quit.)
.PP
The \f[B]limits\f[R] statement prints the limits that this bc(1) is
subject to.
This is like the \f[B]quit\f[R] statement in that it is a compile-time
command.
.PP
An expression by itself is evaluated and printed, followed by a newline.
.SS Print Statement
.PP
The \[lq]expressions\[rq] in a \f[B]print\f[R] statement may also be
strings.
If they are, there are backslash escape sequences that are interpreted
specially.
What those sequences are, and what they cause to be printed, are shown
below:
.PP
.TS
tab(@);
l l.
T{
\f[B]\[rs]a\f[R]
T}@T{
\f[B]\[rs]a\f[R]
T}
T{
\f[B]\[rs]b\f[R]
T}@T{
\f[B]\[rs]b\f[R]
T}
T{
\f[B]\[rs]\[rs]\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]e\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]f\f[R]
T}@T{
\f[B]\[rs]f\f[R]
T}
T{
\f[B]\[rs]n\f[R]
T}@T{
\f[B]\[rs]n\f[R]
T}
T{
\f[B]\[rs]q\f[R]
T}@T{
\f[B]\[dq]\f[R]
T}
T{
\f[B]\[rs]r\f[R]
T}@T{
\f[B]\[rs]r\f[R]
T}
T{
\f[B]\[rs]t\f[R]
T}@T{
\f[B]\[rs]t\f[R]
T}
.TE
.PP
Any other character following a backslash causes the backslash and
character to be printed as-is.
.PP
Any non-string expression in a print statement shall be assigned to
\f[B]last\f[R], like any other expression that is printed.
.SS Order of Evaluation
.PP
All expressions in a statment are evaluated left to right, except as
necessary to maintain order of operations.
This means, for example, assuming that \f[B]i\f[R] is equal to
\f[B]0\f[R], in the expression
.IP
.nf
\f[C]
a[i++] = i++
\f[R]
.fi
.PP
the first (or 0th) element of \f[B]a\f[R] is set to \f[B]1\f[R], and
\f[B]i\f[R] is equal to \f[B]2\f[R] at the end of the expression.
.PP
This includes function arguments.
Thus, assuming \f[B]i\f[R] is equal to \f[B]0\f[R], this means that in
the expression
.IP
.nf
\f[C]
x(i++, i++)
\f[R]
.fi
.PP
the first argument passed to \f[B]x()\f[R] is \f[B]0\f[R], and the
second argument is \f[B]1\f[R], while \f[B]i\f[R] is equal to
\f[B]2\f[R] before the function starts executing.
.SH FUNCTIONS
.PP
Function definitions are as follows:
.IP
.nf
\f[C]
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
\f[R]
.fi
.PP
Any \f[B]I\f[R] in the parameter list or \f[B]auto\f[R] list may be
replaced with \f[B]I[]\f[R] to make a parameter or \f[B]auto\f[R] var an
array, and any \f[B]I\f[R] in the parameter list may be replaced with
\f[B]*I[]\f[R] to make a parameter an array reference.
Callers of functions that take array references should not put an
asterisk in the call; they must be called with just \f[B]I[]\f[R] like
normal array parameters and will be automatically converted into
references.
.PP
As a \f[B]non-portable extension\f[R], the opening brace of a
\f[B]define\f[R] statement may appear on the next line.
.PP
As a \f[B]non-portable extension\f[R], the return statement may also be
in one of the following forms:
.IP "1." 3
\f[B]return\f[R]
.IP "2." 3
\f[B]return\f[R] \f[B](\f[R] \f[B])\f[R]
.IP "3." 3
\f[B]return\f[R] \f[B]E\f[R]
.PP
The first two, or not specifying a \f[B]return\f[R] statement, is
equivalent to \f[B]return (0)\f[R], unless the function is a
\f[B]void\f[R] function (see the \f[I]Void Functions\f[R] subsection
below).
.SS Void Functions
.PP
Functions can also be \f[B]void\f[R] functions, defined as follows:
.IP
.nf
\f[C]
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
\f[R]
.fi
.PP
They can only be used as standalone expressions, where such an
expression would be printed alone, except in a print statement.
.PP
Void functions can only use the first two \f[B]return\f[R] statements
listed above.
They can also omit the return statement entirely.
.PP
The word \[lq]void\[rq] is not treated as a keyword; it is still
possible to have variables, arrays, and functions named \f[B]void\f[R].
The word \[lq]void\[rq] is only treated specially right after the
\f[B]define\f[R] keyword.
.PP
This is a \f[B]non-portable extension\f[R].
.SS Array References
.PP
For any array in the parameter list, if the array is declared in the
form
.IP
.nf
\f[C]
*I[]
\f[R]
.fi
.PP
it is a \f[B]reference\f[R].
Any changes to the array in the function are reflected, when the
function returns, to the array that was passed in.
.PP
Other than this, all function arguments are passed by value.
.PP
This is a \f[B]non-portable extension\f[R].
.SH LIBRARY
.PP
All of the functions below are available when the \f[B]-l\f[R] or
\f[B]\[en]mathlib\f[R] command-line flags are given.
.SS Standard Library
.PP
The
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
defines the following functions for the math library:
.TP
\f[B]s(x)\f[R]
Returns the sine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]c(x)\f[R]
Returns the cosine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]a(x)\f[R]
Returns the arctangent of \f[B]x\f[R], in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]l(x)\f[R]
Returns the natural logarithm of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]e(x)\f[R]
Returns the mathematical constant \f[B]e\f[R] raised to the power of
\f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]j(x, n)\f[R]
Returns the bessel integer order \f[B]n\f[R] (truncated) of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.SS Transcendental Functions
.PP
All transcendental functions can return slightly inaccurate results (up
to 1 ULP (https://en.wikipedia.org/wiki/Unit_in_the_last_place)).
This is unavoidable, and this
article (https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT) explains
why it is impossible and unnecessary to calculate exact results for the
transcendental functions.
.PP
Because of the possible inaccuracy, I recommend that users call those
functions with the precision (\f[B]scale\f[R]) set to at least 1 higher
than is necessary.
If exact results are \f[I]absolutely\f[R] required, users can double the
precision (\f[B]scale\f[R]) and then truncate.
.PP
The transcendental functions in the standard math library are:
.IP \[bu] 2
\f[B]s(x)\f[R]
.IP \[bu] 2
\f[B]c(x)\f[R]
.IP \[bu] 2
\f[B]a(x)\f[R]
.IP \[bu] 2
\f[B]l(x)\f[R]
.IP \[bu] 2
\f[B]e(x)\f[R]
.IP \[bu] 2
\f[B]j(x, n)\f[R]
.SH RESET
.PP
When bc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any functions that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all functions returned) is skipped.
.PP
Thus, when bc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.PP
Note that this reset behavior is different from the GNU bc(1), which
attempts to start executing the statement right after the one that
caused an error.
.SH PERFORMANCE
.PP
Most bc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This bc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]BC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]BC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]BC_BASE_DIGS\f[R].
.PP
The actual values of \f[B]BC_LONG_BIT\f[R] and \f[B]BC_BASE_DIGS\f[R]
can be queried with the \f[B]limits\f[R] statement.
.PP
In addition, this bc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]BC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on bc(1):
.TP
\f[B]BC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
bc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]BC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]BC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]BC_BASE_DIGS\f[R].
.TP
\f[B]BC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]BC_BASE_POW\f[R].
.TP
\f[B]BC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]BC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]BC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
The actual values can be queried with the \f[B]limits\f[R] statement.
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
bc(1) recognizes the following environment variables:
.TP
\f[B]POSIXLY_CORRECT\f[R]
If this variable exists (no matter the contents), bc(1) behaves as if
the \f[B]-s\f[R] option was given.
.TP
\f[B]BC_ENV_ARGS\f[R]
This is another way to give command-line arguments to bc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]BC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
.RS
.PP
The code that parses \f[B]BC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some bc file.bc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]bc\[dq] file.bc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]BC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]BC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), bc(1) will output lines to that length,
including the backslash (\f[B]\[rs]\f[R]).
The default line length is \f[B]70\f[R].
.SH EXIT STATUS
.PP
bc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, attempting to convert a negative number to a hardware
integer, overflow when converting a number to a hardware integer, and
attempting to use a non-integer where an integer is required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]) operator and the corresponding assignment
operator.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, using a token
where it is invalid, giving an invalid expression, giving an invalid
print statement, giving an invalid function definition, attempting to
assign to an expression that is not a named expression (see the
\f[I]Named Expressions\f[R] subsection of the \f[B]SYNTAX\f[R] section),
giving an invalid \f[B]auto\f[R] list, having a duplicate
\f[B]auto\f[R]/function parameter, failing to find the end of a code
block, attempting to return a value from a \f[B]void\f[R] function,
attempting to use a variable as a reference, and using any extensions
when the option \f[B]-s\f[R] or any equivalents were given.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a \f[B]void\f[R] function call as a value in an
expression.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (bc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, bc(1)
always exits and returns \f[B]4\f[R], no matter what mode bc(1) is in.
.PP
The other statuses will only be returned when bc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
bc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Per the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, bc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, bc(1) turns on \[lq]TTY mode.\[rq]
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause bc(1) to stop execution of the
current input.
If bc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If bc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If bc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to bc(1) as it is
executing a file, it can seem as though bc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause bc(1) to clean up and
exit, and it uses the default handler for all other signals.
.SH LOCALES
.PP
This bc(1) ships with support for adding error messages for different
locales and thus, supports \f[B]LC_MESSAGES\f[R].
.SH SEE ALSO
.PP
dc(1)
.SH STANDARDS
.PP
bc(1) is compliant with the IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
The flags \f[B]-efghiqsvVw\f[R], all long options, and the extensions
noted above are extensions to that specification.
.PP
Note that the specification explicitly says that bc(1) only accepts
numbers that use a period (\f[B].\f[R]) as a radix point, regardless of
the value of \f[B]LC_NUMERIC\f[R].
.PP
This bc(1) supports error messages for different locales, and thus, it
supports \f[B]LC_MESSAGES\f[R].
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHORS
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/bc/EHP.1.md b/contrib/bc/manuals/bc/EHP.1.md
index 11050003420f..2c9ab3909dd6 100644
--- a/contrib/bc/manuals/bc/EHP.1.md
+++ b/contrib/bc/manuals/bc/EHP.1.md
@@ -1,1063 +1,1072 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# NAME
bc - arbitrary-precision decimal arithmetic language and calculator
# SYNOPSIS
**bc** [**-ghilPqsvVw**] [**--global-stacks**] [**--help**] [**--interactive**] [**--mathlib**] [**--no-prompt**] [**--quiet**] [**--standard**] [**--warn**] [**--version**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...]
[*file*...]
# DESCRIPTION
bc(1) is an interactive processor for a language first standardized in 1991 by
POSIX. (The current standard is [here][1].) The language provides unlimited
precision decimal arithmetic and is somewhat C-like, but there are differences.
Such differences will be noted in this document.
After parsing and handling options, this bc(1) reads any files given on the
command line and executes them before reading from **stdin**.
# OPTIONS
The following are the options that bc(1) accepts.
**-g**, **--global-stacks**
Turns the globals **ibase**, **obase**, and **scale** into stacks.
This has the effect that a copy of the current value of all three are pushed
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
However, since using this flag means that functions cannot set **ibase**,
**obase**, or **scale** globally, functions that are made to do so cannot
work anymore. There are two possible use cases for that, and each has a
solution.
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o="bc -e ibase=A -e obase=8"
alias h2b="bc -e ibase=G -e obase=2"
Second, if the purpose of a function is to set **ibase**, **obase**, or
**scale** globally for any other purpose, it could be split into one to
three functions (based on how many globals it sets) and each of those
functions could return the desired value for a global.
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
**-h**, **--help**
: Prints a usage message and quits.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-l**, **--mathlib**
: Sets **scale** (see the **SYNTAX** section) to **20** and loads the included
math library before running any code, including any expressions or files
specified on the command line.
To learn what is in the library, see the **LIBRARY** section.
**-P**, **--no-prompt**
: This option is a no-op.
This is a **non-portable extension**.
**-q**, **--quiet**
: This option is for compatibility with the [GNU bc(1)][2]; it is a no-op.
Without this option, GNU bc(1) prints a copyright header. This bc(1) only
prints the copyright header if one or more of the **-v**, **-V**, or
**--version** options are given.
This is a **non-portable extension**.
**-s**, **--standard**
: Process exactly the language defined by the [standard][1] and error if any
extensions are used.
This is a **non-portable extension**.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
This is a **non-portable extension**.
**-w**, **--warn**
: Like **-s** and **--standard**, except that warnings (and not errors) are
printed for non-standard extensions and execution continues normally.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **BC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **bc <file> >&-**, it will quit with an error. This
is done so that bc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **bc <file> 2>&-**, it will quit with an error. This
is done so that bc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
The syntax for bc(1) programs is mostly C-like, with some differences. This
bc(1) follows the [POSIX standard][1], which is a much more thorough resource
for the language this bc(1) accepts. This section is meant to be a summary and a
listing of all the extensions to the standard.
In the sections below, **E** means expression, **S** means statement, and **I**
means identifier.
Identifiers (**I**) start with a lowercase letter and can be followed by any
number (up to **BC_NAME_MAX-1**) of lowercase letters (**a-z**), digits
(**0-9**), and underscores (**\_**). The regex is **\[a-z\]\[a-z0-9\_\]\***.
Identifiers with more than one character (letter) are a
**non-portable extension**.
**ibase** is a global variable determining how to interpret constant numbers. It
is the "input" base, or the number base used for interpreting input numbers.
**ibase** is initially **10**. If the **-s** (**--standard**) and **-w**
(**--warn**) flags were not given on the command line, the max allowable value
for **ibase** is **36**. Otherwise, it is **16**. The min allowable value for
**ibase** is **2**. The max allowable value for **ibase** can be queried in
bc(1) programs with the **maxibase()** built-in function.
**obase** is a global variable determining how to output results. It is the
"output" base, or the number base used for outputting numbers. **obase** is
initially **10**. The max allowable value for **obase** is **BC_BASE_MAX** and
can be queried in bc(1) programs with the **maxobase()** built-in function. The
min allowable value for **obase** is **2**. Values are output in the specified
base.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a global variable that
sets the precision of any operations, with exceptions. **scale** is initially
**0**. **scale** cannot be negative. The max allowable value for **scale** is
**BC_SCALE_MAX** and can be queried in bc(1) programs with the **maxscale()**
built-in function.
bc(1) has both *global* variables and *local* variables. All *local*
variables are local to the function; they are parameters or are introduced in
the **auto** list of a function (see the **FUNCTIONS** section). If a variable
is accessed which is not a parameter or in the **auto** list, it is assumed to
be *global*. If a parent function has a *local* variable version of a variable
that a child function considers *global*, the value of that *global* variable in
the child function is the value of the variable in the parent function, not the
value of the actual *global* variable.
All of the above applies to arrays as well.
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence operator is an
assignment operator *and* the expression is notsurrounded by parentheses.
The value that is printed is also assigned to the special variable **last**. A
single dot (**.**) may also be used as a synonym for **last**. These are
**non-portable extensions**.
Either semicolons or newlines may separate statements.
## Comments
There are two kinds of comments:
1. Block comments are enclosed in **/\*** and **\*/**.
2. Line comments go from **#** until, and not including, the next newline. This
is a **non-portable extension**.
## Named Expressions
The following are named expressions in bc(1):
1. Variables: **I**
2. Array Elements: **I[E]**
3. **ibase**
4. **obase**
5. **scale**
6. **last** or a single dot (**.**)
Number 6 is a **non-portable extension**.
Variables and arrays do not interfere; users can have arrays named the same as
variables. This also applies to functions (see the **FUNCTIONS** section), so a
user can have a variable, array, and function that all have the same name, and
they will not shadow each other, whether inside of functions or not.
Named expressions are required as the operand of **increment**/**decrement**
operators and as the left side of **assignment** operators (see the *Operators*
subsection).
## Operands
The following are valid operands in bc(1):
1. Numbers (see the *Numbers* subsection below).
2. Array indices (**I[E]**).
3. **(E)**: The value of **E** (used to change precedence).
4. **sqrt(E)**: The square root of **E**. **E** must be non-negative.
5. **length(E)**: The number of significant decimal digits in **E**.
6. **length(I[])**: The number of elements in the array **I**. This is a
**non-portable extension**.
7. **scale(E)**: The *scale* of **E**.
8. **abs(E)**: The absolute value of **E**. This is a **non-portable
extension**.
9. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a non-**void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
10. **read()**: Reads a line from **stdin** and uses that as an expression. The
result of that expression is the result of the **read()** operand. This is a
**non-portable extension**.
11. **maxibase()**: The max allowable **ibase**. This is a **non-portable
extension**.
12. **maxobase()**: The max allowable **obase**. This is a **non-portable
extension**.
13. **maxscale()**: The max allowable **scale**. This is a **non-portable
extension**.
## Numbers
Numbers are strings made up of digits, uppercase letters, and at most **1**
period for a radix. Numbers can have up to **BC_NUM_MAX** digits. Uppercase
letters are equal to **9** + their position in the alphabet (i.e., **A** equals
**10**, or **9+1**). If a digit or letter makes no sense with the current value
of **ibase**, they are set to the value of the highest valid digit in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **Z** alone always equals decimal
**35**.
## Operators
The following arithmetic and logical operators can be used. They are listed in
order of decreasing precedence. Operators in the same group have the same
precedence.
**++** **--**
: Type: Prefix and Postfix
Associativity: None
Description: **increment**, **decrement**
**-** **!**
: Type: Prefix
Associativity: None
Description: **negation**, **boolean not**
**\^**
: Type: Binary
Associativity: Right
Description: **power**
**\*** **/** **%**
: Type: Binary
Associativity: Left
Description: **multiply**, **divide**, **modulus**
**+** **-**
: Type: Binary
Associativity: Left
Description: **add**, **subtract**
**=** **+=** **-=** **\*=** **/=** **%=** **\^=**
: Type: Binary
Associativity: Right
Description: **assignment**
**==** **\<=** **\>=** **!=** **\<** **\>**
: Type: Binary
Associativity: Left
Description: **relational**
**&&**
: Type: Binary
Associativity: Left
Description: **boolean and**
**||**
: Type: Binary
Associativity: Left
Description: **boolean or**
The operators will be described in more detail below.
**++** **--**
: The prefix and postfix **increment** and **decrement** operators behave
exactly like they would in C. They require a named expression (see the
*Named Expressions* subsection) as an operand.
The prefix versions of these operators are more efficient; use them where
possible.
**-**
: The **negation** operator returns **0** if a user attempts to negate any
expression with the value **0**. Otherwise, a copy of the expression with
its sign flipped is returned.
**!**
: The **boolean not** operator returns **1** if the expression is **0**, or
**0** otherwise.
This is a **non-portable extension**.
**\^**
: The **power** operator (not the **exclusive or** operator, as it would be in
C) takes two expressions and raises the first to the power of the value of
the second. The *scale* of the result is equal to **scale**.
The second expression must be an integer (no *scale*), and if it is
negative, the first value must be non-zero.
**\***
: The **multiply** operator takes two expressions, multiplies them, and
returns the product. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result is
equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The **divide** operator takes two expressions, divides them, and returns the
quotient. The *scale* of the result shall be the value of **scale**.
The second expression must be non-zero.
**%**
: The **modulus** operator takes two expressions, **a** and **b**, and
evaluates them by 1) Computing **a/b** to current **scale** and 2) Using the
result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The second expression must be non-zero.
**+**
: The **add** operator takes two expressions, **a** and **b**, and returns the
sum, with a *scale* equal to the max of the *scale*s of **a** and **b**.
**-**
: The **subtract** operator takes two expressions, **a** and **b**, and
returns the difference, with a *scale* equal to the max of the *scale*s of
**a** and **b**.
**=** **+=** **-=** **\*=** **/=** **%=** **\^=**
: The **assignment** operators take two expressions, **a** and **b** where
**a** is a named expression (see the *Named Expressions* subsection).
For **=**, **b** is copied and the result is assigned to **a**. For all
others, **a** and **b** are applied as operands to the corresponding
arithmetic operator and the result is assigned to **a**.
**==** **\<=** **\>=** **!=** **\<** **\>**
: The **relational** operators compare two expressions, **a** and **b**, and
if the relation holds, according to C language semantics, the result is
**1**. Otherwise, it is **0**.
Note that unlike in C, these operators have a lower precedence than the
**assignment** operators, which means that **a=b\>c** is interpreted as
**(a=b)\>c**.
Also, unlike the [standard][1] requires, these operators can appear anywhere
any other expressions can be used. This allowance is a
**non-portable extension**.
**&&**
: The **boolean and** operator takes two expressions and returns **1** if both
expressions are non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
**||**
: The **boolean or** operator takes two expressions and returns **1** if one
of the expressions is non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
## Statements
The following items are statements:
1. **E**
2. **{** **S** **;** ... **;** **S** **}**
3. **if** **(** **E** **)** **S**
4. **if** **(** **E** **)** **S** **else** **S**
5. **while** **(** **E** **)** **S**
6. **for** **(** **E** **;** **E** **;** **E** **)** **S**
7. An empty statement
8. **break**
9. **continue**
10. **quit**
11. **halt**
12. **limits**
13. A string of characters, enclosed in double quotes
14. **print** **E** **,** ... **,** **E**
15. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
Numbers 4, 9, 11, 12, 14, and 15 are **non-portable extensions**.
Also, as a **non-portable extension**, any or all of the expressions in the
header of a for loop may be omitted. If the condition (second expression) is
omitted, it is assumed to be a constant **1**.
The **break** statement causes a loop to stop iterating and resume execution
immediately following a loop. This is only allowed in loops.
The **continue** statement causes a loop iteration to stop early and returns to
the start of the loop, including testing the loop condition. This is only
allowed in loops.
The **if** **else** statement does the same thing as in C.
The **quit** statement causes bc(1) to quit, even if it is on a branch that will
not be executed (it is a compile-time command).
The **halt** statement causes bc(1) to quit, if it is executed. (Unlike **quit**
if it is on a branch of an **if** statement that is not executed, bc(1) does not
quit.)
The **limits** statement prints the limits that this bc(1) is subject to. This
is like the **quit** statement in that it is a compile-time command.
An expression by itself is evaluated and printed, followed by a newline.
## Print Statement
The "expressions" in a **print** statement may also be strings. If they are, there
are backslash escape sequences that are interpreted specially. What those
sequences are, and what they cause to be printed, are shown below:
-------- -------
**\\a** **\\a**
**\\b** **\\b**
**\\\\** **\\**
**\\e** **\\**
**\\f** **\\f**
**\\n** **\\n**
**\\q** **"**
**\\r** **\\r**
**\\t** **\\t**
-------- -------
Any other character following a backslash causes the backslash and character to
be printed as-is.
Any non-string expression in a print statement shall be assigned to **last**,
like any other expression that is printed.
## Order of Evaluation
All expressions in a statment are evaluated left to right, except as necessary
to maintain order of operations. This means, for example, assuming that **i** is
equal to **0**, in the expression
a[i++] = i++
the first (or 0th) element of **a** is set to **1**, and **i** is equal to **2**
at the end of the expression.
This includes function arguments. Thus, assuming **i** is equal to **0**, this
means that in the expression
x(i++, i++)
the first argument passed to **x()** is **0**, and the second argument is **1**,
while **i** is equal to **2** before the function starts executing.
# FUNCTIONS
Function definitions are as follows:
```
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
```
Any **I** in the parameter list or **auto** list may be replaced with **I[]** to
make a parameter or **auto** var an array, and any **I** in the parameter list
may be replaced with **\*I[]** to make a parameter an array reference. Callers
of functions that take array references should not put an asterisk in the call;
they must be called with just **I[]** like normal array parameters and will be
automatically converted into references.
As a **non-portable extension**, the opening brace of a **define** statement may
appear on the next line.
As a **non-portable extension**, the return statement may also be in one of the
following forms:
1. **return**
2. **return** **(** **)**
3. **return** **E**
The first two, or not specifying a **return** statement, is equivalent to
**return (0)**, unless the function is a **void** function (see the *Void
Functions* subsection below).
## Void Functions
Functions can also be **void** functions, defined as follows:
```
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
```
They can only be used as standalone expressions, where such an expression would
be printed alone, except in a print statement.
Void functions can only use the first two **return** statements listed above.
They can also omit the return statement entirely.
The word "void" is not treated as a keyword; it is still possible to have
variables, arrays, and functions named **void**. The word "void" is only
treated specially right after the **define** keyword.
This is a **non-portable extension**.
## Array References
For any array in the parameter list, if the array is declared in the form
```
*I[]
```
it is a **reference**. Any changes to the array in the function are reflected,
when the function returns, to the array that was passed in.
Other than this, all function arguments are passed by value.
This is a **non-portable extension**.
# LIBRARY
All of the functions below are available when the **-l** or **--mathlib**
command-line flags are given.
## Standard Library
The [standard][1] defines the following functions for the math library:
**s(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**c(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a(x)**
: Returns the arctangent of **x**, in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l(x)**
: Returns the natural logarithm of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**e(x)**
: Returns the mathematical constant **e** raised to the power of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**j(x, n)**
: Returns the bessel integer order **n** (truncated) of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
## Transcendental Functions
All transcendental functions can return slightly inaccurate results (up to 1
[ULP][4]). This is unavoidable, and [this article][5] explains why it is
impossible and unnecessary to calculate exact results for the transcendental
functions.
Because of the possible inaccuracy, I recommend that users call those functions
with the precision (**scale**) set to at least 1 higher than is necessary. If
exact results are *absolutely* required, users can double the precision
(**scale**) and then truncate.
The transcendental functions in the standard math library are:
* **s(x)**
* **c(x)**
* **a(x)**
* **l(x)**
* **e(x)**
* **j(x, n)**
# RESET
When bc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any functions that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
functions returned) is skipped.
Thus, when bc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
Note that this reset behavior is different from the GNU bc(1), which attempts to
start executing the statement right after the one that caused an error.
# PERFORMANCE
Most bc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This bc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **BC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **BC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**BC_BASE_DIGS**.
The actual values of **BC_LONG_BIT** and **BC_BASE_DIGS** can be queried with
the **limits** statement.
In addition, this bc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **BC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on bc(1):
**BC_LONG_BIT**
: The number of bits in the **long** type in the environment where bc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**BC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **BC_LONG_BIT**.
**BC_BASE_POW**
: The max decimal number that each large integer can store (see
**BC_BASE_DIGS**) plus **1**. Depends on **BC_BASE_DIGS**.
**BC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **BC_LONG_BIT**.
**BC_BASE_MAX**
: The maximum output base. Set at **BC_BASE_POW**.
**BC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**BC_SCALE_MAX**
: The maximum **scale**. Set at **BC_OVERFLOW_MAX-1**.
**BC_STRING_MAX**
: The maximum length of strings. Set at **BC_OVERFLOW_MAX-1**.
**BC_NAME_MAX**
: The maximum length of identifiers. Set at **BC_OVERFLOW_MAX-1**.
**BC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **BC_OVERFLOW_MAX-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**BC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
The actual values can be queried with the **limits** statement.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
bc(1) recognizes the following environment variables:
**POSIXLY_CORRECT**
: If this variable exists (no matter the contents), bc(1) behaves as if
the **-s** option was given.
**BC_ENV_ARGS**
: This is another way to give command-line arguments to bc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **BC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
The code that parses **BC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some bc file.bc"** will be correctly parsed, but the string
**"/home/gavin/some \"bc\" file.bc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **BC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**BC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), bc(1) will output
lines to that length, including the backslash (**\\**). The default line
length is **70**.
# EXIT STATUS
bc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**) operator and the corresponding assignment operator.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, using a token where it is invalid,
giving an invalid expression, giving an invalid print statement, giving an
invalid function definition, attempting to assign to an expression that is
not a named expression (see the *Named Expressions* subsection of the
**SYNTAX** section), giving an invalid **auto** list, having a duplicate
**auto**/function parameter, failing to find the end of a code block,
attempting to return a value from a **void** function, attempting to use a
variable as a reference, and using any extensions when the option **-s** or
any equivalents were given.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a **void** function call as a value in an expression.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (bc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, bc(1) always exits
and returns **4**, no matter what mode bc(1) is in.
The other statuses will only be returned when bc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since bc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Per the [standard][1], bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, bc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, bc(1) turns
on "TTY mode."
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause bc(1) to stop execution of the current input. If
bc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If bc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If bc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to bc(1) as it is executing a file, it
can seem as though bc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause bc(1) to clean up and exit, and it uses the
default handler for all other signals.
# LOCALES
This bc(1) ships with support for adding error messages for different locales
and thus, supports **LC_MESSAGES**.
# SEE ALSO
dc(1)
# STANDARDS
bc(1) is compliant with the [IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1]
specification. The flags **-efghiqsvVw**, all long options, and the extensions
noted above are extensions to that specification.
Note that the specification explicitly says that bc(1) only accepts numbers that
use a period (**.**) as a radix point, regardless of the value of
**LC_NUMERIC**.
This bc(1) supports error messages for different locales, and thus, it supports
**LC_MESSAGES**.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHORS
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
[2]: https://www.gnu.org/software/bc/
[3]: https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero
[4]: https://en.wikipedia.org/wiki/Unit_in_the_last_place
[5]: https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT
[6]: https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero
diff --git a/contrib/bc/manuals/bc/EN.1 b/contrib/bc/manuals/bc/EN.1
index c8e3a327b2f8..faa6bf488e28 100644
--- a/contrib/bc/manuals/bc/EN.1
+++ b/contrib/bc/manuals/bc/EN.1
@@ -1,1294 +1,1307 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "BC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "BC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH NAME
.PP
bc - arbitrary-precision decimal arithmetic language and calculator
.SH SYNOPSIS
.PP
\f[B]bc\f[R] [\f[B]-ghilPqsvVw\f[R]] [\f[B]\[en]global-stacks\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]mathlib\f[R]] [\f[B]\[en]no-prompt\f[R]]
[\f[B]\[en]quiet\f[R]] [\f[B]\[en]standard\f[R]] [\f[B]\[en]warn\f[R]]
[\f[B]\[en]version\f[R]] [\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
bc(1) is an interactive processor for a language first standardized in
1991 by POSIX.
(The current standard is
here (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).)
The language provides unlimited precision decimal arithmetic and is
somewhat C-like, but there are differences.
Such differences will be noted in this document.
.PP
After parsing and handling options, this bc(1) reads any files given on
the command line and executes them before reading from \f[B]stdin\f[R].
.PP
This bc(1) is a drop-in replacement for \f[I]any\f[R] bc(1), including
(and especially) the GNU bc(1).
.SH OPTIONS
.PP
The following are the options that bc(1) accepts.
.PP
\f[B]-g\f[R], \f[B]\[en]global-stacks\f[R]
.IP
.nf
\f[C]
Turns the globals **ibase**, **obase**, and **scale** into stacks.
This has the effect that a copy of the current value of all three are pushed
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
However, since using this flag means that functions cannot set **ibase**,
**obase**, or **scale** globally, functions that are made to do so cannot
work anymore. There are two possible use cases for that, and each has a
solution.
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o=\[dq]bc -e ibase=A -e obase=8\[dq]
alias h2b=\[dq]bc -e ibase=G -e obase=2\[dq]
Second, if the purpose of a function is to set **ibase**, **obase**, or
**scale** globally for any other purpose, it could be split into one to
three functions (based on how many globals it sets) and each of those
functions could return the desired value for a global.
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
\f[R]
.fi
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-l\f[R], \f[B]\[en]mathlib\f[R]
Sets \f[B]scale\f[R] (see the \f[B]SYNTAX\f[R] section) to \f[B]20\f[R]
and loads the included math library before running any code, including
any expressions or files specified on the command line.
.RS
.PP
To learn what is in the library, see the \f[B]LIBRARY\f[R] section.
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
Disables the prompt in TTY mode.
(The prompt is only enabled in TTY mode.
See the \f[B]TTY MODE\f[R] section) This is mostly for those users that
do not want a prompt or are not used to having them in bc(1).
Most of those users would want to put this option in
\f[B]BC_ENV_ARGS\f[R] (see the \f[B]ENVIRONMENT VARIABLES\f[R] section).
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-q\f[R], \f[B]\[en]quiet\f[R]
This option is for compatibility with the GNU
bc(1) (https://www.gnu.org/software/bc/); it is a no-op.
Without this option, GNU bc(1) prints a copyright header.
This bc(1) only prints the copyright header if one or more of the
\f[B]-v\f[R], \f[B]-V\f[R], or \f[B]\[en]version\f[R] options are given.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-s\f[R], \f[B]\[en]standard\f[R]
Process exactly the language defined by the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
and error if any extensions are used.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-w\f[R], \f[B]\[en]warn\f[R]
Like \f[B]-s\f[R] and \f[B]\[en]standard\f[R], except that warnings (and
not errors) are printed for non-standard extensions and execution
continues normally.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]BC_ENV_ARGS\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]bc >&-\f[R], it will quit with an error.
This is done so that bc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]bc 2>&-\f[R], it will quit with an error.
This is done so that bc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
The syntax for bc(1) programs is mostly C-like, with some differences.
This bc(1) follows the POSIX
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
which is a much more thorough resource for the language this bc(1)
accepts.
This section is meant to be a summary and a listing of all the
extensions to the standard.
.PP
In the sections below, \f[B]E\f[R] means expression, \f[B]S\f[R] means
statement, and \f[B]I\f[R] means identifier.
.PP
Identifiers (\f[B]I\f[R]) start with a lowercase letter and can be
followed by any number (up to \f[B]BC_NAME_MAX-1\f[R]) of lowercase
letters (\f[B]a-z\f[R]), digits (\f[B]0-9\f[R]), and underscores
(\f[B]_\f[R]).
The regex is \f[B][a-z][a-z0-9_]*\f[R].
Identifiers with more than one character (letter) are a
\f[B]non-portable extension\f[R].
.PP
\f[B]ibase\f[R] is a global variable determining how to interpret
constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
If the \f[B]-s\f[R] (\f[B]\[en]standard\f[R]) and \f[B]-w\f[R]
(\f[B]\[en]warn\f[R]) flags were not given on the command line, the max
allowable value for \f[B]ibase\f[R] is \f[B]36\f[R].
Otherwise, it is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in bc(1)
programs with the \f[B]maxibase()\f[R] built-in function.
.PP
\f[B]obase\f[R] is a global variable determining how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]BC_BASE_MAX\f[R] and
can be queried in bc(1) programs with the \f[B]maxobase()\f[R] built-in
function.
The min allowable value for \f[B]obase\f[R] is \f[B]2\f[R].
Values are output in the specified base.
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a global variable that sets the precision of any operations, with
exceptions.
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] is \f[B]BC_SCALE_MAX\f[R]
and can be queried in bc(1) programs with the \f[B]maxscale()\f[R]
built-in function.
.PP
bc(1) has both \f[I]global\f[R] variables and \f[I]local\f[R] variables.
All \f[I]local\f[R] variables are local to the function; they are
parameters or are introduced in the \f[B]auto\f[R] list of a function
(see the \f[B]FUNCTIONS\f[R] section).
If a variable is accessed which is not a parameter or in the
\f[B]auto\f[R] list, it is assumed to be \f[I]global\f[R].
If a parent function has a \f[I]local\f[R] variable version of a
variable that a child function considers \f[I]global\f[R], the value of
that \f[I]global\f[R] variable in the child function is the value of the
variable in the parent function, not the value of the actual
\f[I]global\f[R] variable.
.PP
All of the above applies to arrays as well.
.PP
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence
operator is an assignment operator \f[I]and\f[R] the expression is
notsurrounded by parentheses.
.PP
The value that is printed is also assigned to the special variable
\f[B]last\f[R].
A single dot (\f[B].\f[R]) may also be used as a synonym for
\f[B]last\f[R].
These are \f[B]non-portable extensions\f[R].
.PP
Either semicolons or newlines may separate statements.
.SS Comments
.PP
There are two kinds of comments:
.IP "1." 3
Block comments are enclosed in \f[B]/*\f[R] and \f[B]*/\f[R].
.IP "2." 3
Line comments go from \f[B]#\f[R] until, and not including, the next
newline.
This is a \f[B]non-portable extension\f[R].
.SS Named Expressions
.PP
The following are named expressions in bc(1):
.IP "1." 3
Variables: \f[B]I\f[R]
.IP "2." 3
Array Elements: \f[B]I[E]\f[R]
.IP "3." 3
\f[B]ibase\f[R]
.IP "4." 3
\f[B]obase\f[R]
.IP "5." 3
\f[B]scale\f[R]
.IP "6." 3
\f[B]last\f[R] or a single dot (\f[B].\f[R])
.PP
Number 6 is a \f[B]non-portable extension\f[R].
.PP
Variables and arrays do not interfere; users can have arrays named the
same as variables.
This also applies to functions (see the \f[B]FUNCTIONS\f[R] section), so
a user can have a variable, array, and function that all have the same
name, and they will not shadow each other, whether inside of functions
or not.
.PP
Named expressions are required as the operand of
\f[B]increment\f[R]/\f[B]decrement\f[R] operators and as the left side
of \f[B]assignment\f[R] operators (see the \f[I]Operators\f[R]
subsection).
.SS Operands
.PP
The following are valid operands in bc(1):
.IP " 1." 4
Numbers (see the \f[I]Numbers\f[R] subsection below).
.IP " 2." 4
Array indices (\f[B]I[E]\f[R]).
.IP " 3." 4
\f[B](E)\f[R]: The value of \f[B]E\f[R] (used to change precedence).
.IP " 4." 4
\f[B]sqrt(E)\f[R]: The square root of \f[B]E\f[R].
\f[B]E\f[R] must be non-negative.
.IP " 5." 4
\f[B]length(E)\f[R]: The number of significant decimal digits in
\f[B]E\f[R].
.IP " 6." 4
\f[B]length(I[])\f[R]: The number of elements in the array \f[B]I\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 7." 4
\f[B]scale(E)\f[R]: The \f[I]scale\f[R] of \f[B]E\f[R].
.IP " 8." 4
\f[B]abs(E)\f[R]: The absolute value of \f[B]E\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 9." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a non-\f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.IP "10." 4
\f[B]read()\f[R]: Reads a line from \f[B]stdin\f[R] and uses that as an
expression.
The result of that expression is the result of the \f[B]read()\f[R]
operand.
This is a \f[B]non-portable extension\f[R].
.IP "11." 4
\f[B]maxibase()\f[R]: The max allowable \f[B]ibase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "12." 4
\f[B]maxobase()\f[R]: The max allowable \f[B]obase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "13." 4
\f[B]maxscale()\f[R]: The max allowable \f[B]scale\f[R].
This is a \f[B]non-portable extension\f[R].
.SS Numbers
.PP
Numbers are strings made up of digits, uppercase letters, and at most
\f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]BC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]Z\f[R] alone always equals decimal \f[B]35\f[R].
.SS Operators
.PP
The following arithmetic and logical operators can be used.
They are listed in order of decreasing precedence.
Operators in the same group have the same precedence.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
Type: Prefix and Postfix
.RS
.PP
Associativity: None
.PP
Description: \f[B]increment\f[R], \f[B]decrement\f[R]
.RE
.TP
\f[B]-\f[R] \f[B]!\f[R]
Type: Prefix
.RS
.PP
Associativity: None
.PP
Description: \f[B]negation\f[R], \f[B]boolean not\f[R]
.RE
.TP
\f[B]\[ha]\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]power\f[R]
.RE
.TP
\f[B]*\f[R] \f[B]/\f[R] \f[B]%\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]multiply\f[R], \f[B]divide\f[R], \f[B]modulus\f[R]
.RE
.TP
\f[B]+\f[R] \f[B]-\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]add\f[R], \f[B]subtract\f[R]
.RE
.TP
\f[B]=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]assignment\f[R]
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]relational\f[R]
.RE
.TP
\f[B]&&\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean and\f[R]
.RE
.TP
\f[B]||\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean or\f[R]
.RE
.PP
The operators will be described in more detail below.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
The prefix and postfix \f[B]increment\f[R] and \f[B]decrement\f[R]
operators behave exactly like they would in C.
They require a named expression (see the \f[I]Named Expressions\f[R]
subsection) as an operand.
.RS
.PP
The prefix versions of these operators are more efficient; use them
where possible.
.RE
.TP
\f[B]-\f[R]
The \f[B]negation\f[R] operator returns \f[B]0\f[R] if a user attempts
to negate any expression with the value \f[B]0\f[R].
Otherwise, a copy of the expression with its sign flipped is returned.
.TP
\f[B]!\f[R]
The \f[B]boolean not\f[R] operator returns \f[B]1\f[R] if the expression
is \f[B]0\f[R], or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The \f[B]power\f[R] operator (not the \f[B]exclusive or\f[R] operator,
as it would be in C) takes two expressions and raises the first to the
power of the value of the second.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]), and if it
is negative, the first value must be non-zero.
.RE
.TP
\f[B]*\f[R]
The \f[B]multiply\f[R] operator takes two expressions, multiplies them,
and returns the product.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The \f[B]divide\f[R] operator takes two expressions, divides them, and
returns the quotient.
The \f[I]scale\f[R] of the result shall be the value of \f[B]scale\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]%\f[R]
The \f[B]modulus\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and evaluates them by 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R] and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]+\f[R]
The \f[B]add\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the sum, with a \f[I]scale\f[R] equal to the
max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]-\f[R]
The \f[B]subtract\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the difference, with a \f[I]scale\f[R] equal to
the max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R]
The \f[B]assignment\f[R] operators take two expressions, \f[B]a\f[R] and
\f[B]b\f[R] where \f[B]a\f[R] is a named expression (see the \f[I]Named
Expressions\f[R] subsection).
.RS
.PP
For \f[B]=\f[R], \f[B]b\f[R] is copied and the result is assigned to
\f[B]a\f[R].
For all others, \f[B]a\f[R] and \f[B]b\f[R] are applied as operands to
the corresponding arithmetic operator and the result is assigned to
\f[B]a\f[R].
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
The \f[B]relational\f[R] operators compare two expressions, \f[B]a\f[R]
and \f[B]b\f[R], and if the relation holds, according to C language
semantics, the result is \f[B]1\f[R].
Otherwise, it is \f[B]0\f[R].
.RS
.PP
Note that unlike in C, these operators have a lower precedence than the
\f[B]assignment\f[R] operators, which means that \f[B]a=b>c\f[R] is
interpreted as \f[B](a=b)>c\f[R].
.PP
Also, unlike the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
requires, these operators can appear anywhere any other expressions can
be used.
This allowance is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]&&\f[R]
The \f[B]boolean and\f[R] operator takes two expressions and returns
\f[B]1\f[R] if both expressions are non-zero, \f[B]0\f[R] otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]||\f[R]
The \f[B]boolean or\f[R] operator takes two expressions and returns
\f[B]1\f[R] if one of the expressions is non-zero, \f[B]0\f[R]
otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Statements
.PP
The following items are statements:
.IP " 1." 4
\f[B]E\f[R]
.IP " 2." 4
\f[B]{\f[R] \f[B]S\f[R] \f[B];\f[R] \&... \f[B];\f[R] \f[B]S\f[R]
\f[B]}\f[R]
.IP " 3." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 4." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
\f[B]else\f[R] \f[B]S\f[R]
.IP " 5." 4
\f[B]while\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 6." 4
\f[B]for\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B];\f[R] \f[B]E\f[R]
\f[B];\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 7." 4
An empty statement
.IP " 8." 4
\f[B]break\f[R]
.IP " 9." 4
\f[B]continue\f[R]
.IP "10." 4
\f[B]quit\f[R]
.IP "11." 4
\f[B]halt\f[R]
.IP "12." 4
\f[B]limits\f[R]
.IP "13." 4
A string of characters, enclosed in double quotes
.IP "14." 4
\f[B]print\f[R] \f[B]E\f[R] \f[B],\f[R] \&... \f[B],\f[R] \f[B]E\f[R]
.IP "15." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a \f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.PP
Numbers 4, 9, 11, 12, 14, and 15 are \f[B]non-portable extensions\f[R].
.PP
Also, as a \f[B]non-portable extension\f[R], any or all of the
expressions in the header of a for loop may be omitted.
If the condition (second expression) is omitted, it is assumed to be a
constant \f[B]1\f[R].
.PP
The \f[B]break\f[R] statement causes a loop to stop iterating and resume
execution immediately following a loop.
This is only allowed in loops.
.PP
The \f[B]continue\f[R] statement causes a loop iteration to stop early
and returns to the start of the loop, including testing the loop
condition.
This is only allowed in loops.
.PP
The \f[B]if\f[R] \f[B]else\f[R] statement does the same thing as in C.
.PP
The \f[B]quit\f[R] statement causes bc(1) to quit, even if it is on a
branch that will not be executed (it is a compile-time command).
.PP
The \f[B]halt\f[R] statement causes bc(1) to quit, if it is executed.
(Unlike \f[B]quit\f[R] if it is on a branch of an \f[B]if\f[R] statement
that is not executed, bc(1) does not quit.)
.PP
The \f[B]limits\f[R] statement prints the limits that this bc(1) is
subject to.
This is like the \f[B]quit\f[R] statement in that it is a compile-time
command.
.PP
An expression by itself is evaluated and printed, followed by a newline.
.SS Print Statement
.PP
The \[lq]expressions\[rq] in a \f[B]print\f[R] statement may also be
strings.
If they are, there are backslash escape sequences that are interpreted
specially.
What those sequences are, and what they cause to be printed, are shown
below:
.PP
.TS
tab(@);
l l.
T{
\f[B]\[rs]a\f[R]
T}@T{
\f[B]\[rs]a\f[R]
T}
T{
\f[B]\[rs]b\f[R]
T}@T{
\f[B]\[rs]b\f[R]
T}
T{
\f[B]\[rs]\[rs]\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]e\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]f\f[R]
T}@T{
\f[B]\[rs]f\f[R]
T}
T{
\f[B]\[rs]n\f[R]
T}@T{
\f[B]\[rs]n\f[R]
T}
T{
\f[B]\[rs]q\f[R]
T}@T{
\f[B]\[dq]\f[R]
T}
T{
\f[B]\[rs]r\f[R]
T}@T{
\f[B]\[rs]r\f[R]
T}
T{
\f[B]\[rs]t\f[R]
T}@T{
\f[B]\[rs]t\f[R]
T}
.TE
.PP
Any other character following a backslash causes the backslash and
character to be printed as-is.
.PP
Any non-string expression in a print statement shall be assigned to
\f[B]last\f[R], like any other expression that is printed.
.SS Order of Evaluation
.PP
All expressions in a statment are evaluated left to right, except as
necessary to maintain order of operations.
This means, for example, assuming that \f[B]i\f[R] is equal to
\f[B]0\f[R], in the expression
.IP
.nf
\f[C]
a[i++] = i++
\f[R]
.fi
.PP
the first (or 0th) element of \f[B]a\f[R] is set to \f[B]1\f[R], and
\f[B]i\f[R] is equal to \f[B]2\f[R] at the end of the expression.
.PP
This includes function arguments.
Thus, assuming \f[B]i\f[R] is equal to \f[B]0\f[R], this means that in
the expression
.IP
.nf
\f[C]
x(i++, i++)
\f[R]
.fi
.PP
the first argument passed to \f[B]x()\f[R] is \f[B]0\f[R], and the
second argument is \f[B]1\f[R], while \f[B]i\f[R] is equal to
\f[B]2\f[R] before the function starts executing.
.SH FUNCTIONS
.PP
Function definitions are as follows:
.IP
.nf
\f[C]
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
\f[R]
.fi
.PP
Any \f[B]I\f[R] in the parameter list or \f[B]auto\f[R] list may be
replaced with \f[B]I[]\f[R] to make a parameter or \f[B]auto\f[R] var an
array, and any \f[B]I\f[R] in the parameter list may be replaced with
\f[B]*I[]\f[R] to make a parameter an array reference.
Callers of functions that take array references should not put an
asterisk in the call; they must be called with just \f[B]I[]\f[R] like
normal array parameters and will be automatically converted into
references.
.PP
As a \f[B]non-portable extension\f[R], the opening brace of a
\f[B]define\f[R] statement may appear on the next line.
.PP
As a \f[B]non-portable extension\f[R], the return statement may also be
in one of the following forms:
.IP "1." 3
\f[B]return\f[R]
.IP "2." 3
\f[B]return\f[R] \f[B](\f[R] \f[B])\f[R]
.IP "3." 3
\f[B]return\f[R] \f[B]E\f[R]
.PP
The first two, or not specifying a \f[B]return\f[R] statement, is
equivalent to \f[B]return (0)\f[R], unless the function is a
\f[B]void\f[R] function (see the \f[I]Void Functions\f[R] subsection
below).
.SS Void Functions
.PP
Functions can also be \f[B]void\f[R] functions, defined as follows:
.IP
.nf
\f[C]
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
\f[R]
.fi
.PP
They can only be used as standalone expressions, where such an
expression would be printed alone, except in a print statement.
.PP
Void functions can only use the first two \f[B]return\f[R] statements
listed above.
They can also omit the return statement entirely.
.PP
The word \[lq]void\[rq] is not treated as a keyword; it is still
possible to have variables, arrays, and functions named \f[B]void\f[R].
The word \[lq]void\[rq] is only treated specially right after the
\f[B]define\f[R] keyword.
.PP
This is a \f[B]non-portable extension\f[R].
.SS Array References
.PP
For any array in the parameter list, if the array is declared in the
form
.IP
.nf
\f[C]
*I[]
\f[R]
.fi
.PP
it is a \f[B]reference\f[R].
Any changes to the array in the function are reflected, when the
function returns, to the array that was passed in.
.PP
Other than this, all function arguments are passed by value.
.PP
This is a \f[B]non-portable extension\f[R].
.SH LIBRARY
.PP
All of the functions below are available when the \f[B]-l\f[R] or
\f[B]\[en]mathlib\f[R] command-line flags are given.
.SS Standard Library
.PP
The
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
defines the following functions for the math library:
.TP
\f[B]s(x)\f[R]
Returns the sine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]c(x)\f[R]
Returns the cosine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]a(x)\f[R]
Returns the arctangent of \f[B]x\f[R], in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]l(x)\f[R]
Returns the natural logarithm of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]e(x)\f[R]
Returns the mathematical constant \f[B]e\f[R] raised to the power of
\f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]j(x, n)\f[R]
Returns the bessel integer order \f[B]n\f[R] (truncated) of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.SS Transcendental Functions
.PP
All transcendental functions can return slightly inaccurate results (up
to 1 ULP (https://en.wikipedia.org/wiki/Unit_in_the_last_place)).
This is unavoidable, and this
article (https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT) explains
why it is impossible and unnecessary to calculate exact results for the
transcendental functions.
.PP
Because of the possible inaccuracy, I recommend that users call those
functions with the precision (\f[B]scale\f[R]) set to at least 1 higher
than is necessary.
If exact results are \f[I]absolutely\f[R] required, users can double the
precision (\f[B]scale\f[R]) and then truncate.
.PP
The transcendental functions in the standard math library are:
.IP \[bu] 2
\f[B]s(x)\f[R]
.IP \[bu] 2
\f[B]c(x)\f[R]
.IP \[bu] 2
\f[B]a(x)\f[R]
.IP \[bu] 2
\f[B]l(x)\f[R]
.IP \[bu] 2
\f[B]e(x)\f[R]
.IP \[bu] 2
\f[B]j(x, n)\f[R]
.SH RESET
.PP
When bc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any functions that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all functions returned) is skipped.
.PP
Thus, when bc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.PP
Note that this reset behavior is different from the GNU bc(1), which
attempts to start executing the statement right after the one that
caused an error.
.SH PERFORMANCE
.PP
Most bc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This bc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]BC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]BC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]BC_BASE_DIGS\f[R].
.PP
The actual values of \f[B]BC_LONG_BIT\f[R] and \f[B]BC_BASE_DIGS\f[R]
can be queried with the \f[B]limits\f[R] statement.
.PP
In addition, this bc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]BC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on bc(1):
.TP
\f[B]BC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
bc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]BC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]BC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]BC_BASE_DIGS\f[R].
.TP
\f[B]BC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]BC_BASE_POW\f[R].
.TP
\f[B]BC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]BC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]BC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
The actual values can be queried with the \f[B]limits\f[R] statement.
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
bc(1) recognizes the following environment variables:
.TP
\f[B]POSIXLY_CORRECT\f[R]
If this variable exists (no matter the contents), bc(1) behaves as if
the \f[B]-s\f[R] option was given.
.TP
\f[B]BC_ENV_ARGS\f[R]
This is another way to give command-line arguments to bc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]BC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
.RS
.PP
The code that parses \f[B]BC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some bc file.bc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]bc\[dq] file.bc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]BC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]BC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), bc(1) will output lines to that length,
including the backslash (\f[B]\[rs]\f[R]).
The default line length is \f[B]70\f[R].
.SH EXIT STATUS
.PP
bc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, attempting to convert a negative number to a hardware
integer, overflow when converting a number to a hardware integer, and
attempting to use a non-integer where an integer is required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]) operator and the corresponding assignment
operator.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, using a token
where it is invalid, giving an invalid expression, giving an invalid
print statement, giving an invalid function definition, attempting to
assign to an expression that is not a named expression (see the
\f[I]Named Expressions\f[R] subsection of the \f[B]SYNTAX\f[R] section),
giving an invalid \f[B]auto\f[R] list, having a duplicate
\f[B]auto\f[R]/function parameter, failing to find the end of a code
block, attempting to return a value from a \f[B]void\f[R] function,
attempting to use a variable as a reference, and using any extensions
when the option \f[B]-s\f[R] or any equivalents were given.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a \f[B]void\f[R] function call as a value in an
expression.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (bc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, bc(1)
always exits and returns \f[B]4\f[R], no matter what mode bc(1) is in.
.PP
The other statuses will only be returned when bc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
bc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Per the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, bc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, bc(1) turns on \[lq]TTY mode.\[rq]
.PP
TTY mode is required for history to be enabled (see the \f[B]COMMAND
LINE HISTORY\f[R] section).
It is also required to enable special handling for \f[B]SIGINT\f[R]
signals.
.PP
The prompt is enabled in TTY mode.
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause bc(1) to stop execution of the
current input.
If bc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If bc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If bc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to bc(1) as it is
executing a file, it can seem as though bc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause bc(1) to clean up and
exit, and it uses the default handler for all other signals.
The one exception is \f[B]SIGHUP\f[R]; in that case, when bc(1) is in
TTY mode, a \f[B]SIGHUP\f[R] will cause bc(1) to clean up and exit.
.SH COMMAND LINE HISTORY
.PP
bc(1) supports interactive command-line editing.
If bc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), history is
enabled.
Previous lines can be recalled and edited with the arrow keys.
.PP
\f[B]Note\f[R]: tabs are converted to 8 spaces.
.SH SEE ALSO
.PP
dc(1)
.SH STANDARDS
.PP
bc(1) is compliant with the IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
The flags \f[B]-efghiqsvVw\f[R], all long options, and the extensions
noted above are extensions to that specification.
.PP
Note that the specification explicitly says that bc(1) only accepts
numbers that use a period (\f[B].\f[R]) as a radix point, regardless of
the value of \f[B]LC_NUMERIC\f[R].
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHORS
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/bc/EN.1.md b/contrib/bc/manuals/bc/EN.1.md
index 950a00c4cd3d..c82779aa6818 100644
--- a/contrib/bc/manuals/bc/EN.1.md
+++ b/contrib/bc/manuals/bc/EN.1.md
@@ -1,1077 +1,1086 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# NAME
bc - arbitrary-precision decimal arithmetic language and calculator
# SYNOPSIS
**bc** [**-ghilPqsvVw**] [**--global-stacks**] [**--help**] [**--interactive**] [**--mathlib**] [**--no-prompt**] [**--quiet**] [**--standard**] [**--warn**] [**--version**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...]
[*file*...]
# DESCRIPTION
bc(1) is an interactive processor for a language first standardized in 1991 by
POSIX. (The current standard is [here][1].) The language provides unlimited
precision decimal arithmetic and is somewhat C-like, but there are differences.
Such differences will be noted in this document.
After parsing and handling options, this bc(1) reads any files given on the
command line and executes them before reading from **stdin**.
This bc(1) is a drop-in replacement for *any* bc(1), including (and
especially) the GNU bc(1).
# OPTIONS
The following are the options that bc(1) accepts.
**-g**, **--global-stacks**
Turns the globals **ibase**, **obase**, and **scale** into stacks.
This has the effect that a copy of the current value of all three are pushed
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
However, since using this flag means that functions cannot set **ibase**,
**obase**, or **scale** globally, functions that are made to do so cannot
work anymore. There are two possible use cases for that, and each has a
solution.
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o="bc -e ibase=A -e obase=8"
alias h2b="bc -e ibase=G -e obase=2"
Second, if the purpose of a function is to set **ibase**, **obase**, or
**scale** globally for any other purpose, it could be split into one to
three functions (based on how many globals it sets) and each of those
functions could return the desired value for a global.
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
**-h**, **--help**
: Prints a usage message and quits.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-l**, **--mathlib**
: Sets **scale** (see the **SYNTAX** section) to **20** and loads the included
math library before running any code, including any expressions or files
specified on the command line.
To learn what is in the library, see the **LIBRARY** section.
**-P**, **--no-prompt**
: Disables the prompt in TTY mode. (The prompt is only enabled in TTY mode.
See the **TTY MODE** section) This is mostly for those users that do not
want a prompt or are not used to having them in bc(1). Most of those users
would want to put this option in **BC_ENV_ARGS** (see the
**ENVIRONMENT VARIABLES** section).
This is a **non-portable extension**.
**-q**, **--quiet**
: This option is for compatibility with the [GNU bc(1)][2]; it is a no-op.
Without this option, GNU bc(1) prints a copyright header. This bc(1) only
prints the copyright header if one or more of the **-v**, **-V**, or
**--version** options are given.
This is a **non-portable extension**.
**-s**, **--standard**
: Process exactly the language defined by the [standard][1] and error if any
extensions are used.
This is a **non-portable extension**.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
This is a **non-portable extension**.
**-w**, **--warn**
: Like **-s** and **--standard**, except that warnings (and not errors) are
printed for non-standard extensions and execution continues normally.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **BC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **bc <file> >&-**, it will quit with an error. This
is done so that bc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **bc <file> 2>&-**, it will quit with an error. This
is done so that bc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
The syntax for bc(1) programs is mostly C-like, with some differences. This
bc(1) follows the [POSIX standard][1], which is a much more thorough resource
for the language this bc(1) accepts. This section is meant to be a summary and a
listing of all the extensions to the standard.
In the sections below, **E** means expression, **S** means statement, and **I**
means identifier.
Identifiers (**I**) start with a lowercase letter and can be followed by any
number (up to **BC_NAME_MAX-1**) of lowercase letters (**a-z**), digits
(**0-9**), and underscores (**\_**). The regex is **\[a-z\]\[a-z0-9\_\]\***.
Identifiers with more than one character (letter) are a
**non-portable extension**.
**ibase** is a global variable determining how to interpret constant numbers. It
is the "input" base, or the number base used for interpreting input numbers.
**ibase** is initially **10**. If the **-s** (**--standard**) and **-w**
(**--warn**) flags were not given on the command line, the max allowable value
for **ibase** is **36**. Otherwise, it is **16**. The min allowable value for
**ibase** is **2**. The max allowable value for **ibase** can be queried in
bc(1) programs with the **maxibase()** built-in function.
**obase** is a global variable determining how to output results. It is the
"output" base, or the number base used for outputting numbers. **obase** is
initially **10**. The max allowable value for **obase** is **BC_BASE_MAX** and
can be queried in bc(1) programs with the **maxobase()** built-in function. The
min allowable value for **obase** is **2**. Values are output in the specified
base.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a global variable that
sets the precision of any operations, with exceptions. **scale** is initially
**0**. **scale** cannot be negative. The max allowable value for **scale** is
**BC_SCALE_MAX** and can be queried in bc(1) programs with the **maxscale()**
built-in function.
bc(1) has both *global* variables and *local* variables. All *local*
variables are local to the function; they are parameters or are introduced in
the **auto** list of a function (see the **FUNCTIONS** section). If a variable
is accessed which is not a parameter or in the **auto** list, it is assumed to
be *global*. If a parent function has a *local* variable version of a variable
that a child function considers *global*, the value of that *global* variable in
the child function is the value of the variable in the parent function, not the
value of the actual *global* variable.
All of the above applies to arrays as well.
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence operator is an
assignment operator *and* the expression is notsurrounded by parentheses.
The value that is printed is also assigned to the special variable **last**. A
single dot (**.**) may also be used as a synonym for **last**. These are
**non-portable extensions**.
Either semicolons or newlines may separate statements.
## Comments
There are two kinds of comments:
1. Block comments are enclosed in **/\*** and **\*/**.
2. Line comments go from **#** until, and not including, the next newline. This
is a **non-portable extension**.
## Named Expressions
The following are named expressions in bc(1):
1. Variables: **I**
2. Array Elements: **I[E]**
3. **ibase**
4. **obase**
5. **scale**
6. **last** or a single dot (**.**)
Number 6 is a **non-portable extension**.
Variables and arrays do not interfere; users can have arrays named the same as
variables. This also applies to functions (see the **FUNCTIONS** section), so a
user can have a variable, array, and function that all have the same name, and
they will not shadow each other, whether inside of functions or not.
Named expressions are required as the operand of **increment**/**decrement**
operators and as the left side of **assignment** operators (see the *Operators*
subsection).
## Operands
The following are valid operands in bc(1):
1. Numbers (see the *Numbers* subsection below).
2. Array indices (**I[E]**).
3. **(E)**: The value of **E** (used to change precedence).
4. **sqrt(E)**: The square root of **E**. **E** must be non-negative.
5. **length(E)**: The number of significant decimal digits in **E**.
6. **length(I[])**: The number of elements in the array **I**. This is a
**non-portable extension**.
7. **scale(E)**: The *scale* of **E**.
8. **abs(E)**: The absolute value of **E**. This is a **non-portable
extension**.
9. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a non-**void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
10. **read()**: Reads a line from **stdin** and uses that as an expression. The
result of that expression is the result of the **read()** operand. This is a
**non-portable extension**.
11. **maxibase()**: The max allowable **ibase**. This is a **non-portable
extension**.
12. **maxobase()**: The max allowable **obase**. This is a **non-portable
extension**.
13. **maxscale()**: The max allowable **scale**. This is a **non-portable
extension**.
## Numbers
Numbers are strings made up of digits, uppercase letters, and at most **1**
period for a radix. Numbers can have up to **BC_NUM_MAX** digits. Uppercase
letters are equal to **9** + their position in the alphabet (i.e., **A** equals
**10**, or **9+1**). If a digit or letter makes no sense with the current value
of **ibase**, they are set to the value of the highest valid digit in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **Z** alone always equals decimal
**35**.
## Operators
The following arithmetic and logical operators can be used. They are listed in
order of decreasing precedence. Operators in the same group have the same
precedence.
**++** **--**
: Type: Prefix and Postfix
Associativity: None
Description: **increment**, **decrement**
**-** **!**
: Type: Prefix
Associativity: None
Description: **negation**, **boolean not**
**\^**
: Type: Binary
Associativity: Right
Description: **power**
**\*** **/** **%**
: Type: Binary
Associativity: Left
Description: **multiply**, **divide**, **modulus**
**+** **-**
: Type: Binary
Associativity: Left
Description: **add**, **subtract**
**=** **+=** **-=** **\*=** **/=** **%=** **\^=**
: Type: Binary
Associativity: Right
Description: **assignment**
**==** **\<=** **\>=** **!=** **\<** **\>**
: Type: Binary
Associativity: Left
Description: **relational**
**&&**
: Type: Binary
Associativity: Left
Description: **boolean and**
**||**
: Type: Binary
Associativity: Left
Description: **boolean or**
The operators will be described in more detail below.
**++** **--**
: The prefix and postfix **increment** and **decrement** operators behave
exactly like they would in C. They require a named expression (see the
*Named Expressions* subsection) as an operand.
The prefix versions of these operators are more efficient; use them where
possible.
**-**
: The **negation** operator returns **0** if a user attempts to negate any
expression with the value **0**. Otherwise, a copy of the expression with
its sign flipped is returned.
**!**
: The **boolean not** operator returns **1** if the expression is **0**, or
**0** otherwise.
This is a **non-portable extension**.
**\^**
: The **power** operator (not the **exclusive or** operator, as it would be in
C) takes two expressions and raises the first to the power of the value of
the second. The *scale* of the result is equal to **scale**.
The second expression must be an integer (no *scale*), and if it is
negative, the first value must be non-zero.
**\***
: The **multiply** operator takes two expressions, multiplies them, and
returns the product. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result is
equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The **divide** operator takes two expressions, divides them, and returns the
quotient. The *scale* of the result shall be the value of **scale**.
The second expression must be non-zero.
**%**
: The **modulus** operator takes two expressions, **a** and **b**, and
evaluates them by 1) Computing **a/b** to current **scale** and 2) Using the
result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The second expression must be non-zero.
**+**
: The **add** operator takes two expressions, **a** and **b**, and returns the
sum, with a *scale* equal to the max of the *scale*s of **a** and **b**.
**-**
: The **subtract** operator takes two expressions, **a** and **b**, and
returns the difference, with a *scale* equal to the max of the *scale*s of
**a** and **b**.
**=** **+=** **-=** **\*=** **/=** **%=** **\^=**
: The **assignment** operators take two expressions, **a** and **b** where
**a** is a named expression (see the *Named Expressions* subsection).
For **=**, **b** is copied and the result is assigned to **a**. For all
others, **a** and **b** are applied as operands to the corresponding
arithmetic operator and the result is assigned to **a**.
**==** **\<=** **\>=** **!=** **\<** **\>**
: The **relational** operators compare two expressions, **a** and **b**, and
if the relation holds, according to C language semantics, the result is
**1**. Otherwise, it is **0**.
Note that unlike in C, these operators have a lower precedence than the
**assignment** operators, which means that **a=b\>c** is interpreted as
**(a=b)\>c**.
Also, unlike the [standard][1] requires, these operators can appear anywhere
any other expressions can be used. This allowance is a
**non-portable extension**.
**&&**
: The **boolean and** operator takes two expressions and returns **1** if both
expressions are non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
**||**
: The **boolean or** operator takes two expressions and returns **1** if one
of the expressions is non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
## Statements
The following items are statements:
1. **E**
2. **{** **S** **;** ... **;** **S** **}**
3. **if** **(** **E** **)** **S**
4. **if** **(** **E** **)** **S** **else** **S**
5. **while** **(** **E** **)** **S**
6. **for** **(** **E** **;** **E** **;** **E** **)** **S**
7. An empty statement
8. **break**
9. **continue**
10. **quit**
11. **halt**
12. **limits**
13. A string of characters, enclosed in double quotes
14. **print** **E** **,** ... **,** **E**
15. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
Numbers 4, 9, 11, 12, 14, and 15 are **non-portable extensions**.
Also, as a **non-portable extension**, any or all of the expressions in the
header of a for loop may be omitted. If the condition (second expression) is
omitted, it is assumed to be a constant **1**.
The **break** statement causes a loop to stop iterating and resume execution
immediately following a loop. This is only allowed in loops.
The **continue** statement causes a loop iteration to stop early and returns to
the start of the loop, including testing the loop condition. This is only
allowed in loops.
The **if** **else** statement does the same thing as in C.
The **quit** statement causes bc(1) to quit, even if it is on a branch that will
not be executed (it is a compile-time command).
The **halt** statement causes bc(1) to quit, if it is executed. (Unlike **quit**
if it is on a branch of an **if** statement that is not executed, bc(1) does not
quit.)
The **limits** statement prints the limits that this bc(1) is subject to. This
is like the **quit** statement in that it is a compile-time command.
An expression by itself is evaluated and printed, followed by a newline.
## Print Statement
The "expressions" in a **print** statement may also be strings. If they are, there
are backslash escape sequences that are interpreted specially. What those
sequences are, and what they cause to be printed, are shown below:
-------- -------
**\\a** **\\a**
**\\b** **\\b**
**\\\\** **\\**
**\\e** **\\**
**\\f** **\\f**
**\\n** **\\n**
**\\q** **"**
**\\r** **\\r**
**\\t** **\\t**
-------- -------
Any other character following a backslash causes the backslash and character to
be printed as-is.
Any non-string expression in a print statement shall be assigned to **last**,
like any other expression that is printed.
## Order of Evaluation
All expressions in a statment are evaluated left to right, except as necessary
to maintain order of operations. This means, for example, assuming that **i** is
equal to **0**, in the expression
a[i++] = i++
the first (or 0th) element of **a** is set to **1**, and **i** is equal to **2**
at the end of the expression.
This includes function arguments. Thus, assuming **i** is equal to **0**, this
means that in the expression
x(i++, i++)
the first argument passed to **x()** is **0**, and the second argument is **1**,
while **i** is equal to **2** before the function starts executing.
# FUNCTIONS
Function definitions are as follows:
```
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
```
Any **I** in the parameter list or **auto** list may be replaced with **I[]** to
make a parameter or **auto** var an array, and any **I** in the parameter list
may be replaced with **\*I[]** to make a parameter an array reference. Callers
of functions that take array references should not put an asterisk in the call;
they must be called with just **I[]** like normal array parameters and will be
automatically converted into references.
As a **non-portable extension**, the opening brace of a **define** statement may
appear on the next line.
As a **non-portable extension**, the return statement may also be in one of the
following forms:
1. **return**
2. **return** **(** **)**
3. **return** **E**
The first two, or not specifying a **return** statement, is equivalent to
**return (0)**, unless the function is a **void** function (see the *Void
Functions* subsection below).
## Void Functions
Functions can also be **void** functions, defined as follows:
```
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
```
They can only be used as standalone expressions, where such an expression would
be printed alone, except in a print statement.
Void functions can only use the first two **return** statements listed above.
They can also omit the return statement entirely.
The word "void" is not treated as a keyword; it is still possible to have
variables, arrays, and functions named **void**. The word "void" is only
treated specially right after the **define** keyword.
This is a **non-portable extension**.
## Array References
For any array in the parameter list, if the array is declared in the form
```
*I[]
```
it is a **reference**. Any changes to the array in the function are reflected,
when the function returns, to the array that was passed in.
Other than this, all function arguments are passed by value.
This is a **non-portable extension**.
# LIBRARY
All of the functions below are available when the **-l** or **--mathlib**
command-line flags are given.
## Standard Library
The [standard][1] defines the following functions for the math library:
**s(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**c(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a(x)**
: Returns the arctangent of **x**, in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l(x)**
: Returns the natural logarithm of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**e(x)**
: Returns the mathematical constant **e** raised to the power of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**j(x, n)**
: Returns the bessel integer order **n** (truncated) of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
## Transcendental Functions
All transcendental functions can return slightly inaccurate results (up to 1
[ULP][4]). This is unavoidable, and [this article][5] explains why it is
impossible and unnecessary to calculate exact results for the transcendental
functions.
Because of the possible inaccuracy, I recommend that users call those functions
with the precision (**scale**) set to at least 1 higher than is necessary. If
exact results are *absolutely* required, users can double the precision
(**scale**) and then truncate.
The transcendental functions in the standard math library are:
* **s(x)**
* **c(x)**
* **a(x)**
* **l(x)**
* **e(x)**
* **j(x, n)**
# RESET
When bc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any functions that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
functions returned) is skipped.
Thus, when bc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
Note that this reset behavior is different from the GNU bc(1), which attempts to
start executing the statement right after the one that caused an error.
# PERFORMANCE
Most bc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This bc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **BC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **BC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**BC_BASE_DIGS**.
The actual values of **BC_LONG_BIT** and **BC_BASE_DIGS** can be queried with
the **limits** statement.
In addition, this bc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **BC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on bc(1):
**BC_LONG_BIT**
: The number of bits in the **long** type in the environment where bc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**BC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **BC_LONG_BIT**.
**BC_BASE_POW**
: The max decimal number that each large integer can store (see
**BC_BASE_DIGS**) plus **1**. Depends on **BC_BASE_DIGS**.
**BC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **BC_LONG_BIT**.
**BC_BASE_MAX**
: The maximum output base. Set at **BC_BASE_POW**.
**BC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**BC_SCALE_MAX**
: The maximum **scale**. Set at **BC_OVERFLOW_MAX-1**.
**BC_STRING_MAX**
: The maximum length of strings. Set at **BC_OVERFLOW_MAX-1**.
**BC_NAME_MAX**
: The maximum length of identifiers. Set at **BC_OVERFLOW_MAX-1**.
**BC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **BC_OVERFLOW_MAX-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**BC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
The actual values can be queried with the **limits** statement.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
bc(1) recognizes the following environment variables:
**POSIXLY_CORRECT**
: If this variable exists (no matter the contents), bc(1) behaves as if
the **-s** option was given.
**BC_ENV_ARGS**
: This is another way to give command-line arguments to bc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **BC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
The code that parses **BC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some bc file.bc"** will be correctly parsed, but the string
**"/home/gavin/some \"bc\" file.bc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **BC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**BC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), bc(1) will output
lines to that length, including the backslash (**\\**). The default line
length is **70**.
# EXIT STATUS
bc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**) operator and the corresponding assignment operator.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, using a token where it is invalid,
giving an invalid expression, giving an invalid print statement, giving an
invalid function definition, attempting to assign to an expression that is
not a named expression (see the *Named Expressions* subsection of the
**SYNTAX** section), giving an invalid **auto** list, having a duplicate
**auto**/function parameter, failing to find the end of a code block,
attempting to return a value from a **void** function, attempting to use a
variable as a reference, and using any extensions when the option **-s** or
any equivalents were given.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a **void** function call as a value in an expression.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (bc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, bc(1) always exits
and returns **4**, no matter what mode bc(1) is in.
The other statuses will only be returned when bc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since bc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Per the [standard][1], bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, bc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, bc(1) turns
on "TTY mode."
TTY mode is required for history to be enabled (see the **COMMAND LINE HISTORY**
section). It is also required to enable special handling for **SIGINT** signals.
The prompt is enabled in TTY mode.
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause bc(1) to stop execution of the current input. If
bc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If bc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If bc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to bc(1) as it is executing a file, it
can seem as though bc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause bc(1) to clean up and exit, and it uses the
default handler for all other signals. The one exception is **SIGHUP**; in that
case, when bc(1) is in TTY mode, a **SIGHUP** will cause bc(1) to clean up and
exit.
# COMMAND LINE HISTORY
bc(1) supports interactive command-line editing. If bc(1) is in TTY mode (see
the **TTY MODE** section), history is enabled. Previous lines can be recalled
and edited with the arrow keys.
**Note**: tabs are converted to 8 spaces.
# SEE ALSO
dc(1)
# STANDARDS
bc(1) is compliant with the [IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1]
specification. The flags **-efghiqsvVw**, all long options, and the extensions
noted above are extensions to that specification.
Note that the specification explicitly says that bc(1) only accepts numbers that
use a period (**.**) as a radix point, regardless of the value of
**LC_NUMERIC**.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHORS
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
[2]: https://www.gnu.org/software/bc/
[3]: https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero
[4]: https://en.wikipedia.org/wiki/Unit_in_the_last_place
[5]: https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT
[6]: https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero
diff --git a/contrib/bc/manuals/bc/ENP.1 b/contrib/bc/manuals/bc/ENP.1
index 2116cc69d38d..7334888bb012 100644
--- a/contrib/bc/manuals/bc/ENP.1
+++ b/contrib/bc/manuals/bc/ENP.1
@@ -1,1287 +1,1300 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "BC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "BC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH NAME
.PP
bc - arbitrary-precision decimal arithmetic language and calculator
.SH SYNOPSIS
.PP
\f[B]bc\f[R] [\f[B]-ghilPqsvVw\f[R]] [\f[B]\[en]global-stacks\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]mathlib\f[R]] [\f[B]\[en]no-prompt\f[R]]
[\f[B]\[en]quiet\f[R]] [\f[B]\[en]standard\f[R]] [\f[B]\[en]warn\f[R]]
[\f[B]\[en]version\f[R]] [\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
bc(1) is an interactive processor for a language first standardized in
1991 by POSIX.
(The current standard is
here (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).)
The language provides unlimited precision decimal arithmetic and is
somewhat C-like, but there are differences.
Such differences will be noted in this document.
.PP
After parsing and handling options, this bc(1) reads any files given on
the command line and executes them before reading from \f[B]stdin\f[R].
.PP
This bc(1) is a drop-in replacement for \f[I]any\f[R] bc(1), including
(and especially) the GNU bc(1).
.SH OPTIONS
.PP
The following are the options that bc(1) accepts.
.PP
\f[B]-g\f[R], \f[B]\[en]global-stacks\f[R]
.IP
.nf
\f[C]
Turns the globals **ibase**, **obase**, and **scale** into stacks.
This has the effect that a copy of the current value of all three are pushed
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
However, since using this flag means that functions cannot set **ibase**,
**obase**, or **scale** globally, functions that are made to do so cannot
work anymore. There are two possible use cases for that, and each has a
solution.
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o=\[dq]bc -e ibase=A -e obase=8\[dq]
alias h2b=\[dq]bc -e ibase=G -e obase=2\[dq]
Second, if the purpose of a function is to set **ibase**, **obase**, or
**scale** globally for any other purpose, it could be split into one to
three functions (based on how many globals it sets) and each of those
functions could return the desired value for a global.
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
\f[R]
.fi
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-l\f[R], \f[B]\[en]mathlib\f[R]
Sets \f[B]scale\f[R] (see the \f[B]SYNTAX\f[R] section) to \f[B]20\f[R]
and loads the included math library before running any code, including
any expressions or files specified on the command line.
.RS
.PP
To learn what is in the library, see the \f[B]LIBRARY\f[R] section.
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
This option is a no-op.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-q\f[R], \f[B]\[en]quiet\f[R]
This option is for compatibility with the GNU
bc(1) (https://www.gnu.org/software/bc/); it is a no-op.
Without this option, GNU bc(1) prints a copyright header.
This bc(1) only prints the copyright header if one or more of the
\f[B]-v\f[R], \f[B]-V\f[R], or \f[B]\[en]version\f[R] options are given.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-s\f[R], \f[B]\[en]standard\f[R]
Process exactly the language defined by the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
and error if any extensions are used.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-w\f[R], \f[B]\[en]warn\f[R]
Like \f[B]-s\f[R] and \f[B]\[en]standard\f[R], except that warnings (and
not errors) are printed for non-standard extensions and execution
continues normally.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]BC_ENV_ARGS\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]bc >&-\f[R], it will quit with an error.
This is done so that bc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]bc 2>&-\f[R], it will quit with an error.
This is done so that bc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
The syntax for bc(1) programs is mostly C-like, with some differences.
This bc(1) follows the POSIX
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
which is a much more thorough resource for the language this bc(1)
accepts.
This section is meant to be a summary and a listing of all the
extensions to the standard.
.PP
In the sections below, \f[B]E\f[R] means expression, \f[B]S\f[R] means
statement, and \f[B]I\f[R] means identifier.
.PP
Identifiers (\f[B]I\f[R]) start with a lowercase letter and can be
followed by any number (up to \f[B]BC_NAME_MAX-1\f[R]) of lowercase
letters (\f[B]a-z\f[R]), digits (\f[B]0-9\f[R]), and underscores
(\f[B]_\f[R]).
The regex is \f[B][a-z][a-z0-9_]*\f[R].
Identifiers with more than one character (letter) are a
\f[B]non-portable extension\f[R].
.PP
\f[B]ibase\f[R] is a global variable determining how to interpret
constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
If the \f[B]-s\f[R] (\f[B]\[en]standard\f[R]) and \f[B]-w\f[R]
(\f[B]\[en]warn\f[R]) flags were not given on the command line, the max
allowable value for \f[B]ibase\f[R] is \f[B]36\f[R].
Otherwise, it is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in bc(1)
programs with the \f[B]maxibase()\f[R] built-in function.
.PP
\f[B]obase\f[R] is a global variable determining how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]BC_BASE_MAX\f[R] and
can be queried in bc(1) programs with the \f[B]maxobase()\f[R] built-in
function.
The min allowable value for \f[B]obase\f[R] is \f[B]2\f[R].
Values are output in the specified base.
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a global variable that sets the precision of any operations, with
exceptions.
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] is \f[B]BC_SCALE_MAX\f[R]
and can be queried in bc(1) programs with the \f[B]maxscale()\f[R]
built-in function.
.PP
bc(1) has both \f[I]global\f[R] variables and \f[I]local\f[R] variables.
All \f[I]local\f[R] variables are local to the function; they are
parameters or are introduced in the \f[B]auto\f[R] list of a function
(see the \f[B]FUNCTIONS\f[R] section).
If a variable is accessed which is not a parameter or in the
\f[B]auto\f[R] list, it is assumed to be \f[I]global\f[R].
If a parent function has a \f[I]local\f[R] variable version of a
variable that a child function considers \f[I]global\f[R], the value of
that \f[I]global\f[R] variable in the child function is the value of the
variable in the parent function, not the value of the actual
\f[I]global\f[R] variable.
.PP
All of the above applies to arrays as well.
.PP
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence
operator is an assignment operator \f[I]and\f[R] the expression is
notsurrounded by parentheses.
.PP
The value that is printed is also assigned to the special variable
\f[B]last\f[R].
A single dot (\f[B].\f[R]) may also be used as a synonym for
\f[B]last\f[R].
These are \f[B]non-portable extensions\f[R].
.PP
Either semicolons or newlines may separate statements.
.SS Comments
.PP
There are two kinds of comments:
.IP "1." 3
Block comments are enclosed in \f[B]/*\f[R] and \f[B]*/\f[R].
.IP "2." 3
Line comments go from \f[B]#\f[R] until, and not including, the next
newline.
This is a \f[B]non-portable extension\f[R].
.SS Named Expressions
.PP
The following are named expressions in bc(1):
.IP "1." 3
Variables: \f[B]I\f[R]
.IP "2." 3
Array Elements: \f[B]I[E]\f[R]
.IP "3." 3
\f[B]ibase\f[R]
.IP "4." 3
\f[B]obase\f[R]
.IP "5." 3
\f[B]scale\f[R]
.IP "6." 3
\f[B]last\f[R] or a single dot (\f[B].\f[R])
.PP
Number 6 is a \f[B]non-portable extension\f[R].
.PP
Variables and arrays do not interfere; users can have arrays named the
same as variables.
This also applies to functions (see the \f[B]FUNCTIONS\f[R] section), so
a user can have a variable, array, and function that all have the same
name, and they will not shadow each other, whether inside of functions
or not.
.PP
Named expressions are required as the operand of
\f[B]increment\f[R]/\f[B]decrement\f[R] operators and as the left side
of \f[B]assignment\f[R] operators (see the \f[I]Operators\f[R]
subsection).
.SS Operands
.PP
The following are valid operands in bc(1):
.IP " 1." 4
Numbers (see the \f[I]Numbers\f[R] subsection below).
.IP " 2." 4
Array indices (\f[B]I[E]\f[R]).
.IP " 3." 4
\f[B](E)\f[R]: The value of \f[B]E\f[R] (used to change precedence).
.IP " 4." 4
\f[B]sqrt(E)\f[R]: The square root of \f[B]E\f[R].
\f[B]E\f[R] must be non-negative.
.IP " 5." 4
\f[B]length(E)\f[R]: The number of significant decimal digits in
\f[B]E\f[R].
.IP " 6." 4
\f[B]length(I[])\f[R]: The number of elements in the array \f[B]I\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 7." 4
\f[B]scale(E)\f[R]: The \f[I]scale\f[R] of \f[B]E\f[R].
.IP " 8." 4
\f[B]abs(E)\f[R]: The absolute value of \f[B]E\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 9." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a non-\f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.IP "10." 4
\f[B]read()\f[R]: Reads a line from \f[B]stdin\f[R] and uses that as an
expression.
The result of that expression is the result of the \f[B]read()\f[R]
operand.
This is a \f[B]non-portable extension\f[R].
.IP "11." 4
\f[B]maxibase()\f[R]: The max allowable \f[B]ibase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "12." 4
\f[B]maxobase()\f[R]: The max allowable \f[B]obase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "13." 4
\f[B]maxscale()\f[R]: The max allowable \f[B]scale\f[R].
This is a \f[B]non-portable extension\f[R].
.SS Numbers
.PP
Numbers are strings made up of digits, uppercase letters, and at most
\f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]BC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]Z\f[R] alone always equals decimal \f[B]35\f[R].
.SS Operators
.PP
The following arithmetic and logical operators can be used.
They are listed in order of decreasing precedence.
Operators in the same group have the same precedence.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
Type: Prefix and Postfix
.RS
.PP
Associativity: None
.PP
Description: \f[B]increment\f[R], \f[B]decrement\f[R]
.RE
.TP
\f[B]-\f[R] \f[B]!\f[R]
Type: Prefix
.RS
.PP
Associativity: None
.PP
Description: \f[B]negation\f[R], \f[B]boolean not\f[R]
.RE
.TP
\f[B]\[ha]\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]power\f[R]
.RE
.TP
\f[B]*\f[R] \f[B]/\f[R] \f[B]%\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]multiply\f[R], \f[B]divide\f[R], \f[B]modulus\f[R]
.RE
.TP
\f[B]+\f[R] \f[B]-\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]add\f[R], \f[B]subtract\f[R]
.RE
.TP
\f[B]=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]assignment\f[R]
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]relational\f[R]
.RE
.TP
\f[B]&&\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean and\f[R]
.RE
.TP
\f[B]||\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean or\f[R]
.RE
.PP
The operators will be described in more detail below.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
The prefix and postfix \f[B]increment\f[R] and \f[B]decrement\f[R]
operators behave exactly like they would in C.
They require a named expression (see the \f[I]Named Expressions\f[R]
subsection) as an operand.
.RS
.PP
The prefix versions of these operators are more efficient; use them
where possible.
.RE
.TP
\f[B]-\f[R]
The \f[B]negation\f[R] operator returns \f[B]0\f[R] if a user attempts
to negate any expression with the value \f[B]0\f[R].
Otherwise, a copy of the expression with its sign flipped is returned.
.TP
\f[B]!\f[R]
The \f[B]boolean not\f[R] operator returns \f[B]1\f[R] if the expression
is \f[B]0\f[R], or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The \f[B]power\f[R] operator (not the \f[B]exclusive or\f[R] operator,
as it would be in C) takes two expressions and raises the first to the
power of the value of the second.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]), and if it
is negative, the first value must be non-zero.
.RE
.TP
\f[B]*\f[R]
The \f[B]multiply\f[R] operator takes two expressions, multiplies them,
and returns the product.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The \f[B]divide\f[R] operator takes two expressions, divides them, and
returns the quotient.
The \f[I]scale\f[R] of the result shall be the value of \f[B]scale\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]%\f[R]
The \f[B]modulus\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and evaluates them by 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R] and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]+\f[R]
The \f[B]add\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the sum, with a \f[I]scale\f[R] equal to the
max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]-\f[R]
The \f[B]subtract\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the difference, with a \f[I]scale\f[R] equal to
the max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R]
The \f[B]assignment\f[R] operators take two expressions, \f[B]a\f[R] and
\f[B]b\f[R] where \f[B]a\f[R] is a named expression (see the \f[I]Named
Expressions\f[R] subsection).
.RS
.PP
For \f[B]=\f[R], \f[B]b\f[R] is copied and the result is assigned to
\f[B]a\f[R].
For all others, \f[B]a\f[R] and \f[B]b\f[R] are applied as operands to
the corresponding arithmetic operator and the result is assigned to
\f[B]a\f[R].
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
The \f[B]relational\f[R] operators compare two expressions, \f[B]a\f[R]
and \f[B]b\f[R], and if the relation holds, according to C language
semantics, the result is \f[B]1\f[R].
Otherwise, it is \f[B]0\f[R].
.RS
.PP
Note that unlike in C, these operators have a lower precedence than the
\f[B]assignment\f[R] operators, which means that \f[B]a=b>c\f[R] is
interpreted as \f[B](a=b)>c\f[R].
.PP
Also, unlike the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
requires, these operators can appear anywhere any other expressions can
be used.
This allowance is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]&&\f[R]
The \f[B]boolean and\f[R] operator takes two expressions and returns
\f[B]1\f[R] if both expressions are non-zero, \f[B]0\f[R] otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]||\f[R]
The \f[B]boolean or\f[R] operator takes two expressions and returns
\f[B]1\f[R] if one of the expressions is non-zero, \f[B]0\f[R]
otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Statements
.PP
The following items are statements:
.IP " 1." 4
\f[B]E\f[R]
.IP " 2." 4
\f[B]{\f[R] \f[B]S\f[R] \f[B];\f[R] \&... \f[B];\f[R] \f[B]S\f[R]
\f[B]}\f[R]
.IP " 3." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 4." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
\f[B]else\f[R] \f[B]S\f[R]
.IP " 5." 4
\f[B]while\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 6." 4
\f[B]for\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B];\f[R] \f[B]E\f[R]
\f[B];\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 7." 4
An empty statement
.IP " 8." 4
\f[B]break\f[R]
.IP " 9." 4
\f[B]continue\f[R]
.IP "10." 4
\f[B]quit\f[R]
.IP "11." 4
\f[B]halt\f[R]
.IP "12." 4
\f[B]limits\f[R]
.IP "13." 4
A string of characters, enclosed in double quotes
.IP "14." 4
\f[B]print\f[R] \f[B]E\f[R] \f[B],\f[R] \&... \f[B],\f[R] \f[B]E\f[R]
.IP "15." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a \f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.PP
Numbers 4, 9, 11, 12, 14, and 15 are \f[B]non-portable extensions\f[R].
.PP
Also, as a \f[B]non-portable extension\f[R], any or all of the
expressions in the header of a for loop may be omitted.
If the condition (second expression) is omitted, it is assumed to be a
constant \f[B]1\f[R].
.PP
The \f[B]break\f[R] statement causes a loop to stop iterating and resume
execution immediately following a loop.
This is only allowed in loops.
.PP
The \f[B]continue\f[R] statement causes a loop iteration to stop early
and returns to the start of the loop, including testing the loop
condition.
This is only allowed in loops.
.PP
The \f[B]if\f[R] \f[B]else\f[R] statement does the same thing as in C.
.PP
The \f[B]quit\f[R] statement causes bc(1) to quit, even if it is on a
branch that will not be executed (it is a compile-time command).
.PP
The \f[B]halt\f[R] statement causes bc(1) to quit, if it is executed.
(Unlike \f[B]quit\f[R] if it is on a branch of an \f[B]if\f[R] statement
that is not executed, bc(1) does not quit.)
.PP
The \f[B]limits\f[R] statement prints the limits that this bc(1) is
subject to.
This is like the \f[B]quit\f[R] statement in that it is a compile-time
command.
.PP
An expression by itself is evaluated and printed, followed by a newline.
.SS Print Statement
.PP
The \[lq]expressions\[rq] in a \f[B]print\f[R] statement may also be
strings.
If they are, there are backslash escape sequences that are interpreted
specially.
What those sequences are, and what they cause to be printed, are shown
below:
.PP
.TS
tab(@);
l l.
T{
\f[B]\[rs]a\f[R]
T}@T{
\f[B]\[rs]a\f[R]
T}
T{
\f[B]\[rs]b\f[R]
T}@T{
\f[B]\[rs]b\f[R]
T}
T{
\f[B]\[rs]\[rs]\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]e\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]f\f[R]
T}@T{
\f[B]\[rs]f\f[R]
T}
T{
\f[B]\[rs]n\f[R]
T}@T{
\f[B]\[rs]n\f[R]
T}
T{
\f[B]\[rs]q\f[R]
T}@T{
\f[B]\[dq]\f[R]
T}
T{
\f[B]\[rs]r\f[R]
T}@T{
\f[B]\[rs]r\f[R]
T}
T{
\f[B]\[rs]t\f[R]
T}@T{
\f[B]\[rs]t\f[R]
T}
.TE
.PP
Any other character following a backslash causes the backslash and
character to be printed as-is.
.PP
Any non-string expression in a print statement shall be assigned to
\f[B]last\f[R], like any other expression that is printed.
.SS Order of Evaluation
.PP
All expressions in a statment are evaluated left to right, except as
necessary to maintain order of operations.
This means, for example, assuming that \f[B]i\f[R] is equal to
\f[B]0\f[R], in the expression
.IP
.nf
\f[C]
a[i++] = i++
\f[R]
.fi
.PP
the first (or 0th) element of \f[B]a\f[R] is set to \f[B]1\f[R], and
\f[B]i\f[R] is equal to \f[B]2\f[R] at the end of the expression.
.PP
This includes function arguments.
Thus, assuming \f[B]i\f[R] is equal to \f[B]0\f[R], this means that in
the expression
.IP
.nf
\f[C]
x(i++, i++)
\f[R]
.fi
.PP
the first argument passed to \f[B]x()\f[R] is \f[B]0\f[R], and the
second argument is \f[B]1\f[R], while \f[B]i\f[R] is equal to
\f[B]2\f[R] before the function starts executing.
.SH FUNCTIONS
.PP
Function definitions are as follows:
.IP
.nf
\f[C]
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
\f[R]
.fi
.PP
Any \f[B]I\f[R] in the parameter list or \f[B]auto\f[R] list may be
replaced with \f[B]I[]\f[R] to make a parameter or \f[B]auto\f[R] var an
array, and any \f[B]I\f[R] in the parameter list may be replaced with
\f[B]*I[]\f[R] to make a parameter an array reference.
Callers of functions that take array references should not put an
asterisk in the call; they must be called with just \f[B]I[]\f[R] like
normal array parameters and will be automatically converted into
references.
.PP
As a \f[B]non-portable extension\f[R], the opening brace of a
\f[B]define\f[R] statement may appear on the next line.
.PP
As a \f[B]non-portable extension\f[R], the return statement may also be
in one of the following forms:
.IP "1." 3
\f[B]return\f[R]
.IP "2." 3
\f[B]return\f[R] \f[B](\f[R] \f[B])\f[R]
.IP "3." 3
\f[B]return\f[R] \f[B]E\f[R]
.PP
The first two, or not specifying a \f[B]return\f[R] statement, is
equivalent to \f[B]return (0)\f[R], unless the function is a
\f[B]void\f[R] function (see the \f[I]Void Functions\f[R] subsection
below).
.SS Void Functions
.PP
Functions can also be \f[B]void\f[R] functions, defined as follows:
.IP
.nf
\f[C]
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
\f[R]
.fi
.PP
They can only be used as standalone expressions, where such an
expression would be printed alone, except in a print statement.
.PP
Void functions can only use the first two \f[B]return\f[R] statements
listed above.
They can also omit the return statement entirely.
.PP
The word \[lq]void\[rq] is not treated as a keyword; it is still
possible to have variables, arrays, and functions named \f[B]void\f[R].
The word \[lq]void\[rq] is only treated specially right after the
\f[B]define\f[R] keyword.
.PP
This is a \f[B]non-portable extension\f[R].
.SS Array References
.PP
For any array in the parameter list, if the array is declared in the
form
.IP
.nf
\f[C]
*I[]
\f[R]
.fi
.PP
it is a \f[B]reference\f[R].
Any changes to the array in the function are reflected, when the
function returns, to the array that was passed in.
.PP
Other than this, all function arguments are passed by value.
.PP
This is a \f[B]non-portable extension\f[R].
.SH LIBRARY
.PP
All of the functions below are available when the \f[B]-l\f[R] or
\f[B]\[en]mathlib\f[R] command-line flags are given.
.SS Standard Library
.PP
The
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
defines the following functions for the math library:
.TP
\f[B]s(x)\f[R]
Returns the sine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]c(x)\f[R]
Returns the cosine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]a(x)\f[R]
Returns the arctangent of \f[B]x\f[R], in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]l(x)\f[R]
Returns the natural logarithm of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]e(x)\f[R]
Returns the mathematical constant \f[B]e\f[R] raised to the power of
\f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]j(x, n)\f[R]
Returns the bessel integer order \f[B]n\f[R] (truncated) of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.SS Transcendental Functions
.PP
All transcendental functions can return slightly inaccurate results (up
to 1 ULP (https://en.wikipedia.org/wiki/Unit_in_the_last_place)).
This is unavoidable, and this
article (https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT) explains
why it is impossible and unnecessary to calculate exact results for the
transcendental functions.
.PP
Because of the possible inaccuracy, I recommend that users call those
functions with the precision (\f[B]scale\f[R]) set to at least 1 higher
than is necessary.
If exact results are \f[I]absolutely\f[R] required, users can double the
precision (\f[B]scale\f[R]) and then truncate.
.PP
The transcendental functions in the standard math library are:
.IP \[bu] 2
\f[B]s(x)\f[R]
.IP \[bu] 2
\f[B]c(x)\f[R]
.IP \[bu] 2
\f[B]a(x)\f[R]
.IP \[bu] 2
\f[B]l(x)\f[R]
.IP \[bu] 2
\f[B]e(x)\f[R]
.IP \[bu] 2
\f[B]j(x, n)\f[R]
.SH RESET
.PP
When bc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any functions that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all functions returned) is skipped.
.PP
Thus, when bc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.PP
Note that this reset behavior is different from the GNU bc(1), which
attempts to start executing the statement right after the one that
caused an error.
.SH PERFORMANCE
.PP
Most bc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This bc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]BC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]BC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]BC_BASE_DIGS\f[R].
.PP
The actual values of \f[B]BC_LONG_BIT\f[R] and \f[B]BC_BASE_DIGS\f[R]
can be queried with the \f[B]limits\f[R] statement.
.PP
In addition, this bc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]BC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on bc(1):
.TP
\f[B]BC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
bc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]BC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]BC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]BC_BASE_DIGS\f[R].
.TP
\f[B]BC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]BC_BASE_POW\f[R].
.TP
\f[B]BC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]BC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]BC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
The actual values can be queried with the \f[B]limits\f[R] statement.
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
bc(1) recognizes the following environment variables:
.TP
\f[B]POSIXLY_CORRECT\f[R]
If this variable exists (no matter the contents), bc(1) behaves as if
the \f[B]-s\f[R] option was given.
.TP
\f[B]BC_ENV_ARGS\f[R]
This is another way to give command-line arguments to bc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]BC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
.RS
.PP
The code that parses \f[B]BC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some bc file.bc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]bc\[dq] file.bc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]BC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]BC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), bc(1) will output lines to that length,
including the backslash (\f[B]\[rs]\f[R]).
The default line length is \f[B]70\f[R].
.SH EXIT STATUS
.PP
bc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, attempting to convert a negative number to a hardware
integer, overflow when converting a number to a hardware integer, and
attempting to use a non-integer where an integer is required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]) operator and the corresponding assignment
operator.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, using a token
where it is invalid, giving an invalid expression, giving an invalid
print statement, giving an invalid function definition, attempting to
assign to an expression that is not a named expression (see the
\f[I]Named Expressions\f[R] subsection of the \f[B]SYNTAX\f[R] section),
giving an invalid \f[B]auto\f[R] list, having a duplicate
\f[B]auto\f[R]/function parameter, failing to find the end of a code
block, attempting to return a value from a \f[B]void\f[R] function,
attempting to use a variable as a reference, and using any extensions
when the option \f[B]-s\f[R] or any equivalents were given.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a \f[B]void\f[R] function call as a value in an
expression.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (bc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, bc(1)
always exits and returns \f[B]4\f[R], no matter what mode bc(1) is in.
.PP
The other statuses will only be returned when bc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
bc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Per the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, bc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, bc(1) turns on \[lq]TTY mode.\[rq]
.PP
TTY mode is required for history to be enabled (see the \f[B]COMMAND
LINE HISTORY\f[R] section).
It is also required to enable special handling for \f[B]SIGINT\f[R]
signals.
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause bc(1) to stop execution of the
current input.
If bc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If bc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If bc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to bc(1) as it is
executing a file, it can seem as though bc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause bc(1) to clean up and
exit, and it uses the default handler for all other signals.
The one exception is \f[B]SIGHUP\f[R]; in that case, when bc(1) is in
TTY mode, a \f[B]SIGHUP\f[R] will cause bc(1) to clean up and exit.
.SH COMMAND LINE HISTORY
.PP
bc(1) supports interactive command-line editing.
If bc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), history is
enabled.
Previous lines can be recalled and edited with the arrow keys.
.PP
\f[B]Note\f[R]: tabs are converted to 8 spaces.
.SH SEE ALSO
.PP
dc(1)
.SH STANDARDS
.PP
bc(1) is compliant with the IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
The flags \f[B]-efghiqsvVw\f[R], all long options, and the extensions
noted above are extensions to that specification.
.PP
Note that the specification explicitly says that bc(1) only accepts
numbers that use a period (\f[B].\f[R]) as a radix point, regardless of
the value of \f[B]LC_NUMERIC\f[R].
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHORS
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/bc/ENP.1.md b/contrib/bc/manuals/bc/ENP.1.md
index 20c380dd1bb2..711e3161c162 100644
--- a/contrib/bc/manuals/bc/ENP.1.md
+++ b/contrib/bc/manuals/bc/ENP.1.md
@@ -1,1071 +1,1080 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# NAME
bc - arbitrary-precision decimal arithmetic language and calculator
# SYNOPSIS
**bc** [**-ghilPqsvVw**] [**--global-stacks**] [**--help**] [**--interactive**] [**--mathlib**] [**--no-prompt**] [**--quiet**] [**--standard**] [**--warn**] [**--version**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...]
[*file*...]
# DESCRIPTION
bc(1) is an interactive processor for a language first standardized in 1991 by
POSIX. (The current standard is [here][1].) The language provides unlimited
precision decimal arithmetic and is somewhat C-like, but there are differences.
Such differences will be noted in this document.
After parsing and handling options, this bc(1) reads any files given on the
command line and executes them before reading from **stdin**.
This bc(1) is a drop-in replacement for *any* bc(1), including (and
especially) the GNU bc(1).
# OPTIONS
The following are the options that bc(1) accepts.
**-g**, **--global-stacks**
Turns the globals **ibase**, **obase**, and **scale** into stacks.
This has the effect that a copy of the current value of all three are pushed
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
However, since using this flag means that functions cannot set **ibase**,
**obase**, or **scale** globally, functions that are made to do so cannot
work anymore. There are two possible use cases for that, and each has a
solution.
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o="bc -e ibase=A -e obase=8"
alias h2b="bc -e ibase=G -e obase=2"
Second, if the purpose of a function is to set **ibase**, **obase**, or
**scale** globally for any other purpose, it could be split into one to
three functions (based on how many globals it sets) and each of those
functions could return the desired value for a global.
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
**-h**, **--help**
: Prints a usage message and quits.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-l**, **--mathlib**
: Sets **scale** (see the **SYNTAX** section) to **20** and loads the included
math library before running any code, including any expressions or files
specified on the command line.
To learn what is in the library, see the **LIBRARY** section.
**-P**, **--no-prompt**
: This option is a no-op.
This is a **non-portable extension**.
**-q**, **--quiet**
: This option is for compatibility with the [GNU bc(1)][2]; it is a no-op.
Without this option, GNU bc(1) prints a copyright header. This bc(1) only
prints the copyright header if one or more of the **-v**, **-V**, or
**--version** options are given.
This is a **non-portable extension**.
**-s**, **--standard**
: Process exactly the language defined by the [standard][1] and error if any
extensions are used.
This is a **non-portable extension**.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
This is a **non-portable extension**.
**-w**, **--warn**
: Like **-s** and **--standard**, except that warnings (and not errors) are
printed for non-standard extensions and execution continues normally.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **BC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **bc <file> >&-**, it will quit with an error. This
is done so that bc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **bc <file> 2>&-**, it will quit with an error. This
is done so that bc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
The syntax for bc(1) programs is mostly C-like, with some differences. This
bc(1) follows the [POSIX standard][1], which is a much more thorough resource
for the language this bc(1) accepts. This section is meant to be a summary and a
listing of all the extensions to the standard.
In the sections below, **E** means expression, **S** means statement, and **I**
means identifier.
Identifiers (**I**) start with a lowercase letter and can be followed by any
number (up to **BC_NAME_MAX-1**) of lowercase letters (**a-z**), digits
(**0-9**), and underscores (**\_**). The regex is **\[a-z\]\[a-z0-9\_\]\***.
Identifiers with more than one character (letter) are a
**non-portable extension**.
**ibase** is a global variable determining how to interpret constant numbers. It
is the "input" base, or the number base used for interpreting input numbers.
**ibase** is initially **10**. If the **-s** (**--standard**) and **-w**
(**--warn**) flags were not given on the command line, the max allowable value
for **ibase** is **36**. Otherwise, it is **16**. The min allowable value for
**ibase** is **2**. The max allowable value for **ibase** can be queried in
bc(1) programs with the **maxibase()** built-in function.
**obase** is a global variable determining how to output results. It is the
"output" base, or the number base used for outputting numbers. **obase** is
initially **10**. The max allowable value for **obase** is **BC_BASE_MAX** and
can be queried in bc(1) programs with the **maxobase()** built-in function. The
min allowable value for **obase** is **2**. Values are output in the specified
base.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a global variable that
sets the precision of any operations, with exceptions. **scale** is initially
**0**. **scale** cannot be negative. The max allowable value for **scale** is
**BC_SCALE_MAX** and can be queried in bc(1) programs with the **maxscale()**
built-in function.
bc(1) has both *global* variables and *local* variables. All *local*
variables are local to the function; they are parameters or are introduced in
the **auto** list of a function (see the **FUNCTIONS** section). If a variable
is accessed which is not a parameter or in the **auto** list, it is assumed to
be *global*. If a parent function has a *local* variable version of a variable
that a child function considers *global*, the value of that *global* variable in
the child function is the value of the variable in the parent function, not the
value of the actual *global* variable.
All of the above applies to arrays as well.
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence operator is an
assignment operator *and* the expression is notsurrounded by parentheses.
The value that is printed is also assigned to the special variable **last**. A
single dot (**.**) may also be used as a synonym for **last**. These are
**non-portable extensions**.
Either semicolons or newlines may separate statements.
## Comments
There are two kinds of comments:
1. Block comments are enclosed in **/\*** and **\*/**.
2. Line comments go from **#** until, and not including, the next newline. This
is a **non-portable extension**.
## Named Expressions
The following are named expressions in bc(1):
1. Variables: **I**
2. Array Elements: **I[E]**
3. **ibase**
4. **obase**
5. **scale**
6. **last** or a single dot (**.**)
Number 6 is a **non-portable extension**.
Variables and arrays do not interfere; users can have arrays named the same as
variables. This also applies to functions (see the **FUNCTIONS** section), so a
user can have a variable, array, and function that all have the same name, and
they will not shadow each other, whether inside of functions or not.
Named expressions are required as the operand of **increment**/**decrement**
operators and as the left side of **assignment** operators (see the *Operators*
subsection).
## Operands
The following are valid operands in bc(1):
1. Numbers (see the *Numbers* subsection below).
2. Array indices (**I[E]**).
3. **(E)**: The value of **E** (used to change precedence).
4. **sqrt(E)**: The square root of **E**. **E** must be non-negative.
5. **length(E)**: The number of significant decimal digits in **E**.
6. **length(I[])**: The number of elements in the array **I**. This is a
**non-portable extension**.
7. **scale(E)**: The *scale* of **E**.
8. **abs(E)**: The absolute value of **E**. This is a **non-portable
extension**.
9. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a non-**void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
10. **read()**: Reads a line from **stdin** and uses that as an expression. The
result of that expression is the result of the **read()** operand. This is a
**non-portable extension**.
11. **maxibase()**: The max allowable **ibase**. This is a **non-portable
extension**.
12. **maxobase()**: The max allowable **obase**. This is a **non-portable
extension**.
13. **maxscale()**: The max allowable **scale**. This is a **non-portable
extension**.
## Numbers
Numbers are strings made up of digits, uppercase letters, and at most **1**
period for a radix. Numbers can have up to **BC_NUM_MAX** digits. Uppercase
letters are equal to **9** + their position in the alphabet (i.e., **A** equals
**10**, or **9+1**). If a digit or letter makes no sense with the current value
of **ibase**, they are set to the value of the highest valid digit in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **Z** alone always equals decimal
**35**.
## Operators
The following arithmetic and logical operators can be used. They are listed in
order of decreasing precedence. Operators in the same group have the same
precedence.
**++** **--**
: Type: Prefix and Postfix
Associativity: None
Description: **increment**, **decrement**
**-** **!**
: Type: Prefix
Associativity: None
Description: **negation**, **boolean not**
**\^**
: Type: Binary
Associativity: Right
Description: **power**
**\*** **/** **%**
: Type: Binary
Associativity: Left
Description: **multiply**, **divide**, **modulus**
**+** **-**
: Type: Binary
Associativity: Left
Description: **add**, **subtract**
**=** **+=** **-=** **\*=** **/=** **%=** **\^=**
: Type: Binary
Associativity: Right
Description: **assignment**
**==** **\<=** **\>=** **!=** **\<** **\>**
: Type: Binary
Associativity: Left
Description: **relational**
**&&**
: Type: Binary
Associativity: Left
Description: **boolean and**
**||**
: Type: Binary
Associativity: Left
Description: **boolean or**
The operators will be described in more detail below.
**++** **--**
: The prefix and postfix **increment** and **decrement** operators behave
exactly like they would in C. They require a named expression (see the
*Named Expressions* subsection) as an operand.
The prefix versions of these operators are more efficient; use them where
possible.
**-**
: The **negation** operator returns **0** if a user attempts to negate any
expression with the value **0**. Otherwise, a copy of the expression with
its sign flipped is returned.
**!**
: The **boolean not** operator returns **1** if the expression is **0**, or
**0** otherwise.
This is a **non-portable extension**.
**\^**
: The **power** operator (not the **exclusive or** operator, as it would be in
C) takes two expressions and raises the first to the power of the value of
the second. The *scale* of the result is equal to **scale**.
The second expression must be an integer (no *scale*), and if it is
negative, the first value must be non-zero.
**\***
: The **multiply** operator takes two expressions, multiplies them, and
returns the product. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result is
equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The **divide** operator takes two expressions, divides them, and returns the
quotient. The *scale* of the result shall be the value of **scale**.
The second expression must be non-zero.
**%**
: The **modulus** operator takes two expressions, **a** and **b**, and
evaluates them by 1) Computing **a/b** to current **scale** and 2) Using the
result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The second expression must be non-zero.
**+**
: The **add** operator takes two expressions, **a** and **b**, and returns the
sum, with a *scale* equal to the max of the *scale*s of **a** and **b**.
**-**
: The **subtract** operator takes two expressions, **a** and **b**, and
returns the difference, with a *scale* equal to the max of the *scale*s of
**a** and **b**.
**=** **+=** **-=** **\*=** **/=** **%=** **\^=**
: The **assignment** operators take two expressions, **a** and **b** where
**a** is a named expression (see the *Named Expressions* subsection).
For **=**, **b** is copied and the result is assigned to **a**. For all
others, **a** and **b** are applied as operands to the corresponding
arithmetic operator and the result is assigned to **a**.
**==** **\<=** **\>=** **!=** **\<** **\>**
: The **relational** operators compare two expressions, **a** and **b**, and
if the relation holds, according to C language semantics, the result is
**1**. Otherwise, it is **0**.
Note that unlike in C, these operators have a lower precedence than the
**assignment** operators, which means that **a=b\>c** is interpreted as
**(a=b)\>c**.
Also, unlike the [standard][1] requires, these operators can appear anywhere
any other expressions can be used. This allowance is a
**non-portable extension**.
**&&**
: The **boolean and** operator takes two expressions and returns **1** if both
expressions are non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
**||**
: The **boolean or** operator takes two expressions and returns **1** if one
of the expressions is non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
## Statements
The following items are statements:
1. **E**
2. **{** **S** **;** ... **;** **S** **}**
3. **if** **(** **E** **)** **S**
4. **if** **(** **E** **)** **S** **else** **S**
5. **while** **(** **E** **)** **S**
6. **for** **(** **E** **;** **E** **;** **E** **)** **S**
7. An empty statement
8. **break**
9. **continue**
10. **quit**
11. **halt**
12. **limits**
13. A string of characters, enclosed in double quotes
14. **print** **E** **,** ... **,** **E**
15. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
Numbers 4, 9, 11, 12, 14, and 15 are **non-portable extensions**.
Also, as a **non-portable extension**, any or all of the expressions in the
header of a for loop may be omitted. If the condition (second expression) is
omitted, it is assumed to be a constant **1**.
The **break** statement causes a loop to stop iterating and resume execution
immediately following a loop. This is only allowed in loops.
The **continue** statement causes a loop iteration to stop early and returns to
the start of the loop, including testing the loop condition. This is only
allowed in loops.
The **if** **else** statement does the same thing as in C.
The **quit** statement causes bc(1) to quit, even if it is on a branch that will
not be executed (it is a compile-time command).
The **halt** statement causes bc(1) to quit, if it is executed. (Unlike **quit**
if it is on a branch of an **if** statement that is not executed, bc(1) does not
quit.)
The **limits** statement prints the limits that this bc(1) is subject to. This
is like the **quit** statement in that it is a compile-time command.
An expression by itself is evaluated and printed, followed by a newline.
## Print Statement
The "expressions" in a **print** statement may also be strings. If they are, there
are backslash escape sequences that are interpreted specially. What those
sequences are, and what they cause to be printed, are shown below:
-------- -------
**\\a** **\\a**
**\\b** **\\b**
**\\\\** **\\**
**\\e** **\\**
**\\f** **\\f**
**\\n** **\\n**
**\\q** **"**
**\\r** **\\r**
**\\t** **\\t**
-------- -------
Any other character following a backslash causes the backslash and character to
be printed as-is.
Any non-string expression in a print statement shall be assigned to **last**,
like any other expression that is printed.
## Order of Evaluation
All expressions in a statment are evaluated left to right, except as necessary
to maintain order of operations. This means, for example, assuming that **i** is
equal to **0**, in the expression
a[i++] = i++
the first (or 0th) element of **a** is set to **1**, and **i** is equal to **2**
at the end of the expression.
This includes function arguments. Thus, assuming **i** is equal to **0**, this
means that in the expression
x(i++, i++)
the first argument passed to **x()** is **0**, and the second argument is **1**,
while **i** is equal to **2** before the function starts executing.
# FUNCTIONS
Function definitions are as follows:
```
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
```
Any **I** in the parameter list or **auto** list may be replaced with **I[]** to
make a parameter or **auto** var an array, and any **I** in the parameter list
may be replaced with **\*I[]** to make a parameter an array reference. Callers
of functions that take array references should not put an asterisk in the call;
they must be called with just **I[]** like normal array parameters and will be
automatically converted into references.
As a **non-portable extension**, the opening brace of a **define** statement may
appear on the next line.
As a **non-portable extension**, the return statement may also be in one of the
following forms:
1. **return**
2. **return** **(** **)**
3. **return** **E**
The first two, or not specifying a **return** statement, is equivalent to
**return (0)**, unless the function is a **void** function (see the *Void
Functions* subsection below).
## Void Functions
Functions can also be **void** functions, defined as follows:
```
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
```
They can only be used as standalone expressions, where such an expression would
be printed alone, except in a print statement.
Void functions can only use the first two **return** statements listed above.
They can also omit the return statement entirely.
The word "void" is not treated as a keyword; it is still possible to have
variables, arrays, and functions named **void**. The word "void" is only
treated specially right after the **define** keyword.
This is a **non-portable extension**.
## Array References
For any array in the parameter list, if the array is declared in the form
```
*I[]
```
it is a **reference**. Any changes to the array in the function are reflected,
when the function returns, to the array that was passed in.
Other than this, all function arguments are passed by value.
This is a **non-portable extension**.
# LIBRARY
All of the functions below are available when the **-l** or **--mathlib**
command-line flags are given.
## Standard Library
The [standard][1] defines the following functions for the math library:
**s(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**c(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a(x)**
: Returns the arctangent of **x**, in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l(x)**
: Returns the natural logarithm of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**e(x)**
: Returns the mathematical constant **e** raised to the power of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**j(x, n)**
: Returns the bessel integer order **n** (truncated) of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
## Transcendental Functions
All transcendental functions can return slightly inaccurate results (up to 1
[ULP][4]). This is unavoidable, and [this article][5] explains why it is
impossible and unnecessary to calculate exact results for the transcendental
functions.
Because of the possible inaccuracy, I recommend that users call those functions
with the precision (**scale**) set to at least 1 higher than is necessary. If
exact results are *absolutely* required, users can double the precision
(**scale**) and then truncate.
The transcendental functions in the standard math library are:
* **s(x)**
* **c(x)**
* **a(x)**
* **l(x)**
* **e(x)**
* **j(x, n)**
# RESET
When bc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any functions that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
functions returned) is skipped.
Thus, when bc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
Note that this reset behavior is different from the GNU bc(1), which attempts to
start executing the statement right after the one that caused an error.
# PERFORMANCE
Most bc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This bc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **BC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **BC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**BC_BASE_DIGS**.
The actual values of **BC_LONG_BIT** and **BC_BASE_DIGS** can be queried with
the **limits** statement.
In addition, this bc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **BC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on bc(1):
**BC_LONG_BIT**
: The number of bits in the **long** type in the environment where bc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**BC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **BC_LONG_BIT**.
**BC_BASE_POW**
: The max decimal number that each large integer can store (see
**BC_BASE_DIGS**) plus **1**. Depends on **BC_BASE_DIGS**.
**BC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **BC_LONG_BIT**.
**BC_BASE_MAX**
: The maximum output base. Set at **BC_BASE_POW**.
**BC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**BC_SCALE_MAX**
: The maximum **scale**. Set at **BC_OVERFLOW_MAX-1**.
**BC_STRING_MAX**
: The maximum length of strings. Set at **BC_OVERFLOW_MAX-1**.
**BC_NAME_MAX**
: The maximum length of identifiers. Set at **BC_OVERFLOW_MAX-1**.
**BC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **BC_OVERFLOW_MAX-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**BC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
The actual values can be queried with the **limits** statement.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
bc(1) recognizes the following environment variables:
**POSIXLY_CORRECT**
: If this variable exists (no matter the contents), bc(1) behaves as if
the **-s** option was given.
**BC_ENV_ARGS**
: This is another way to give command-line arguments to bc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **BC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
The code that parses **BC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some bc file.bc"** will be correctly parsed, but the string
**"/home/gavin/some \"bc\" file.bc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **BC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**BC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), bc(1) will output
lines to that length, including the backslash (**\\**). The default line
length is **70**.
# EXIT STATUS
bc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**) operator and the corresponding assignment operator.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, using a token where it is invalid,
giving an invalid expression, giving an invalid print statement, giving an
invalid function definition, attempting to assign to an expression that is
not a named expression (see the *Named Expressions* subsection of the
**SYNTAX** section), giving an invalid **auto** list, having a duplicate
**auto**/function parameter, failing to find the end of a code block,
attempting to return a value from a **void** function, attempting to use a
variable as a reference, and using any extensions when the option **-s** or
any equivalents were given.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a **void** function call as a value in an expression.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (bc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, bc(1) always exits
and returns **4**, no matter what mode bc(1) is in.
The other statuses will only be returned when bc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since bc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Per the [standard][1], bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, bc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, bc(1) turns
on "TTY mode."
TTY mode is required for history to be enabled (see the **COMMAND LINE HISTORY**
section). It is also required to enable special handling for **SIGINT** signals.
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause bc(1) to stop execution of the current input. If
bc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If bc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If bc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to bc(1) as it is executing a file, it
can seem as though bc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause bc(1) to clean up and exit, and it uses the
default handler for all other signals. The one exception is **SIGHUP**; in that
case, when bc(1) is in TTY mode, a **SIGHUP** will cause bc(1) to clean up and
exit.
# COMMAND LINE HISTORY
bc(1) supports interactive command-line editing. If bc(1) is in TTY mode (see
the **TTY MODE** section), history is enabled. Previous lines can be recalled
and edited with the arrow keys.
**Note**: tabs are converted to 8 spaces.
# SEE ALSO
dc(1)
# STANDARDS
bc(1) is compliant with the [IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1]
specification. The flags **-efghiqsvVw**, all long options, and the extensions
noted above are extensions to that specification.
Note that the specification explicitly says that bc(1) only accepts numbers that
use a period (**.**) as a radix point, regardless of the value of
**LC_NUMERIC**.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHORS
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
[2]: https://www.gnu.org/software/bc/
[3]: https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero
[4]: https://en.wikipedia.org/wiki/Unit_in_the_last_place
[5]: https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT
[6]: https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero
diff --git a/contrib/bc/manuals/bc/EP.1 b/contrib/bc/manuals/bc/EP.1
index 2213f7fd3141..ba27d5cc4862 100644
--- a/contrib/bc/manuals/bc/EP.1
+++ b/contrib/bc/manuals/bc/EP.1
@@ -1,1294 +1,1307 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "BC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "BC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH NAME
.PP
bc - arbitrary-precision decimal arithmetic language and calculator
.SH SYNOPSIS
.PP
\f[B]bc\f[R] [\f[B]-ghilPqsvVw\f[R]] [\f[B]\[en]global-stacks\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]mathlib\f[R]] [\f[B]\[en]no-prompt\f[R]]
[\f[B]\[en]quiet\f[R]] [\f[B]\[en]standard\f[R]] [\f[B]\[en]warn\f[R]]
[\f[B]\[en]version\f[R]] [\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
bc(1) is an interactive processor for a language first standardized in
1991 by POSIX.
(The current standard is
here (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).)
The language provides unlimited precision decimal arithmetic and is
somewhat C-like, but there are differences.
Such differences will be noted in this document.
.PP
After parsing and handling options, this bc(1) reads any files given on
the command line and executes them before reading from \f[B]stdin\f[R].
.PP
This bc(1) is a drop-in replacement for \f[I]any\f[R] bc(1), including
(and especially) the GNU bc(1).
.SH OPTIONS
.PP
The following are the options that bc(1) accepts.
.PP
\f[B]-g\f[R], \f[B]\[en]global-stacks\f[R]
.IP
.nf
\f[C]
Turns the globals **ibase**, **obase**, and **scale** into stacks.
This has the effect that a copy of the current value of all three are pushed
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
However, since using this flag means that functions cannot set **ibase**,
**obase**, or **scale** globally, functions that are made to do so cannot
work anymore. There are two possible use cases for that, and each has a
solution.
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o=\[dq]bc -e ibase=A -e obase=8\[dq]
alias h2b=\[dq]bc -e ibase=G -e obase=2\[dq]
Second, if the purpose of a function is to set **ibase**, **obase**, or
**scale** globally for any other purpose, it could be split into one to
three functions (based on how many globals it sets) and each of those
functions could return the desired value for a global.
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
\f[R]
.fi
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-l\f[R], \f[B]\[en]mathlib\f[R]
Sets \f[B]scale\f[R] (see the \f[B]SYNTAX\f[R] section) to \f[B]20\f[R]
and loads the included math library before running any code, including
any expressions or files specified on the command line.
.RS
.PP
To learn what is in the library, see the \f[B]LIBRARY\f[R] section.
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
This option is a no-op.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-q\f[R], \f[B]\[en]quiet\f[R]
This option is for compatibility with the GNU
bc(1) (https://www.gnu.org/software/bc/); it is a no-op.
Without this option, GNU bc(1) prints a copyright header.
This bc(1) only prints the copyright header if one or more of the
\f[B]-v\f[R], \f[B]-V\f[R], or \f[B]\[en]version\f[R] options are given.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-s\f[R], \f[B]\[en]standard\f[R]
Process exactly the language defined by the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
and error if any extensions are used.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-w\f[R], \f[B]\[en]warn\f[R]
Like \f[B]-s\f[R] and \f[B]\[en]standard\f[R], except that warnings (and
not errors) are printed for non-standard extensions and execution
continues normally.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]BC_ENV_ARGS\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]bc >&-\f[R], it will quit with an error.
This is done so that bc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]bc 2>&-\f[R], it will quit with an error.
This is done so that bc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
The syntax for bc(1) programs is mostly C-like, with some differences.
This bc(1) follows the POSIX
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
which is a much more thorough resource for the language this bc(1)
accepts.
This section is meant to be a summary and a listing of all the
extensions to the standard.
.PP
In the sections below, \f[B]E\f[R] means expression, \f[B]S\f[R] means
statement, and \f[B]I\f[R] means identifier.
.PP
Identifiers (\f[B]I\f[R]) start with a lowercase letter and can be
followed by any number (up to \f[B]BC_NAME_MAX-1\f[R]) of lowercase
letters (\f[B]a-z\f[R]), digits (\f[B]0-9\f[R]), and underscores
(\f[B]_\f[R]).
The regex is \f[B][a-z][a-z0-9_]*\f[R].
Identifiers with more than one character (letter) are a
\f[B]non-portable extension\f[R].
.PP
\f[B]ibase\f[R] is a global variable determining how to interpret
constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
If the \f[B]-s\f[R] (\f[B]\[en]standard\f[R]) and \f[B]-w\f[R]
(\f[B]\[en]warn\f[R]) flags were not given on the command line, the max
allowable value for \f[B]ibase\f[R] is \f[B]36\f[R].
Otherwise, it is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in bc(1)
programs with the \f[B]maxibase()\f[R] built-in function.
.PP
\f[B]obase\f[R] is a global variable determining how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]BC_BASE_MAX\f[R] and
can be queried in bc(1) programs with the \f[B]maxobase()\f[R] built-in
function.
The min allowable value for \f[B]obase\f[R] is \f[B]2\f[R].
Values are output in the specified base.
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a global variable that sets the precision of any operations, with
exceptions.
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] is \f[B]BC_SCALE_MAX\f[R]
and can be queried in bc(1) programs with the \f[B]maxscale()\f[R]
built-in function.
.PP
bc(1) has both \f[I]global\f[R] variables and \f[I]local\f[R] variables.
All \f[I]local\f[R] variables are local to the function; they are
parameters or are introduced in the \f[B]auto\f[R] list of a function
(see the \f[B]FUNCTIONS\f[R] section).
If a variable is accessed which is not a parameter or in the
\f[B]auto\f[R] list, it is assumed to be \f[I]global\f[R].
If a parent function has a \f[I]local\f[R] variable version of a
variable that a child function considers \f[I]global\f[R], the value of
that \f[I]global\f[R] variable in the child function is the value of the
variable in the parent function, not the value of the actual
\f[I]global\f[R] variable.
.PP
All of the above applies to arrays as well.
.PP
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence
operator is an assignment operator \f[I]and\f[R] the expression is
notsurrounded by parentheses.
.PP
The value that is printed is also assigned to the special variable
\f[B]last\f[R].
A single dot (\f[B].\f[R]) may also be used as a synonym for
\f[B]last\f[R].
These are \f[B]non-portable extensions\f[R].
.PP
Either semicolons or newlines may separate statements.
.SS Comments
.PP
There are two kinds of comments:
.IP "1." 3
Block comments are enclosed in \f[B]/*\f[R] and \f[B]*/\f[R].
.IP "2." 3
Line comments go from \f[B]#\f[R] until, and not including, the next
newline.
This is a \f[B]non-portable extension\f[R].
.SS Named Expressions
.PP
The following are named expressions in bc(1):
.IP "1." 3
Variables: \f[B]I\f[R]
.IP "2." 3
Array Elements: \f[B]I[E]\f[R]
.IP "3." 3
\f[B]ibase\f[R]
.IP "4." 3
\f[B]obase\f[R]
.IP "5." 3
\f[B]scale\f[R]
.IP "6." 3
\f[B]last\f[R] or a single dot (\f[B].\f[R])
.PP
Number 6 is a \f[B]non-portable extension\f[R].
.PP
Variables and arrays do not interfere; users can have arrays named the
same as variables.
This also applies to functions (see the \f[B]FUNCTIONS\f[R] section), so
a user can have a variable, array, and function that all have the same
name, and they will not shadow each other, whether inside of functions
or not.
.PP
Named expressions are required as the operand of
\f[B]increment\f[R]/\f[B]decrement\f[R] operators and as the left side
of \f[B]assignment\f[R] operators (see the \f[I]Operators\f[R]
subsection).
.SS Operands
.PP
The following are valid operands in bc(1):
.IP " 1." 4
Numbers (see the \f[I]Numbers\f[R] subsection below).
.IP " 2." 4
Array indices (\f[B]I[E]\f[R]).
.IP " 3." 4
\f[B](E)\f[R]: The value of \f[B]E\f[R] (used to change precedence).
.IP " 4." 4
\f[B]sqrt(E)\f[R]: The square root of \f[B]E\f[R].
\f[B]E\f[R] must be non-negative.
.IP " 5." 4
\f[B]length(E)\f[R]: The number of significant decimal digits in
\f[B]E\f[R].
.IP " 6." 4
\f[B]length(I[])\f[R]: The number of elements in the array \f[B]I\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 7." 4
\f[B]scale(E)\f[R]: The \f[I]scale\f[R] of \f[B]E\f[R].
.IP " 8." 4
\f[B]abs(E)\f[R]: The absolute value of \f[B]E\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 9." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a non-\f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.IP "10." 4
\f[B]read()\f[R]: Reads a line from \f[B]stdin\f[R] and uses that as an
expression.
The result of that expression is the result of the \f[B]read()\f[R]
operand.
This is a \f[B]non-portable extension\f[R].
.IP "11." 4
\f[B]maxibase()\f[R]: The max allowable \f[B]ibase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "12." 4
\f[B]maxobase()\f[R]: The max allowable \f[B]obase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "13." 4
\f[B]maxscale()\f[R]: The max allowable \f[B]scale\f[R].
This is a \f[B]non-portable extension\f[R].
.SS Numbers
.PP
Numbers are strings made up of digits, uppercase letters, and at most
\f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]BC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]Z\f[R] alone always equals decimal \f[B]35\f[R].
.SS Operators
.PP
The following arithmetic and logical operators can be used.
They are listed in order of decreasing precedence.
Operators in the same group have the same precedence.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
Type: Prefix and Postfix
.RS
.PP
Associativity: None
.PP
Description: \f[B]increment\f[R], \f[B]decrement\f[R]
.RE
.TP
\f[B]-\f[R] \f[B]!\f[R]
Type: Prefix
.RS
.PP
Associativity: None
.PP
Description: \f[B]negation\f[R], \f[B]boolean not\f[R]
.RE
.TP
\f[B]\[ha]\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]power\f[R]
.RE
.TP
\f[B]*\f[R] \f[B]/\f[R] \f[B]%\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]multiply\f[R], \f[B]divide\f[R], \f[B]modulus\f[R]
.RE
.TP
\f[B]+\f[R] \f[B]-\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]add\f[R], \f[B]subtract\f[R]
.RE
.TP
\f[B]=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]assignment\f[R]
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]relational\f[R]
.RE
.TP
\f[B]&&\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean and\f[R]
.RE
.TP
\f[B]||\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean or\f[R]
.RE
.PP
The operators will be described in more detail below.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
The prefix and postfix \f[B]increment\f[R] and \f[B]decrement\f[R]
operators behave exactly like they would in C.
They require a named expression (see the \f[I]Named Expressions\f[R]
subsection) as an operand.
.RS
.PP
The prefix versions of these operators are more efficient; use them
where possible.
.RE
.TP
\f[B]-\f[R]
The \f[B]negation\f[R] operator returns \f[B]0\f[R] if a user attempts
to negate any expression with the value \f[B]0\f[R].
Otherwise, a copy of the expression with its sign flipped is returned.
.TP
\f[B]!\f[R]
The \f[B]boolean not\f[R] operator returns \f[B]1\f[R] if the expression
is \f[B]0\f[R], or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The \f[B]power\f[R] operator (not the \f[B]exclusive or\f[R] operator,
as it would be in C) takes two expressions and raises the first to the
power of the value of the second.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]), and if it
is negative, the first value must be non-zero.
.RE
.TP
\f[B]*\f[R]
The \f[B]multiply\f[R] operator takes two expressions, multiplies them,
and returns the product.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The \f[B]divide\f[R] operator takes two expressions, divides them, and
returns the quotient.
The \f[I]scale\f[R] of the result shall be the value of \f[B]scale\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]%\f[R]
The \f[B]modulus\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and evaluates them by 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R] and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]+\f[R]
The \f[B]add\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the sum, with a \f[I]scale\f[R] equal to the
max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]-\f[R]
The \f[B]subtract\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the difference, with a \f[I]scale\f[R] equal to
the max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R]
The \f[B]assignment\f[R] operators take two expressions, \f[B]a\f[R] and
\f[B]b\f[R] where \f[B]a\f[R] is a named expression (see the \f[I]Named
Expressions\f[R] subsection).
.RS
.PP
For \f[B]=\f[R], \f[B]b\f[R] is copied and the result is assigned to
\f[B]a\f[R].
For all others, \f[B]a\f[R] and \f[B]b\f[R] are applied as operands to
the corresponding arithmetic operator and the result is assigned to
\f[B]a\f[R].
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
The \f[B]relational\f[R] operators compare two expressions, \f[B]a\f[R]
and \f[B]b\f[R], and if the relation holds, according to C language
semantics, the result is \f[B]1\f[R].
Otherwise, it is \f[B]0\f[R].
.RS
.PP
Note that unlike in C, these operators have a lower precedence than the
\f[B]assignment\f[R] operators, which means that \f[B]a=b>c\f[R] is
interpreted as \f[B](a=b)>c\f[R].
.PP
Also, unlike the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
requires, these operators can appear anywhere any other expressions can
be used.
This allowance is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]&&\f[R]
The \f[B]boolean and\f[R] operator takes two expressions and returns
\f[B]1\f[R] if both expressions are non-zero, \f[B]0\f[R] otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]||\f[R]
The \f[B]boolean or\f[R] operator takes two expressions and returns
\f[B]1\f[R] if one of the expressions is non-zero, \f[B]0\f[R]
otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Statements
.PP
The following items are statements:
.IP " 1." 4
\f[B]E\f[R]
.IP " 2." 4
\f[B]{\f[R] \f[B]S\f[R] \f[B];\f[R] \&... \f[B];\f[R] \f[B]S\f[R]
\f[B]}\f[R]
.IP " 3." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 4." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
\f[B]else\f[R] \f[B]S\f[R]
.IP " 5." 4
\f[B]while\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 6." 4
\f[B]for\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B];\f[R] \f[B]E\f[R]
\f[B];\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 7." 4
An empty statement
.IP " 8." 4
\f[B]break\f[R]
.IP " 9." 4
\f[B]continue\f[R]
.IP "10." 4
\f[B]quit\f[R]
.IP "11." 4
\f[B]halt\f[R]
.IP "12." 4
\f[B]limits\f[R]
.IP "13." 4
A string of characters, enclosed in double quotes
.IP "14." 4
\f[B]print\f[R] \f[B]E\f[R] \f[B],\f[R] \&... \f[B],\f[R] \f[B]E\f[R]
.IP "15." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a \f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.PP
Numbers 4, 9, 11, 12, 14, and 15 are \f[B]non-portable extensions\f[R].
.PP
Also, as a \f[B]non-portable extension\f[R], any or all of the
expressions in the header of a for loop may be omitted.
If the condition (second expression) is omitted, it is assumed to be a
constant \f[B]1\f[R].
.PP
The \f[B]break\f[R] statement causes a loop to stop iterating and resume
execution immediately following a loop.
This is only allowed in loops.
.PP
The \f[B]continue\f[R] statement causes a loop iteration to stop early
and returns to the start of the loop, including testing the loop
condition.
This is only allowed in loops.
.PP
The \f[B]if\f[R] \f[B]else\f[R] statement does the same thing as in C.
.PP
The \f[B]quit\f[R] statement causes bc(1) to quit, even if it is on a
branch that will not be executed (it is a compile-time command).
.PP
The \f[B]halt\f[R] statement causes bc(1) to quit, if it is executed.
(Unlike \f[B]quit\f[R] if it is on a branch of an \f[B]if\f[R] statement
that is not executed, bc(1) does not quit.)
.PP
The \f[B]limits\f[R] statement prints the limits that this bc(1) is
subject to.
This is like the \f[B]quit\f[R] statement in that it is a compile-time
command.
.PP
An expression by itself is evaluated and printed, followed by a newline.
.SS Print Statement
.PP
The \[lq]expressions\[rq] in a \f[B]print\f[R] statement may also be
strings.
If they are, there are backslash escape sequences that are interpreted
specially.
What those sequences are, and what they cause to be printed, are shown
below:
.PP
.TS
tab(@);
l l.
T{
\f[B]\[rs]a\f[R]
T}@T{
\f[B]\[rs]a\f[R]
T}
T{
\f[B]\[rs]b\f[R]
T}@T{
\f[B]\[rs]b\f[R]
T}
T{
\f[B]\[rs]\[rs]\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]e\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]f\f[R]
T}@T{
\f[B]\[rs]f\f[R]
T}
T{
\f[B]\[rs]n\f[R]
T}@T{
\f[B]\[rs]n\f[R]
T}
T{
\f[B]\[rs]q\f[R]
T}@T{
\f[B]\[dq]\f[R]
T}
T{
\f[B]\[rs]r\f[R]
T}@T{
\f[B]\[rs]r\f[R]
T}
T{
\f[B]\[rs]t\f[R]
T}@T{
\f[B]\[rs]t\f[R]
T}
.TE
.PP
Any other character following a backslash causes the backslash and
character to be printed as-is.
.PP
Any non-string expression in a print statement shall be assigned to
\f[B]last\f[R], like any other expression that is printed.
.SS Order of Evaluation
.PP
All expressions in a statment are evaluated left to right, except as
necessary to maintain order of operations.
This means, for example, assuming that \f[B]i\f[R] is equal to
\f[B]0\f[R], in the expression
.IP
.nf
\f[C]
a[i++] = i++
\f[R]
.fi
.PP
the first (or 0th) element of \f[B]a\f[R] is set to \f[B]1\f[R], and
\f[B]i\f[R] is equal to \f[B]2\f[R] at the end of the expression.
.PP
This includes function arguments.
Thus, assuming \f[B]i\f[R] is equal to \f[B]0\f[R], this means that in
the expression
.IP
.nf
\f[C]
x(i++, i++)
\f[R]
.fi
.PP
the first argument passed to \f[B]x()\f[R] is \f[B]0\f[R], and the
second argument is \f[B]1\f[R], while \f[B]i\f[R] is equal to
\f[B]2\f[R] before the function starts executing.
.SH FUNCTIONS
.PP
Function definitions are as follows:
.IP
.nf
\f[C]
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
\f[R]
.fi
.PP
Any \f[B]I\f[R] in the parameter list or \f[B]auto\f[R] list may be
replaced with \f[B]I[]\f[R] to make a parameter or \f[B]auto\f[R] var an
array, and any \f[B]I\f[R] in the parameter list may be replaced with
\f[B]*I[]\f[R] to make a parameter an array reference.
Callers of functions that take array references should not put an
asterisk in the call; they must be called with just \f[B]I[]\f[R] like
normal array parameters and will be automatically converted into
references.
.PP
As a \f[B]non-portable extension\f[R], the opening brace of a
\f[B]define\f[R] statement may appear on the next line.
.PP
As a \f[B]non-portable extension\f[R], the return statement may also be
in one of the following forms:
.IP "1." 3
\f[B]return\f[R]
.IP "2." 3
\f[B]return\f[R] \f[B](\f[R] \f[B])\f[R]
.IP "3." 3
\f[B]return\f[R] \f[B]E\f[R]
.PP
The first two, or not specifying a \f[B]return\f[R] statement, is
equivalent to \f[B]return (0)\f[R], unless the function is a
\f[B]void\f[R] function (see the \f[I]Void Functions\f[R] subsection
below).
.SS Void Functions
.PP
Functions can also be \f[B]void\f[R] functions, defined as follows:
.IP
.nf
\f[C]
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
\f[R]
.fi
.PP
They can only be used as standalone expressions, where such an
expression would be printed alone, except in a print statement.
.PP
Void functions can only use the first two \f[B]return\f[R] statements
listed above.
They can also omit the return statement entirely.
.PP
The word \[lq]void\[rq] is not treated as a keyword; it is still
possible to have variables, arrays, and functions named \f[B]void\f[R].
The word \[lq]void\[rq] is only treated specially right after the
\f[B]define\f[R] keyword.
.PP
This is a \f[B]non-portable extension\f[R].
.SS Array References
.PP
For any array in the parameter list, if the array is declared in the
form
.IP
.nf
\f[C]
*I[]
\f[R]
.fi
.PP
it is a \f[B]reference\f[R].
Any changes to the array in the function are reflected, when the
function returns, to the array that was passed in.
.PP
Other than this, all function arguments are passed by value.
.PP
This is a \f[B]non-portable extension\f[R].
.SH LIBRARY
.PP
All of the functions below are available when the \f[B]-l\f[R] or
\f[B]\[en]mathlib\f[R] command-line flags are given.
.SS Standard Library
.PP
The
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
defines the following functions for the math library:
.TP
\f[B]s(x)\f[R]
Returns the sine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]c(x)\f[R]
Returns the cosine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]a(x)\f[R]
Returns the arctangent of \f[B]x\f[R], in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]l(x)\f[R]
Returns the natural logarithm of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]e(x)\f[R]
Returns the mathematical constant \f[B]e\f[R] raised to the power of
\f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]j(x, n)\f[R]
Returns the bessel integer order \f[B]n\f[R] (truncated) of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.SS Transcendental Functions
.PP
All transcendental functions can return slightly inaccurate results (up
to 1 ULP (https://en.wikipedia.org/wiki/Unit_in_the_last_place)).
This is unavoidable, and this
article (https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT) explains
why it is impossible and unnecessary to calculate exact results for the
transcendental functions.
.PP
Because of the possible inaccuracy, I recommend that users call those
functions with the precision (\f[B]scale\f[R]) set to at least 1 higher
than is necessary.
If exact results are \f[I]absolutely\f[R] required, users can double the
precision (\f[B]scale\f[R]) and then truncate.
.PP
The transcendental functions in the standard math library are:
.IP \[bu] 2
\f[B]s(x)\f[R]
.IP \[bu] 2
\f[B]c(x)\f[R]
.IP \[bu] 2
\f[B]a(x)\f[R]
.IP \[bu] 2
\f[B]l(x)\f[R]
.IP \[bu] 2
\f[B]e(x)\f[R]
.IP \[bu] 2
\f[B]j(x, n)\f[R]
.SH RESET
.PP
When bc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any functions that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all functions returned) is skipped.
.PP
Thus, when bc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.PP
Note that this reset behavior is different from the GNU bc(1), which
attempts to start executing the statement right after the one that
caused an error.
.SH PERFORMANCE
.PP
Most bc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This bc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]BC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]BC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]BC_BASE_DIGS\f[R].
.PP
The actual values of \f[B]BC_LONG_BIT\f[R] and \f[B]BC_BASE_DIGS\f[R]
can be queried with the \f[B]limits\f[R] statement.
.PP
In addition, this bc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]BC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on bc(1):
.TP
\f[B]BC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
bc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]BC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]BC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]BC_BASE_DIGS\f[R].
.TP
\f[B]BC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]BC_BASE_POW\f[R].
.TP
\f[B]BC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]BC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]BC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
The actual values can be queried with the \f[B]limits\f[R] statement.
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
bc(1) recognizes the following environment variables:
.TP
\f[B]POSIXLY_CORRECT\f[R]
If this variable exists (no matter the contents), bc(1) behaves as if
the \f[B]-s\f[R] option was given.
.TP
\f[B]BC_ENV_ARGS\f[R]
This is another way to give command-line arguments to bc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]BC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
.RS
.PP
The code that parses \f[B]BC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some bc file.bc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]bc\[dq] file.bc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]BC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]BC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), bc(1) will output lines to that length,
including the backslash (\f[B]\[rs]\f[R]).
The default line length is \f[B]70\f[R].
.SH EXIT STATUS
.PP
bc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, attempting to convert a negative number to a hardware
integer, overflow when converting a number to a hardware integer, and
attempting to use a non-integer where an integer is required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]) operator and the corresponding assignment
operator.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, using a token
where it is invalid, giving an invalid expression, giving an invalid
print statement, giving an invalid function definition, attempting to
assign to an expression that is not a named expression (see the
\f[I]Named Expressions\f[R] subsection of the \f[B]SYNTAX\f[R] section),
giving an invalid \f[B]auto\f[R] list, having a duplicate
\f[B]auto\f[R]/function parameter, failing to find the end of a code
block, attempting to return a value from a \f[B]void\f[R] function,
attempting to use a variable as a reference, and using any extensions
when the option \f[B]-s\f[R] or any equivalents were given.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a \f[B]void\f[R] function call as a value in an
expression.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (bc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, bc(1)
always exits and returns \f[B]4\f[R], no matter what mode bc(1) is in.
.PP
The other statuses will only be returned when bc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
bc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Per the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, bc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, bc(1) turns on \[lq]TTY mode.\[rq]
.PP
TTY mode is required for history to be enabled (see the \f[B]COMMAND
LINE HISTORY\f[R] section).
It is also required to enable special handling for \f[B]SIGINT\f[R]
signals.
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause bc(1) to stop execution of the
current input.
If bc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If bc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If bc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to bc(1) as it is
executing a file, it can seem as though bc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause bc(1) to clean up and
exit, and it uses the default handler for all other signals.
The one exception is \f[B]SIGHUP\f[R]; in that case, when bc(1) is in
TTY mode, a \f[B]SIGHUP\f[R] will cause bc(1) to clean up and exit.
.SH COMMAND LINE HISTORY
.PP
bc(1) supports interactive command-line editing.
If bc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), history is
enabled.
Previous lines can be recalled and edited with the arrow keys.
.PP
\f[B]Note\f[R]: tabs are converted to 8 spaces.
.SH LOCALES
.PP
This bc(1) ships with support for adding error messages for different
locales and thus, supports \f[B]LC_MESSAGES\f[R].
.SH SEE ALSO
.PP
dc(1)
.SH STANDARDS
.PP
bc(1) is compliant with the IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
The flags \f[B]-efghiqsvVw\f[R], all long options, and the extensions
noted above are extensions to that specification.
.PP
Note that the specification explicitly says that bc(1) only accepts
numbers that use a period (\f[B].\f[R]) as a radix point, regardless of
the value of \f[B]LC_NUMERIC\f[R].
.PP
This bc(1) supports error messages for different locales, and thus, it
supports \f[B]LC_MESSAGES\f[R].
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHORS
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/bc/EP.1.md b/contrib/bc/manuals/bc/EP.1.md
index d60706d46d91..fe6107ce86d7 100644
--- a/contrib/bc/manuals/bc/EP.1.md
+++ b/contrib/bc/manuals/bc/EP.1.md
@@ -1,1079 +1,1088 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# NAME
bc - arbitrary-precision decimal arithmetic language and calculator
# SYNOPSIS
**bc** [**-ghilPqsvVw**] [**--global-stacks**] [**--help**] [**--interactive**] [**--mathlib**] [**--no-prompt**] [**--quiet**] [**--standard**] [**--warn**] [**--version**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...]
[*file*...]
# DESCRIPTION
bc(1) is an interactive processor for a language first standardized in 1991 by
POSIX. (The current standard is [here][1].) The language provides unlimited
precision decimal arithmetic and is somewhat C-like, but there are differences.
Such differences will be noted in this document.
After parsing and handling options, this bc(1) reads any files given on the
command line and executes them before reading from **stdin**.
This bc(1) is a drop-in replacement for *any* bc(1), including (and
especially) the GNU bc(1).
# OPTIONS
The following are the options that bc(1) accepts.
**-g**, **--global-stacks**
Turns the globals **ibase**, **obase**, and **scale** into stacks.
This has the effect that a copy of the current value of all three are pushed
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
However, since using this flag means that functions cannot set **ibase**,
**obase**, or **scale** globally, functions that are made to do so cannot
work anymore. There are two possible use cases for that, and each has a
solution.
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o="bc -e ibase=A -e obase=8"
alias h2b="bc -e ibase=G -e obase=2"
Second, if the purpose of a function is to set **ibase**, **obase**, or
**scale** globally for any other purpose, it could be split into one to
three functions (based on how many globals it sets) and each of those
functions could return the desired value for a global.
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
**-h**, **--help**
: Prints a usage message and quits.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-l**, **--mathlib**
: Sets **scale** (see the **SYNTAX** section) to **20** and loads the included
math library before running any code, including any expressions or files
specified on the command line.
To learn what is in the library, see the **LIBRARY** section.
**-P**, **--no-prompt**
: This option is a no-op.
This is a **non-portable extension**.
**-q**, **--quiet**
: This option is for compatibility with the [GNU bc(1)][2]; it is a no-op.
Without this option, GNU bc(1) prints a copyright header. This bc(1) only
prints the copyright header if one or more of the **-v**, **-V**, or
**--version** options are given.
This is a **non-portable extension**.
**-s**, **--standard**
: Process exactly the language defined by the [standard][1] and error if any
extensions are used.
This is a **non-portable extension**.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
This is a **non-portable extension**.
**-w**, **--warn**
: Like **-s** and **--standard**, except that warnings (and not errors) are
printed for non-standard extensions and execution continues normally.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **BC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **bc <file> >&-**, it will quit with an error. This
is done so that bc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **bc <file> 2>&-**, it will quit with an error. This
is done so that bc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
The syntax for bc(1) programs is mostly C-like, with some differences. This
bc(1) follows the [POSIX standard][1], which is a much more thorough resource
for the language this bc(1) accepts. This section is meant to be a summary and a
listing of all the extensions to the standard.
In the sections below, **E** means expression, **S** means statement, and **I**
means identifier.
Identifiers (**I**) start with a lowercase letter and can be followed by any
number (up to **BC_NAME_MAX-1**) of lowercase letters (**a-z**), digits
(**0-9**), and underscores (**\_**). The regex is **\[a-z\]\[a-z0-9\_\]\***.
Identifiers with more than one character (letter) are a
**non-portable extension**.
**ibase** is a global variable determining how to interpret constant numbers. It
is the "input" base, or the number base used for interpreting input numbers.
**ibase** is initially **10**. If the **-s** (**--standard**) and **-w**
(**--warn**) flags were not given on the command line, the max allowable value
for **ibase** is **36**. Otherwise, it is **16**. The min allowable value for
**ibase** is **2**. The max allowable value for **ibase** can be queried in
bc(1) programs with the **maxibase()** built-in function.
**obase** is a global variable determining how to output results. It is the
"output" base, or the number base used for outputting numbers. **obase** is
initially **10**. The max allowable value for **obase** is **BC_BASE_MAX** and
can be queried in bc(1) programs with the **maxobase()** built-in function. The
min allowable value for **obase** is **2**. Values are output in the specified
base.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a global variable that
sets the precision of any operations, with exceptions. **scale** is initially
**0**. **scale** cannot be negative. The max allowable value for **scale** is
**BC_SCALE_MAX** and can be queried in bc(1) programs with the **maxscale()**
built-in function.
bc(1) has both *global* variables and *local* variables. All *local*
variables are local to the function; they are parameters or are introduced in
the **auto** list of a function (see the **FUNCTIONS** section). If a variable
is accessed which is not a parameter or in the **auto** list, it is assumed to
be *global*. If a parent function has a *local* variable version of a variable
that a child function considers *global*, the value of that *global* variable in
the child function is the value of the variable in the parent function, not the
value of the actual *global* variable.
All of the above applies to arrays as well.
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence operator is an
assignment operator *and* the expression is notsurrounded by parentheses.
The value that is printed is also assigned to the special variable **last**. A
single dot (**.**) may also be used as a synonym for **last**. These are
**non-portable extensions**.
Either semicolons or newlines may separate statements.
## Comments
There are two kinds of comments:
1. Block comments are enclosed in **/\*** and **\*/**.
2. Line comments go from **#** until, and not including, the next newline. This
is a **non-portable extension**.
## Named Expressions
The following are named expressions in bc(1):
1. Variables: **I**
2. Array Elements: **I[E]**
3. **ibase**
4. **obase**
5. **scale**
6. **last** or a single dot (**.**)
Number 6 is a **non-portable extension**.
Variables and arrays do not interfere; users can have arrays named the same as
variables. This also applies to functions (see the **FUNCTIONS** section), so a
user can have a variable, array, and function that all have the same name, and
they will not shadow each other, whether inside of functions or not.
Named expressions are required as the operand of **increment**/**decrement**
operators and as the left side of **assignment** operators (see the *Operators*
subsection).
## Operands
The following are valid operands in bc(1):
1. Numbers (see the *Numbers* subsection below).
2. Array indices (**I[E]**).
3. **(E)**: The value of **E** (used to change precedence).
4. **sqrt(E)**: The square root of **E**. **E** must be non-negative.
5. **length(E)**: The number of significant decimal digits in **E**.
6. **length(I[])**: The number of elements in the array **I**. This is a
**non-portable extension**.
7. **scale(E)**: The *scale* of **E**.
8. **abs(E)**: The absolute value of **E**. This is a **non-portable
extension**.
9. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a non-**void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
10. **read()**: Reads a line from **stdin** and uses that as an expression. The
result of that expression is the result of the **read()** operand. This is a
**non-portable extension**.
11. **maxibase()**: The max allowable **ibase**. This is a **non-portable
extension**.
12. **maxobase()**: The max allowable **obase**. This is a **non-portable
extension**.
13. **maxscale()**: The max allowable **scale**. This is a **non-portable
extension**.
## Numbers
Numbers are strings made up of digits, uppercase letters, and at most **1**
period for a radix. Numbers can have up to **BC_NUM_MAX** digits. Uppercase
letters are equal to **9** + their position in the alphabet (i.e., **A** equals
**10**, or **9+1**). If a digit or letter makes no sense with the current value
of **ibase**, they are set to the value of the highest valid digit in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **Z** alone always equals decimal
**35**.
## Operators
The following arithmetic and logical operators can be used. They are listed in
order of decreasing precedence. Operators in the same group have the same
precedence.
**++** **--**
: Type: Prefix and Postfix
Associativity: None
Description: **increment**, **decrement**
**-** **!**
: Type: Prefix
Associativity: None
Description: **negation**, **boolean not**
**\^**
: Type: Binary
Associativity: Right
Description: **power**
**\*** **/** **%**
: Type: Binary
Associativity: Left
Description: **multiply**, **divide**, **modulus**
**+** **-**
: Type: Binary
Associativity: Left
Description: **add**, **subtract**
**=** **+=** **-=** **\*=** **/=** **%=** **\^=**
: Type: Binary
Associativity: Right
Description: **assignment**
**==** **\<=** **\>=** **!=** **\<** **\>**
: Type: Binary
Associativity: Left
Description: **relational**
**&&**
: Type: Binary
Associativity: Left
Description: **boolean and**
**||**
: Type: Binary
Associativity: Left
Description: **boolean or**
The operators will be described in more detail below.
**++** **--**
: The prefix and postfix **increment** and **decrement** operators behave
exactly like they would in C. They require a named expression (see the
*Named Expressions* subsection) as an operand.
The prefix versions of these operators are more efficient; use them where
possible.
**-**
: The **negation** operator returns **0** if a user attempts to negate any
expression with the value **0**. Otherwise, a copy of the expression with
its sign flipped is returned.
**!**
: The **boolean not** operator returns **1** if the expression is **0**, or
**0** otherwise.
This is a **non-portable extension**.
**\^**
: The **power** operator (not the **exclusive or** operator, as it would be in
C) takes two expressions and raises the first to the power of the value of
the second. The *scale* of the result is equal to **scale**.
The second expression must be an integer (no *scale*), and if it is
negative, the first value must be non-zero.
**\***
: The **multiply** operator takes two expressions, multiplies them, and
returns the product. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result is
equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The **divide** operator takes two expressions, divides them, and returns the
quotient. The *scale* of the result shall be the value of **scale**.
The second expression must be non-zero.
**%**
: The **modulus** operator takes two expressions, **a** and **b**, and
evaluates them by 1) Computing **a/b** to current **scale** and 2) Using the
result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The second expression must be non-zero.
**+**
: The **add** operator takes two expressions, **a** and **b**, and returns the
sum, with a *scale* equal to the max of the *scale*s of **a** and **b**.
**-**
: The **subtract** operator takes two expressions, **a** and **b**, and
returns the difference, with a *scale* equal to the max of the *scale*s of
**a** and **b**.
**=** **+=** **-=** **\*=** **/=** **%=** **\^=**
: The **assignment** operators take two expressions, **a** and **b** where
**a** is a named expression (see the *Named Expressions* subsection).
For **=**, **b** is copied and the result is assigned to **a**. For all
others, **a** and **b** are applied as operands to the corresponding
arithmetic operator and the result is assigned to **a**.
**==** **\<=** **\>=** **!=** **\<** **\>**
: The **relational** operators compare two expressions, **a** and **b**, and
if the relation holds, according to C language semantics, the result is
**1**. Otherwise, it is **0**.
Note that unlike in C, these operators have a lower precedence than the
**assignment** operators, which means that **a=b\>c** is interpreted as
**(a=b)\>c**.
Also, unlike the [standard][1] requires, these operators can appear anywhere
any other expressions can be used. This allowance is a
**non-portable extension**.
**&&**
: The **boolean and** operator takes two expressions and returns **1** if both
expressions are non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
**||**
: The **boolean or** operator takes two expressions and returns **1** if one
of the expressions is non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
## Statements
The following items are statements:
1. **E**
2. **{** **S** **;** ... **;** **S** **}**
3. **if** **(** **E** **)** **S**
4. **if** **(** **E** **)** **S** **else** **S**
5. **while** **(** **E** **)** **S**
6. **for** **(** **E** **;** **E** **;** **E** **)** **S**
7. An empty statement
8. **break**
9. **continue**
10. **quit**
11. **halt**
12. **limits**
13. A string of characters, enclosed in double quotes
14. **print** **E** **,** ... **,** **E**
15. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
Numbers 4, 9, 11, 12, 14, and 15 are **non-portable extensions**.
Also, as a **non-portable extension**, any or all of the expressions in the
header of a for loop may be omitted. If the condition (second expression) is
omitted, it is assumed to be a constant **1**.
The **break** statement causes a loop to stop iterating and resume execution
immediately following a loop. This is only allowed in loops.
The **continue** statement causes a loop iteration to stop early and returns to
the start of the loop, including testing the loop condition. This is only
allowed in loops.
The **if** **else** statement does the same thing as in C.
The **quit** statement causes bc(1) to quit, even if it is on a branch that will
not be executed (it is a compile-time command).
The **halt** statement causes bc(1) to quit, if it is executed. (Unlike **quit**
if it is on a branch of an **if** statement that is not executed, bc(1) does not
quit.)
The **limits** statement prints the limits that this bc(1) is subject to. This
is like the **quit** statement in that it is a compile-time command.
An expression by itself is evaluated and printed, followed by a newline.
## Print Statement
The "expressions" in a **print** statement may also be strings. If they are, there
are backslash escape sequences that are interpreted specially. What those
sequences are, and what they cause to be printed, are shown below:
-------- -------
**\\a** **\\a**
**\\b** **\\b**
**\\\\** **\\**
**\\e** **\\**
**\\f** **\\f**
**\\n** **\\n**
**\\q** **"**
**\\r** **\\r**
**\\t** **\\t**
-------- -------
Any other character following a backslash causes the backslash and character to
be printed as-is.
Any non-string expression in a print statement shall be assigned to **last**,
like any other expression that is printed.
## Order of Evaluation
All expressions in a statment are evaluated left to right, except as necessary
to maintain order of operations. This means, for example, assuming that **i** is
equal to **0**, in the expression
a[i++] = i++
the first (or 0th) element of **a** is set to **1**, and **i** is equal to **2**
at the end of the expression.
This includes function arguments. Thus, assuming **i** is equal to **0**, this
means that in the expression
x(i++, i++)
the first argument passed to **x()** is **0**, and the second argument is **1**,
while **i** is equal to **2** before the function starts executing.
# FUNCTIONS
Function definitions are as follows:
```
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
```
Any **I** in the parameter list or **auto** list may be replaced with **I[]** to
make a parameter or **auto** var an array, and any **I** in the parameter list
may be replaced with **\*I[]** to make a parameter an array reference. Callers
of functions that take array references should not put an asterisk in the call;
they must be called with just **I[]** like normal array parameters and will be
automatically converted into references.
As a **non-portable extension**, the opening brace of a **define** statement may
appear on the next line.
As a **non-portable extension**, the return statement may also be in one of the
following forms:
1. **return**
2. **return** **(** **)**
3. **return** **E**
The first two, or not specifying a **return** statement, is equivalent to
**return (0)**, unless the function is a **void** function (see the *Void
Functions* subsection below).
## Void Functions
Functions can also be **void** functions, defined as follows:
```
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
```
They can only be used as standalone expressions, where such an expression would
be printed alone, except in a print statement.
Void functions can only use the first two **return** statements listed above.
They can also omit the return statement entirely.
The word "void" is not treated as a keyword; it is still possible to have
variables, arrays, and functions named **void**. The word "void" is only
treated specially right after the **define** keyword.
This is a **non-portable extension**.
## Array References
For any array in the parameter list, if the array is declared in the form
```
*I[]
```
it is a **reference**. Any changes to the array in the function are reflected,
when the function returns, to the array that was passed in.
Other than this, all function arguments are passed by value.
This is a **non-portable extension**.
# LIBRARY
All of the functions below are available when the **-l** or **--mathlib**
command-line flags are given.
## Standard Library
The [standard][1] defines the following functions for the math library:
**s(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**c(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a(x)**
: Returns the arctangent of **x**, in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l(x)**
: Returns the natural logarithm of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**e(x)**
: Returns the mathematical constant **e** raised to the power of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**j(x, n)**
: Returns the bessel integer order **n** (truncated) of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
## Transcendental Functions
All transcendental functions can return slightly inaccurate results (up to 1
[ULP][4]). This is unavoidable, and [this article][5] explains why it is
impossible and unnecessary to calculate exact results for the transcendental
functions.
Because of the possible inaccuracy, I recommend that users call those functions
with the precision (**scale**) set to at least 1 higher than is necessary. If
exact results are *absolutely* required, users can double the precision
(**scale**) and then truncate.
The transcendental functions in the standard math library are:
* **s(x)**
* **c(x)**
* **a(x)**
* **l(x)**
* **e(x)**
* **j(x, n)**
# RESET
When bc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any functions that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
functions returned) is skipped.
Thus, when bc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
Note that this reset behavior is different from the GNU bc(1), which attempts to
start executing the statement right after the one that caused an error.
# PERFORMANCE
Most bc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This bc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **BC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **BC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**BC_BASE_DIGS**.
The actual values of **BC_LONG_BIT** and **BC_BASE_DIGS** can be queried with
the **limits** statement.
In addition, this bc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **BC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on bc(1):
**BC_LONG_BIT**
: The number of bits in the **long** type in the environment where bc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**BC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **BC_LONG_BIT**.
**BC_BASE_POW**
: The max decimal number that each large integer can store (see
**BC_BASE_DIGS**) plus **1**. Depends on **BC_BASE_DIGS**.
**BC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **BC_LONG_BIT**.
**BC_BASE_MAX**
: The maximum output base. Set at **BC_BASE_POW**.
**BC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**BC_SCALE_MAX**
: The maximum **scale**. Set at **BC_OVERFLOW_MAX-1**.
**BC_STRING_MAX**
: The maximum length of strings. Set at **BC_OVERFLOW_MAX-1**.
**BC_NAME_MAX**
: The maximum length of identifiers. Set at **BC_OVERFLOW_MAX-1**.
**BC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **BC_OVERFLOW_MAX-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**BC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
The actual values can be queried with the **limits** statement.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
bc(1) recognizes the following environment variables:
**POSIXLY_CORRECT**
: If this variable exists (no matter the contents), bc(1) behaves as if
the **-s** option was given.
**BC_ENV_ARGS**
: This is another way to give command-line arguments to bc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **BC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
The code that parses **BC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some bc file.bc"** will be correctly parsed, but the string
**"/home/gavin/some \"bc\" file.bc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **BC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**BC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), bc(1) will output
lines to that length, including the backslash (**\\**). The default line
length is **70**.
# EXIT STATUS
bc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**) operator and the corresponding assignment operator.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, using a token where it is invalid,
giving an invalid expression, giving an invalid print statement, giving an
invalid function definition, attempting to assign to an expression that is
not a named expression (see the *Named Expressions* subsection of the
**SYNTAX** section), giving an invalid **auto** list, having a duplicate
**auto**/function parameter, failing to find the end of a code block,
attempting to return a value from a **void** function, attempting to use a
variable as a reference, and using any extensions when the option **-s** or
any equivalents were given.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a **void** function call as a value in an expression.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (bc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, bc(1) always exits
and returns **4**, no matter what mode bc(1) is in.
The other statuses will only be returned when bc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since bc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Per the [standard][1], bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, bc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, bc(1) turns
on "TTY mode."
TTY mode is required for history to be enabled (see the **COMMAND LINE HISTORY**
section). It is also required to enable special handling for **SIGINT** signals.
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause bc(1) to stop execution of the current input. If
bc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If bc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If bc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to bc(1) as it is executing a file, it
can seem as though bc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause bc(1) to clean up and exit, and it uses the
default handler for all other signals. The one exception is **SIGHUP**; in that
case, when bc(1) is in TTY mode, a **SIGHUP** will cause bc(1) to clean up and
exit.
# COMMAND LINE HISTORY
bc(1) supports interactive command-line editing. If bc(1) is in TTY mode (see
the **TTY MODE** section), history is enabled. Previous lines can be recalled
and edited with the arrow keys.
**Note**: tabs are converted to 8 spaces.
# LOCALES
This bc(1) ships with support for adding error messages for different locales
and thus, supports **LC_MESSAGES**.
# SEE ALSO
dc(1)
# STANDARDS
bc(1) is compliant with the [IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1]
specification. The flags **-efghiqsvVw**, all long options, and the extensions
noted above are extensions to that specification.
Note that the specification explicitly says that bc(1) only accepts numbers that
use a period (**.**) as a radix point, regardless of the value of
**LC_NUMERIC**.
This bc(1) supports error messages for different locales, and thus, it supports
**LC_MESSAGES**.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHORS
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
[2]: https://www.gnu.org/software/bc/
[3]: https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero
[4]: https://en.wikipedia.org/wiki/Unit_in_the_last_place
[5]: https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT
[6]: https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero
diff --git a/contrib/bc/manuals/bc/H.1 b/contrib/bc/manuals/bc/H.1
index df3fdf974c82..fb824377e4f1 100644
--- a/contrib/bc/manuals/bc/H.1
+++ b/contrib/bc/manuals/bc/H.1
@@ -1,2025 +1,2038 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "BC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "BC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH NAME
.PP
bc - arbitrary-precision decimal arithmetic language and calculator
.SH SYNOPSIS
.PP
\f[B]bc\f[R] [\f[B]-ghilPqsvVw\f[R]] [\f[B]\[en]global-stacks\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]mathlib\f[R]] [\f[B]\[en]no-prompt\f[R]]
[\f[B]\[en]quiet\f[R]] [\f[B]\[en]standard\f[R]] [\f[B]\[en]warn\f[R]]
[\f[B]\[en]version\f[R]] [\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
bc(1) is an interactive processor for a language first standardized in
1991 by POSIX.
(The current standard is
here (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).)
The language provides unlimited precision decimal arithmetic and is
somewhat C-like, but there are differences.
Such differences will be noted in this document.
.PP
After parsing and handling options, this bc(1) reads any files given on
the command line and executes them before reading from \f[B]stdin\f[R].
.SH OPTIONS
.PP
The following are the options that bc(1) accepts.
.TP
\f[B]-g\f[R], \f[B]\[en]global-stacks\f[R]
Turns the globals \f[B]ibase\f[R], \f[B]obase\f[R], \f[B]scale\f[R], and
\f[B]seed\f[R] into stacks.
.RS
.PP
This has the effect that a copy of the current value of all four are
pushed onto a stack for every function call, as well as popped when
every function returns.
This means that functions can assign to any and all of those globals
without worrying that the change will affect other functions.
Thus, a hypothetical function named \f[B]output(x,b)\f[R] that simply
printed \f[B]x\f[R] in base \f[B]b\f[R] could be written like this:
.IP
.nf
\f[C]
define void output(x, b) {
obase=b
x
}
\f[R]
.fi
.PP
instead of like this:
.IP
.nf
\f[C]
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
\f[R]
.fi
.PP
This makes writing functions much easier.
.PP
(\f[B]Note\f[R]: the function \f[B]output(x,b)\f[R] exists in the
extended math library.
See the \f[B]LIBRARY\f[R] section.)
.PP
However, since using this flag means that functions cannot set
\f[B]ibase\f[R], \f[B]obase\f[R], \f[B]scale\f[R], or \f[B]seed\f[R]
globally, functions that are made to do so cannot work anymore.
There are two possible use cases for that, and each has a solution.
.PP
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases.
Examples:
.IP
.nf
\f[C]
alias d2o=\[dq]bc -e ibase=A -e obase=8\[dq]
alias h2b=\[dq]bc -e ibase=G -e obase=2\[dq]
\f[R]
.fi
.PP
Second, if the purpose of a function is to set \f[B]ibase\f[R],
\f[B]obase\f[R], \f[B]scale\f[R], or \f[B]seed\f[R] globally for any
other purpose, it could be split into one to four functions (based on
how many globals it sets) and each of those functions could return the
desired value for a global.
.PP
For functions that set \f[B]seed\f[R], the value assigned to
\f[B]seed\f[R] is not propagated to parent functions.
This means that the sequence of pseudo-random numbers that they see will
not be the same sequence of pseudo-random numbers that any parent sees.
This is only the case once \f[B]seed\f[R] has been set.
.PP
If a function desires to not affect the sequence of pseudo-random
numbers of its parents, but wants to use the same \f[B]seed\f[R], it can
use the following line:
.IP
.nf
\f[C]
seed = seed
\f[R]
.fi
.PP
If the behavior of this option is desired for every run of bc(1), then
users could make sure to define \f[B]BC_ENV_ARGS\f[R] and include this
option (see the \f[B]ENVIRONMENT VARIABLES\f[R] section for more
details).
.PP
If \f[B]-s\f[R], \f[B]-w\f[R], or any equivalents are used, this option
is ignored.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-l\f[R], \f[B]\[en]mathlib\f[R]
Sets \f[B]scale\f[R] (see the \f[B]SYNTAX\f[R] section) to \f[B]20\f[R]
and loads the included math library and the extended math library before
running any code, including any expressions or files specified on the
command line.
.RS
.PP
To learn what is in the libraries, see the \f[B]LIBRARY\f[R] section.
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
Disables the prompt in TTY mode.
(The prompt is only enabled in TTY mode.
See the \f[B]TTY MODE\f[R] section) This is mostly for those users that
do not want a prompt or are not used to having them in bc(1).
Most of those users would want to put this option in
\f[B]BC_ENV_ARGS\f[R] (see the \f[B]ENVIRONMENT VARIABLES\f[R] section).
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-q\f[R], \f[B]\[en]quiet\f[R]
This option is for compatibility with the GNU
bc(1) (https://www.gnu.org/software/bc/); it is a no-op.
Without this option, GNU bc(1) prints a copyright header.
This bc(1) only prints the copyright header if one or more of the
\f[B]-v\f[R], \f[B]-V\f[R], or \f[B]\[en]version\f[R] options are given.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-s\f[R], \f[B]\[en]standard\f[R]
Process exactly the language defined by the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
and error if any extensions are used.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-w\f[R], \f[B]\[en]warn\f[R]
Like \f[B]-s\f[R] and \f[B]\[en]standard\f[R], except that warnings (and
not errors) are printed for non-standard extensions and execution
continues normally.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]BC_ENV_ARGS\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]bc >&-\f[R], it will quit with an error.
This is done so that bc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]bc 2>&-\f[R], it will quit with an error.
This is done so that bc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
The syntax for bc(1) programs is mostly C-like, with some differences.
This bc(1) follows the POSIX
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
which is a much more thorough resource for the language this bc(1)
accepts.
This section is meant to be a summary and a listing of all the
extensions to the standard.
.PP
In the sections below, \f[B]E\f[R] means expression, \f[B]S\f[R] means
statement, and \f[B]I\f[R] means identifier.
.PP
Identifiers (\f[B]I\f[R]) start with a lowercase letter and can be
followed by any number (up to \f[B]BC_NAME_MAX-1\f[R]) of lowercase
letters (\f[B]a-z\f[R]), digits (\f[B]0-9\f[R]), and underscores
(\f[B]_\f[R]).
The regex is \f[B][a-z][a-z0-9_]*\f[R].
Identifiers with more than one character (letter) are a
\f[B]non-portable extension\f[R].
.PP
\f[B]ibase\f[R] is a global variable determining how to interpret
constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
If the \f[B]-s\f[R] (\f[B]\[en]standard\f[R]) and \f[B]-w\f[R]
(\f[B]\[en]warn\f[R]) flags were not given on the command line, the max
allowable value for \f[B]ibase\f[R] is \f[B]36\f[R].
Otherwise, it is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in bc(1)
programs with the \f[B]maxibase()\f[R] built-in function.
.PP
\f[B]obase\f[R] is a global variable determining how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]BC_BASE_MAX\f[R] and
can be queried in bc(1) programs with the \f[B]maxobase()\f[R] built-in
function.
The min allowable value for \f[B]obase\f[R] is \f[B]0\f[R].
If \f[B]obase\f[R] is \f[B]0\f[R], values are output in scientific
notation, and if \f[B]obase\f[R] is \f[B]1\f[R], values are output in
engineering notation.
Otherwise, values are output in the specified base.
.PP
Outputting in scientific and engineering notations are \f[B]non-portable
extensions\f[R].
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a global variable that sets the precision of any operations, with
exceptions.
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] is \f[B]BC_SCALE_MAX\f[R]
and can be queried in bc(1) programs with the \f[B]maxscale()\f[R]
built-in function.
.PP
bc(1) has both \f[I]global\f[R] variables and \f[I]local\f[R] variables.
All \f[I]local\f[R] variables are local to the function; they are
parameters or are introduced in the \f[B]auto\f[R] list of a function
(see the \f[B]FUNCTIONS\f[R] section).
If a variable is accessed which is not a parameter or in the
\f[B]auto\f[R] list, it is assumed to be \f[I]global\f[R].
If a parent function has a \f[I]local\f[R] variable version of a
variable that a child function considers \f[I]global\f[R], the value of
that \f[I]global\f[R] variable in the child function is the value of the
variable in the parent function, not the value of the actual
\f[I]global\f[R] variable.
.PP
All of the above applies to arrays as well.
.PP
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence
operator is an assignment operator \f[I]and\f[R] the expression is
notsurrounded by parentheses.
.PP
The value that is printed is also assigned to the special variable
\f[B]last\f[R].
A single dot (\f[B].\f[R]) may also be used as a synonym for
\f[B]last\f[R].
These are \f[B]non-portable extensions\f[R].
.PP
Either semicolons or newlines may separate statements.
.SS Comments
.PP
There are two kinds of comments:
.IP "1." 3
Block comments are enclosed in \f[B]/*\f[R] and \f[B]*/\f[R].
.IP "2." 3
Line comments go from \f[B]#\f[R] until, and not including, the next
newline.
This is a \f[B]non-portable extension\f[R].
.SS Named Expressions
.PP
The following are named expressions in bc(1):
.IP "1." 3
Variables: \f[B]I\f[R]
.IP "2." 3
Array Elements: \f[B]I[E]\f[R]
.IP "3." 3
\f[B]ibase\f[R]
.IP "4." 3
\f[B]obase\f[R]
.IP "5." 3
\f[B]scale\f[R]
.IP "6." 3
\f[B]seed\f[R]
.IP "7." 3
\f[B]last\f[R] or a single dot (\f[B].\f[R])
.PP
Numbers 6 and 7 are \f[B]non-portable extensions\f[R].
.PP
The meaning of \f[B]seed\f[R] is dependent on the current pseudo-random
number generator but is guaranteed to not change except for new major
versions.
.PP
The \f[I]scale\f[R] and sign of the value may be significant.
.PP
If a previously used \f[B]seed\f[R] value is assigned to \f[B]seed\f[R]
and used again, the pseudo-random number generator is guaranteed to
produce the same sequence of pseudo-random numbers as it did when the
\f[B]seed\f[R] value was previously used.
.PP
The exact value assigned to \f[B]seed\f[R] is not guaranteed to be
returned if \f[B]seed\f[R] is queried again immediately.
However, if \f[B]seed\f[R] \f[I]does\f[R] return a different value, both
values, when assigned to \f[B]seed\f[R], are guaranteed to produce the
same sequence of pseudo-random numbers.
This means that certain values assigned to \f[B]seed\f[R] will
\f[I]not\f[R] produce unique sequences of pseudo-random numbers.
The value of \f[B]seed\f[R] will change after any use of the
\f[B]rand()\f[R] and \f[B]irand(E)\f[R] operands (see the
\f[I]Operands\f[R] subsection below), except if the parameter passed to
\f[B]irand(E)\f[R] is \f[B]0\f[R], \f[B]1\f[R], or negative.
.PP
There is no limit to the length (number of significant decimal digits)
or \f[I]scale\f[R] of the value that can be assigned to \f[B]seed\f[R].
.PP
Variables and arrays do not interfere; users can have arrays named the
same as variables.
This also applies to functions (see the \f[B]FUNCTIONS\f[R] section), so
a user can have a variable, array, and function that all have the same
name, and they will not shadow each other, whether inside of functions
or not.
.PP
Named expressions are required as the operand of
\f[B]increment\f[R]/\f[B]decrement\f[R] operators and as the left side
of \f[B]assignment\f[R] operators (see the \f[I]Operators\f[R]
subsection).
.SS Operands
.PP
The following are valid operands in bc(1):
.IP " 1." 4
Numbers (see the \f[I]Numbers\f[R] subsection below).
.IP " 2." 4
Array indices (\f[B]I[E]\f[R]).
.IP " 3." 4
\f[B](E)\f[R]: The value of \f[B]E\f[R] (used to change precedence).
.IP " 4." 4
\f[B]sqrt(E)\f[R]: The square root of \f[B]E\f[R].
\f[B]E\f[R] must be non-negative.
.IP " 5." 4
\f[B]length(E)\f[R]: The number of significant decimal digits in
\f[B]E\f[R].
.IP " 6." 4
\f[B]length(I[])\f[R]: The number of elements in the array \f[B]I\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 7." 4
\f[B]scale(E)\f[R]: The \f[I]scale\f[R] of \f[B]E\f[R].
.IP " 8." 4
\f[B]abs(E)\f[R]: The absolute value of \f[B]E\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 9." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a non-\f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.IP "10." 4
\f[B]read()\f[R]: Reads a line from \f[B]stdin\f[R] and uses that as an
expression.
The result of that expression is the result of the \f[B]read()\f[R]
operand.
This is a \f[B]non-portable extension\f[R].
.IP "11." 4
\f[B]maxibase()\f[R]: The max allowable \f[B]ibase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "12." 4
\f[B]maxobase()\f[R]: The max allowable \f[B]obase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "13." 4
\f[B]maxscale()\f[R]: The max allowable \f[B]scale\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "14." 4
\f[B]rand()\f[R]: A pseudo-random integer between \f[B]0\f[R]
(inclusive) and \f[B]BC_RAND_MAX\f[R] (inclusive).
Using this operand will change the value of \f[B]seed\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "15." 4
\f[B]irand(E)\f[R]: A pseudo-random integer between \f[B]0\f[R]
(inclusive) and the value of \f[B]E\f[R] (exclusive).
If \f[B]E\f[R] is negative or is a non-integer (\f[B]E\f[R]\[cq]s
\f[I]scale\f[R] is not \f[B]0\f[R]), an error is raised, and bc(1)
resets (see the \f[B]RESET\f[R] section) while \f[B]seed\f[R] remains
unchanged.
If \f[B]E\f[R] is larger than \f[B]BC_RAND_MAX\f[R], the higher bound is
honored by generating several pseudo-random integers, multiplying them
by appropriate powers of \f[B]BC_RAND_MAX+1\f[R], and adding them
together.
Thus, the size of integer that can be generated with this operand is
unbounded.
Using this operand will change the value of \f[B]seed\f[R], unless the
value of \f[B]E\f[R] is \f[B]0\f[R] or \f[B]1\f[R].
In that case, \f[B]0\f[R] is returned, and \f[B]seed\f[R] is
\f[I]not\f[R] changed.
This is a \f[B]non-portable extension\f[R].
.IP "16." 4
\f[B]maxrand()\f[R]: The max integer returned by \f[B]rand()\f[R].
This is a \f[B]non-portable extension\f[R].
.PP
The integers generated by \f[B]rand()\f[R] and \f[B]irand(E)\f[R] are
guaranteed to be as unbiased as possible, subject to the limitations of
the pseudo-random number generator.
.PP
\f[B]Note\f[R]: The values returned by the pseudo-random number
generator with \f[B]rand()\f[R] and \f[B]irand(E)\f[R] are guaranteed to
\f[I]NOT\f[R] be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator.
However, they \f[I]are\f[R] guaranteed to be reproducible with identical
\f[B]seed\f[R] values.
This means that the pseudo-random values from bc(1) should only be used
where a reproducible stream of pseudo-random numbers is
\f[I]ESSENTIAL\f[R].
In any other case, use a non-seeded pseudo-random number generator.
.SS Numbers
.PP
Numbers are strings made up of digits, uppercase letters, and at most
\f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]BC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]Z\f[R] alone always equals decimal \f[B]35\f[R].
.PP
In addition, bc(1) accepts numbers in scientific notation.
These have the form \f[B]<number>e<integer>\f[R].
The exponent (the portion after the \f[B]e\f[R]) must be an integer.
An example is \f[B]1.89237e9\f[R], which is equal to
\f[B]1892370000\f[R].
Negative exponents are also allowed, so \f[B]4.2890e-3\f[R] is equal to
\f[B]0.0042890\f[R].
.PP
Using scientific notation is an error or warning if the \f[B]-s\f[R] or
\f[B]-w\f[R], respectively, command-line options (or equivalents) are
given.
.PP
\f[B]WARNING\f[R]: Both the number and the exponent in scientific
notation are interpreted according to the current \f[B]ibase\f[R], but
the number is still multiplied by \f[B]10\[ha]exponent\f[R] regardless
of the current \f[B]ibase\f[R].
For example, if \f[B]ibase\f[R] is \f[B]16\f[R] and bc(1) is given the
number string \f[B]FFeA\f[R], the resulting decimal number will be
\f[B]2550000000000\f[R], and if bc(1) is given the number string
\f[B]10e-4\f[R], the resulting decimal number will be \f[B]0.0016\f[R].
.PP
Accepting input as scientific notation is a \f[B]non-portable
extension\f[R].
.SS Operators
.PP
The following arithmetic and logical operators can be used.
They are listed in order of decreasing precedence.
Operators in the same group have the same precedence.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
Type: Prefix and Postfix
.RS
.PP
Associativity: None
.PP
Description: \f[B]increment\f[R], \f[B]decrement\f[R]
.RE
.TP
\f[B]-\f[R] \f[B]!\f[R]
Type: Prefix
.RS
.PP
Associativity: None
.PP
Description: \f[B]negation\f[R], \f[B]boolean not\f[R]
.RE
.TP
\f[B]$\f[R]
Type: Postfix
.RS
.PP
Associativity: None
.PP
Description: \f[B]truncation\f[R]
.RE
.TP
\f[B]\[at]\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]set precision\f[R]
.RE
.TP
\f[B]\[ha]\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]power\f[R]
.RE
.TP
\f[B]*\f[R] \f[B]/\f[R] \f[B]%\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]multiply\f[R], \f[B]divide\f[R], \f[B]modulus\f[R]
.RE
.TP
\f[B]+\f[R] \f[B]-\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]add\f[R], \f[B]subtract\f[R]
.RE
.TP
\f[B]<<\f[R] \f[B]>>\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]shift left\f[R], \f[B]shift right\f[R]
.RE
.TP
\f[B]=\f[R] \f[B]<<=\f[R] \f[B]>>=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R] \f[B]\[at]=\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]assignment\f[R]
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]relational\f[R]
.RE
.TP
\f[B]&&\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean and\f[R]
.RE
.TP
\f[B]||\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean or\f[R]
.RE
.PP
The operators will be described in more detail below.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
The prefix and postfix \f[B]increment\f[R] and \f[B]decrement\f[R]
operators behave exactly like they would in C.
They require a named expression (see the \f[I]Named Expressions\f[R]
subsection) as an operand.
.RS
.PP
The prefix versions of these operators are more efficient; use them
where possible.
.RE
.TP
\f[B]-\f[R]
The \f[B]negation\f[R] operator returns \f[B]0\f[R] if a user attempts
to negate any expression with the value \f[B]0\f[R].
Otherwise, a copy of the expression with its sign flipped is returned.
.TP
\f[B]!\f[R]
The \f[B]boolean not\f[R] operator returns \f[B]1\f[R] if the expression
is \f[B]0\f[R], or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]$\f[R]
The \f[B]truncation\f[R] operator returns a copy of the given expression
with all of its \f[I]scale\f[R] removed.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[at]\f[R]
The \f[B]set precision\f[R] operator takes two expressions and returns a
copy of the first with its \f[I]scale\f[R] equal to the value of the
second expression.
That could either mean that the number is returned without change (if
the \f[I]scale\f[R] of the first expression matches the value of the
second expression), extended (if it is less), or truncated (if it is
more).
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]) and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The \f[B]power\f[R] operator (not the \f[B]exclusive or\f[R] operator,
as it would be in C) takes two expressions and raises the first to the
power of the value of the second.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]), and if it
is negative, the first value must be non-zero.
.RE
.TP
\f[B]*\f[R]
The \f[B]multiply\f[R] operator takes two expressions, multiplies them,
and returns the product.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The \f[B]divide\f[R] operator takes two expressions, divides them, and
returns the quotient.
The \f[I]scale\f[R] of the result shall be the value of \f[B]scale\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]%\f[R]
The \f[B]modulus\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and evaluates them by 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R] and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]+\f[R]
The \f[B]add\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the sum, with a \f[I]scale\f[R] equal to the
max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]-\f[R]
The \f[B]subtract\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the difference, with a \f[I]scale\f[R] equal to
the max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]<<\f[R]
The \f[B]left shift\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns a copy of the value of \f[B]a\f[R] with its
decimal point moved \f[B]b\f[R] places to the right.
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]) and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]>>\f[R]
The \f[B]right shift\f[R] operator takes two expressions, \f[B]a\f[R]
and \f[B]b\f[R], and returns a copy of the value of \f[B]a\f[R] with its
decimal point moved \f[B]b\f[R] places to the left.
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]) and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]=\f[R] \f[B]<<=\f[R] \f[B]>>=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R] \f[B]\[at]=\f[R]
The \f[B]assignment\f[R] operators take two expressions, \f[B]a\f[R] and
\f[B]b\f[R] where \f[B]a\f[R] is a named expression (see the \f[I]Named
Expressions\f[R] subsection).
.RS
.PP
For \f[B]=\f[R], \f[B]b\f[R] is copied and the result is assigned to
\f[B]a\f[R].
For all others, \f[B]a\f[R] and \f[B]b\f[R] are applied as operands to
the corresponding arithmetic operator and the result is assigned to
\f[B]a\f[R].
.PP
The \f[B]assignment\f[R] operators that correspond to operators that are
extensions are themselves \f[B]non-portable extensions\f[R].
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
The \f[B]relational\f[R] operators compare two expressions, \f[B]a\f[R]
and \f[B]b\f[R], and if the relation holds, according to C language
semantics, the result is \f[B]1\f[R].
Otherwise, it is \f[B]0\f[R].
.RS
.PP
Note that unlike in C, these operators have a lower precedence than the
\f[B]assignment\f[R] operators, which means that \f[B]a=b>c\f[R] is
interpreted as \f[B](a=b)>c\f[R].
.PP
Also, unlike the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
requires, these operators can appear anywhere any other expressions can
be used.
This allowance is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]&&\f[R]
The \f[B]boolean and\f[R] operator takes two expressions and returns
\f[B]1\f[R] if both expressions are non-zero, \f[B]0\f[R] otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]||\f[R]
The \f[B]boolean or\f[R] operator takes two expressions and returns
\f[B]1\f[R] if one of the expressions is non-zero, \f[B]0\f[R]
otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Statements
.PP
The following items are statements:
.IP " 1." 4
\f[B]E\f[R]
.IP " 2." 4
\f[B]{\f[R] \f[B]S\f[R] \f[B];\f[R] \&... \f[B];\f[R] \f[B]S\f[R]
\f[B]}\f[R]
.IP " 3." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 4." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
\f[B]else\f[R] \f[B]S\f[R]
.IP " 5." 4
\f[B]while\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 6." 4
\f[B]for\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B];\f[R] \f[B]E\f[R]
\f[B];\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 7." 4
An empty statement
.IP " 8." 4
\f[B]break\f[R]
.IP " 9." 4
\f[B]continue\f[R]
.IP "10." 4
\f[B]quit\f[R]
.IP "11." 4
\f[B]halt\f[R]
.IP "12." 4
\f[B]limits\f[R]
.IP "13." 4
A string of characters, enclosed in double quotes
.IP "14." 4
\f[B]print\f[R] \f[B]E\f[R] \f[B],\f[R] \&... \f[B],\f[R] \f[B]E\f[R]
.IP "15." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a \f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.PP
Numbers 4, 9, 11, 12, 14, and 15 are \f[B]non-portable extensions\f[R].
.PP
Also, as a \f[B]non-portable extension\f[R], any or all of the
expressions in the header of a for loop may be omitted.
If the condition (second expression) is omitted, it is assumed to be a
constant \f[B]1\f[R].
.PP
The \f[B]break\f[R] statement causes a loop to stop iterating and resume
execution immediately following a loop.
This is only allowed in loops.
.PP
The \f[B]continue\f[R] statement causes a loop iteration to stop early
and returns to the start of the loop, including testing the loop
condition.
This is only allowed in loops.
.PP
The \f[B]if\f[R] \f[B]else\f[R] statement does the same thing as in C.
.PP
The \f[B]quit\f[R] statement causes bc(1) to quit, even if it is on a
branch that will not be executed (it is a compile-time command).
.PP
The \f[B]halt\f[R] statement causes bc(1) to quit, if it is executed.
(Unlike \f[B]quit\f[R] if it is on a branch of an \f[B]if\f[R] statement
that is not executed, bc(1) does not quit.)
.PP
The \f[B]limits\f[R] statement prints the limits that this bc(1) is
subject to.
This is like the \f[B]quit\f[R] statement in that it is a compile-time
command.
.PP
An expression by itself is evaluated and printed, followed by a newline.
.PP
Both scientific notation and engineering notation are available for
printing the results of expressions.
Scientific notation is activated by assigning \f[B]0\f[R] to
\f[B]obase\f[R], and engineering notation is activated by assigning
\f[B]1\f[R] to \f[B]obase\f[R].
To deactivate them, just assign a different value to \f[B]obase\f[R].
.PP
Scientific notation and engineering notation are disabled if bc(1) is
run with either the \f[B]-s\f[R] or \f[B]-w\f[R] command-line options
(or equivalents).
.PP
Printing numbers in scientific notation and/or engineering notation is a
\f[B]non-portable extension\f[R].
.SS Print Statement
.PP
The \[lq]expressions\[rq] in a \f[B]print\f[R] statement may also be
strings.
If they are, there are backslash escape sequences that are interpreted
specially.
What those sequences are, and what they cause to be printed, are shown
below:
.PP
.TS
tab(@);
l l.
T{
\f[B]\[rs]a\f[R]
T}@T{
\f[B]\[rs]a\f[R]
T}
T{
\f[B]\[rs]b\f[R]
T}@T{
\f[B]\[rs]b\f[R]
T}
T{
\f[B]\[rs]\[rs]\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]e\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]f\f[R]
T}@T{
\f[B]\[rs]f\f[R]
T}
T{
\f[B]\[rs]n\f[R]
T}@T{
\f[B]\[rs]n\f[R]
T}
T{
\f[B]\[rs]q\f[R]
T}@T{
\f[B]\[dq]\f[R]
T}
T{
\f[B]\[rs]r\f[R]
T}@T{
\f[B]\[rs]r\f[R]
T}
T{
\f[B]\[rs]t\f[R]
T}@T{
\f[B]\[rs]t\f[R]
T}
.TE
.PP
Any other character following a backslash causes the backslash and
character to be printed as-is.
.PP
Any non-string expression in a print statement shall be assigned to
\f[B]last\f[R], like any other expression that is printed.
.SS Order of Evaluation
.PP
All expressions in a statment are evaluated left to right, except as
necessary to maintain order of operations.
This means, for example, assuming that \f[B]i\f[R] is equal to
\f[B]0\f[R], in the expression
.IP
.nf
\f[C]
a[i++] = i++
\f[R]
.fi
.PP
the first (or 0th) element of \f[B]a\f[R] is set to \f[B]1\f[R], and
\f[B]i\f[R] is equal to \f[B]2\f[R] at the end of the expression.
.PP
This includes function arguments.
Thus, assuming \f[B]i\f[R] is equal to \f[B]0\f[R], this means that in
the expression
.IP
.nf
\f[C]
x(i++, i++)
\f[R]
.fi
.PP
the first argument passed to \f[B]x()\f[R] is \f[B]0\f[R], and the
second argument is \f[B]1\f[R], while \f[B]i\f[R] is equal to
\f[B]2\f[R] before the function starts executing.
.SH FUNCTIONS
.PP
Function definitions are as follows:
.IP
.nf
\f[C]
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
\f[R]
.fi
.PP
Any \f[B]I\f[R] in the parameter list or \f[B]auto\f[R] list may be
replaced with \f[B]I[]\f[R] to make a parameter or \f[B]auto\f[R] var an
array, and any \f[B]I\f[R] in the parameter list may be replaced with
\f[B]*I[]\f[R] to make a parameter an array reference.
Callers of functions that take array references should not put an
asterisk in the call; they must be called with just \f[B]I[]\f[R] like
normal array parameters and will be automatically converted into
references.
.PP
As a \f[B]non-portable extension\f[R], the opening brace of a
\f[B]define\f[R] statement may appear on the next line.
.PP
As a \f[B]non-portable extension\f[R], the return statement may also be
in one of the following forms:
.IP "1." 3
\f[B]return\f[R]
.IP "2." 3
\f[B]return\f[R] \f[B](\f[R] \f[B])\f[R]
.IP "3." 3
\f[B]return\f[R] \f[B]E\f[R]
.PP
The first two, or not specifying a \f[B]return\f[R] statement, is
equivalent to \f[B]return (0)\f[R], unless the function is a
\f[B]void\f[R] function (see the \f[I]Void Functions\f[R] subsection
below).
.SS Void Functions
.PP
Functions can also be \f[B]void\f[R] functions, defined as follows:
.IP
.nf
\f[C]
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
\f[R]
.fi
.PP
They can only be used as standalone expressions, where such an
expression would be printed alone, except in a print statement.
.PP
Void functions can only use the first two \f[B]return\f[R] statements
listed above.
They can also omit the return statement entirely.
.PP
The word \[lq]void\[rq] is not treated as a keyword; it is still
possible to have variables, arrays, and functions named \f[B]void\f[R].
The word \[lq]void\[rq] is only treated specially right after the
\f[B]define\f[R] keyword.
.PP
This is a \f[B]non-portable extension\f[R].
.SS Array References
.PP
For any array in the parameter list, if the array is declared in the
form
.IP
.nf
\f[C]
*I[]
\f[R]
.fi
.PP
it is a \f[B]reference\f[R].
Any changes to the array in the function are reflected, when the
function returns, to the array that was passed in.
.PP
Other than this, all function arguments are passed by value.
.PP
This is a \f[B]non-portable extension\f[R].
.SH LIBRARY
.PP
All of the functions below, including the functions in the extended math
library (see the \f[I]Extended Library\f[R] subsection below), are
available when the \f[B]-l\f[R] or \f[B]\[en]mathlib\f[R] command-line
flags are given, except that the extended math library is not available
when the \f[B]-s\f[R] option, the \f[B]-w\f[R] option, or equivalents
are given.
.SS Standard Library
.PP
The
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
defines the following functions for the math library:
.TP
\f[B]s(x)\f[R]
Returns the sine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]c(x)\f[R]
Returns the cosine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]a(x)\f[R]
Returns the arctangent of \f[B]x\f[R], in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]l(x)\f[R]
Returns the natural logarithm of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]e(x)\f[R]
Returns the mathematical constant \f[B]e\f[R] raised to the power of
\f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]j(x, n)\f[R]
Returns the bessel integer order \f[B]n\f[R] (truncated) of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.SS Extended Library
.PP
The extended library is \f[I]not\f[R] loaded when the
\f[B]-s\f[R]/\f[B]\[en]standard\f[R] or \f[B]-w\f[R]/\f[B]\[en]warn\f[R]
options are given since they are not part of the library defined by the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).
.PP
The extended library is a \f[B]non-portable extension\f[R].
.TP
\f[B]p(x, y)\f[R]
Calculates \f[B]x\f[R] to the power of \f[B]y\f[R], even if \f[B]y\f[R]
is not an integer, and returns the result to the current
\f[B]scale\f[R].
.RS
.PP
It is an error if \f[B]y\f[R] is negative and \f[B]x\f[R] is
\f[B]0\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]r(x, p)\f[R]
Returns \f[B]x\f[R] rounded to \f[B]p\f[R] decimal places according to
the rounding mode round half away from
\f[B]0\f[R] (https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero).
.TP
\f[B]ceil(x, p)\f[R]
Returns \f[B]x\f[R] rounded to \f[B]p\f[R] decimal places according to
the rounding mode round away from
\f[B]0\f[R] (https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero).
.TP
\f[B]f(x)\f[R]
Returns the factorial of the truncated absolute value of \f[B]x\f[R].
.TP
\f[B]perm(n, k)\f[R]
Returns the permutation of the truncated absolute value of \f[B]n\f[R]
of the truncated absolute value of \f[B]k\f[R], if \f[B]k <= n\f[R].
If not, it returns \f[B]0\f[R].
.TP
\f[B]comb(n, k)\f[R]
Returns the combination of the truncated absolute value of \f[B]n\f[R]
of the truncated absolute value of \f[B]k\f[R], if \f[B]k <= n\f[R].
If not, it returns \f[B]0\f[R].
.TP
\f[B]l2(x)\f[R]
Returns the logarithm base \f[B]2\f[R] of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]l10(x)\f[R]
Returns the logarithm base \f[B]10\f[R] of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]log(x, b)\f[R]
Returns the logarithm base \f[B]b\f[R] of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]cbrt(x)\f[R]
Returns the cube root of \f[B]x\f[R].
.TP
\f[B]root(x, n)\f[R]
Calculates the truncated value of \f[B]n\f[R], \f[B]r\f[R], and returns
the \f[B]r\f[R]th root of \f[B]x\f[R] to the current \f[B]scale\f[R].
.RS
.PP
If \f[B]r\f[R] is \f[B]0\f[R] or negative, this raises an error and
causes bc(1) to reset (see the \f[B]RESET\f[R] section).
It also raises an error and causes bc(1) to reset if \f[B]r\f[R] is even
and \f[B]x\f[R] is negative.
.RE
.TP
\f[B]pi(p)\f[R]
Returns \f[B]pi\f[R] to \f[B]p\f[R] decimal places.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]t(x)\f[R]
Returns the tangent of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]a2(y, x)\f[R]
Returns the arctangent of \f[B]y/x\f[R], in radians.
If both \f[B]y\f[R] and \f[B]x\f[R] are equal to \f[B]0\f[R], it raises
an error and causes bc(1) to reset (see the \f[B]RESET\f[R] section).
Otherwise, if \f[B]x\f[R] is greater than \f[B]0\f[R], it returns
\f[B]a(y/x)\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is greater than
or equal to \f[B]0\f[R], it returns \f[B]a(y/x)+pi\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]a(y/x)-pi\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is greater than
\f[B]0\f[R], it returns \f[B]pi/2\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]-pi/2\f[R].
.RS
.PP
This function is the same as the \f[B]atan2()\f[R] function in many
programming languages.
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]sin(x)\f[R]
Returns the sine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is an alias of \f[B]s(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]cos(x)\f[R]
Returns the cosine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is an alias of \f[B]c(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]tan(x)\f[R]
Returns the tangent of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
If \f[B]x\f[R] is equal to \f[B]1\f[R] or \f[B]-1\f[R], this raises an
error and causes bc(1) to reset (see the \f[B]RESET\f[R] section).
.PP
This is an alias of \f[B]t(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]atan(x)\f[R]
Returns the arctangent of \f[B]x\f[R], in radians.
.RS
.PP
This is an alias of \f[B]a(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]atan2(y, x)\f[R]
Returns the arctangent of \f[B]y/x\f[R], in radians.
If both \f[B]y\f[R] and \f[B]x\f[R] are equal to \f[B]0\f[R], it raises
an error and causes bc(1) to reset (see the \f[B]RESET\f[R] section).
Otherwise, if \f[B]x\f[R] is greater than \f[B]0\f[R], it returns
\f[B]a(y/x)\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is greater than
or equal to \f[B]0\f[R], it returns \f[B]a(y/x)+pi\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]a(y/x)-pi\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is greater than
\f[B]0\f[R], it returns \f[B]pi/2\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]-pi/2\f[R].
.RS
.PP
This function is the same as the \f[B]atan2()\f[R] function in many
programming languages.
.PP
This is an alias of \f[B]a2(y, x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]r2d(x)\f[R]
Converts \f[B]x\f[R] from radians to degrees and returns the result.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]d2r(x)\f[R]
Converts \f[B]x\f[R] from degrees to radians and returns the result.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]frand(p)\f[R]
Generates a pseudo-random number between \f[B]0\f[R] (inclusive) and
\f[B]1\f[R] (exclusive) with the number of decimal digits after the
decimal point equal to the truncated absolute value of \f[B]p\f[R].
If \f[B]p\f[R] is not \f[B]0\f[R], then calling this function will
change the value of \f[B]seed\f[R].
If \f[B]p\f[R] is \f[B]0\f[R], then \f[B]0\f[R] is returned, and
\f[B]seed\f[R] is \f[I]not\f[R] changed.
.TP
\f[B]ifrand(i, p)\f[R]
Generates a pseudo-random number that is between \f[B]0\f[R] (inclusive)
and the truncated absolute value of \f[B]i\f[R] (exclusive) with the
number of decimal digits after the decimal point equal to the truncated
absolute value of \f[B]p\f[R].
If the absolute value of \f[B]i\f[R] is greater than or equal to
\f[B]2\f[R], and \f[B]p\f[R] is not \f[B]0\f[R], then calling this
function will change the value of \f[B]seed\f[R]; otherwise, \f[B]0\f[R]
is returned and \f[B]seed\f[R] is not changed.
.TP
\f[B]srand(x)\f[R]
Returns \f[B]x\f[R] with its sign flipped with probability
\f[B]0.5\f[R].
In other words, it randomizes the sign of \f[B]x\f[R].
.TP
\f[B]brand()\f[R]
Returns a random boolean value (either \f[B]0\f[R] or \f[B]1\f[R]).
.TP
\f[B]ubytes(x)\f[R]
Returns the numbers of unsigned integer bytes required to hold the
truncated absolute value of \f[B]x\f[R].
.TP
\f[B]sbytes(x)\f[R]
Returns the numbers of signed, two\[cq]s-complement integer bytes
required to hold the truncated value of \f[B]x\f[R].
.TP
\f[B]hex(x)\f[R]
Outputs the hexadecimal (base \f[B]16\f[R]) representation of
\f[B]x\f[R].
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]binary(x)\f[R]
Outputs the binary (base \f[B]2\f[R]) representation of \f[B]x\f[R].
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]output(x, b)\f[R]
Outputs the base \f[B]b\f[R] representation of \f[B]x\f[R].
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in as few power of two bytes as possible.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or is negative, an error message is
printed instead, but bc(1) is not reset (see the \f[B]RESET\f[R]
section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in as few power of two bytes as
possible.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, an error message is printed instead,
but bc(1) is not reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uintn(x, n)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]n\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]n\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]intn(x, n)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]n\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]n\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint8(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]1\f[R] byte.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]1\f[R] byte, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int8(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]1\f[R] byte.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]1\f[R] byte, an
error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint16(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]2\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]2\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int16(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]2\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]2\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint32(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]4\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]4\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int32(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]4\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]4\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint64(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]8\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]8\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int64(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]8\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]8\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]hex_uint(x, n)\f[R]
Outputs the representation of the truncated absolute value of
\f[B]x\f[R] as an unsigned integer in hexadecimal using \f[B]n\f[R]
bytes.
Not all of the value will be output if \f[B]n\f[R] is too small.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]binary_uint(x, n)\f[R]
Outputs the representation of the truncated absolute value of
\f[B]x\f[R] as an unsigned integer in binary using \f[B]n\f[R] bytes.
Not all of the value will be output if \f[B]n\f[R] is too small.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]output_uint(x, n)\f[R]
Outputs the representation of the truncated absolute value of
\f[B]x\f[R] as an unsigned integer in the current \f[B]obase\f[R] (see
the \f[B]SYNTAX\f[R] section) using \f[B]n\f[R] bytes.
Not all of the value will be output if \f[B]n\f[R] is too small.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]output_byte(x, i)\f[R]
Outputs byte \f[B]i\f[R] of the truncated absolute value of \f[B]x\f[R],
where \f[B]0\f[R] is the least significant byte and \f[B]number_of_bytes
- 1\f[R] is the most significant byte.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.SS Transcendental Functions
.PP
All transcendental functions can return slightly inaccurate results (up
to 1 ULP (https://en.wikipedia.org/wiki/Unit_in_the_last_place)).
This is unavoidable, and this
article (https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT) explains
why it is impossible and unnecessary to calculate exact results for the
transcendental functions.
.PP
Because of the possible inaccuracy, I recommend that users call those
functions with the precision (\f[B]scale\f[R]) set to at least 1 higher
than is necessary.
If exact results are \f[I]absolutely\f[R] required, users can double the
precision (\f[B]scale\f[R]) and then truncate.
.PP
The transcendental functions in the standard math library are:
.IP \[bu] 2
\f[B]s(x)\f[R]
.IP \[bu] 2
\f[B]c(x)\f[R]
.IP \[bu] 2
\f[B]a(x)\f[R]
.IP \[bu] 2
\f[B]l(x)\f[R]
.IP \[bu] 2
\f[B]e(x)\f[R]
.IP \[bu] 2
\f[B]j(x, n)\f[R]
.PP
The transcendental functions in the extended math library are:
.IP \[bu] 2
\f[B]l2(x)\f[R]
.IP \[bu] 2
\f[B]l10(x)\f[R]
.IP \[bu] 2
\f[B]log(x, b)\f[R]
.IP \[bu] 2
\f[B]pi(p)\f[R]
.IP \[bu] 2
\f[B]t(x)\f[R]
.IP \[bu] 2
\f[B]a2(y, x)\f[R]
.IP \[bu] 2
\f[B]sin(x)\f[R]
.IP \[bu] 2
\f[B]cos(x)\f[R]
.IP \[bu] 2
\f[B]tan(x)\f[R]
.IP \[bu] 2
\f[B]atan(x)\f[R]
.IP \[bu] 2
\f[B]atan2(y, x)\f[R]
.IP \[bu] 2
\f[B]r2d(x)\f[R]
.IP \[bu] 2
\f[B]d2r(x)\f[R]
.SH RESET
.PP
When bc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any functions that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all functions returned) is skipped.
.PP
Thus, when bc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.PP
Note that this reset behavior is different from the GNU bc(1), which
attempts to start executing the statement right after the one that
caused an error.
.SH PERFORMANCE
.PP
Most bc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This bc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]BC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]BC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]BC_BASE_DIGS\f[R].
.PP
The actual values of \f[B]BC_LONG_BIT\f[R] and \f[B]BC_BASE_DIGS\f[R]
can be queried with the \f[B]limits\f[R] statement.
.PP
In addition, this bc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]BC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on bc(1):
.TP
\f[B]BC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
bc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]BC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]BC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]BC_BASE_DIGS\f[R].
.TP
\f[B]BC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]BC_BASE_POW\f[R].
.TP
\f[B]BC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]BC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_RAND_MAX\f[R]
The maximum integer (inclusive) returned by the \f[B]rand()\f[R]
operand.
Set at \f[B]2\[ha]BC_LONG_BIT-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]BC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
The actual values can be queried with the \f[B]limits\f[R] statement.
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
bc(1) recognizes the following environment variables:
.TP
\f[B]POSIXLY_CORRECT\f[R]
If this variable exists (no matter the contents), bc(1) behaves as if
the \f[B]-s\f[R] option was given.
.TP
\f[B]BC_ENV_ARGS\f[R]
This is another way to give command-line arguments to bc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]BC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
.RS
.PP
The code that parses \f[B]BC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some bc file.bc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]bc\[dq] file.bc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]BC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]BC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), bc(1) will output lines to that length,
including the backslash (\f[B]\[rs]\f[R]).
The default line length is \f[B]70\f[R].
.SH EXIT STATUS
.PP
bc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, using a negative number as a bound for the
pseudo-random number generator, attempting to convert a negative number
to a hardware integer, overflow when converting a number to a hardware
integer, and attempting to use a non-integer where an integer is
required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]), places (\f[B]\[at]\f[R]), left shift
(\f[B]<<\f[R]), and right shift (\f[B]>>\f[R]) operators and their
corresponding assignment operators.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, using a token
where it is invalid, giving an invalid expression, giving an invalid
print statement, giving an invalid function definition, attempting to
assign to an expression that is not a named expression (see the
\f[I]Named Expressions\f[R] subsection of the \f[B]SYNTAX\f[R] section),
giving an invalid \f[B]auto\f[R] list, having a duplicate
\f[B]auto\f[R]/function parameter, failing to find the end of a code
block, attempting to return a value from a \f[B]void\f[R] function,
attempting to use a variable as a reference, and using any extensions
when the option \f[B]-s\f[R] or any equivalents were given.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a \f[B]void\f[R] function call as a value in an
expression.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (bc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, bc(1)
always exits and returns \f[B]4\f[R], no matter what mode bc(1) is in.
.PP
The other statuses will only be returned when bc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
bc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Per the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, bc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, bc(1) turns on \[lq]TTY mode.\[rq]
.PP
The prompt is enabled in TTY mode.
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause bc(1) to stop execution of the
current input.
If bc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If bc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If bc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to bc(1) as it is
executing a file, it can seem as though bc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause bc(1) to clean up and
exit, and it uses the default handler for all other signals.
.SH LOCALES
.PP
This bc(1) ships with support for adding error messages for different
locales and thus, supports \f[B]LC_MESSAGES\f[R].
.SH SEE ALSO
.PP
dc(1)
.SH STANDARDS
.PP
bc(1) is compliant with the IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
The flags \f[B]-efghiqsvVw\f[R], all long options, and the extensions
noted above are extensions to that specification.
.PP
Note that the specification explicitly says that bc(1) only accepts
numbers that use a period (\f[B].\f[R]) as a radix point, regardless of
the value of \f[B]LC_NUMERIC\f[R].
.PP
This bc(1) supports error messages for different locales, and thus, it
supports \f[B]LC_MESSAGES\f[R].
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHORS
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/bc/H.1.md b/contrib/bc/manuals/bc/H.1.md
index 476bc32019b2..f663b8008c4a 100644
--- a/contrib/bc/manuals/bc/H.1.md
+++ b/contrib/bc/manuals/bc/H.1.md
@@ -1,1679 +1,1688 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# NAME
bc - arbitrary-precision decimal arithmetic language and calculator
# SYNOPSIS
**bc** [**-ghilPqsvVw**] [**--global-stacks**] [**--help**] [**--interactive**] [**--mathlib**] [**--no-prompt**] [**--quiet**] [**--standard**] [**--warn**] [**--version**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...]
[*file*...]
# DESCRIPTION
bc(1) is an interactive processor for a language first standardized in 1991 by
POSIX. (The current standard is [here][1].) The language provides unlimited
precision decimal arithmetic and is somewhat C-like, but there are differences.
Such differences will be noted in this document.
After parsing and handling options, this bc(1) reads any files given on the
command line and executes them before reading from **stdin**.
# OPTIONS
The following are the options that bc(1) accepts.
**-g**, **--global-stacks**
: Turns the globals **ibase**, **obase**, **scale**, and **seed** into stacks.
This has the effect that a copy of the current value of all four are pushed
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
(**Note**: the function **output(x,b)** exists in the extended math library.
See the **LIBRARY** section.)
However, since using this flag means that functions cannot set **ibase**,
**obase**, **scale**, or **seed** globally, functions that are made to do so
cannot work anymore. There are two possible use cases for that, and each has
a solution.
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o="bc -e ibase=A -e obase=8"
alias h2b="bc -e ibase=G -e obase=2"
Second, if the purpose of a function is to set **ibase**, **obase**,
**scale**, or **seed** globally for any other purpose, it could be split
into one to four functions (based on how many globals it sets) and each of
those functions could return the desired value for a global.
For functions that set **seed**, the value assigned to **seed** is not
propagated to parent functions. This means that the sequence of
pseudo-random numbers that they see will not be the same sequence of
pseudo-random numbers that any parent sees. This is only the case once
**seed** has been set.
If a function desires to not affect the sequence of pseudo-random numbers
of its parents, but wants to use the same **seed**, it can use the following
line:
seed = seed
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
**-h**, **--help**
: Prints a usage message and quits.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-l**, **--mathlib**
: Sets **scale** (see the **SYNTAX** section) to **20** and loads the included
math library and the extended math library before running any code,
including any expressions or files specified on the command line.
To learn what is in the libraries, see the **LIBRARY** section.
**-P**, **--no-prompt**
: Disables the prompt in TTY mode. (The prompt is only enabled in TTY mode.
See the **TTY MODE** section) This is mostly for those users that do not
want a prompt or are not used to having them in bc(1). Most of those users
would want to put this option in **BC_ENV_ARGS** (see the
**ENVIRONMENT VARIABLES** section).
This is a **non-portable extension**.
**-q**, **--quiet**
: This option is for compatibility with the [GNU bc(1)][2]; it is a no-op.
Without this option, GNU bc(1) prints a copyright header. This bc(1) only
prints the copyright header if one or more of the **-v**, **-V**, or
**--version** options are given.
This is a **non-portable extension**.
**-s**, **--standard**
: Process exactly the language defined by the [standard][1] and error if any
extensions are used.
This is a **non-portable extension**.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
This is a **non-portable extension**.
**-w**, **--warn**
: Like **-s** and **--standard**, except that warnings (and not errors) are
printed for non-standard extensions and execution continues normally.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **BC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **bc <file> >&-**, it will quit with an error. This
is done so that bc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **bc <file> 2>&-**, it will quit with an error. This
is done so that bc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
The syntax for bc(1) programs is mostly C-like, with some differences. This
bc(1) follows the [POSIX standard][1], which is a much more thorough resource
for the language this bc(1) accepts. This section is meant to be a summary and a
listing of all the extensions to the standard.
In the sections below, **E** means expression, **S** means statement, and **I**
means identifier.
Identifiers (**I**) start with a lowercase letter and can be followed by any
number (up to **BC_NAME_MAX-1**) of lowercase letters (**a-z**), digits
(**0-9**), and underscores (**\_**). The regex is **\[a-z\]\[a-z0-9\_\]\***.
Identifiers with more than one character (letter) are a
**non-portable extension**.
**ibase** is a global variable determining how to interpret constant numbers. It
is the "input" base, or the number base used for interpreting input numbers.
**ibase** is initially **10**. If the **-s** (**--standard**) and **-w**
(**--warn**) flags were not given on the command line, the max allowable value
for **ibase** is **36**. Otherwise, it is **16**. The min allowable value for
**ibase** is **2**. The max allowable value for **ibase** can be queried in
bc(1) programs with the **maxibase()** built-in function.
**obase** is a global variable determining how to output results. It is the
"output" base, or the number base used for outputting numbers. **obase** is
initially **10**. The max allowable value for **obase** is **BC_BASE_MAX** and
can be queried in bc(1) programs with the **maxobase()** built-in function. The
min allowable value for **obase** is **0**. If **obase** is **0**, values are
output in scientific notation, and if **obase** is **1**, values are output in
engineering notation. Otherwise, values are output in the specified base.
Outputting in scientific and engineering notations are **non-portable
extensions**.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a global variable that
sets the precision of any operations, with exceptions. **scale** is initially
**0**. **scale** cannot be negative. The max allowable value for **scale** is
**BC_SCALE_MAX** and can be queried in bc(1) programs with the **maxscale()**
built-in function.
bc(1) has both *global* variables and *local* variables. All *local*
variables are local to the function; they are parameters or are introduced in
the **auto** list of a function (see the **FUNCTIONS** section). If a variable
is accessed which is not a parameter or in the **auto** list, it is assumed to
be *global*. If a parent function has a *local* variable version of a variable
that a child function considers *global*, the value of that *global* variable in
the child function is the value of the variable in the parent function, not the
value of the actual *global* variable.
All of the above applies to arrays as well.
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence operator is an
assignment operator *and* the expression is notsurrounded by parentheses.
The value that is printed is also assigned to the special variable **last**. A
single dot (**.**) may also be used as a synonym for **last**. These are
**non-portable extensions**.
Either semicolons or newlines may separate statements.
## Comments
There are two kinds of comments:
1. Block comments are enclosed in **/\*** and **\*/**.
2. Line comments go from **#** until, and not including, the next newline. This
is a **non-portable extension**.
## Named Expressions
The following are named expressions in bc(1):
1. Variables: **I**
2. Array Elements: **I[E]**
3. **ibase**
4. **obase**
5. **scale**
6. **seed**
7. **last** or a single dot (**.**)
Numbers 6 and 7 are **non-portable extensions**.
The meaning of **seed** is dependent on the current pseudo-random number
generator but is guaranteed to not change except for new major versions.
The *scale* and sign of the value may be significant.
If a previously used **seed** value is assigned to **seed** and used again, the
pseudo-random number generator is guaranteed to produce the same sequence of
pseudo-random numbers as it did when the **seed** value was previously used.
The exact value assigned to **seed** is not guaranteed to be returned if
**seed** is queried again immediately. However, if **seed** *does* return a
different value, both values, when assigned to **seed**, are guaranteed to
produce the same sequence of pseudo-random numbers. This means that certain
values assigned to **seed** will *not* produce unique sequences of pseudo-random
numbers. The value of **seed** will change after any use of the **rand()** and
**irand(E)** operands (see the *Operands* subsection below), except if the
parameter passed to **irand(E)** is **0**, **1**, or negative.
There is no limit to the length (number of significant decimal digits) or
*scale* of the value that can be assigned to **seed**.
Variables and arrays do not interfere; users can have arrays named the same as
variables. This also applies to functions (see the **FUNCTIONS** section), so a
user can have a variable, array, and function that all have the same name, and
they will not shadow each other, whether inside of functions or not.
Named expressions are required as the operand of **increment**/**decrement**
operators and as the left side of **assignment** operators (see the *Operators*
subsection).
## Operands
The following are valid operands in bc(1):
1. Numbers (see the *Numbers* subsection below).
2. Array indices (**I[E]**).
3. **(E)**: The value of **E** (used to change precedence).
4. **sqrt(E)**: The square root of **E**. **E** must be non-negative.
5. **length(E)**: The number of significant decimal digits in **E**.
6. **length(I[])**: The number of elements in the array **I**. This is a
**non-portable extension**.
7. **scale(E)**: The *scale* of **E**.
8. **abs(E)**: The absolute value of **E**. This is a **non-portable
extension**.
9. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a non-**void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
10. **read()**: Reads a line from **stdin** and uses that as an expression. The
result of that expression is the result of the **read()** operand. This is a
**non-portable extension**.
11. **maxibase()**: The max allowable **ibase**. This is a **non-portable
extension**.
12. **maxobase()**: The max allowable **obase**. This is a **non-portable
extension**.
13. **maxscale()**: The max allowable **scale**. This is a **non-portable
extension**.
14. **rand()**: A pseudo-random integer between **0** (inclusive) and
**BC_RAND_MAX** (inclusive). Using this operand will change the value of
**seed**. This is a **non-portable extension**.
15. **irand(E)**: A pseudo-random integer between **0** (inclusive) and the
value of **E** (exclusive). If **E** is negative or is a non-integer
(**E**'s *scale* is not **0**), an error is raised, and bc(1) resets (see
the **RESET** section) while **seed** remains unchanged. If **E** is larger
than **BC_RAND_MAX**, the higher bound is honored by generating several
pseudo-random integers, multiplying them by appropriate powers of
**BC_RAND_MAX+1**, and adding them together. Thus, the size of integer that
can be generated with this operand is unbounded. Using this operand will
change the value of **seed**, unless the value of **E** is **0** or **1**.
In that case, **0** is returned, and **seed** is *not* changed. This is a
**non-portable extension**.
16. **maxrand()**: The max integer returned by **rand()**. This is a
**non-portable extension**.
The integers generated by **rand()** and **irand(E)** are guaranteed to be as
unbiased as possible, subject to the limitations of the pseudo-random number
generator.
**Note**: The values returned by the pseudo-random number generator with
**rand()** and **irand(E)** are guaranteed to *NOT* be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator. However,
they *are* guaranteed to be reproducible with identical **seed** values. This
means that the pseudo-random values from bc(1) should only be used where a
reproducible stream of pseudo-random numbers is *ESSENTIAL*. In any other case,
use a non-seeded pseudo-random number generator.
## Numbers
Numbers are strings made up of digits, uppercase letters, and at most **1**
period for a radix. Numbers can have up to **BC_NUM_MAX** digits. Uppercase
letters are equal to **9** + their position in the alphabet (i.e., **A** equals
**10**, or **9+1**). If a digit or letter makes no sense with the current value
of **ibase**, they are set to the value of the highest valid digit in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **Z** alone always equals decimal
**35**.
In addition, bc(1) accepts numbers in scientific notation. These have the form
**\<number\>e\<integer\>**. The exponent (the portion after the **e**) must be
an integer. An example is **1.89237e9**, which is equal to **1892370000**.
Negative exponents are also allowed, so **4.2890e-3** is equal to **0.0042890**.
Using scientific notation is an error or warning if the **-s** or **-w**,
respectively, command-line options (or equivalents) are given.
**WARNING**: Both the number and the exponent in scientific notation are
interpreted according to the current **ibase**, but the number is still
multiplied by **10\^exponent** regardless of the current **ibase**. For example,
if **ibase** is **16** and bc(1) is given the number string **FFeA**, the
resulting decimal number will be **2550000000000**, and if bc(1) is given the
number string **10e-4**, the resulting decimal number will be **0.0016**.
Accepting input as scientific notation is a **non-portable extension**.
## Operators
The following arithmetic and logical operators can be used. They are listed in
order of decreasing precedence. Operators in the same group have the same
precedence.
**++** **--**
: Type: Prefix and Postfix
Associativity: None
Description: **increment**, **decrement**
**-** **!**
: Type: Prefix
Associativity: None
Description: **negation**, **boolean not**
**\$**
: Type: Postfix
Associativity: None
Description: **truncation**
**\@**
: Type: Binary
Associativity: Right
Description: **set precision**
**\^**
: Type: Binary
Associativity: Right
Description: **power**
**\*** **/** **%**
: Type: Binary
Associativity: Left
Description: **multiply**, **divide**, **modulus**
**+** **-**
: Type: Binary
Associativity: Left
Description: **add**, **subtract**
**\<\<** **\>\>**
: Type: Binary
Associativity: Left
Description: **shift left**, **shift right**
**=** **\<\<=** **\>\>=** **+=** **-=** **\*=** **/=** **%=** **\^=** **\@=**
: Type: Binary
Associativity: Right
Description: **assignment**
**==** **\<=** **\>=** **!=** **\<** **\>**
: Type: Binary
Associativity: Left
Description: **relational**
**&&**
: Type: Binary
Associativity: Left
Description: **boolean and**
**||**
: Type: Binary
Associativity: Left
Description: **boolean or**
The operators will be described in more detail below.
**++** **--**
: The prefix and postfix **increment** and **decrement** operators behave
exactly like they would in C. They require a named expression (see the
*Named Expressions* subsection) as an operand.
The prefix versions of these operators are more efficient; use them where
possible.
**-**
: The **negation** operator returns **0** if a user attempts to negate any
expression with the value **0**. Otherwise, a copy of the expression with
its sign flipped is returned.
**!**
: The **boolean not** operator returns **1** if the expression is **0**, or
**0** otherwise.
This is a **non-portable extension**.
**\$**
: The **truncation** operator returns a copy of the given expression with all
of its *scale* removed.
This is a **non-portable extension**.
**\@**
: The **set precision** operator takes two expressions and returns a copy of
the first with its *scale* equal to the value of the second expression. That
could either mean that the number is returned without change (if the
*scale* of the first expression matches the value of the second
expression), extended (if it is less), or truncated (if it is more).
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**\^**
: The **power** operator (not the **exclusive or** operator, as it would be in
C) takes two expressions and raises the first to the power of the value of
the second. The *scale* of the result is equal to **scale**.
The second expression must be an integer (no *scale*), and if it is
negative, the first value must be non-zero.
**\***
: The **multiply** operator takes two expressions, multiplies them, and
returns the product. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result is
equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The **divide** operator takes two expressions, divides them, and returns the
quotient. The *scale* of the result shall be the value of **scale**.
The second expression must be non-zero.
**%**
: The **modulus** operator takes two expressions, **a** and **b**, and
evaluates them by 1) Computing **a/b** to current **scale** and 2) Using the
result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The second expression must be non-zero.
**+**
: The **add** operator takes two expressions, **a** and **b**, and returns the
sum, with a *scale* equal to the max of the *scale*s of **a** and **b**.
**-**
: The **subtract** operator takes two expressions, **a** and **b**, and
returns the difference, with a *scale* equal to the max of the *scale*s of
**a** and **b**.
**\<\<**
: The **left shift** operator takes two expressions, **a** and **b**, and
returns a copy of the value of **a** with its decimal point moved **b**
places to the right.
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**\>\>**
: The **right shift** operator takes two expressions, **a** and **b**, and
returns a copy of the value of **a** with its decimal point moved **b**
places to the left.
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**=** **\<\<=** **\>\>=** **+=** **-=** **\*=** **/=** **%=** **\^=** **\@=**
: The **assignment** operators take two expressions, **a** and **b** where
**a** is a named expression (see the *Named Expressions* subsection).
For **=**, **b** is copied and the result is assigned to **a**. For all
others, **a** and **b** are applied as operands to the corresponding
arithmetic operator and the result is assigned to **a**.
The **assignment** operators that correspond to operators that are
extensions are themselves **non-portable extensions**.
**==** **\<=** **\>=** **!=** **\<** **\>**
: The **relational** operators compare two expressions, **a** and **b**, and
if the relation holds, according to C language semantics, the result is
**1**. Otherwise, it is **0**.
Note that unlike in C, these operators have a lower precedence than the
**assignment** operators, which means that **a=b\>c** is interpreted as
**(a=b)\>c**.
Also, unlike the [standard][1] requires, these operators can appear anywhere
any other expressions can be used. This allowance is a
**non-portable extension**.
**&&**
: The **boolean and** operator takes two expressions and returns **1** if both
expressions are non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
**||**
: The **boolean or** operator takes two expressions and returns **1** if one
of the expressions is non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
## Statements
The following items are statements:
1. **E**
2. **{** **S** **;** ... **;** **S** **}**
3. **if** **(** **E** **)** **S**
4. **if** **(** **E** **)** **S** **else** **S**
5. **while** **(** **E** **)** **S**
6. **for** **(** **E** **;** **E** **;** **E** **)** **S**
7. An empty statement
8. **break**
9. **continue**
10. **quit**
11. **halt**
12. **limits**
13. A string of characters, enclosed in double quotes
14. **print** **E** **,** ... **,** **E**
15. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
Numbers 4, 9, 11, 12, 14, and 15 are **non-portable extensions**.
Also, as a **non-portable extension**, any or all of the expressions in the
header of a for loop may be omitted. If the condition (second expression) is
omitted, it is assumed to be a constant **1**.
The **break** statement causes a loop to stop iterating and resume execution
immediately following a loop. This is only allowed in loops.
The **continue** statement causes a loop iteration to stop early and returns to
the start of the loop, including testing the loop condition. This is only
allowed in loops.
The **if** **else** statement does the same thing as in C.
The **quit** statement causes bc(1) to quit, even if it is on a branch that will
not be executed (it is a compile-time command).
The **halt** statement causes bc(1) to quit, if it is executed. (Unlike **quit**
if it is on a branch of an **if** statement that is not executed, bc(1) does not
quit.)
The **limits** statement prints the limits that this bc(1) is subject to. This
is like the **quit** statement in that it is a compile-time command.
An expression by itself is evaluated and printed, followed by a newline.
Both scientific notation and engineering notation are available for printing the
results of expressions. Scientific notation is activated by assigning **0** to
**obase**, and engineering notation is activated by assigning **1** to
**obase**. To deactivate them, just assign a different value to **obase**.
Scientific notation and engineering notation are disabled if bc(1) is run with
either the **-s** or **-w** command-line options (or equivalents).
Printing numbers in scientific notation and/or engineering notation is a
**non-portable extension**.
## Print Statement
The "expressions" in a **print** statement may also be strings. If they are, there
are backslash escape sequences that are interpreted specially. What those
sequences are, and what they cause to be printed, are shown below:
-------- -------
**\\a** **\\a**
**\\b** **\\b**
**\\\\** **\\**
**\\e** **\\**
**\\f** **\\f**
**\\n** **\\n**
**\\q** **"**
**\\r** **\\r**
**\\t** **\\t**
-------- -------
Any other character following a backslash causes the backslash and character to
be printed as-is.
Any non-string expression in a print statement shall be assigned to **last**,
like any other expression that is printed.
## Order of Evaluation
All expressions in a statment are evaluated left to right, except as necessary
to maintain order of operations. This means, for example, assuming that **i** is
equal to **0**, in the expression
a[i++] = i++
the first (or 0th) element of **a** is set to **1**, and **i** is equal to **2**
at the end of the expression.
This includes function arguments. Thus, assuming **i** is equal to **0**, this
means that in the expression
x(i++, i++)
the first argument passed to **x()** is **0**, and the second argument is **1**,
while **i** is equal to **2** before the function starts executing.
# FUNCTIONS
Function definitions are as follows:
```
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
```
Any **I** in the parameter list or **auto** list may be replaced with **I[]** to
make a parameter or **auto** var an array, and any **I** in the parameter list
may be replaced with **\*I[]** to make a parameter an array reference. Callers
of functions that take array references should not put an asterisk in the call;
they must be called with just **I[]** like normal array parameters and will be
automatically converted into references.
As a **non-portable extension**, the opening brace of a **define** statement may
appear on the next line.
As a **non-portable extension**, the return statement may also be in one of the
following forms:
1. **return**
2. **return** **(** **)**
3. **return** **E**
The first two, or not specifying a **return** statement, is equivalent to
**return (0)**, unless the function is a **void** function (see the *Void
Functions* subsection below).
## Void Functions
Functions can also be **void** functions, defined as follows:
```
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
```
They can only be used as standalone expressions, where such an expression would
be printed alone, except in a print statement.
Void functions can only use the first two **return** statements listed above.
They can also omit the return statement entirely.
The word "void" is not treated as a keyword; it is still possible to have
variables, arrays, and functions named **void**. The word "void" is only
treated specially right after the **define** keyword.
This is a **non-portable extension**.
## Array References
For any array in the parameter list, if the array is declared in the form
```
*I[]
```
it is a **reference**. Any changes to the array in the function are reflected,
when the function returns, to the array that was passed in.
Other than this, all function arguments are passed by value.
This is a **non-portable extension**.
# LIBRARY
All of the functions below, including the functions in the extended math
library (see the *Extended Library* subsection below), are available when the
**-l** or **--mathlib** command-line flags are given, except that the extended
math library is not available when the **-s** option, the **-w** option, or
equivalents are given.
## Standard Library
The [standard][1] defines the following functions for the math library:
**s(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**c(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a(x)**
: Returns the arctangent of **x**, in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l(x)**
: Returns the natural logarithm of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**e(x)**
: Returns the mathematical constant **e** raised to the power of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**j(x, n)**
: Returns the bessel integer order **n** (truncated) of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
## Extended Library
The extended library is *not* loaded when the **-s**/**--standard** or
**-w**/**--warn** options are given since they are not part of the library
defined by the [standard][1].
The extended library is a **non-portable extension**.
**p(x, y)**
: Calculates **x** to the power of **y**, even if **y** is not an integer, and
returns the result to the current **scale**.
It is an error if **y** is negative and **x** is **0**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**r(x, p)**
: Returns **x** rounded to **p** decimal places according to the rounding mode
[round half away from **0**][3].
**ceil(x, p)**
: Returns **x** rounded to **p** decimal places according to the rounding mode
[round away from **0**][6].
**f(x)**
: Returns the factorial of the truncated absolute value of **x**.
**perm(n, k)**
: Returns the permutation of the truncated absolute value of **n** of the
truncated absolute value of **k**, if **k \<= n**. If not, it returns **0**.
**comb(n, k)**
: Returns the combination of the truncated absolute value of **n** of the
truncated absolute value of **k**, if **k \<= n**. If not, it returns **0**.
**l2(x)**
: Returns the logarithm base **2** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l10(x)**
: Returns the logarithm base **10** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**log(x, b)**
: Returns the logarithm base **b** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**cbrt(x)**
: Returns the cube root of **x**.
**root(x, n)**
: Calculates the truncated value of **n**, **r**, and returns the **r**th root
of **x** to the current **scale**.
If **r** is **0** or negative, this raises an error and causes bc(1) to
reset (see the **RESET** section). It also raises an error and causes bc(1)
to reset if **r** is even and **x** is negative.
**pi(p)**
: Returns **pi** to **p** decimal places.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**t(x)**
: Returns the tangent of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a2(y, x)**
: Returns the arctangent of **y/x**, in radians. If both **y** and **x** are
equal to **0**, it raises an error and causes bc(1) to reset (see the
**RESET** section). Otherwise, if **x** is greater than **0**, it returns
**a(y/x)**. If **x** is less than **0**, and **y** is greater than or equal
to **0**, it returns **a(y/x)+pi**. If **x** is less than **0**, and **y**
is less than **0**, it returns **a(y/x)-pi**. If **x** is equal to **0**,
and **y** is greater than **0**, it returns **pi/2**. If **x** is equal to
**0**, and **y** is less than **0**, it returns **-pi/2**.
This function is the same as the **atan2()** function in many programming
languages.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**sin(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is an alias of **s(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**cos(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is an alias of **c(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**tan(x)**
: Returns the tangent of **x**, which is assumed to be in radians.
If **x** is equal to **1** or **-1**, this raises an error and causes bc(1)
to reset (see the **RESET** section).
This is an alias of **t(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**atan(x)**
: Returns the arctangent of **x**, in radians.
This is an alias of **a(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**atan2(y, x)**
: Returns the arctangent of **y/x**, in radians. If both **y** and **x** are
equal to **0**, it raises an error and causes bc(1) to reset (see the
**RESET** section). Otherwise, if **x** is greater than **0**, it returns
**a(y/x)**. If **x** is less than **0**, and **y** is greater than or equal
to **0**, it returns **a(y/x)+pi**. If **x** is less than **0**, and **y**
is less than **0**, it returns **a(y/x)-pi**. If **x** is equal to **0**,
and **y** is greater than **0**, it returns **pi/2**. If **x** is equal to
**0**, and **y** is less than **0**, it returns **-pi/2**.
This function is the same as the **atan2()** function in many programming
languages.
This is an alias of **a2(y, x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**r2d(x)**
: Converts **x** from radians to degrees and returns the result.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**d2r(x)**
: Converts **x** from degrees to radians and returns the result.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**frand(p)**
: Generates a pseudo-random number between **0** (inclusive) and **1**
(exclusive) with the number of decimal digits after the decimal point equal
to the truncated absolute value of **p**. If **p** is not **0**, then
calling this function will change the value of **seed**. If **p** is **0**,
then **0** is returned, and **seed** is *not* changed.
**ifrand(i, p)**
: Generates a pseudo-random number that is between **0** (inclusive) and the
truncated absolute value of **i** (exclusive) with the number of decimal
digits after the decimal point equal to the truncated absolute value of
**p**. If the absolute value of **i** is greater than or equal to **2**, and
**p** is not **0**, then calling this function will change the value of
**seed**; otherwise, **0** is returned and **seed** is not changed.
**srand(x)**
: Returns **x** with its sign flipped with probability **0.5**. In other
words, it randomizes the sign of **x**.
**brand()**
: Returns a random boolean value (either **0** or **1**).
**ubytes(x)**
: Returns the numbers of unsigned integer bytes required to hold the truncated
absolute value of **x**.
**sbytes(x)**
: Returns the numbers of signed, two's-complement integer bytes required to
hold the truncated value of **x**.
**hex(x)**
: Outputs the hexadecimal (base **16**) representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**binary(x)**
: Outputs the binary (base **2**) representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output(x, b)**
: Outputs the base **b** representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in as few power of two bytes as possible. Both outputs are
split into bytes separated by spaces.
If **x** is not an integer or is negative, an error message is printed
instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in as few power of two bytes as possible. Both
outputs are split into bytes separated by spaces.
If **x** is not an integer, an error message is printed instead, but bc(1)
is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uintn(x, n)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **n** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **n** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**intn(x, n)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **n** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **n** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint8(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **1** byte. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **1** byte, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int8(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **1** byte. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **1** byte, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint16(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **2** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **2** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int16(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **2** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **2** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint32(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **4** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **4** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int32(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **4** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **4** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint64(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **8** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **8** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int64(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **8** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **8** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**hex_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in hexadecimal using **n** bytes. Not all of the value will
be output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**binary_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in binary using **n** bytes. Not all of the value will be
output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in the current **obase** (see the **SYNTAX** section) using
**n** bytes. Not all of the value will be output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output_byte(x, i)**
: Outputs byte **i** of the truncated absolute value of **x**, where **0** is
the least significant byte and **number_of_bytes - 1** is the most
significant byte.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
## Transcendental Functions
All transcendental functions can return slightly inaccurate results (up to 1
[ULP][4]). This is unavoidable, and [this article][5] explains why it is
impossible and unnecessary to calculate exact results for the transcendental
functions.
Because of the possible inaccuracy, I recommend that users call those functions
with the precision (**scale**) set to at least 1 higher than is necessary. If
exact results are *absolutely* required, users can double the precision
(**scale**) and then truncate.
The transcendental functions in the standard math library are:
* **s(x)**
* **c(x)**
* **a(x)**
* **l(x)**
* **e(x)**
* **j(x, n)**
The transcendental functions in the extended math library are:
* **l2(x)**
* **l10(x)**
* **log(x, b)**
* **pi(p)**
* **t(x)**
* **a2(y, x)**
* **sin(x)**
* **cos(x)**
* **tan(x)**
* **atan(x)**
* **atan2(y, x)**
* **r2d(x)**
* **d2r(x)**
# RESET
When bc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any functions that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
functions returned) is skipped.
Thus, when bc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
Note that this reset behavior is different from the GNU bc(1), which attempts to
start executing the statement right after the one that caused an error.
# PERFORMANCE
Most bc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This bc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **BC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **BC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**BC_BASE_DIGS**.
The actual values of **BC_LONG_BIT** and **BC_BASE_DIGS** can be queried with
the **limits** statement.
In addition, this bc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **BC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on bc(1):
**BC_LONG_BIT**
: The number of bits in the **long** type in the environment where bc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**BC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **BC_LONG_BIT**.
**BC_BASE_POW**
: The max decimal number that each large integer can store (see
**BC_BASE_DIGS**) plus **1**. Depends on **BC_BASE_DIGS**.
**BC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **BC_LONG_BIT**.
**BC_BASE_MAX**
: The maximum output base. Set at **BC_BASE_POW**.
**BC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**BC_SCALE_MAX**
: The maximum **scale**. Set at **BC_OVERFLOW_MAX-1**.
**BC_STRING_MAX**
: The maximum length of strings. Set at **BC_OVERFLOW_MAX-1**.
**BC_NAME_MAX**
: The maximum length of identifiers. Set at **BC_OVERFLOW_MAX-1**.
**BC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **BC_OVERFLOW_MAX-1**.
**BC_RAND_MAX**
: The maximum integer (inclusive) returned by the **rand()** operand. Set at
**2\^BC_LONG_BIT-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**BC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
The actual values can be queried with the **limits** statement.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
bc(1) recognizes the following environment variables:
**POSIXLY_CORRECT**
: If this variable exists (no matter the contents), bc(1) behaves as if
the **-s** option was given.
**BC_ENV_ARGS**
: This is another way to give command-line arguments to bc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **BC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
The code that parses **BC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some bc file.bc"** will be correctly parsed, but the string
**"/home/gavin/some \"bc\" file.bc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **BC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**BC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), bc(1) will output
lines to that length, including the backslash (**\\**). The default line
length is **70**.
# EXIT STATUS
bc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, using a negative number as a bound for the pseudo-random number
generator, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**), places (**\@**), left shift (**\<\<**), and right shift (**\>\>**)
operators and their corresponding assignment operators.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, using a token where it is invalid,
giving an invalid expression, giving an invalid print statement, giving an
invalid function definition, attempting to assign to an expression that is
not a named expression (see the *Named Expressions* subsection of the
**SYNTAX** section), giving an invalid **auto** list, having a duplicate
**auto**/function parameter, failing to find the end of a code block,
attempting to return a value from a **void** function, attempting to use a
variable as a reference, and using any extensions when the option **-s** or
any equivalents were given.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a **void** function call as a value in an expression.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (bc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, bc(1) always exits
and returns **4**, no matter what mode bc(1) is in.
The other statuses will only be returned when bc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since bc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Per the [standard][1], bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, bc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, bc(1) turns
on "TTY mode."
The prompt is enabled in TTY mode.
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause bc(1) to stop execution of the current input. If
bc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If bc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If bc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to bc(1) as it is executing a file, it
can seem as though bc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause bc(1) to clean up and exit, and it uses the
default handler for all other signals.
# LOCALES
This bc(1) ships with support for adding error messages for different locales
and thus, supports **LC_MESSAGES**.
# SEE ALSO
dc(1)
# STANDARDS
bc(1) is compliant with the [IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1]
specification. The flags **-efghiqsvVw**, all long options, and the extensions
noted above are extensions to that specification.
Note that the specification explicitly says that bc(1) only accepts numbers that
use a period (**.**) as a radix point, regardless of the value of
**LC_NUMERIC**.
This bc(1) supports error messages for different locales, and thus, it supports
**LC_MESSAGES**.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHORS
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
[2]: https://www.gnu.org/software/bc/
[3]: https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero
[4]: https://en.wikipedia.org/wiki/Unit_in_the_last_place
[5]: https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT
[6]: https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero
diff --git a/contrib/bc/manuals/bc/HN.1 b/contrib/bc/manuals/bc/HN.1
index f4b78449838c..0dbb8208f1fa 100644
--- a/contrib/bc/manuals/bc/HN.1
+++ b/contrib/bc/manuals/bc/HN.1
@@ -1,2018 +1,2031 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "BC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "BC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH NAME
.PP
bc - arbitrary-precision decimal arithmetic language and calculator
.SH SYNOPSIS
.PP
\f[B]bc\f[R] [\f[B]-ghilPqsvVw\f[R]] [\f[B]\[en]global-stacks\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]mathlib\f[R]] [\f[B]\[en]no-prompt\f[R]]
[\f[B]\[en]quiet\f[R]] [\f[B]\[en]standard\f[R]] [\f[B]\[en]warn\f[R]]
[\f[B]\[en]version\f[R]] [\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
bc(1) is an interactive processor for a language first standardized in
1991 by POSIX.
(The current standard is
here (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).)
The language provides unlimited precision decimal arithmetic and is
somewhat C-like, but there are differences.
Such differences will be noted in this document.
.PP
After parsing and handling options, this bc(1) reads any files given on
the command line and executes them before reading from \f[B]stdin\f[R].
.SH OPTIONS
.PP
The following are the options that bc(1) accepts.
.TP
\f[B]-g\f[R], \f[B]\[en]global-stacks\f[R]
Turns the globals \f[B]ibase\f[R], \f[B]obase\f[R], \f[B]scale\f[R], and
\f[B]seed\f[R] into stacks.
.RS
.PP
This has the effect that a copy of the current value of all four are
pushed onto a stack for every function call, as well as popped when
every function returns.
This means that functions can assign to any and all of those globals
without worrying that the change will affect other functions.
Thus, a hypothetical function named \f[B]output(x,b)\f[R] that simply
printed \f[B]x\f[R] in base \f[B]b\f[R] could be written like this:
.IP
.nf
\f[C]
define void output(x, b) {
obase=b
x
}
\f[R]
.fi
.PP
instead of like this:
.IP
.nf
\f[C]
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
\f[R]
.fi
.PP
This makes writing functions much easier.
.PP
(\f[B]Note\f[R]: the function \f[B]output(x,b)\f[R] exists in the
extended math library.
See the \f[B]LIBRARY\f[R] section.)
.PP
However, since using this flag means that functions cannot set
\f[B]ibase\f[R], \f[B]obase\f[R], \f[B]scale\f[R], or \f[B]seed\f[R]
globally, functions that are made to do so cannot work anymore.
There are two possible use cases for that, and each has a solution.
.PP
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases.
Examples:
.IP
.nf
\f[C]
alias d2o=\[dq]bc -e ibase=A -e obase=8\[dq]
alias h2b=\[dq]bc -e ibase=G -e obase=2\[dq]
\f[R]
.fi
.PP
Second, if the purpose of a function is to set \f[B]ibase\f[R],
\f[B]obase\f[R], \f[B]scale\f[R], or \f[B]seed\f[R] globally for any
other purpose, it could be split into one to four functions (based on
how many globals it sets) and each of those functions could return the
desired value for a global.
.PP
For functions that set \f[B]seed\f[R], the value assigned to
\f[B]seed\f[R] is not propagated to parent functions.
This means that the sequence of pseudo-random numbers that they see will
not be the same sequence of pseudo-random numbers that any parent sees.
This is only the case once \f[B]seed\f[R] has been set.
.PP
If a function desires to not affect the sequence of pseudo-random
numbers of its parents, but wants to use the same \f[B]seed\f[R], it can
use the following line:
.IP
.nf
\f[C]
seed = seed
\f[R]
.fi
.PP
If the behavior of this option is desired for every run of bc(1), then
users could make sure to define \f[B]BC_ENV_ARGS\f[R] and include this
option (see the \f[B]ENVIRONMENT VARIABLES\f[R] section for more
details).
.PP
If \f[B]-s\f[R], \f[B]-w\f[R], or any equivalents are used, this option
is ignored.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-l\f[R], \f[B]\[en]mathlib\f[R]
Sets \f[B]scale\f[R] (see the \f[B]SYNTAX\f[R] section) to \f[B]20\f[R]
and loads the included math library and the extended math library before
running any code, including any expressions or files specified on the
command line.
.RS
.PP
To learn what is in the libraries, see the \f[B]LIBRARY\f[R] section.
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
Disables the prompt in TTY mode.
(The prompt is only enabled in TTY mode.
See the \f[B]TTY MODE\f[R] section) This is mostly for those users that
do not want a prompt or are not used to having them in bc(1).
Most of those users would want to put this option in
\f[B]BC_ENV_ARGS\f[R] (see the \f[B]ENVIRONMENT VARIABLES\f[R] section).
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-q\f[R], \f[B]\[en]quiet\f[R]
This option is for compatibility with the GNU
bc(1) (https://www.gnu.org/software/bc/); it is a no-op.
Without this option, GNU bc(1) prints a copyright header.
This bc(1) only prints the copyright header if one or more of the
\f[B]-v\f[R], \f[B]-V\f[R], or \f[B]\[en]version\f[R] options are given.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-s\f[R], \f[B]\[en]standard\f[R]
Process exactly the language defined by the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
and error if any extensions are used.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-w\f[R], \f[B]\[en]warn\f[R]
Like \f[B]-s\f[R] and \f[B]\[en]standard\f[R], except that warnings (and
not errors) are printed for non-standard extensions and execution
continues normally.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]BC_ENV_ARGS\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]bc >&-\f[R], it will quit with an error.
This is done so that bc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]bc 2>&-\f[R], it will quit with an error.
This is done so that bc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
The syntax for bc(1) programs is mostly C-like, with some differences.
This bc(1) follows the POSIX
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
which is a much more thorough resource for the language this bc(1)
accepts.
This section is meant to be a summary and a listing of all the
extensions to the standard.
.PP
In the sections below, \f[B]E\f[R] means expression, \f[B]S\f[R] means
statement, and \f[B]I\f[R] means identifier.
.PP
Identifiers (\f[B]I\f[R]) start with a lowercase letter and can be
followed by any number (up to \f[B]BC_NAME_MAX-1\f[R]) of lowercase
letters (\f[B]a-z\f[R]), digits (\f[B]0-9\f[R]), and underscores
(\f[B]_\f[R]).
The regex is \f[B][a-z][a-z0-9_]*\f[R].
Identifiers with more than one character (letter) are a
\f[B]non-portable extension\f[R].
.PP
\f[B]ibase\f[R] is a global variable determining how to interpret
constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
If the \f[B]-s\f[R] (\f[B]\[en]standard\f[R]) and \f[B]-w\f[R]
(\f[B]\[en]warn\f[R]) flags were not given on the command line, the max
allowable value for \f[B]ibase\f[R] is \f[B]36\f[R].
Otherwise, it is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in bc(1)
programs with the \f[B]maxibase()\f[R] built-in function.
.PP
\f[B]obase\f[R] is a global variable determining how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]BC_BASE_MAX\f[R] and
can be queried in bc(1) programs with the \f[B]maxobase()\f[R] built-in
function.
The min allowable value for \f[B]obase\f[R] is \f[B]0\f[R].
If \f[B]obase\f[R] is \f[B]0\f[R], values are output in scientific
notation, and if \f[B]obase\f[R] is \f[B]1\f[R], values are output in
engineering notation.
Otherwise, values are output in the specified base.
.PP
Outputting in scientific and engineering notations are \f[B]non-portable
extensions\f[R].
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a global variable that sets the precision of any operations, with
exceptions.
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] is \f[B]BC_SCALE_MAX\f[R]
and can be queried in bc(1) programs with the \f[B]maxscale()\f[R]
built-in function.
.PP
bc(1) has both \f[I]global\f[R] variables and \f[I]local\f[R] variables.
All \f[I]local\f[R] variables are local to the function; they are
parameters or are introduced in the \f[B]auto\f[R] list of a function
(see the \f[B]FUNCTIONS\f[R] section).
If a variable is accessed which is not a parameter or in the
\f[B]auto\f[R] list, it is assumed to be \f[I]global\f[R].
If a parent function has a \f[I]local\f[R] variable version of a
variable that a child function considers \f[I]global\f[R], the value of
that \f[I]global\f[R] variable in the child function is the value of the
variable in the parent function, not the value of the actual
\f[I]global\f[R] variable.
.PP
All of the above applies to arrays as well.
.PP
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence
operator is an assignment operator \f[I]and\f[R] the expression is
notsurrounded by parentheses.
.PP
The value that is printed is also assigned to the special variable
\f[B]last\f[R].
A single dot (\f[B].\f[R]) may also be used as a synonym for
\f[B]last\f[R].
These are \f[B]non-portable extensions\f[R].
.PP
Either semicolons or newlines may separate statements.
.SS Comments
.PP
There are two kinds of comments:
.IP "1." 3
Block comments are enclosed in \f[B]/*\f[R] and \f[B]*/\f[R].
.IP "2." 3
Line comments go from \f[B]#\f[R] until, and not including, the next
newline.
This is a \f[B]non-portable extension\f[R].
.SS Named Expressions
.PP
The following are named expressions in bc(1):
.IP "1." 3
Variables: \f[B]I\f[R]
.IP "2." 3
Array Elements: \f[B]I[E]\f[R]
.IP "3." 3
\f[B]ibase\f[R]
.IP "4." 3
\f[B]obase\f[R]
.IP "5." 3
\f[B]scale\f[R]
.IP "6." 3
\f[B]seed\f[R]
.IP "7." 3
\f[B]last\f[R] or a single dot (\f[B].\f[R])
.PP
Numbers 6 and 7 are \f[B]non-portable extensions\f[R].
.PP
The meaning of \f[B]seed\f[R] is dependent on the current pseudo-random
number generator but is guaranteed to not change except for new major
versions.
.PP
The \f[I]scale\f[R] and sign of the value may be significant.
.PP
If a previously used \f[B]seed\f[R] value is assigned to \f[B]seed\f[R]
and used again, the pseudo-random number generator is guaranteed to
produce the same sequence of pseudo-random numbers as it did when the
\f[B]seed\f[R] value was previously used.
.PP
The exact value assigned to \f[B]seed\f[R] is not guaranteed to be
returned if \f[B]seed\f[R] is queried again immediately.
However, if \f[B]seed\f[R] \f[I]does\f[R] return a different value, both
values, when assigned to \f[B]seed\f[R], are guaranteed to produce the
same sequence of pseudo-random numbers.
This means that certain values assigned to \f[B]seed\f[R] will
\f[I]not\f[R] produce unique sequences of pseudo-random numbers.
The value of \f[B]seed\f[R] will change after any use of the
\f[B]rand()\f[R] and \f[B]irand(E)\f[R] operands (see the
\f[I]Operands\f[R] subsection below), except if the parameter passed to
\f[B]irand(E)\f[R] is \f[B]0\f[R], \f[B]1\f[R], or negative.
.PP
There is no limit to the length (number of significant decimal digits)
or \f[I]scale\f[R] of the value that can be assigned to \f[B]seed\f[R].
.PP
Variables and arrays do not interfere; users can have arrays named the
same as variables.
This also applies to functions (see the \f[B]FUNCTIONS\f[R] section), so
a user can have a variable, array, and function that all have the same
name, and they will not shadow each other, whether inside of functions
or not.
.PP
Named expressions are required as the operand of
\f[B]increment\f[R]/\f[B]decrement\f[R] operators and as the left side
of \f[B]assignment\f[R] operators (see the \f[I]Operators\f[R]
subsection).
.SS Operands
.PP
The following are valid operands in bc(1):
.IP " 1." 4
Numbers (see the \f[I]Numbers\f[R] subsection below).
.IP " 2." 4
Array indices (\f[B]I[E]\f[R]).
.IP " 3." 4
\f[B](E)\f[R]: The value of \f[B]E\f[R] (used to change precedence).
.IP " 4." 4
\f[B]sqrt(E)\f[R]: The square root of \f[B]E\f[R].
\f[B]E\f[R] must be non-negative.
.IP " 5." 4
\f[B]length(E)\f[R]: The number of significant decimal digits in
\f[B]E\f[R].
.IP " 6." 4
\f[B]length(I[])\f[R]: The number of elements in the array \f[B]I\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 7." 4
\f[B]scale(E)\f[R]: The \f[I]scale\f[R] of \f[B]E\f[R].
.IP " 8." 4
\f[B]abs(E)\f[R]: The absolute value of \f[B]E\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 9." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a non-\f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.IP "10." 4
\f[B]read()\f[R]: Reads a line from \f[B]stdin\f[R] and uses that as an
expression.
The result of that expression is the result of the \f[B]read()\f[R]
operand.
This is a \f[B]non-portable extension\f[R].
.IP "11." 4
\f[B]maxibase()\f[R]: The max allowable \f[B]ibase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "12." 4
\f[B]maxobase()\f[R]: The max allowable \f[B]obase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "13." 4
\f[B]maxscale()\f[R]: The max allowable \f[B]scale\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "14." 4
\f[B]rand()\f[R]: A pseudo-random integer between \f[B]0\f[R]
(inclusive) and \f[B]BC_RAND_MAX\f[R] (inclusive).
Using this operand will change the value of \f[B]seed\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "15." 4
\f[B]irand(E)\f[R]: A pseudo-random integer between \f[B]0\f[R]
(inclusive) and the value of \f[B]E\f[R] (exclusive).
If \f[B]E\f[R] is negative or is a non-integer (\f[B]E\f[R]\[cq]s
\f[I]scale\f[R] is not \f[B]0\f[R]), an error is raised, and bc(1)
resets (see the \f[B]RESET\f[R] section) while \f[B]seed\f[R] remains
unchanged.
If \f[B]E\f[R] is larger than \f[B]BC_RAND_MAX\f[R], the higher bound is
honored by generating several pseudo-random integers, multiplying them
by appropriate powers of \f[B]BC_RAND_MAX+1\f[R], and adding them
together.
Thus, the size of integer that can be generated with this operand is
unbounded.
Using this operand will change the value of \f[B]seed\f[R], unless the
value of \f[B]E\f[R] is \f[B]0\f[R] or \f[B]1\f[R].
In that case, \f[B]0\f[R] is returned, and \f[B]seed\f[R] is
\f[I]not\f[R] changed.
This is a \f[B]non-portable extension\f[R].
.IP "16." 4
\f[B]maxrand()\f[R]: The max integer returned by \f[B]rand()\f[R].
This is a \f[B]non-portable extension\f[R].
.PP
The integers generated by \f[B]rand()\f[R] and \f[B]irand(E)\f[R] are
guaranteed to be as unbiased as possible, subject to the limitations of
the pseudo-random number generator.
.PP
\f[B]Note\f[R]: The values returned by the pseudo-random number
generator with \f[B]rand()\f[R] and \f[B]irand(E)\f[R] are guaranteed to
\f[I]NOT\f[R] be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator.
However, they \f[I]are\f[R] guaranteed to be reproducible with identical
\f[B]seed\f[R] values.
This means that the pseudo-random values from bc(1) should only be used
where a reproducible stream of pseudo-random numbers is
\f[I]ESSENTIAL\f[R].
In any other case, use a non-seeded pseudo-random number generator.
.SS Numbers
.PP
Numbers are strings made up of digits, uppercase letters, and at most
\f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]BC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]Z\f[R] alone always equals decimal \f[B]35\f[R].
.PP
In addition, bc(1) accepts numbers in scientific notation.
These have the form \f[B]<number>e<integer>\f[R].
The exponent (the portion after the \f[B]e\f[R]) must be an integer.
An example is \f[B]1.89237e9\f[R], which is equal to
\f[B]1892370000\f[R].
Negative exponents are also allowed, so \f[B]4.2890e-3\f[R] is equal to
\f[B]0.0042890\f[R].
.PP
Using scientific notation is an error or warning if the \f[B]-s\f[R] or
\f[B]-w\f[R], respectively, command-line options (or equivalents) are
given.
.PP
\f[B]WARNING\f[R]: Both the number and the exponent in scientific
notation are interpreted according to the current \f[B]ibase\f[R], but
the number is still multiplied by \f[B]10\[ha]exponent\f[R] regardless
of the current \f[B]ibase\f[R].
For example, if \f[B]ibase\f[R] is \f[B]16\f[R] and bc(1) is given the
number string \f[B]FFeA\f[R], the resulting decimal number will be
\f[B]2550000000000\f[R], and if bc(1) is given the number string
\f[B]10e-4\f[R], the resulting decimal number will be \f[B]0.0016\f[R].
.PP
Accepting input as scientific notation is a \f[B]non-portable
extension\f[R].
.SS Operators
.PP
The following arithmetic and logical operators can be used.
They are listed in order of decreasing precedence.
Operators in the same group have the same precedence.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
Type: Prefix and Postfix
.RS
.PP
Associativity: None
.PP
Description: \f[B]increment\f[R], \f[B]decrement\f[R]
.RE
.TP
\f[B]-\f[R] \f[B]!\f[R]
Type: Prefix
.RS
.PP
Associativity: None
.PP
Description: \f[B]negation\f[R], \f[B]boolean not\f[R]
.RE
.TP
\f[B]$\f[R]
Type: Postfix
.RS
.PP
Associativity: None
.PP
Description: \f[B]truncation\f[R]
.RE
.TP
\f[B]\[at]\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]set precision\f[R]
.RE
.TP
\f[B]\[ha]\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]power\f[R]
.RE
.TP
\f[B]*\f[R] \f[B]/\f[R] \f[B]%\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]multiply\f[R], \f[B]divide\f[R], \f[B]modulus\f[R]
.RE
.TP
\f[B]+\f[R] \f[B]-\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]add\f[R], \f[B]subtract\f[R]
.RE
.TP
\f[B]<<\f[R] \f[B]>>\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]shift left\f[R], \f[B]shift right\f[R]
.RE
.TP
\f[B]=\f[R] \f[B]<<=\f[R] \f[B]>>=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R] \f[B]\[at]=\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]assignment\f[R]
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]relational\f[R]
.RE
.TP
\f[B]&&\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean and\f[R]
.RE
.TP
\f[B]||\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean or\f[R]
.RE
.PP
The operators will be described in more detail below.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
The prefix and postfix \f[B]increment\f[R] and \f[B]decrement\f[R]
operators behave exactly like they would in C.
They require a named expression (see the \f[I]Named Expressions\f[R]
subsection) as an operand.
.RS
.PP
The prefix versions of these operators are more efficient; use them
where possible.
.RE
.TP
\f[B]-\f[R]
The \f[B]negation\f[R] operator returns \f[B]0\f[R] if a user attempts
to negate any expression with the value \f[B]0\f[R].
Otherwise, a copy of the expression with its sign flipped is returned.
.TP
\f[B]!\f[R]
The \f[B]boolean not\f[R] operator returns \f[B]1\f[R] if the expression
is \f[B]0\f[R], or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]$\f[R]
The \f[B]truncation\f[R] operator returns a copy of the given expression
with all of its \f[I]scale\f[R] removed.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[at]\f[R]
The \f[B]set precision\f[R] operator takes two expressions and returns a
copy of the first with its \f[I]scale\f[R] equal to the value of the
second expression.
That could either mean that the number is returned without change (if
the \f[I]scale\f[R] of the first expression matches the value of the
second expression), extended (if it is less), or truncated (if it is
more).
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]) and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The \f[B]power\f[R] operator (not the \f[B]exclusive or\f[R] operator,
as it would be in C) takes two expressions and raises the first to the
power of the value of the second.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]), and if it
is negative, the first value must be non-zero.
.RE
.TP
\f[B]*\f[R]
The \f[B]multiply\f[R] operator takes two expressions, multiplies them,
and returns the product.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The \f[B]divide\f[R] operator takes two expressions, divides them, and
returns the quotient.
The \f[I]scale\f[R] of the result shall be the value of \f[B]scale\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]%\f[R]
The \f[B]modulus\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and evaluates them by 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R] and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]+\f[R]
The \f[B]add\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the sum, with a \f[I]scale\f[R] equal to the
max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]-\f[R]
The \f[B]subtract\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the difference, with a \f[I]scale\f[R] equal to
the max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]<<\f[R]
The \f[B]left shift\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns a copy of the value of \f[B]a\f[R] with its
decimal point moved \f[B]b\f[R] places to the right.
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]) and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]>>\f[R]
The \f[B]right shift\f[R] operator takes two expressions, \f[B]a\f[R]
and \f[B]b\f[R], and returns a copy of the value of \f[B]a\f[R] with its
decimal point moved \f[B]b\f[R] places to the left.
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]) and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]=\f[R] \f[B]<<=\f[R] \f[B]>>=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R] \f[B]\[at]=\f[R]
The \f[B]assignment\f[R] operators take two expressions, \f[B]a\f[R] and
\f[B]b\f[R] where \f[B]a\f[R] is a named expression (see the \f[I]Named
Expressions\f[R] subsection).
.RS
.PP
For \f[B]=\f[R], \f[B]b\f[R] is copied and the result is assigned to
\f[B]a\f[R].
For all others, \f[B]a\f[R] and \f[B]b\f[R] are applied as operands to
the corresponding arithmetic operator and the result is assigned to
\f[B]a\f[R].
.PP
The \f[B]assignment\f[R] operators that correspond to operators that are
extensions are themselves \f[B]non-portable extensions\f[R].
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
The \f[B]relational\f[R] operators compare two expressions, \f[B]a\f[R]
and \f[B]b\f[R], and if the relation holds, according to C language
semantics, the result is \f[B]1\f[R].
Otherwise, it is \f[B]0\f[R].
.RS
.PP
Note that unlike in C, these operators have a lower precedence than the
\f[B]assignment\f[R] operators, which means that \f[B]a=b>c\f[R] is
interpreted as \f[B](a=b)>c\f[R].
.PP
Also, unlike the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
requires, these operators can appear anywhere any other expressions can
be used.
This allowance is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]&&\f[R]
The \f[B]boolean and\f[R] operator takes two expressions and returns
\f[B]1\f[R] if both expressions are non-zero, \f[B]0\f[R] otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]||\f[R]
The \f[B]boolean or\f[R] operator takes two expressions and returns
\f[B]1\f[R] if one of the expressions is non-zero, \f[B]0\f[R]
otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Statements
.PP
The following items are statements:
.IP " 1." 4
\f[B]E\f[R]
.IP " 2." 4
\f[B]{\f[R] \f[B]S\f[R] \f[B];\f[R] \&... \f[B];\f[R] \f[B]S\f[R]
\f[B]}\f[R]
.IP " 3." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 4." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
\f[B]else\f[R] \f[B]S\f[R]
.IP " 5." 4
\f[B]while\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 6." 4
\f[B]for\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B];\f[R] \f[B]E\f[R]
\f[B];\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 7." 4
An empty statement
.IP " 8." 4
\f[B]break\f[R]
.IP " 9." 4
\f[B]continue\f[R]
.IP "10." 4
\f[B]quit\f[R]
.IP "11." 4
\f[B]halt\f[R]
.IP "12." 4
\f[B]limits\f[R]
.IP "13." 4
A string of characters, enclosed in double quotes
.IP "14." 4
\f[B]print\f[R] \f[B]E\f[R] \f[B],\f[R] \&... \f[B],\f[R] \f[B]E\f[R]
.IP "15." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a \f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.PP
Numbers 4, 9, 11, 12, 14, and 15 are \f[B]non-portable extensions\f[R].
.PP
Also, as a \f[B]non-portable extension\f[R], any or all of the
expressions in the header of a for loop may be omitted.
If the condition (second expression) is omitted, it is assumed to be a
constant \f[B]1\f[R].
.PP
The \f[B]break\f[R] statement causes a loop to stop iterating and resume
execution immediately following a loop.
This is only allowed in loops.
.PP
The \f[B]continue\f[R] statement causes a loop iteration to stop early
and returns to the start of the loop, including testing the loop
condition.
This is only allowed in loops.
.PP
The \f[B]if\f[R] \f[B]else\f[R] statement does the same thing as in C.
.PP
The \f[B]quit\f[R] statement causes bc(1) to quit, even if it is on a
branch that will not be executed (it is a compile-time command).
.PP
The \f[B]halt\f[R] statement causes bc(1) to quit, if it is executed.
(Unlike \f[B]quit\f[R] if it is on a branch of an \f[B]if\f[R] statement
that is not executed, bc(1) does not quit.)
.PP
The \f[B]limits\f[R] statement prints the limits that this bc(1) is
subject to.
This is like the \f[B]quit\f[R] statement in that it is a compile-time
command.
.PP
An expression by itself is evaluated and printed, followed by a newline.
.PP
Both scientific notation and engineering notation are available for
printing the results of expressions.
Scientific notation is activated by assigning \f[B]0\f[R] to
\f[B]obase\f[R], and engineering notation is activated by assigning
\f[B]1\f[R] to \f[B]obase\f[R].
To deactivate them, just assign a different value to \f[B]obase\f[R].
.PP
Scientific notation and engineering notation are disabled if bc(1) is
run with either the \f[B]-s\f[R] or \f[B]-w\f[R] command-line options
(or equivalents).
.PP
Printing numbers in scientific notation and/or engineering notation is a
\f[B]non-portable extension\f[R].
.SS Print Statement
.PP
The \[lq]expressions\[rq] in a \f[B]print\f[R] statement may also be
strings.
If they are, there are backslash escape sequences that are interpreted
specially.
What those sequences are, and what they cause to be printed, are shown
below:
.PP
.TS
tab(@);
l l.
T{
\f[B]\[rs]a\f[R]
T}@T{
\f[B]\[rs]a\f[R]
T}
T{
\f[B]\[rs]b\f[R]
T}@T{
\f[B]\[rs]b\f[R]
T}
T{
\f[B]\[rs]\[rs]\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]e\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]f\f[R]
T}@T{
\f[B]\[rs]f\f[R]
T}
T{
\f[B]\[rs]n\f[R]
T}@T{
\f[B]\[rs]n\f[R]
T}
T{
\f[B]\[rs]q\f[R]
T}@T{
\f[B]\[dq]\f[R]
T}
T{
\f[B]\[rs]r\f[R]
T}@T{
\f[B]\[rs]r\f[R]
T}
T{
\f[B]\[rs]t\f[R]
T}@T{
\f[B]\[rs]t\f[R]
T}
.TE
.PP
Any other character following a backslash causes the backslash and
character to be printed as-is.
.PP
Any non-string expression in a print statement shall be assigned to
\f[B]last\f[R], like any other expression that is printed.
.SS Order of Evaluation
.PP
All expressions in a statment are evaluated left to right, except as
necessary to maintain order of operations.
This means, for example, assuming that \f[B]i\f[R] is equal to
\f[B]0\f[R], in the expression
.IP
.nf
\f[C]
a[i++] = i++
\f[R]
.fi
.PP
the first (or 0th) element of \f[B]a\f[R] is set to \f[B]1\f[R], and
\f[B]i\f[R] is equal to \f[B]2\f[R] at the end of the expression.
.PP
This includes function arguments.
Thus, assuming \f[B]i\f[R] is equal to \f[B]0\f[R], this means that in
the expression
.IP
.nf
\f[C]
x(i++, i++)
\f[R]
.fi
.PP
the first argument passed to \f[B]x()\f[R] is \f[B]0\f[R], and the
second argument is \f[B]1\f[R], while \f[B]i\f[R] is equal to
\f[B]2\f[R] before the function starts executing.
.SH FUNCTIONS
.PP
Function definitions are as follows:
.IP
.nf
\f[C]
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
\f[R]
.fi
.PP
Any \f[B]I\f[R] in the parameter list or \f[B]auto\f[R] list may be
replaced with \f[B]I[]\f[R] to make a parameter or \f[B]auto\f[R] var an
array, and any \f[B]I\f[R] in the parameter list may be replaced with
\f[B]*I[]\f[R] to make a parameter an array reference.
Callers of functions that take array references should not put an
asterisk in the call; they must be called with just \f[B]I[]\f[R] like
normal array parameters and will be automatically converted into
references.
.PP
As a \f[B]non-portable extension\f[R], the opening brace of a
\f[B]define\f[R] statement may appear on the next line.
.PP
As a \f[B]non-portable extension\f[R], the return statement may also be
in one of the following forms:
.IP "1." 3
\f[B]return\f[R]
.IP "2." 3
\f[B]return\f[R] \f[B](\f[R] \f[B])\f[R]
.IP "3." 3
\f[B]return\f[R] \f[B]E\f[R]
.PP
The first two, or not specifying a \f[B]return\f[R] statement, is
equivalent to \f[B]return (0)\f[R], unless the function is a
\f[B]void\f[R] function (see the \f[I]Void Functions\f[R] subsection
below).
.SS Void Functions
.PP
Functions can also be \f[B]void\f[R] functions, defined as follows:
.IP
.nf
\f[C]
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
\f[R]
.fi
.PP
They can only be used as standalone expressions, where such an
expression would be printed alone, except in a print statement.
.PP
Void functions can only use the first two \f[B]return\f[R] statements
listed above.
They can also omit the return statement entirely.
.PP
The word \[lq]void\[rq] is not treated as a keyword; it is still
possible to have variables, arrays, and functions named \f[B]void\f[R].
The word \[lq]void\[rq] is only treated specially right after the
\f[B]define\f[R] keyword.
.PP
This is a \f[B]non-portable extension\f[R].
.SS Array References
.PP
For any array in the parameter list, if the array is declared in the
form
.IP
.nf
\f[C]
*I[]
\f[R]
.fi
.PP
it is a \f[B]reference\f[R].
Any changes to the array in the function are reflected, when the
function returns, to the array that was passed in.
.PP
Other than this, all function arguments are passed by value.
.PP
This is a \f[B]non-portable extension\f[R].
.SH LIBRARY
.PP
All of the functions below, including the functions in the extended math
library (see the \f[I]Extended Library\f[R] subsection below), are
available when the \f[B]-l\f[R] or \f[B]\[en]mathlib\f[R] command-line
flags are given, except that the extended math library is not available
when the \f[B]-s\f[R] option, the \f[B]-w\f[R] option, or equivalents
are given.
.SS Standard Library
.PP
The
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
defines the following functions for the math library:
.TP
\f[B]s(x)\f[R]
Returns the sine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]c(x)\f[R]
Returns the cosine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]a(x)\f[R]
Returns the arctangent of \f[B]x\f[R], in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]l(x)\f[R]
Returns the natural logarithm of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]e(x)\f[R]
Returns the mathematical constant \f[B]e\f[R] raised to the power of
\f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]j(x, n)\f[R]
Returns the bessel integer order \f[B]n\f[R] (truncated) of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.SS Extended Library
.PP
The extended library is \f[I]not\f[R] loaded when the
\f[B]-s\f[R]/\f[B]\[en]standard\f[R] or \f[B]-w\f[R]/\f[B]\[en]warn\f[R]
options are given since they are not part of the library defined by the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).
.PP
The extended library is a \f[B]non-portable extension\f[R].
.TP
\f[B]p(x, y)\f[R]
Calculates \f[B]x\f[R] to the power of \f[B]y\f[R], even if \f[B]y\f[R]
is not an integer, and returns the result to the current
\f[B]scale\f[R].
.RS
.PP
It is an error if \f[B]y\f[R] is negative and \f[B]x\f[R] is
\f[B]0\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]r(x, p)\f[R]
Returns \f[B]x\f[R] rounded to \f[B]p\f[R] decimal places according to
the rounding mode round half away from
\f[B]0\f[R] (https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero).
.TP
\f[B]ceil(x, p)\f[R]
Returns \f[B]x\f[R] rounded to \f[B]p\f[R] decimal places according to
the rounding mode round away from
\f[B]0\f[R] (https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero).
.TP
\f[B]f(x)\f[R]
Returns the factorial of the truncated absolute value of \f[B]x\f[R].
.TP
\f[B]perm(n, k)\f[R]
Returns the permutation of the truncated absolute value of \f[B]n\f[R]
of the truncated absolute value of \f[B]k\f[R], if \f[B]k <= n\f[R].
If not, it returns \f[B]0\f[R].
.TP
\f[B]comb(n, k)\f[R]
Returns the combination of the truncated absolute value of \f[B]n\f[R]
of the truncated absolute value of \f[B]k\f[R], if \f[B]k <= n\f[R].
If not, it returns \f[B]0\f[R].
.TP
\f[B]l2(x)\f[R]
Returns the logarithm base \f[B]2\f[R] of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]l10(x)\f[R]
Returns the logarithm base \f[B]10\f[R] of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]log(x, b)\f[R]
Returns the logarithm base \f[B]b\f[R] of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]cbrt(x)\f[R]
Returns the cube root of \f[B]x\f[R].
.TP
\f[B]root(x, n)\f[R]
Calculates the truncated value of \f[B]n\f[R], \f[B]r\f[R], and returns
the \f[B]r\f[R]th root of \f[B]x\f[R] to the current \f[B]scale\f[R].
.RS
.PP
If \f[B]r\f[R] is \f[B]0\f[R] or negative, this raises an error and
causes bc(1) to reset (see the \f[B]RESET\f[R] section).
It also raises an error and causes bc(1) to reset if \f[B]r\f[R] is even
and \f[B]x\f[R] is negative.
.RE
.TP
\f[B]pi(p)\f[R]
Returns \f[B]pi\f[R] to \f[B]p\f[R] decimal places.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]t(x)\f[R]
Returns the tangent of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]a2(y, x)\f[R]
Returns the arctangent of \f[B]y/x\f[R], in radians.
If both \f[B]y\f[R] and \f[B]x\f[R] are equal to \f[B]0\f[R], it raises
an error and causes bc(1) to reset (see the \f[B]RESET\f[R] section).
Otherwise, if \f[B]x\f[R] is greater than \f[B]0\f[R], it returns
\f[B]a(y/x)\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is greater than
or equal to \f[B]0\f[R], it returns \f[B]a(y/x)+pi\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]a(y/x)-pi\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is greater than
\f[B]0\f[R], it returns \f[B]pi/2\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]-pi/2\f[R].
.RS
.PP
This function is the same as the \f[B]atan2()\f[R] function in many
programming languages.
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]sin(x)\f[R]
Returns the sine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is an alias of \f[B]s(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]cos(x)\f[R]
Returns the cosine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is an alias of \f[B]c(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]tan(x)\f[R]
Returns the tangent of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
If \f[B]x\f[R] is equal to \f[B]1\f[R] or \f[B]-1\f[R], this raises an
error and causes bc(1) to reset (see the \f[B]RESET\f[R] section).
.PP
This is an alias of \f[B]t(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]atan(x)\f[R]
Returns the arctangent of \f[B]x\f[R], in radians.
.RS
.PP
This is an alias of \f[B]a(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]atan2(y, x)\f[R]
Returns the arctangent of \f[B]y/x\f[R], in radians.
If both \f[B]y\f[R] and \f[B]x\f[R] are equal to \f[B]0\f[R], it raises
an error and causes bc(1) to reset (see the \f[B]RESET\f[R] section).
Otherwise, if \f[B]x\f[R] is greater than \f[B]0\f[R], it returns
\f[B]a(y/x)\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is greater than
or equal to \f[B]0\f[R], it returns \f[B]a(y/x)+pi\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]a(y/x)-pi\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is greater than
\f[B]0\f[R], it returns \f[B]pi/2\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]-pi/2\f[R].
.RS
.PP
This function is the same as the \f[B]atan2()\f[R] function in many
programming languages.
.PP
This is an alias of \f[B]a2(y, x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]r2d(x)\f[R]
Converts \f[B]x\f[R] from radians to degrees and returns the result.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]d2r(x)\f[R]
Converts \f[B]x\f[R] from degrees to radians and returns the result.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]frand(p)\f[R]
Generates a pseudo-random number between \f[B]0\f[R] (inclusive) and
\f[B]1\f[R] (exclusive) with the number of decimal digits after the
decimal point equal to the truncated absolute value of \f[B]p\f[R].
If \f[B]p\f[R] is not \f[B]0\f[R], then calling this function will
change the value of \f[B]seed\f[R].
If \f[B]p\f[R] is \f[B]0\f[R], then \f[B]0\f[R] is returned, and
\f[B]seed\f[R] is \f[I]not\f[R] changed.
.TP
\f[B]ifrand(i, p)\f[R]
Generates a pseudo-random number that is between \f[B]0\f[R] (inclusive)
and the truncated absolute value of \f[B]i\f[R] (exclusive) with the
number of decimal digits after the decimal point equal to the truncated
absolute value of \f[B]p\f[R].
If the absolute value of \f[B]i\f[R] is greater than or equal to
\f[B]2\f[R], and \f[B]p\f[R] is not \f[B]0\f[R], then calling this
function will change the value of \f[B]seed\f[R]; otherwise, \f[B]0\f[R]
is returned and \f[B]seed\f[R] is not changed.
.TP
\f[B]srand(x)\f[R]
Returns \f[B]x\f[R] with its sign flipped with probability
\f[B]0.5\f[R].
In other words, it randomizes the sign of \f[B]x\f[R].
.TP
\f[B]brand()\f[R]
Returns a random boolean value (either \f[B]0\f[R] or \f[B]1\f[R]).
.TP
\f[B]ubytes(x)\f[R]
Returns the numbers of unsigned integer bytes required to hold the
truncated absolute value of \f[B]x\f[R].
.TP
\f[B]sbytes(x)\f[R]
Returns the numbers of signed, two\[cq]s-complement integer bytes
required to hold the truncated value of \f[B]x\f[R].
.TP
\f[B]hex(x)\f[R]
Outputs the hexadecimal (base \f[B]16\f[R]) representation of
\f[B]x\f[R].
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]binary(x)\f[R]
Outputs the binary (base \f[B]2\f[R]) representation of \f[B]x\f[R].
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]output(x, b)\f[R]
Outputs the base \f[B]b\f[R] representation of \f[B]x\f[R].
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in as few power of two bytes as possible.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or is negative, an error message is
printed instead, but bc(1) is not reset (see the \f[B]RESET\f[R]
section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in as few power of two bytes as
possible.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, an error message is printed instead,
but bc(1) is not reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uintn(x, n)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]n\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]n\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]intn(x, n)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]n\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]n\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint8(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]1\f[R] byte.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]1\f[R] byte, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int8(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]1\f[R] byte.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]1\f[R] byte, an
error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint16(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]2\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]2\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int16(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]2\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]2\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint32(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]4\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]4\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int32(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]4\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]4\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint64(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]8\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]8\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int64(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]8\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]8\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]hex_uint(x, n)\f[R]
Outputs the representation of the truncated absolute value of
\f[B]x\f[R] as an unsigned integer in hexadecimal using \f[B]n\f[R]
bytes.
Not all of the value will be output if \f[B]n\f[R] is too small.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]binary_uint(x, n)\f[R]
Outputs the representation of the truncated absolute value of
\f[B]x\f[R] as an unsigned integer in binary using \f[B]n\f[R] bytes.
Not all of the value will be output if \f[B]n\f[R] is too small.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]output_uint(x, n)\f[R]
Outputs the representation of the truncated absolute value of
\f[B]x\f[R] as an unsigned integer in the current \f[B]obase\f[R] (see
the \f[B]SYNTAX\f[R] section) using \f[B]n\f[R] bytes.
Not all of the value will be output if \f[B]n\f[R] is too small.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]output_byte(x, i)\f[R]
Outputs byte \f[B]i\f[R] of the truncated absolute value of \f[B]x\f[R],
where \f[B]0\f[R] is the least significant byte and \f[B]number_of_bytes
- 1\f[R] is the most significant byte.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.SS Transcendental Functions
.PP
All transcendental functions can return slightly inaccurate results (up
to 1 ULP (https://en.wikipedia.org/wiki/Unit_in_the_last_place)).
This is unavoidable, and this
article (https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT) explains
why it is impossible and unnecessary to calculate exact results for the
transcendental functions.
.PP
Because of the possible inaccuracy, I recommend that users call those
functions with the precision (\f[B]scale\f[R]) set to at least 1 higher
than is necessary.
If exact results are \f[I]absolutely\f[R] required, users can double the
precision (\f[B]scale\f[R]) and then truncate.
.PP
The transcendental functions in the standard math library are:
.IP \[bu] 2
\f[B]s(x)\f[R]
.IP \[bu] 2
\f[B]c(x)\f[R]
.IP \[bu] 2
\f[B]a(x)\f[R]
.IP \[bu] 2
\f[B]l(x)\f[R]
.IP \[bu] 2
\f[B]e(x)\f[R]
.IP \[bu] 2
\f[B]j(x, n)\f[R]
.PP
The transcendental functions in the extended math library are:
.IP \[bu] 2
\f[B]l2(x)\f[R]
.IP \[bu] 2
\f[B]l10(x)\f[R]
.IP \[bu] 2
\f[B]log(x, b)\f[R]
.IP \[bu] 2
\f[B]pi(p)\f[R]
.IP \[bu] 2
\f[B]t(x)\f[R]
.IP \[bu] 2
\f[B]a2(y, x)\f[R]
.IP \[bu] 2
\f[B]sin(x)\f[R]
.IP \[bu] 2
\f[B]cos(x)\f[R]
.IP \[bu] 2
\f[B]tan(x)\f[R]
.IP \[bu] 2
\f[B]atan(x)\f[R]
.IP \[bu] 2
\f[B]atan2(y, x)\f[R]
.IP \[bu] 2
\f[B]r2d(x)\f[R]
.IP \[bu] 2
\f[B]d2r(x)\f[R]
.SH RESET
.PP
When bc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any functions that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all functions returned) is skipped.
.PP
Thus, when bc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.PP
Note that this reset behavior is different from the GNU bc(1), which
attempts to start executing the statement right after the one that
caused an error.
.SH PERFORMANCE
.PP
Most bc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This bc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]BC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]BC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]BC_BASE_DIGS\f[R].
.PP
The actual values of \f[B]BC_LONG_BIT\f[R] and \f[B]BC_BASE_DIGS\f[R]
can be queried with the \f[B]limits\f[R] statement.
.PP
In addition, this bc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]BC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on bc(1):
.TP
\f[B]BC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
bc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]BC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]BC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]BC_BASE_DIGS\f[R].
.TP
\f[B]BC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]BC_BASE_POW\f[R].
.TP
\f[B]BC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]BC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_RAND_MAX\f[R]
The maximum integer (inclusive) returned by the \f[B]rand()\f[R]
operand.
Set at \f[B]2\[ha]BC_LONG_BIT-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]BC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
The actual values can be queried with the \f[B]limits\f[R] statement.
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
bc(1) recognizes the following environment variables:
.TP
\f[B]POSIXLY_CORRECT\f[R]
If this variable exists (no matter the contents), bc(1) behaves as if
the \f[B]-s\f[R] option was given.
.TP
\f[B]BC_ENV_ARGS\f[R]
This is another way to give command-line arguments to bc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]BC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
.RS
.PP
The code that parses \f[B]BC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some bc file.bc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]bc\[dq] file.bc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]BC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]BC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), bc(1) will output lines to that length,
including the backslash (\f[B]\[rs]\f[R]).
The default line length is \f[B]70\f[R].
.SH EXIT STATUS
.PP
bc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, using a negative number as a bound for the
pseudo-random number generator, attempting to convert a negative number
to a hardware integer, overflow when converting a number to a hardware
integer, and attempting to use a non-integer where an integer is
required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]), places (\f[B]\[at]\f[R]), left shift
(\f[B]<<\f[R]), and right shift (\f[B]>>\f[R]) operators and their
corresponding assignment operators.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, using a token
where it is invalid, giving an invalid expression, giving an invalid
print statement, giving an invalid function definition, attempting to
assign to an expression that is not a named expression (see the
\f[I]Named Expressions\f[R] subsection of the \f[B]SYNTAX\f[R] section),
giving an invalid \f[B]auto\f[R] list, having a duplicate
\f[B]auto\f[R]/function parameter, failing to find the end of a code
block, attempting to return a value from a \f[B]void\f[R] function,
attempting to use a variable as a reference, and using any extensions
when the option \f[B]-s\f[R] or any equivalents were given.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a \f[B]void\f[R] function call as a value in an
expression.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (bc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, bc(1)
always exits and returns \f[B]4\f[R], no matter what mode bc(1) is in.
.PP
The other statuses will only be returned when bc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
bc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Per the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, bc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, bc(1) turns on \[lq]TTY mode.\[rq]
.PP
The prompt is enabled in TTY mode.
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause bc(1) to stop execution of the
current input.
If bc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If bc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If bc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to bc(1) as it is
executing a file, it can seem as though bc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause bc(1) to clean up and
exit, and it uses the default handler for all other signals.
.SH SEE ALSO
.PP
dc(1)
.SH STANDARDS
.PP
bc(1) is compliant with the IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
The flags \f[B]-efghiqsvVw\f[R], all long options, and the extensions
noted above are extensions to that specification.
.PP
Note that the specification explicitly says that bc(1) only accepts
numbers that use a period (\f[B].\f[R]) as a radix point, regardless of
the value of \f[B]LC_NUMERIC\f[R].
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHORS
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/bc/HN.1.md b/contrib/bc/manuals/bc/HN.1.md
index 979e0510822f..cab2e5773219 100644
--- a/contrib/bc/manuals/bc/HN.1.md
+++ b/contrib/bc/manuals/bc/HN.1.md
@@ -1,1671 +1,1680 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# NAME
bc - arbitrary-precision decimal arithmetic language and calculator
# SYNOPSIS
**bc** [**-ghilPqsvVw**] [**--global-stacks**] [**--help**] [**--interactive**] [**--mathlib**] [**--no-prompt**] [**--quiet**] [**--standard**] [**--warn**] [**--version**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...]
[*file*...]
# DESCRIPTION
bc(1) is an interactive processor for a language first standardized in 1991 by
POSIX. (The current standard is [here][1].) The language provides unlimited
precision decimal arithmetic and is somewhat C-like, but there are differences.
Such differences will be noted in this document.
After parsing and handling options, this bc(1) reads any files given on the
command line and executes them before reading from **stdin**.
# OPTIONS
The following are the options that bc(1) accepts.
**-g**, **--global-stacks**
: Turns the globals **ibase**, **obase**, **scale**, and **seed** into stacks.
This has the effect that a copy of the current value of all four are pushed
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
(**Note**: the function **output(x,b)** exists in the extended math library.
See the **LIBRARY** section.)
However, since using this flag means that functions cannot set **ibase**,
**obase**, **scale**, or **seed** globally, functions that are made to do so
cannot work anymore. There are two possible use cases for that, and each has
a solution.
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o="bc -e ibase=A -e obase=8"
alias h2b="bc -e ibase=G -e obase=2"
Second, if the purpose of a function is to set **ibase**, **obase**,
**scale**, or **seed** globally for any other purpose, it could be split
into one to four functions (based on how many globals it sets) and each of
those functions could return the desired value for a global.
For functions that set **seed**, the value assigned to **seed** is not
propagated to parent functions. This means that the sequence of
pseudo-random numbers that they see will not be the same sequence of
pseudo-random numbers that any parent sees. This is only the case once
**seed** has been set.
If a function desires to not affect the sequence of pseudo-random numbers
of its parents, but wants to use the same **seed**, it can use the following
line:
seed = seed
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
**-h**, **--help**
: Prints a usage message and quits.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-l**, **--mathlib**
: Sets **scale** (see the **SYNTAX** section) to **20** and loads the included
math library and the extended math library before running any code,
including any expressions or files specified on the command line.
To learn what is in the libraries, see the **LIBRARY** section.
**-P**, **--no-prompt**
: Disables the prompt in TTY mode. (The prompt is only enabled in TTY mode.
See the **TTY MODE** section) This is mostly for those users that do not
want a prompt or are not used to having them in bc(1). Most of those users
would want to put this option in **BC_ENV_ARGS** (see the
**ENVIRONMENT VARIABLES** section).
This is a **non-portable extension**.
**-q**, **--quiet**
: This option is for compatibility with the [GNU bc(1)][2]; it is a no-op.
Without this option, GNU bc(1) prints a copyright header. This bc(1) only
prints the copyright header if one or more of the **-v**, **-V**, or
**--version** options are given.
This is a **non-portable extension**.
**-s**, **--standard**
: Process exactly the language defined by the [standard][1] and error if any
extensions are used.
This is a **non-portable extension**.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
This is a **non-portable extension**.
**-w**, **--warn**
: Like **-s** and **--standard**, except that warnings (and not errors) are
printed for non-standard extensions and execution continues normally.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **BC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **bc <file> >&-**, it will quit with an error. This
is done so that bc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **bc <file> 2>&-**, it will quit with an error. This
is done so that bc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
The syntax for bc(1) programs is mostly C-like, with some differences. This
bc(1) follows the [POSIX standard][1], which is a much more thorough resource
for the language this bc(1) accepts. This section is meant to be a summary and a
listing of all the extensions to the standard.
In the sections below, **E** means expression, **S** means statement, and **I**
means identifier.
Identifiers (**I**) start with a lowercase letter and can be followed by any
number (up to **BC_NAME_MAX-1**) of lowercase letters (**a-z**), digits
(**0-9**), and underscores (**\_**). The regex is **\[a-z\]\[a-z0-9\_\]\***.
Identifiers with more than one character (letter) are a
**non-portable extension**.
**ibase** is a global variable determining how to interpret constant numbers. It
is the "input" base, or the number base used for interpreting input numbers.
**ibase** is initially **10**. If the **-s** (**--standard**) and **-w**
(**--warn**) flags were not given on the command line, the max allowable value
for **ibase** is **36**. Otherwise, it is **16**. The min allowable value for
**ibase** is **2**. The max allowable value for **ibase** can be queried in
bc(1) programs with the **maxibase()** built-in function.
**obase** is a global variable determining how to output results. It is the
"output" base, or the number base used for outputting numbers. **obase** is
initially **10**. The max allowable value for **obase** is **BC_BASE_MAX** and
can be queried in bc(1) programs with the **maxobase()** built-in function. The
min allowable value for **obase** is **0**. If **obase** is **0**, values are
output in scientific notation, and if **obase** is **1**, values are output in
engineering notation. Otherwise, values are output in the specified base.
Outputting in scientific and engineering notations are **non-portable
extensions**.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a global variable that
sets the precision of any operations, with exceptions. **scale** is initially
**0**. **scale** cannot be negative. The max allowable value for **scale** is
**BC_SCALE_MAX** and can be queried in bc(1) programs with the **maxscale()**
built-in function.
bc(1) has both *global* variables and *local* variables. All *local*
variables are local to the function; they are parameters or are introduced in
the **auto** list of a function (see the **FUNCTIONS** section). If a variable
is accessed which is not a parameter or in the **auto** list, it is assumed to
be *global*. If a parent function has a *local* variable version of a variable
that a child function considers *global*, the value of that *global* variable in
the child function is the value of the variable in the parent function, not the
value of the actual *global* variable.
All of the above applies to arrays as well.
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence operator is an
assignment operator *and* the expression is notsurrounded by parentheses.
The value that is printed is also assigned to the special variable **last**. A
single dot (**.**) may also be used as a synonym for **last**. These are
**non-portable extensions**.
Either semicolons or newlines may separate statements.
## Comments
There are two kinds of comments:
1. Block comments are enclosed in **/\*** and **\*/**.
2. Line comments go from **#** until, and not including, the next newline. This
is a **non-portable extension**.
## Named Expressions
The following are named expressions in bc(1):
1. Variables: **I**
2. Array Elements: **I[E]**
3. **ibase**
4. **obase**
5. **scale**
6. **seed**
7. **last** or a single dot (**.**)
Numbers 6 and 7 are **non-portable extensions**.
The meaning of **seed** is dependent on the current pseudo-random number
generator but is guaranteed to not change except for new major versions.
The *scale* and sign of the value may be significant.
If a previously used **seed** value is assigned to **seed** and used again, the
pseudo-random number generator is guaranteed to produce the same sequence of
pseudo-random numbers as it did when the **seed** value was previously used.
The exact value assigned to **seed** is not guaranteed to be returned if
**seed** is queried again immediately. However, if **seed** *does* return a
different value, both values, when assigned to **seed**, are guaranteed to
produce the same sequence of pseudo-random numbers. This means that certain
values assigned to **seed** will *not* produce unique sequences of pseudo-random
numbers. The value of **seed** will change after any use of the **rand()** and
**irand(E)** operands (see the *Operands* subsection below), except if the
parameter passed to **irand(E)** is **0**, **1**, or negative.
There is no limit to the length (number of significant decimal digits) or
*scale* of the value that can be assigned to **seed**.
Variables and arrays do not interfere; users can have arrays named the same as
variables. This also applies to functions (see the **FUNCTIONS** section), so a
user can have a variable, array, and function that all have the same name, and
they will not shadow each other, whether inside of functions or not.
Named expressions are required as the operand of **increment**/**decrement**
operators and as the left side of **assignment** operators (see the *Operators*
subsection).
## Operands
The following are valid operands in bc(1):
1. Numbers (see the *Numbers* subsection below).
2. Array indices (**I[E]**).
3. **(E)**: The value of **E** (used to change precedence).
4. **sqrt(E)**: The square root of **E**. **E** must be non-negative.
5. **length(E)**: The number of significant decimal digits in **E**.
6. **length(I[])**: The number of elements in the array **I**. This is a
**non-portable extension**.
7. **scale(E)**: The *scale* of **E**.
8. **abs(E)**: The absolute value of **E**. This is a **non-portable
extension**.
9. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a non-**void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
10. **read()**: Reads a line from **stdin** and uses that as an expression. The
result of that expression is the result of the **read()** operand. This is a
**non-portable extension**.
11. **maxibase()**: The max allowable **ibase**. This is a **non-portable
extension**.
12. **maxobase()**: The max allowable **obase**. This is a **non-portable
extension**.
13. **maxscale()**: The max allowable **scale**. This is a **non-portable
extension**.
14. **rand()**: A pseudo-random integer between **0** (inclusive) and
**BC_RAND_MAX** (inclusive). Using this operand will change the value of
**seed**. This is a **non-portable extension**.
15. **irand(E)**: A pseudo-random integer between **0** (inclusive) and the
value of **E** (exclusive). If **E** is negative or is a non-integer
(**E**'s *scale* is not **0**), an error is raised, and bc(1) resets (see
the **RESET** section) while **seed** remains unchanged. If **E** is larger
than **BC_RAND_MAX**, the higher bound is honored by generating several
pseudo-random integers, multiplying them by appropriate powers of
**BC_RAND_MAX+1**, and adding them together. Thus, the size of integer that
can be generated with this operand is unbounded. Using this operand will
change the value of **seed**, unless the value of **E** is **0** or **1**.
In that case, **0** is returned, and **seed** is *not* changed. This is a
**non-portable extension**.
16. **maxrand()**: The max integer returned by **rand()**. This is a
**non-portable extension**.
The integers generated by **rand()** and **irand(E)** are guaranteed to be as
unbiased as possible, subject to the limitations of the pseudo-random number
generator.
**Note**: The values returned by the pseudo-random number generator with
**rand()** and **irand(E)** are guaranteed to *NOT* be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator. However,
they *are* guaranteed to be reproducible with identical **seed** values. This
means that the pseudo-random values from bc(1) should only be used where a
reproducible stream of pseudo-random numbers is *ESSENTIAL*. In any other case,
use a non-seeded pseudo-random number generator.
## Numbers
Numbers are strings made up of digits, uppercase letters, and at most **1**
period for a radix. Numbers can have up to **BC_NUM_MAX** digits. Uppercase
letters are equal to **9** + their position in the alphabet (i.e., **A** equals
**10**, or **9+1**). If a digit or letter makes no sense with the current value
of **ibase**, they are set to the value of the highest valid digit in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **Z** alone always equals decimal
**35**.
In addition, bc(1) accepts numbers in scientific notation. These have the form
**\<number\>e\<integer\>**. The exponent (the portion after the **e**) must be
an integer. An example is **1.89237e9**, which is equal to **1892370000**.
Negative exponents are also allowed, so **4.2890e-3** is equal to **0.0042890**.
Using scientific notation is an error or warning if the **-s** or **-w**,
respectively, command-line options (or equivalents) are given.
**WARNING**: Both the number and the exponent in scientific notation are
interpreted according to the current **ibase**, but the number is still
multiplied by **10\^exponent** regardless of the current **ibase**. For example,
if **ibase** is **16** and bc(1) is given the number string **FFeA**, the
resulting decimal number will be **2550000000000**, and if bc(1) is given the
number string **10e-4**, the resulting decimal number will be **0.0016**.
Accepting input as scientific notation is a **non-portable extension**.
## Operators
The following arithmetic and logical operators can be used. They are listed in
order of decreasing precedence. Operators in the same group have the same
precedence.
**++** **--**
: Type: Prefix and Postfix
Associativity: None
Description: **increment**, **decrement**
**-** **!**
: Type: Prefix
Associativity: None
Description: **negation**, **boolean not**
**\$**
: Type: Postfix
Associativity: None
Description: **truncation**
**\@**
: Type: Binary
Associativity: Right
Description: **set precision**
**\^**
: Type: Binary
Associativity: Right
Description: **power**
**\*** **/** **%**
: Type: Binary
Associativity: Left
Description: **multiply**, **divide**, **modulus**
**+** **-**
: Type: Binary
Associativity: Left
Description: **add**, **subtract**
**\<\<** **\>\>**
: Type: Binary
Associativity: Left
Description: **shift left**, **shift right**
**=** **\<\<=** **\>\>=** **+=** **-=** **\*=** **/=** **%=** **\^=** **\@=**
: Type: Binary
Associativity: Right
Description: **assignment**
**==** **\<=** **\>=** **!=** **\<** **\>**
: Type: Binary
Associativity: Left
Description: **relational**
**&&**
: Type: Binary
Associativity: Left
Description: **boolean and**
**||**
: Type: Binary
Associativity: Left
Description: **boolean or**
The operators will be described in more detail below.
**++** **--**
: The prefix and postfix **increment** and **decrement** operators behave
exactly like they would in C. They require a named expression (see the
*Named Expressions* subsection) as an operand.
The prefix versions of these operators are more efficient; use them where
possible.
**-**
: The **negation** operator returns **0** if a user attempts to negate any
expression with the value **0**. Otherwise, a copy of the expression with
its sign flipped is returned.
**!**
: The **boolean not** operator returns **1** if the expression is **0**, or
**0** otherwise.
This is a **non-portable extension**.
**\$**
: The **truncation** operator returns a copy of the given expression with all
of its *scale* removed.
This is a **non-portable extension**.
**\@**
: The **set precision** operator takes two expressions and returns a copy of
the first with its *scale* equal to the value of the second expression. That
could either mean that the number is returned without change (if the
*scale* of the first expression matches the value of the second
expression), extended (if it is less), or truncated (if it is more).
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**\^**
: The **power** operator (not the **exclusive or** operator, as it would be in
C) takes two expressions and raises the first to the power of the value of
the second. The *scale* of the result is equal to **scale**.
The second expression must be an integer (no *scale*), and if it is
negative, the first value must be non-zero.
**\***
: The **multiply** operator takes two expressions, multiplies them, and
returns the product. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result is
equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The **divide** operator takes two expressions, divides them, and returns the
quotient. The *scale* of the result shall be the value of **scale**.
The second expression must be non-zero.
**%**
: The **modulus** operator takes two expressions, **a** and **b**, and
evaluates them by 1) Computing **a/b** to current **scale** and 2) Using the
result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The second expression must be non-zero.
**+**
: The **add** operator takes two expressions, **a** and **b**, and returns the
sum, with a *scale* equal to the max of the *scale*s of **a** and **b**.
**-**
: The **subtract** operator takes two expressions, **a** and **b**, and
returns the difference, with a *scale* equal to the max of the *scale*s of
**a** and **b**.
**\<\<**
: The **left shift** operator takes two expressions, **a** and **b**, and
returns a copy of the value of **a** with its decimal point moved **b**
places to the right.
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**\>\>**
: The **right shift** operator takes two expressions, **a** and **b**, and
returns a copy of the value of **a** with its decimal point moved **b**
places to the left.
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**=** **\<\<=** **\>\>=** **+=** **-=** **\*=** **/=** **%=** **\^=** **\@=**
: The **assignment** operators take two expressions, **a** and **b** where
**a** is a named expression (see the *Named Expressions* subsection).
For **=**, **b** is copied and the result is assigned to **a**. For all
others, **a** and **b** are applied as operands to the corresponding
arithmetic operator and the result is assigned to **a**.
The **assignment** operators that correspond to operators that are
extensions are themselves **non-portable extensions**.
**==** **\<=** **\>=** **!=** **\<** **\>**
: The **relational** operators compare two expressions, **a** and **b**, and
if the relation holds, according to C language semantics, the result is
**1**. Otherwise, it is **0**.
Note that unlike in C, these operators have a lower precedence than the
**assignment** operators, which means that **a=b\>c** is interpreted as
**(a=b)\>c**.
Also, unlike the [standard][1] requires, these operators can appear anywhere
any other expressions can be used. This allowance is a
**non-portable extension**.
**&&**
: The **boolean and** operator takes two expressions and returns **1** if both
expressions are non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
**||**
: The **boolean or** operator takes two expressions and returns **1** if one
of the expressions is non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
## Statements
The following items are statements:
1. **E**
2. **{** **S** **;** ... **;** **S** **}**
3. **if** **(** **E** **)** **S**
4. **if** **(** **E** **)** **S** **else** **S**
5. **while** **(** **E** **)** **S**
6. **for** **(** **E** **;** **E** **;** **E** **)** **S**
7. An empty statement
8. **break**
9. **continue**
10. **quit**
11. **halt**
12. **limits**
13. A string of characters, enclosed in double quotes
14. **print** **E** **,** ... **,** **E**
15. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
Numbers 4, 9, 11, 12, 14, and 15 are **non-portable extensions**.
Also, as a **non-portable extension**, any or all of the expressions in the
header of a for loop may be omitted. If the condition (second expression) is
omitted, it is assumed to be a constant **1**.
The **break** statement causes a loop to stop iterating and resume execution
immediately following a loop. This is only allowed in loops.
The **continue** statement causes a loop iteration to stop early and returns to
the start of the loop, including testing the loop condition. This is only
allowed in loops.
The **if** **else** statement does the same thing as in C.
The **quit** statement causes bc(1) to quit, even if it is on a branch that will
not be executed (it is a compile-time command).
The **halt** statement causes bc(1) to quit, if it is executed. (Unlike **quit**
if it is on a branch of an **if** statement that is not executed, bc(1) does not
quit.)
The **limits** statement prints the limits that this bc(1) is subject to. This
is like the **quit** statement in that it is a compile-time command.
An expression by itself is evaluated and printed, followed by a newline.
Both scientific notation and engineering notation are available for printing the
results of expressions. Scientific notation is activated by assigning **0** to
**obase**, and engineering notation is activated by assigning **1** to
**obase**. To deactivate them, just assign a different value to **obase**.
Scientific notation and engineering notation are disabled if bc(1) is run with
either the **-s** or **-w** command-line options (or equivalents).
Printing numbers in scientific notation and/or engineering notation is a
**non-portable extension**.
## Print Statement
The "expressions" in a **print** statement may also be strings. If they are, there
are backslash escape sequences that are interpreted specially. What those
sequences are, and what they cause to be printed, are shown below:
-------- -------
**\\a** **\\a**
**\\b** **\\b**
**\\\\** **\\**
**\\e** **\\**
**\\f** **\\f**
**\\n** **\\n**
**\\q** **"**
**\\r** **\\r**
**\\t** **\\t**
-------- -------
Any other character following a backslash causes the backslash and character to
be printed as-is.
Any non-string expression in a print statement shall be assigned to **last**,
like any other expression that is printed.
## Order of Evaluation
All expressions in a statment are evaluated left to right, except as necessary
to maintain order of operations. This means, for example, assuming that **i** is
equal to **0**, in the expression
a[i++] = i++
the first (or 0th) element of **a** is set to **1**, and **i** is equal to **2**
at the end of the expression.
This includes function arguments. Thus, assuming **i** is equal to **0**, this
means that in the expression
x(i++, i++)
the first argument passed to **x()** is **0**, and the second argument is **1**,
while **i** is equal to **2** before the function starts executing.
# FUNCTIONS
Function definitions are as follows:
```
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
```
Any **I** in the parameter list or **auto** list may be replaced with **I[]** to
make a parameter or **auto** var an array, and any **I** in the parameter list
may be replaced with **\*I[]** to make a parameter an array reference. Callers
of functions that take array references should not put an asterisk in the call;
they must be called with just **I[]** like normal array parameters and will be
automatically converted into references.
As a **non-portable extension**, the opening brace of a **define** statement may
appear on the next line.
As a **non-portable extension**, the return statement may also be in one of the
following forms:
1. **return**
2. **return** **(** **)**
3. **return** **E**
The first two, or not specifying a **return** statement, is equivalent to
**return (0)**, unless the function is a **void** function (see the *Void
Functions* subsection below).
## Void Functions
Functions can also be **void** functions, defined as follows:
```
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
```
They can only be used as standalone expressions, where such an expression would
be printed alone, except in a print statement.
Void functions can only use the first two **return** statements listed above.
They can also omit the return statement entirely.
The word "void" is not treated as a keyword; it is still possible to have
variables, arrays, and functions named **void**. The word "void" is only
treated specially right after the **define** keyword.
This is a **non-portable extension**.
## Array References
For any array in the parameter list, if the array is declared in the form
```
*I[]
```
it is a **reference**. Any changes to the array in the function are reflected,
when the function returns, to the array that was passed in.
Other than this, all function arguments are passed by value.
This is a **non-portable extension**.
# LIBRARY
All of the functions below, including the functions in the extended math
library (see the *Extended Library* subsection below), are available when the
**-l** or **--mathlib** command-line flags are given, except that the extended
math library is not available when the **-s** option, the **-w** option, or
equivalents are given.
## Standard Library
The [standard][1] defines the following functions for the math library:
**s(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**c(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a(x)**
: Returns the arctangent of **x**, in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l(x)**
: Returns the natural logarithm of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**e(x)**
: Returns the mathematical constant **e** raised to the power of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**j(x, n)**
: Returns the bessel integer order **n** (truncated) of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
## Extended Library
The extended library is *not* loaded when the **-s**/**--standard** or
**-w**/**--warn** options are given since they are not part of the library
defined by the [standard][1].
The extended library is a **non-portable extension**.
**p(x, y)**
: Calculates **x** to the power of **y**, even if **y** is not an integer, and
returns the result to the current **scale**.
It is an error if **y** is negative and **x** is **0**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**r(x, p)**
: Returns **x** rounded to **p** decimal places according to the rounding mode
[round half away from **0**][3].
**ceil(x, p)**
: Returns **x** rounded to **p** decimal places according to the rounding mode
[round away from **0**][6].
**f(x)**
: Returns the factorial of the truncated absolute value of **x**.
**perm(n, k)**
: Returns the permutation of the truncated absolute value of **n** of the
truncated absolute value of **k**, if **k \<= n**. If not, it returns **0**.
**comb(n, k)**
: Returns the combination of the truncated absolute value of **n** of the
truncated absolute value of **k**, if **k \<= n**. If not, it returns **0**.
**l2(x)**
: Returns the logarithm base **2** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l10(x)**
: Returns the logarithm base **10** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**log(x, b)**
: Returns the logarithm base **b** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**cbrt(x)**
: Returns the cube root of **x**.
**root(x, n)**
: Calculates the truncated value of **n**, **r**, and returns the **r**th root
of **x** to the current **scale**.
If **r** is **0** or negative, this raises an error and causes bc(1) to
reset (see the **RESET** section). It also raises an error and causes bc(1)
to reset if **r** is even and **x** is negative.
**pi(p)**
: Returns **pi** to **p** decimal places.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**t(x)**
: Returns the tangent of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a2(y, x)**
: Returns the arctangent of **y/x**, in radians. If both **y** and **x** are
equal to **0**, it raises an error and causes bc(1) to reset (see the
**RESET** section). Otherwise, if **x** is greater than **0**, it returns
**a(y/x)**. If **x** is less than **0**, and **y** is greater than or equal
to **0**, it returns **a(y/x)+pi**. If **x** is less than **0**, and **y**
is less than **0**, it returns **a(y/x)-pi**. If **x** is equal to **0**,
and **y** is greater than **0**, it returns **pi/2**. If **x** is equal to
**0**, and **y** is less than **0**, it returns **-pi/2**.
This function is the same as the **atan2()** function in many programming
languages.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**sin(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is an alias of **s(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**cos(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is an alias of **c(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**tan(x)**
: Returns the tangent of **x**, which is assumed to be in radians.
If **x** is equal to **1** or **-1**, this raises an error and causes bc(1)
to reset (see the **RESET** section).
This is an alias of **t(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**atan(x)**
: Returns the arctangent of **x**, in radians.
This is an alias of **a(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**atan2(y, x)**
: Returns the arctangent of **y/x**, in radians. If both **y** and **x** are
equal to **0**, it raises an error and causes bc(1) to reset (see the
**RESET** section). Otherwise, if **x** is greater than **0**, it returns
**a(y/x)**. If **x** is less than **0**, and **y** is greater than or equal
to **0**, it returns **a(y/x)+pi**. If **x** is less than **0**, and **y**
is less than **0**, it returns **a(y/x)-pi**. If **x** is equal to **0**,
and **y** is greater than **0**, it returns **pi/2**. If **x** is equal to
**0**, and **y** is less than **0**, it returns **-pi/2**.
This function is the same as the **atan2()** function in many programming
languages.
This is an alias of **a2(y, x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**r2d(x)**
: Converts **x** from radians to degrees and returns the result.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**d2r(x)**
: Converts **x** from degrees to radians and returns the result.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**frand(p)**
: Generates a pseudo-random number between **0** (inclusive) and **1**
(exclusive) with the number of decimal digits after the decimal point equal
to the truncated absolute value of **p**. If **p** is not **0**, then
calling this function will change the value of **seed**. If **p** is **0**,
then **0** is returned, and **seed** is *not* changed.
**ifrand(i, p)**
: Generates a pseudo-random number that is between **0** (inclusive) and the
truncated absolute value of **i** (exclusive) with the number of decimal
digits after the decimal point equal to the truncated absolute value of
**p**. If the absolute value of **i** is greater than or equal to **2**, and
**p** is not **0**, then calling this function will change the value of
**seed**; otherwise, **0** is returned and **seed** is not changed.
**srand(x)**
: Returns **x** with its sign flipped with probability **0.5**. In other
words, it randomizes the sign of **x**.
**brand()**
: Returns a random boolean value (either **0** or **1**).
**ubytes(x)**
: Returns the numbers of unsigned integer bytes required to hold the truncated
absolute value of **x**.
**sbytes(x)**
: Returns the numbers of signed, two's-complement integer bytes required to
hold the truncated value of **x**.
**hex(x)**
: Outputs the hexadecimal (base **16**) representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**binary(x)**
: Outputs the binary (base **2**) representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output(x, b)**
: Outputs the base **b** representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in as few power of two bytes as possible. Both outputs are
split into bytes separated by spaces.
If **x** is not an integer or is negative, an error message is printed
instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in as few power of two bytes as possible. Both
outputs are split into bytes separated by spaces.
If **x** is not an integer, an error message is printed instead, but bc(1)
is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uintn(x, n)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **n** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **n** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**intn(x, n)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **n** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **n** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint8(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **1** byte. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **1** byte, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int8(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **1** byte. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **1** byte, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint16(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **2** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **2** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int16(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **2** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **2** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint32(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **4** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **4** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int32(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **4** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **4** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint64(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **8** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **8** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int64(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **8** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **8** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**hex_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in hexadecimal using **n** bytes. Not all of the value will
be output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**binary_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in binary using **n** bytes. Not all of the value will be
output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in the current **obase** (see the **SYNTAX** section) using
**n** bytes. Not all of the value will be output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output_byte(x, i)**
: Outputs byte **i** of the truncated absolute value of **x**, where **0** is
the least significant byte and **number_of_bytes - 1** is the most
significant byte.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
## Transcendental Functions
All transcendental functions can return slightly inaccurate results (up to 1
[ULP][4]). This is unavoidable, and [this article][5] explains why it is
impossible and unnecessary to calculate exact results for the transcendental
functions.
Because of the possible inaccuracy, I recommend that users call those functions
with the precision (**scale**) set to at least 1 higher than is necessary. If
exact results are *absolutely* required, users can double the precision
(**scale**) and then truncate.
The transcendental functions in the standard math library are:
* **s(x)**
* **c(x)**
* **a(x)**
* **l(x)**
* **e(x)**
* **j(x, n)**
The transcendental functions in the extended math library are:
* **l2(x)**
* **l10(x)**
* **log(x, b)**
* **pi(p)**
* **t(x)**
* **a2(y, x)**
* **sin(x)**
* **cos(x)**
* **tan(x)**
* **atan(x)**
* **atan2(y, x)**
* **r2d(x)**
* **d2r(x)**
# RESET
When bc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any functions that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
functions returned) is skipped.
Thus, when bc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
Note that this reset behavior is different from the GNU bc(1), which attempts to
start executing the statement right after the one that caused an error.
# PERFORMANCE
Most bc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This bc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **BC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **BC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**BC_BASE_DIGS**.
The actual values of **BC_LONG_BIT** and **BC_BASE_DIGS** can be queried with
the **limits** statement.
In addition, this bc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **BC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on bc(1):
**BC_LONG_BIT**
: The number of bits in the **long** type in the environment where bc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**BC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **BC_LONG_BIT**.
**BC_BASE_POW**
: The max decimal number that each large integer can store (see
**BC_BASE_DIGS**) plus **1**. Depends on **BC_BASE_DIGS**.
**BC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **BC_LONG_BIT**.
**BC_BASE_MAX**
: The maximum output base. Set at **BC_BASE_POW**.
**BC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**BC_SCALE_MAX**
: The maximum **scale**. Set at **BC_OVERFLOW_MAX-1**.
**BC_STRING_MAX**
: The maximum length of strings. Set at **BC_OVERFLOW_MAX-1**.
**BC_NAME_MAX**
: The maximum length of identifiers. Set at **BC_OVERFLOW_MAX-1**.
**BC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **BC_OVERFLOW_MAX-1**.
**BC_RAND_MAX**
: The maximum integer (inclusive) returned by the **rand()** operand. Set at
**2\^BC_LONG_BIT-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**BC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
The actual values can be queried with the **limits** statement.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
bc(1) recognizes the following environment variables:
**POSIXLY_CORRECT**
: If this variable exists (no matter the contents), bc(1) behaves as if
the **-s** option was given.
**BC_ENV_ARGS**
: This is another way to give command-line arguments to bc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **BC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
The code that parses **BC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some bc file.bc"** will be correctly parsed, but the string
**"/home/gavin/some \"bc\" file.bc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **BC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**BC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), bc(1) will output
lines to that length, including the backslash (**\\**). The default line
length is **70**.
# EXIT STATUS
bc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, using a negative number as a bound for the pseudo-random number
generator, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**), places (**\@**), left shift (**\<\<**), and right shift (**\>\>**)
operators and their corresponding assignment operators.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, using a token where it is invalid,
giving an invalid expression, giving an invalid print statement, giving an
invalid function definition, attempting to assign to an expression that is
not a named expression (see the *Named Expressions* subsection of the
**SYNTAX** section), giving an invalid **auto** list, having a duplicate
**auto**/function parameter, failing to find the end of a code block,
attempting to return a value from a **void** function, attempting to use a
variable as a reference, and using any extensions when the option **-s** or
any equivalents were given.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a **void** function call as a value in an expression.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (bc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, bc(1) always exits
and returns **4**, no matter what mode bc(1) is in.
The other statuses will only be returned when bc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since bc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Per the [standard][1], bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, bc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, bc(1) turns
on "TTY mode."
The prompt is enabled in TTY mode.
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause bc(1) to stop execution of the current input. If
bc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If bc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If bc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to bc(1) as it is executing a file, it
can seem as though bc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause bc(1) to clean up and exit, and it uses the
default handler for all other signals.
# SEE ALSO
dc(1)
# STANDARDS
bc(1) is compliant with the [IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1]
specification. The flags **-efghiqsvVw**, all long options, and the extensions
noted above are extensions to that specification.
Note that the specification explicitly says that bc(1) only accepts numbers that
use a period (**.**) as a radix point, regardless of the value of
**LC_NUMERIC**.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHORS
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
[2]: https://www.gnu.org/software/bc/
[3]: https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero
[4]: https://en.wikipedia.org/wiki/Unit_in_the_last_place
[5]: https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT
[6]: https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero
diff --git a/contrib/bc/manuals/bc/HNP.1 b/contrib/bc/manuals/bc/HNP.1
index 7b1f36a3866b..11a8dc2a521f 100644
--- a/contrib/bc/manuals/bc/HNP.1
+++ b/contrib/bc/manuals/bc/HNP.1
@@ -1,2011 +1,2024 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "BC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "BC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH NAME
.PP
bc - arbitrary-precision decimal arithmetic language and calculator
.SH SYNOPSIS
.PP
\f[B]bc\f[R] [\f[B]-ghilPqsvVw\f[R]] [\f[B]\[en]global-stacks\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]mathlib\f[R]] [\f[B]\[en]no-prompt\f[R]]
[\f[B]\[en]quiet\f[R]] [\f[B]\[en]standard\f[R]] [\f[B]\[en]warn\f[R]]
[\f[B]\[en]version\f[R]] [\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
bc(1) is an interactive processor for a language first standardized in
1991 by POSIX.
(The current standard is
here (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).)
The language provides unlimited precision decimal arithmetic and is
somewhat C-like, but there are differences.
Such differences will be noted in this document.
.PP
After parsing and handling options, this bc(1) reads any files given on
the command line and executes them before reading from \f[B]stdin\f[R].
.SH OPTIONS
.PP
The following are the options that bc(1) accepts.
.TP
\f[B]-g\f[R], \f[B]\[en]global-stacks\f[R]
Turns the globals \f[B]ibase\f[R], \f[B]obase\f[R], \f[B]scale\f[R], and
\f[B]seed\f[R] into stacks.
.RS
.PP
This has the effect that a copy of the current value of all four are
pushed onto a stack for every function call, as well as popped when
every function returns.
This means that functions can assign to any and all of those globals
without worrying that the change will affect other functions.
Thus, a hypothetical function named \f[B]output(x,b)\f[R] that simply
printed \f[B]x\f[R] in base \f[B]b\f[R] could be written like this:
.IP
.nf
\f[C]
define void output(x, b) {
obase=b
x
}
\f[R]
.fi
.PP
instead of like this:
.IP
.nf
\f[C]
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
\f[R]
.fi
.PP
This makes writing functions much easier.
.PP
(\f[B]Note\f[R]: the function \f[B]output(x,b)\f[R] exists in the
extended math library.
See the \f[B]LIBRARY\f[R] section.)
.PP
However, since using this flag means that functions cannot set
\f[B]ibase\f[R], \f[B]obase\f[R], \f[B]scale\f[R], or \f[B]seed\f[R]
globally, functions that are made to do so cannot work anymore.
There are two possible use cases for that, and each has a solution.
.PP
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases.
Examples:
.IP
.nf
\f[C]
alias d2o=\[dq]bc -e ibase=A -e obase=8\[dq]
alias h2b=\[dq]bc -e ibase=G -e obase=2\[dq]
\f[R]
.fi
.PP
Second, if the purpose of a function is to set \f[B]ibase\f[R],
\f[B]obase\f[R], \f[B]scale\f[R], or \f[B]seed\f[R] globally for any
other purpose, it could be split into one to four functions (based on
how many globals it sets) and each of those functions could return the
desired value for a global.
.PP
For functions that set \f[B]seed\f[R], the value assigned to
\f[B]seed\f[R] is not propagated to parent functions.
This means that the sequence of pseudo-random numbers that they see will
not be the same sequence of pseudo-random numbers that any parent sees.
This is only the case once \f[B]seed\f[R] has been set.
.PP
If a function desires to not affect the sequence of pseudo-random
numbers of its parents, but wants to use the same \f[B]seed\f[R], it can
use the following line:
.IP
.nf
\f[C]
seed = seed
\f[R]
.fi
.PP
If the behavior of this option is desired for every run of bc(1), then
users could make sure to define \f[B]BC_ENV_ARGS\f[R] and include this
option (see the \f[B]ENVIRONMENT VARIABLES\f[R] section for more
details).
.PP
If \f[B]-s\f[R], \f[B]-w\f[R], or any equivalents are used, this option
is ignored.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-l\f[R], \f[B]\[en]mathlib\f[R]
Sets \f[B]scale\f[R] (see the \f[B]SYNTAX\f[R] section) to \f[B]20\f[R]
and loads the included math library and the extended math library before
running any code, including any expressions or files specified on the
command line.
.RS
.PP
To learn what is in the libraries, see the \f[B]LIBRARY\f[R] section.
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
This option is a no-op.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-q\f[R], \f[B]\[en]quiet\f[R]
This option is for compatibility with the GNU
bc(1) (https://www.gnu.org/software/bc/); it is a no-op.
Without this option, GNU bc(1) prints a copyright header.
This bc(1) only prints the copyright header if one or more of the
\f[B]-v\f[R], \f[B]-V\f[R], or \f[B]\[en]version\f[R] options are given.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-s\f[R], \f[B]\[en]standard\f[R]
Process exactly the language defined by the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
and error if any extensions are used.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-w\f[R], \f[B]\[en]warn\f[R]
Like \f[B]-s\f[R] and \f[B]\[en]standard\f[R], except that warnings (and
not errors) are printed for non-standard extensions and execution
continues normally.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]BC_ENV_ARGS\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]bc >&-\f[R], it will quit with an error.
This is done so that bc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]bc 2>&-\f[R], it will quit with an error.
This is done so that bc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
The syntax for bc(1) programs is mostly C-like, with some differences.
This bc(1) follows the POSIX
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
which is a much more thorough resource for the language this bc(1)
accepts.
This section is meant to be a summary and a listing of all the
extensions to the standard.
.PP
In the sections below, \f[B]E\f[R] means expression, \f[B]S\f[R] means
statement, and \f[B]I\f[R] means identifier.
.PP
Identifiers (\f[B]I\f[R]) start with a lowercase letter and can be
followed by any number (up to \f[B]BC_NAME_MAX-1\f[R]) of lowercase
letters (\f[B]a-z\f[R]), digits (\f[B]0-9\f[R]), and underscores
(\f[B]_\f[R]).
The regex is \f[B][a-z][a-z0-9_]*\f[R].
Identifiers with more than one character (letter) are a
\f[B]non-portable extension\f[R].
.PP
\f[B]ibase\f[R] is a global variable determining how to interpret
constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
If the \f[B]-s\f[R] (\f[B]\[en]standard\f[R]) and \f[B]-w\f[R]
(\f[B]\[en]warn\f[R]) flags were not given on the command line, the max
allowable value for \f[B]ibase\f[R] is \f[B]36\f[R].
Otherwise, it is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in bc(1)
programs with the \f[B]maxibase()\f[R] built-in function.
.PP
\f[B]obase\f[R] is a global variable determining how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]BC_BASE_MAX\f[R] and
can be queried in bc(1) programs with the \f[B]maxobase()\f[R] built-in
function.
The min allowable value for \f[B]obase\f[R] is \f[B]0\f[R].
If \f[B]obase\f[R] is \f[B]0\f[R], values are output in scientific
notation, and if \f[B]obase\f[R] is \f[B]1\f[R], values are output in
engineering notation.
Otherwise, values are output in the specified base.
.PP
Outputting in scientific and engineering notations are \f[B]non-portable
extensions\f[R].
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a global variable that sets the precision of any operations, with
exceptions.
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] is \f[B]BC_SCALE_MAX\f[R]
and can be queried in bc(1) programs with the \f[B]maxscale()\f[R]
built-in function.
.PP
bc(1) has both \f[I]global\f[R] variables and \f[I]local\f[R] variables.
All \f[I]local\f[R] variables are local to the function; they are
parameters or are introduced in the \f[B]auto\f[R] list of a function
(see the \f[B]FUNCTIONS\f[R] section).
If a variable is accessed which is not a parameter or in the
\f[B]auto\f[R] list, it is assumed to be \f[I]global\f[R].
If a parent function has a \f[I]local\f[R] variable version of a
variable that a child function considers \f[I]global\f[R], the value of
that \f[I]global\f[R] variable in the child function is the value of the
variable in the parent function, not the value of the actual
\f[I]global\f[R] variable.
.PP
All of the above applies to arrays as well.
.PP
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence
operator is an assignment operator \f[I]and\f[R] the expression is
notsurrounded by parentheses.
.PP
The value that is printed is also assigned to the special variable
\f[B]last\f[R].
A single dot (\f[B].\f[R]) may also be used as a synonym for
\f[B]last\f[R].
These are \f[B]non-portable extensions\f[R].
.PP
Either semicolons or newlines may separate statements.
.SS Comments
.PP
There are two kinds of comments:
.IP "1." 3
Block comments are enclosed in \f[B]/*\f[R] and \f[B]*/\f[R].
.IP "2." 3
Line comments go from \f[B]#\f[R] until, and not including, the next
newline.
This is a \f[B]non-portable extension\f[R].
.SS Named Expressions
.PP
The following are named expressions in bc(1):
.IP "1." 3
Variables: \f[B]I\f[R]
.IP "2." 3
Array Elements: \f[B]I[E]\f[R]
.IP "3." 3
\f[B]ibase\f[R]
.IP "4." 3
\f[B]obase\f[R]
.IP "5." 3
\f[B]scale\f[R]
.IP "6." 3
\f[B]seed\f[R]
.IP "7." 3
\f[B]last\f[R] or a single dot (\f[B].\f[R])
.PP
Numbers 6 and 7 are \f[B]non-portable extensions\f[R].
.PP
The meaning of \f[B]seed\f[R] is dependent on the current pseudo-random
number generator but is guaranteed to not change except for new major
versions.
.PP
The \f[I]scale\f[R] and sign of the value may be significant.
.PP
If a previously used \f[B]seed\f[R] value is assigned to \f[B]seed\f[R]
and used again, the pseudo-random number generator is guaranteed to
produce the same sequence of pseudo-random numbers as it did when the
\f[B]seed\f[R] value was previously used.
.PP
The exact value assigned to \f[B]seed\f[R] is not guaranteed to be
returned if \f[B]seed\f[R] is queried again immediately.
However, if \f[B]seed\f[R] \f[I]does\f[R] return a different value, both
values, when assigned to \f[B]seed\f[R], are guaranteed to produce the
same sequence of pseudo-random numbers.
This means that certain values assigned to \f[B]seed\f[R] will
\f[I]not\f[R] produce unique sequences of pseudo-random numbers.
The value of \f[B]seed\f[R] will change after any use of the
\f[B]rand()\f[R] and \f[B]irand(E)\f[R] operands (see the
\f[I]Operands\f[R] subsection below), except if the parameter passed to
\f[B]irand(E)\f[R] is \f[B]0\f[R], \f[B]1\f[R], or negative.
.PP
There is no limit to the length (number of significant decimal digits)
or \f[I]scale\f[R] of the value that can be assigned to \f[B]seed\f[R].
.PP
Variables and arrays do not interfere; users can have arrays named the
same as variables.
This also applies to functions (see the \f[B]FUNCTIONS\f[R] section), so
a user can have a variable, array, and function that all have the same
name, and they will not shadow each other, whether inside of functions
or not.
.PP
Named expressions are required as the operand of
\f[B]increment\f[R]/\f[B]decrement\f[R] operators and as the left side
of \f[B]assignment\f[R] operators (see the \f[I]Operators\f[R]
subsection).
.SS Operands
.PP
The following are valid operands in bc(1):
.IP " 1." 4
Numbers (see the \f[I]Numbers\f[R] subsection below).
.IP " 2." 4
Array indices (\f[B]I[E]\f[R]).
.IP " 3." 4
\f[B](E)\f[R]: The value of \f[B]E\f[R] (used to change precedence).
.IP " 4." 4
\f[B]sqrt(E)\f[R]: The square root of \f[B]E\f[R].
\f[B]E\f[R] must be non-negative.
.IP " 5." 4
\f[B]length(E)\f[R]: The number of significant decimal digits in
\f[B]E\f[R].
.IP " 6." 4
\f[B]length(I[])\f[R]: The number of elements in the array \f[B]I\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 7." 4
\f[B]scale(E)\f[R]: The \f[I]scale\f[R] of \f[B]E\f[R].
.IP " 8." 4
\f[B]abs(E)\f[R]: The absolute value of \f[B]E\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 9." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a non-\f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.IP "10." 4
\f[B]read()\f[R]: Reads a line from \f[B]stdin\f[R] and uses that as an
expression.
The result of that expression is the result of the \f[B]read()\f[R]
operand.
This is a \f[B]non-portable extension\f[R].
.IP "11." 4
\f[B]maxibase()\f[R]: The max allowable \f[B]ibase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "12." 4
\f[B]maxobase()\f[R]: The max allowable \f[B]obase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "13." 4
\f[B]maxscale()\f[R]: The max allowable \f[B]scale\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "14." 4
\f[B]rand()\f[R]: A pseudo-random integer between \f[B]0\f[R]
(inclusive) and \f[B]BC_RAND_MAX\f[R] (inclusive).
Using this operand will change the value of \f[B]seed\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "15." 4
\f[B]irand(E)\f[R]: A pseudo-random integer between \f[B]0\f[R]
(inclusive) and the value of \f[B]E\f[R] (exclusive).
If \f[B]E\f[R] is negative or is a non-integer (\f[B]E\f[R]\[cq]s
\f[I]scale\f[R] is not \f[B]0\f[R]), an error is raised, and bc(1)
resets (see the \f[B]RESET\f[R] section) while \f[B]seed\f[R] remains
unchanged.
If \f[B]E\f[R] is larger than \f[B]BC_RAND_MAX\f[R], the higher bound is
honored by generating several pseudo-random integers, multiplying them
by appropriate powers of \f[B]BC_RAND_MAX+1\f[R], and adding them
together.
Thus, the size of integer that can be generated with this operand is
unbounded.
Using this operand will change the value of \f[B]seed\f[R], unless the
value of \f[B]E\f[R] is \f[B]0\f[R] or \f[B]1\f[R].
In that case, \f[B]0\f[R] is returned, and \f[B]seed\f[R] is
\f[I]not\f[R] changed.
This is a \f[B]non-portable extension\f[R].
.IP "16." 4
\f[B]maxrand()\f[R]: The max integer returned by \f[B]rand()\f[R].
This is a \f[B]non-portable extension\f[R].
.PP
The integers generated by \f[B]rand()\f[R] and \f[B]irand(E)\f[R] are
guaranteed to be as unbiased as possible, subject to the limitations of
the pseudo-random number generator.
.PP
\f[B]Note\f[R]: The values returned by the pseudo-random number
generator with \f[B]rand()\f[R] and \f[B]irand(E)\f[R] are guaranteed to
\f[I]NOT\f[R] be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator.
However, they \f[I]are\f[R] guaranteed to be reproducible with identical
\f[B]seed\f[R] values.
This means that the pseudo-random values from bc(1) should only be used
where a reproducible stream of pseudo-random numbers is
\f[I]ESSENTIAL\f[R].
In any other case, use a non-seeded pseudo-random number generator.
.SS Numbers
.PP
Numbers are strings made up of digits, uppercase letters, and at most
\f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]BC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]Z\f[R] alone always equals decimal \f[B]35\f[R].
.PP
In addition, bc(1) accepts numbers in scientific notation.
These have the form \f[B]<number>e<integer>\f[R].
The exponent (the portion after the \f[B]e\f[R]) must be an integer.
An example is \f[B]1.89237e9\f[R], which is equal to
\f[B]1892370000\f[R].
Negative exponents are also allowed, so \f[B]4.2890e-3\f[R] is equal to
\f[B]0.0042890\f[R].
.PP
Using scientific notation is an error or warning if the \f[B]-s\f[R] or
\f[B]-w\f[R], respectively, command-line options (or equivalents) are
given.
.PP
\f[B]WARNING\f[R]: Both the number and the exponent in scientific
notation are interpreted according to the current \f[B]ibase\f[R], but
the number is still multiplied by \f[B]10\[ha]exponent\f[R] regardless
of the current \f[B]ibase\f[R].
For example, if \f[B]ibase\f[R] is \f[B]16\f[R] and bc(1) is given the
number string \f[B]FFeA\f[R], the resulting decimal number will be
\f[B]2550000000000\f[R], and if bc(1) is given the number string
\f[B]10e-4\f[R], the resulting decimal number will be \f[B]0.0016\f[R].
.PP
Accepting input as scientific notation is a \f[B]non-portable
extension\f[R].
.SS Operators
.PP
The following arithmetic and logical operators can be used.
They are listed in order of decreasing precedence.
Operators in the same group have the same precedence.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
Type: Prefix and Postfix
.RS
.PP
Associativity: None
.PP
Description: \f[B]increment\f[R], \f[B]decrement\f[R]
.RE
.TP
\f[B]-\f[R] \f[B]!\f[R]
Type: Prefix
.RS
.PP
Associativity: None
.PP
Description: \f[B]negation\f[R], \f[B]boolean not\f[R]
.RE
.TP
\f[B]$\f[R]
Type: Postfix
.RS
.PP
Associativity: None
.PP
Description: \f[B]truncation\f[R]
.RE
.TP
\f[B]\[at]\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]set precision\f[R]
.RE
.TP
\f[B]\[ha]\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]power\f[R]
.RE
.TP
\f[B]*\f[R] \f[B]/\f[R] \f[B]%\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]multiply\f[R], \f[B]divide\f[R], \f[B]modulus\f[R]
.RE
.TP
\f[B]+\f[R] \f[B]-\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]add\f[R], \f[B]subtract\f[R]
.RE
.TP
\f[B]<<\f[R] \f[B]>>\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]shift left\f[R], \f[B]shift right\f[R]
.RE
.TP
\f[B]=\f[R] \f[B]<<=\f[R] \f[B]>>=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R] \f[B]\[at]=\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]assignment\f[R]
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]relational\f[R]
.RE
.TP
\f[B]&&\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean and\f[R]
.RE
.TP
\f[B]||\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean or\f[R]
.RE
.PP
The operators will be described in more detail below.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
The prefix and postfix \f[B]increment\f[R] and \f[B]decrement\f[R]
operators behave exactly like they would in C.
They require a named expression (see the \f[I]Named Expressions\f[R]
subsection) as an operand.
.RS
.PP
The prefix versions of these operators are more efficient; use them
where possible.
.RE
.TP
\f[B]-\f[R]
The \f[B]negation\f[R] operator returns \f[B]0\f[R] if a user attempts
to negate any expression with the value \f[B]0\f[R].
Otherwise, a copy of the expression with its sign flipped is returned.
.TP
\f[B]!\f[R]
The \f[B]boolean not\f[R] operator returns \f[B]1\f[R] if the expression
is \f[B]0\f[R], or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]$\f[R]
The \f[B]truncation\f[R] operator returns a copy of the given expression
with all of its \f[I]scale\f[R] removed.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[at]\f[R]
The \f[B]set precision\f[R] operator takes two expressions and returns a
copy of the first with its \f[I]scale\f[R] equal to the value of the
second expression.
That could either mean that the number is returned without change (if
the \f[I]scale\f[R] of the first expression matches the value of the
second expression), extended (if it is less), or truncated (if it is
more).
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]) and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The \f[B]power\f[R] operator (not the \f[B]exclusive or\f[R] operator,
as it would be in C) takes two expressions and raises the first to the
power of the value of the second.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]), and if it
is negative, the first value must be non-zero.
.RE
.TP
\f[B]*\f[R]
The \f[B]multiply\f[R] operator takes two expressions, multiplies them,
and returns the product.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The \f[B]divide\f[R] operator takes two expressions, divides them, and
returns the quotient.
The \f[I]scale\f[R] of the result shall be the value of \f[B]scale\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]%\f[R]
The \f[B]modulus\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and evaluates them by 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R] and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]+\f[R]
The \f[B]add\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the sum, with a \f[I]scale\f[R] equal to the
max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]-\f[R]
The \f[B]subtract\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the difference, with a \f[I]scale\f[R] equal to
the max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]<<\f[R]
The \f[B]left shift\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns a copy of the value of \f[B]a\f[R] with its
decimal point moved \f[B]b\f[R] places to the right.
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]) and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]>>\f[R]
The \f[B]right shift\f[R] operator takes two expressions, \f[B]a\f[R]
and \f[B]b\f[R], and returns a copy of the value of \f[B]a\f[R] with its
decimal point moved \f[B]b\f[R] places to the left.
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]) and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]=\f[R] \f[B]<<=\f[R] \f[B]>>=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R] \f[B]\[at]=\f[R]
The \f[B]assignment\f[R] operators take two expressions, \f[B]a\f[R] and
\f[B]b\f[R] where \f[B]a\f[R] is a named expression (see the \f[I]Named
Expressions\f[R] subsection).
.RS
.PP
For \f[B]=\f[R], \f[B]b\f[R] is copied and the result is assigned to
\f[B]a\f[R].
For all others, \f[B]a\f[R] and \f[B]b\f[R] are applied as operands to
the corresponding arithmetic operator and the result is assigned to
\f[B]a\f[R].
.PP
The \f[B]assignment\f[R] operators that correspond to operators that are
extensions are themselves \f[B]non-portable extensions\f[R].
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
The \f[B]relational\f[R] operators compare two expressions, \f[B]a\f[R]
and \f[B]b\f[R], and if the relation holds, according to C language
semantics, the result is \f[B]1\f[R].
Otherwise, it is \f[B]0\f[R].
.RS
.PP
Note that unlike in C, these operators have a lower precedence than the
\f[B]assignment\f[R] operators, which means that \f[B]a=b>c\f[R] is
interpreted as \f[B](a=b)>c\f[R].
.PP
Also, unlike the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
requires, these operators can appear anywhere any other expressions can
be used.
This allowance is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]&&\f[R]
The \f[B]boolean and\f[R] operator takes two expressions and returns
\f[B]1\f[R] if both expressions are non-zero, \f[B]0\f[R] otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]||\f[R]
The \f[B]boolean or\f[R] operator takes two expressions and returns
\f[B]1\f[R] if one of the expressions is non-zero, \f[B]0\f[R]
otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Statements
.PP
The following items are statements:
.IP " 1." 4
\f[B]E\f[R]
.IP " 2." 4
\f[B]{\f[R] \f[B]S\f[R] \f[B];\f[R] \&... \f[B];\f[R] \f[B]S\f[R]
\f[B]}\f[R]
.IP " 3." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 4." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
\f[B]else\f[R] \f[B]S\f[R]
.IP " 5." 4
\f[B]while\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 6." 4
\f[B]for\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B];\f[R] \f[B]E\f[R]
\f[B];\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 7." 4
An empty statement
.IP " 8." 4
\f[B]break\f[R]
.IP " 9." 4
\f[B]continue\f[R]
.IP "10." 4
\f[B]quit\f[R]
.IP "11." 4
\f[B]halt\f[R]
.IP "12." 4
\f[B]limits\f[R]
.IP "13." 4
A string of characters, enclosed in double quotes
.IP "14." 4
\f[B]print\f[R] \f[B]E\f[R] \f[B],\f[R] \&... \f[B],\f[R] \f[B]E\f[R]
.IP "15." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a \f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.PP
Numbers 4, 9, 11, 12, 14, and 15 are \f[B]non-portable extensions\f[R].
.PP
Also, as a \f[B]non-portable extension\f[R], any or all of the
expressions in the header of a for loop may be omitted.
If the condition (second expression) is omitted, it is assumed to be a
constant \f[B]1\f[R].
.PP
The \f[B]break\f[R] statement causes a loop to stop iterating and resume
execution immediately following a loop.
This is only allowed in loops.
.PP
The \f[B]continue\f[R] statement causes a loop iteration to stop early
and returns to the start of the loop, including testing the loop
condition.
This is only allowed in loops.
.PP
The \f[B]if\f[R] \f[B]else\f[R] statement does the same thing as in C.
.PP
The \f[B]quit\f[R] statement causes bc(1) to quit, even if it is on a
branch that will not be executed (it is a compile-time command).
.PP
The \f[B]halt\f[R] statement causes bc(1) to quit, if it is executed.
(Unlike \f[B]quit\f[R] if it is on a branch of an \f[B]if\f[R] statement
that is not executed, bc(1) does not quit.)
.PP
The \f[B]limits\f[R] statement prints the limits that this bc(1) is
subject to.
This is like the \f[B]quit\f[R] statement in that it is a compile-time
command.
.PP
An expression by itself is evaluated and printed, followed by a newline.
.PP
Both scientific notation and engineering notation are available for
printing the results of expressions.
Scientific notation is activated by assigning \f[B]0\f[R] to
\f[B]obase\f[R], and engineering notation is activated by assigning
\f[B]1\f[R] to \f[B]obase\f[R].
To deactivate them, just assign a different value to \f[B]obase\f[R].
.PP
Scientific notation and engineering notation are disabled if bc(1) is
run with either the \f[B]-s\f[R] or \f[B]-w\f[R] command-line options
(or equivalents).
.PP
Printing numbers in scientific notation and/or engineering notation is a
\f[B]non-portable extension\f[R].
.SS Print Statement
.PP
The \[lq]expressions\[rq] in a \f[B]print\f[R] statement may also be
strings.
If they are, there are backslash escape sequences that are interpreted
specially.
What those sequences are, and what they cause to be printed, are shown
below:
.PP
.TS
tab(@);
l l.
T{
\f[B]\[rs]a\f[R]
T}@T{
\f[B]\[rs]a\f[R]
T}
T{
\f[B]\[rs]b\f[R]
T}@T{
\f[B]\[rs]b\f[R]
T}
T{
\f[B]\[rs]\[rs]\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]e\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]f\f[R]
T}@T{
\f[B]\[rs]f\f[R]
T}
T{
\f[B]\[rs]n\f[R]
T}@T{
\f[B]\[rs]n\f[R]
T}
T{
\f[B]\[rs]q\f[R]
T}@T{
\f[B]\[dq]\f[R]
T}
T{
\f[B]\[rs]r\f[R]
T}@T{
\f[B]\[rs]r\f[R]
T}
T{
\f[B]\[rs]t\f[R]
T}@T{
\f[B]\[rs]t\f[R]
T}
.TE
.PP
Any other character following a backslash causes the backslash and
character to be printed as-is.
.PP
Any non-string expression in a print statement shall be assigned to
\f[B]last\f[R], like any other expression that is printed.
.SS Order of Evaluation
.PP
All expressions in a statment are evaluated left to right, except as
necessary to maintain order of operations.
This means, for example, assuming that \f[B]i\f[R] is equal to
\f[B]0\f[R], in the expression
.IP
.nf
\f[C]
a[i++] = i++
\f[R]
.fi
.PP
the first (or 0th) element of \f[B]a\f[R] is set to \f[B]1\f[R], and
\f[B]i\f[R] is equal to \f[B]2\f[R] at the end of the expression.
.PP
This includes function arguments.
Thus, assuming \f[B]i\f[R] is equal to \f[B]0\f[R], this means that in
the expression
.IP
.nf
\f[C]
x(i++, i++)
\f[R]
.fi
.PP
the first argument passed to \f[B]x()\f[R] is \f[B]0\f[R], and the
second argument is \f[B]1\f[R], while \f[B]i\f[R] is equal to
\f[B]2\f[R] before the function starts executing.
.SH FUNCTIONS
.PP
Function definitions are as follows:
.IP
.nf
\f[C]
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
\f[R]
.fi
.PP
Any \f[B]I\f[R] in the parameter list or \f[B]auto\f[R] list may be
replaced with \f[B]I[]\f[R] to make a parameter or \f[B]auto\f[R] var an
array, and any \f[B]I\f[R] in the parameter list may be replaced with
\f[B]*I[]\f[R] to make a parameter an array reference.
Callers of functions that take array references should not put an
asterisk in the call; they must be called with just \f[B]I[]\f[R] like
normal array parameters and will be automatically converted into
references.
.PP
As a \f[B]non-portable extension\f[R], the opening brace of a
\f[B]define\f[R] statement may appear on the next line.
.PP
As a \f[B]non-portable extension\f[R], the return statement may also be
in one of the following forms:
.IP "1." 3
\f[B]return\f[R]
.IP "2." 3
\f[B]return\f[R] \f[B](\f[R] \f[B])\f[R]
.IP "3." 3
\f[B]return\f[R] \f[B]E\f[R]
.PP
The first two, or not specifying a \f[B]return\f[R] statement, is
equivalent to \f[B]return (0)\f[R], unless the function is a
\f[B]void\f[R] function (see the \f[I]Void Functions\f[R] subsection
below).
.SS Void Functions
.PP
Functions can also be \f[B]void\f[R] functions, defined as follows:
.IP
.nf
\f[C]
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
\f[R]
.fi
.PP
They can only be used as standalone expressions, where such an
expression would be printed alone, except in a print statement.
.PP
Void functions can only use the first two \f[B]return\f[R] statements
listed above.
They can also omit the return statement entirely.
.PP
The word \[lq]void\[rq] is not treated as a keyword; it is still
possible to have variables, arrays, and functions named \f[B]void\f[R].
The word \[lq]void\[rq] is only treated specially right after the
\f[B]define\f[R] keyword.
.PP
This is a \f[B]non-portable extension\f[R].
.SS Array References
.PP
For any array in the parameter list, if the array is declared in the
form
.IP
.nf
\f[C]
*I[]
\f[R]
.fi
.PP
it is a \f[B]reference\f[R].
Any changes to the array in the function are reflected, when the
function returns, to the array that was passed in.
.PP
Other than this, all function arguments are passed by value.
.PP
This is a \f[B]non-portable extension\f[R].
.SH LIBRARY
.PP
All of the functions below, including the functions in the extended math
library (see the \f[I]Extended Library\f[R] subsection below), are
available when the \f[B]-l\f[R] or \f[B]\[en]mathlib\f[R] command-line
flags are given, except that the extended math library is not available
when the \f[B]-s\f[R] option, the \f[B]-w\f[R] option, or equivalents
are given.
.SS Standard Library
.PP
The
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
defines the following functions for the math library:
.TP
\f[B]s(x)\f[R]
Returns the sine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]c(x)\f[R]
Returns the cosine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]a(x)\f[R]
Returns the arctangent of \f[B]x\f[R], in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]l(x)\f[R]
Returns the natural logarithm of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]e(x)\f[R]
Returns the mathematical constant \f[B]e\f[R] raised to the power of
\f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]j(x, n)\f[R]
Returns the bessel integer order \f[B]n\f[R] (truncated) of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.SS Extended Library
.PP
The extended library is \f[I]not\f[R] loaded when the
\f[B]-s\f[R]/\f[B]\[en]standard\f[R] or \f[B]-w\f[R]/\f[B]\[en]warn\f[R]
options are given since they are not part of the library defined by the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).
.PP
The extended library is a \f[B]non-portable extension\f[R].
.TP
\f[B]p(x, y)\f[R]
Calculates \f[B]x\f[R] to the power of \f[B]y\f[R], even if \f[B]y\f[R]
is not an integer, and returns the result to the current
\f[B]scale\f[R].
.RS
.PP
It is an error if \f[B]y\f[R] is negative and \f[B]x\f[R] is
\f[B]0\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]r(x, p)\f[R]
Returns \f[B]x\f[R] rounded to \f[B]p\f[R] decimal places according to
the rounding mode round half away from
\f[B]0\f[R] (https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero).
.TP
\f[B]ceil(x, p)\f[R]
Returns \f[B]x\f[R] rounded to \f[B]p\f[R] decimal places according to
the rounding mode round away from
\f[B]0\f[R] (https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero).
.TP
\f[B]f(x)\f[R]
Returns the factorial of the truncated absolute value of \f[B]x\f[R].
.TP
\f[B]perm(n, k)\f[R]
Returns the permutation of the truncated absolute value of \f[B]n\f[R]
of the truncated absolute value of \f[B]k\f[R], if \f[B]k <= n\f[R].
If not, it returns \f[B]0\f[R].
.TP
\f[B]comb(n, k)\f[R]
Returns the combination of the truncated absolute value of \f[B]n\f[R]
of the truncated absolute value of \f[B]k\f[R], if \f[B]k <= n\f[R].
If not, it returns \f[B]0\f[R].
.TP
\f[B]l2(x)\f[R]
Returns the logarithm base \f[B]2\f[R] of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]l10(x)\f[R]
Returns the logarithm base \f[B]10\f[R] of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]log(x, b)\f[R]
Returns the logarithm base \f[B]b\f[R] of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]cbrt(x)\f[R]
Returns the cube root of \f[B]x\f[R].
.TP
\f[B]root(x, n)\f[R]
Calculates the truncated value of \f[B]n\f[R], \f[B]r\f[R], and returns
the \f[B]r\f[R]th root of \f[B]x\f[R] to the current \f[B]scale\f[R].
.RS
.PP
If \f[B]r\f[R] is \f[B]0\f[R] or negative, this raises an error and
causes bc(1) to reset (see the \f[B]RESET\f[R] section).
It also raises an error and causes bc(1) to reset if \f[B]r\f[R] is even
and \f[B]x\f[R] is negative.
.RE
.TP
\f[B]pi(p)\f[R]
Returns \f[B]pi\f[R] to \f[B]p\f[R] decimal places.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]t(x)\f[R]
Returns the tangent of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]a2(y, x)\f[R]
Returns the arctangent of \f[B]y/x\f[R], in radians.
If both \f[B]y\f[R] and \f[B]x\f[R] are equal to \f[B]0\f[R], it raises
an error and causes bc(1) to reset (see the \f[B]RESET\f[R] section).
Otherwise, if \f[B]x\f[R] is greater than \f[B]0\f[R], it returns
\f[B]a(y/x)\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is greater than
or equal to \f[B]0\f[R], it returns \f[B]a(y/x)+pi\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]a(y/x)-pi\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is greater than
\f[B]0\f[R], it returns \f[B]pi/2\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]-pi/2\f[R].
.RS
.PP
This function is the same as the \f[B]atan2()\f[R] function in many
programming languages.
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]sin(x)\f[R]
Returns the sine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is an alias of \f[B]s(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]cos(x)\f[R]
Returns the cosine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is an alias of \f[B]c(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]tan(x)\f[R]
Returns the tangent of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
If \f[B]x\f[R] is equal to \f[B]1\f[R] or \f[B]-1\f[R], this raises an
error and causes bc(1) to reset (see the \f[B]RESET\f[R] section).
.PP
This is an alias of \f[B]t(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]atan(x)\f[R]
Returns the arctangent of \f[B]x\f[R], in radians.
.RS
.PP
This is an alias of \f[B]a(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]atan2(y, x)\f[R]
Returns the arctangent of \f[B]y/x\f[R], in radians.
If both \f[B]y\f[R] and \f[B]x\f[R] are equal to \f[B]0\f[R], it raises
an error and causes bc(1) to reset (see the \f[B]RESET\f[R] section).
Otherwise, if \f[B]x\f[R] is greater than \f[B]0\f[R], it returns
\f[B]a(y/x)\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is greater than
or equal to \f[B]0\f[R], it returns \f[B]a(y/x)+pi\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]a(y/x)-pi\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is greater than
\f[B]0\f[R], it returns \f[B]pi/2\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]-pi/2\f[R].
.RS
.PP
This function is the same as the \f[B]atan2()\f[R] function in many
programming languages.
.PP
This is an alias of \f[B]a2(y, x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]r2d(x)\f[R]
Converts \f[B]x\f[R] from radians to degrees and returns the result.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]d2r(x)\f[R]
Converts \f[B]x\f[R] from degrees to radians and returns the result.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]frand(p)\f[R]
Generates a pseudo-random number between \f[B]0\f[R] (inclusive) and
\f[B]1\f[R] (exclusive) with the number of decimal digits after the
decimal point equal to the truncated absolute value of \f[B]p\f[R].
If \f[B]p\f[R] is not \f[B]0\f[R], then calling this function will
change the value of \f[B]seed\f[R].
If \f[B]p\f[R] is \f[B]0\f[R], then \f[B]0\f[R] is returned, and
\f[B]seed\f[R] is \f[I]not\f[R] changed.
.TP
\f[B]ifrand(i, p)\f[R]
Generates a pseudo-random number that is between \f[B]0\f[R] (inclusive)
and the truncated absolute value of \f[B]i\f[R] (exclusive) with the
number of decimal digits after the decimal point equal to the truncated
absolute value of \f[B]p\f[R].
If the absolute value of \f[B]i\f[R] is greater than or equal to
\f[B]2\f[R], and \f[B]p\f[R] is not \f[B]0\f[R], then calling this
function will change the value of \f[B]seed\f[R]; otherwise, \f[B]0\f[R]
is returned and \f[B]seed\f[R] is not changed.
.TP
\f[B]srand(x)\f[R]
Returns \f[B]x\f[R] with its sign flipped with probability
\f[B]0.5\f[R].
In other words, it randomizes the sign of \f[B]x\f[R].
.TP
\f[B]brand()\f[R]
Returns a random boolean value (either \f[B]0\f[R] or \f[B]1\f[R]).
.TP
\f[B]ubytes(x)\f[R]
Returns the numbers of unsigned integer bytes required to hold the
truncated absolute value of \f[B]x\f[R].
.TP
\f[B]sbytes(x)\f[R]
Returns the numbers of signed, two\[cq]s-complement integer bytes
required to hold the truncated value of \f[B]x\f[R].
.TP
\f[B]hex(x)\f[R]
Outputs the hexadecimal (base \f[B]16\f[R]) representation of
\f[B]x\f[R].
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]binary(x)\f[R]
Outputs the binary (base \f[B]2\f[R]) representation of \f[B]x\f[R].
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]output(x, b)\f[R]
Outputs the base \f[B]b\f[R] representation of \f[B]x\f[R].
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in as few power of two bytes as possible.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or is negative, an error message is
printed instead, but bc(1) is not reset (see the \f[B]RESET\f[R]
section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in as few power of two bytes as
possible.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, an error message is printed instead,
but bc(1) is not reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uintn(x, n)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]n\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]n\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]intn(x, n)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]n\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]n\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint8(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]1\f[R] byte.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]1\f[R] byte, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int8(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]1\f[R] byte.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]1\f[R] byte, an
error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint16(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]2\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]2\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int16(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]2\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]2\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint32(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]4\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]4\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int32(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]4\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]4\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint64(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]8\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]8\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int64(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]8\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]8\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]hex_uint(x, n)\f[R]
Outputs the representation of the truncated absolute value of
\f[B]x\f[R] as an unsigned integer in hexadecimal using \f[B]n\f[R]
bytes.
Not all of the value will be output if \f[B]n\f[R] is too small.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]binary_uint(x, n)\f[R]
Outputs the representation of the truncated absolute value of
\f[B]x\f[R] as an unsigned integer in binary using \f[B]n\f[R] bytes.
Not all of the value will be output if \f[B]n\f[R] is too small.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]output_uint(x, n)\f[R]
Outputs the representation of the truncated absolute value of
\f[B]x\f[R] as an unsigned integer in the current \f[B]obase\f[R] (see
the \f[B]SYNTAX\f[R] section) using \f[B]n\f[R] bytes.
Not all of the value will be output if \f[B]n\f[R] is too small.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]output_byte(x, i)\f[R]
Outputs byte \f[B]i\f[R] of the truncated absolute value of \f[B]x\f[R],
where \f[B]0\f[R] is the least significant byte and \f[B]number_of_bytes
- 1\f[R] is the most significant byte.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.SS Transcendental Functions
.PP
All transcendental functions can return slightly inaccurate results (up
to 1 ULP (https://en.wikipedia.org/wiki/Unit_in_the_last_place)).
This is unavoidable, and this
article (https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT) explains
why it is impossible and unnecessary to calculate exact results for the
transcendental functions.
.PP
Because of the possible inaccuracy, I recommend that users call those
functions with the precision (\f[B]scale\f[R]) set to at least 1 higher
than is necessary.
If exact results are \f[I]absolutely\f[R] required, users can double the
precision (\f[B]scale\f[R]) and then truncate.
.PP
The transcendental functions in the standard math library are:
.IP \[bu] 2
\f[B]s(x)\f[R]
.IP \[bu] 2
\f[B]c(x)\f[R]
.IP \[bu] 2
\f[B]a(x)\f[R]
.IP \[bu] 2
\f[B]l(x)\f[R]
.IP \[bu] 2
\f[B]e(x)\f[R]
.IP \[bu] 2
\f[B]j(x, n)\f[R]
.PP
The transcendental functions in the extended math library are:
.IP \[bu] 2
\f[B]l2(x)\f[R]
.IP \[bu] 2
\f[B]l10(x)\f[R]
.IP \[bu] 2
\f[B]log(x, b)\f[R]
.IP \[bu] 2
\f[B]pi(p)\f[R]
.IP \[bu] 2
\f[B]t(x)\f[R]
.IP \[bu] 2
\f[B]a2(y, x)\f[R]
.IP \[bu] 2
\f[B]sin(x)\f[R]
.IP \[bu] 2
\f[B]cos(x)\f[R]
.IP \[bu] 2
\f[B]tan(x)\f[R]
.IP \[bu] 2
\f[B]atan(x)\f[R]
.IP \[bu] 2
\f[B]atan2(y, x)\f[R]
.IP \[bu] 2
\f[B]r2d(x)\f[R]
.IP \[bu] 2
\f[B]d2r(x)\f[R]
.SH RESET
.PP
When bc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any functions that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all functions returned) is skipped.
.PP
Thus, when bc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.PP
Note that this reset behavior is different from the GNU bc(1), which
attempts to start executing the statement right after the one that
caused an error.
.SH PERFORMANCE
.PP
Most bc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This bc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]BC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]BC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]BC_BASE_DIGS\f[R].
.PP
The actual values of \f[B]BC_LONG_BIT\f[R] and \f[B]BC_BASE_DIGS\f[R]
can be queried with the \f[B]limits\f[R] statement.
.PP
In addition, this bc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]BC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on bc(1):
.TP
\f[B]BC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
bc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]BC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]BC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]BC_BASE_DIGS\f[R].
.TP
\f[B]BC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]BC_BASE_POW\f[R].
.TP
\f[B]BC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]BC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_RAND_MAX\f[R]
The maximum integer (inclusive) returned by the \f[B]rand()\f[R]
operand.
Set at \f[B]2\[ha]BC_LONG_BIT-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]BC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
The actual values can be queried with the \f[B]limits\f[R] statement.
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
bc(1) recognizes the following environment variables:
.TP
\f[B]POSIXLY_CORRECT\f[R]
If this variable exists (no matter the contents), bc(1) behaves as if
the \f[B]-s\f[R] option was given.
.TP
\f[B]BC_ENV_ARGS\f[R]
This is another way to give command-line arguments to bc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]BC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
.RS
.PP
The code that parses \f[B]BC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some bc file.bc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]bc\[dq] file.bc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]BC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]BC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), bc(1) will output lines to that length,
including the backslash (\f[B]\[rs]\f[R]).
The default line length is \f[B]70\f[R].
.SH EXIT STATUS
.PP
bc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, using a negative number as a bound for the
pseudo-random number generator, attempting to convert a negative number
to a hardware integer, overflow when converting a number to a hardware
integer, and attempting to use a non-integer where an integer is
required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]), places (\f[B]\[at]\f[R]), left shift
(\f[B]<<\f[R]), and right shift (\f[B]>>\f[R]) operators and their
corresponding assignment operators.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, using a token
where it is invalid, giving an invalid expression, giving an invalid
print statement, giving an invalid function definition, attempting to
assign to an expression that is not a named expression (see the
\f[I]Named Expressions\f[R] subsection of the \f[B]SYNTAX\f[R] section),
giving an invalid \f[B]auto\f[R] list, having a duplicate
\f[B]auto\f[R]/function parameter, failing to find the end of a code
block, attempting to return a value from a \f[B]void\f[R] function,
attempting to use a variable as a reference, and using any extensions
when the option \f[B]-s\f[R] or any equivalents were given.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a \f[B]void\f[R] function call as a value in an
expression.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (bc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, bc(1)
always exits and returns \f[B]4\f[R], no matter what mode bc(1) is in.
.PP
The other statuses will only be returned when bc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
bc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Per the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, bc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, bc(1) turns on \[lq]TTY mode.\[rq]
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause bc(1) to stop execution of the
current input.
If bc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If bc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If bc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to bc(1) as it is
executing a file, it can seem as though bc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause bc(1) to clean up and
exit, and it uses the default handler for all other signals.
.SH SEE ALSO
.PP
dc(1)
.SH STANDARDS
.PP
bc(1) is compliant with the IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
The flags \f[B]-efghiqsvVw\f[R], all long options, and the extensions
noted above are extensions to that specification.
.PP
Note that the specification explicitly says that bc(1) only accepts
numbers that use a period (\f[B].\f[R]) as a radix point, regardless of
the value of \f[B]LC_NUMERIC\f[R].
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHORS
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/bc/HNP.1.md b/contrib/bc/manuals/bc/HNP.1.md
index 608cca1f4c21..33feb013e6cf 100644
--- a/contrib/bc/manuals/bc/HNP.1.md
+++ b/contrib/bc/manuals/bc/HNP.1.md
@@ -1,1665 +1,1674 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# NAME
bc - arbitrary-precision decimal arithmetic language and calculator
# SYNOPSIS
**bc** [**-ghilPqsvVw**] [**--global-stacks**] [**--help**] [**--interactive**] [**--mathlib**] [**--no-prompt**] [**--quiet**] [**--standard**] [**--warn**] [**--version**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...]
[*file*...]
# DESCRIPTION
bc(1) is an interactive processor for a language first standardized in 1991 by
POSIX. (The current standard is [here][1].) The language provides unlimited
precision decimal arithmetic and is somewhat C-like, but there are differences.
Such differences will be noted in this document.
After parsing and handling options, this bc(1) reads any files given on the
command line and executes them before reading from **stdin**.
# OPTIONS
The following are the options that bc(1) accepts.
**-g**, **--global-stacks**
: Turns the globals **ibase**, **obase**, **scale**, and **seed** into stacks.
This has the effect that a copy of the current value of all four are pushed
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
(**Note**: the function **output(x,b)** exists in the extended math library.
See the **LIBRARY** section.)
However, since using this flag means that functions cannot set **ibase**,
**obase**, **scale**, or **seed** globally, functions that are made to do so
cannot work anymore. There are two possible use cases for that, and each has
a solution.
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o="bc -e ibase=A -e obase=8"
alias h2b="bc -e ibase=G -e obase=2"
Second, if the purpose of a function is to set **ibase**, **obase**,
**scale**, or **seed** globally for any other purpose, it could be split
into one to four functions (based on how many globals it sets) and each of
those functions could return the desired value for a global.
For functions that set **seed**, the value assigned to **seed** is not
propagated to parent functions. This means that the sequence of
pseudo-random numbers that they see will not be the same sequence of
pseudo-random numbers that any parent sees. This is only the case once
**seed** has been set.
If a function desires to not affect the sequence of pseudo-random numbers
of its parents, but wants to use the same **seed**, it can use the following
line:
seed = seed
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
**-h**, **--help**
: Prints a usage message and quits.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-l**, **--mathlib**
: Sets **scale** (see the **SYNTAX** section) to **20** and loads the included
math library and the extended math library before running any code,
including any expressions or files specified on the command line.
To learn what is in the libraries, see the **LIBRARY** section.
**-P**, **--no-prompt**
: This option is a no-op.
This is a **non-portable extension**.
**-q**, **--quiet**
: This option is for compatibility with the [GNU bc(1)][2]; it is a no-op.
Without this option, GNU bc(1) prints a copyright header. This bc(1) only
prints the copyright header if one or more of the **-v**, **-V**, or
**--version** options are given.
This is a **non-portable extension**.
**-s**, **--standard**
: Process exactly the language defined by the [standard][1] and error if any
extensions are used.
This is a **non-portable extension**.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
This is a **non-portable extension**.
**-w**, **--warn**
: Like **-s** and **--standard**, except that warnings (and not errors) are
printed for non-standard extensions and execution continues normally.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **BC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **bc <file> >&-**, it will quit with an error. This
is done so that bc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **bc <file> 2>&-**, it will quit with an error. This
is done so that bc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
The syntax for bc(1) programs is mostly C-like, with some differences. This
bc(1) follows the [POSIX standard][1], which is a much more thorough resource
for the language this bc(1) accepts. This section is meant to be a summary and a
listing of all the extensions to the standard.
In the sections below, **E** means expression, **S** means statement, and **I**
means identifier.
Identifiers (**I**) start with a lowercase letter and can be followed by any
number (up to **BC_NAME_MAX-1**) of lowercase letters (**a-z**), digits
(**0-9**), and underscores (**\_**). The regex is **\[a-z\]\[a-z0-9\_\]\***.
Identifiers with more than one character (letter) are a
**non-portable extension**.
**ibase** is a global variable determining how to interpret constant numbers. It
is the "input" base, or the number base used for interpreting input numbers.
**ibase** is initially **10**. If the **-s** (**--standard**) and **-w**
(**--warn**) flags were not given on the command line, the max allowable value
for **ibase** is **36**. Otherwise, it is **16**. The min allowable value for
**ibase** is **2**. The max allowable value for **ibase** can be queried in
bc(1) programs with the **maxibase()** built-in function.
**obase** is a global variable determining how to output results. It is the
"output" base, or the number base used for outputting numbers. **obase** is
initially **10**. The max allowable value for **obase** is **BC_BASE_MAX** and
can be queried in bc(1) programs with the **maxobase()** built-in function. The
min allowable value for **obase** is **0**. If **obase** is **0**, values are
output in scientific notation, and if **obase** is **1**, values are output in
engineering notation. Otherwise, values are output in the specified base.
Outputting in scientific and engineering notations are **non-portable
extensions**.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a global variable that
sets the precision of any operations, with exceptions. **scale** is initially
**0**. **scale** cannot be negative. The max allowable value for **scale** is
**BC_SCALE_MAX** and can be queried in bc(1) programs with the **maxscale()**
built-in function.
bc(1) has both *global* variables and *local* variables. All *local*
variables are local to the function; they are parameters or are introduced in
the **auto** list of a function (see the **FUNCTIONS** section). If a variable
is accessed which is not a parameter or in the **auto** list, it is assumed to
be *global*. If a parent function has a *local* variable version of a variable
that a child function considers *global*, the value of that *global* variable in
the child function is the value of the variable in the parent function, not the
value of the actual *global* variable.
All of the above applies to arrays as well.
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence operator is an
assignment operator *and* the expression is notsurrounded by parentheses.
The value that is printed is also assigned to the special variable **last**. A
single dot (**.**) may also be used as a synonym for **last**. These are
**non-portable extensions**.
Either semicolons or newlines may separate statements.
## Comments
There are two kinds of comments:
1. Block comments are enclosed in **/\*** and **\*/**.
2. Line comments go from **#** until, and not including, the next newline. This
is a **non-portable extension**.
## Named Expressions
The following are named expressions in bc(1):
1. Variables: **I**
2. Array Elements: **I[E]**
3. **ibase**
4. **obase**
5. **scale**
6. **seed**
7. **last** or a single dot (**.**)
Numbers 6 and 7 are **non-portable extensions**.
The meaning of **seed** is dependent on the current pseudo-random number
generator but is guaranteed to not change except for new major versions.
The *scale* and sign of the value may be significant.
If a previously used **seed** value is assigned to **seed** and used again, the
pseudo-random number generator is guaranteed to produce the same sequence of
pseudo-random numbers as it did when the **seed** value was previously used.
The exact value assigned to **seed** is not guaranteed to be returned if
**seed** is queried again immediately. However, if **seed** *does* return a
different value, both values, when assigned to **seed**, are guaranteed to
produce the same sequence of pseudo-random numbers. This means that certain
values assigned to **seed** will *not* produce unique sequences of pseudo-random
numbers. The value of **seed** will change after any use of the **rand()** and
**irand(E)** operands (see the *Operands* subsection below), except if the
parameter passed to **irand(E)** is **0**, **1**, or negative.
There is no limit to the length (number of significant decimal digits) or
*scale* of the value that can be assigned to **seed**.
Variables and arrays do not interfere; users can have arrays named the same as
variables. This also applies to functions (see the **FUNCTIONS** section), so a
user can have a variable, array, and function that all have the same name, and
they will not shadow each other, whether inside of functions or not.
Named expressions are required as the operand of **increment**/**decrement**
operators and as the left side of **assignment** operators (see the *Operators*
subsection).
## Operands
The following are valid operands in bc(1):
1. Numbers (see the *Numbers* subsection below).
2. Array indices (**I[E]**).
3. **(E)**: The value of **E** (used to change precedence).
4. **sqrt(E)**: The square root of **E**. **E** must be non-negative.
5. **length(E)**: The number of significant decimal digits in **E**.
6. **length(I[])**: The number of elements in the array **I**. This is a
**non-portable extension**.
7. **scale(E)**: The *scale* of **E**.
8. **abs(E)**: The absolute value of **E**. This is a **non-portable
extension**.
9. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a non-**void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
10. **read()**: Reads a line from **stdin** and uses that as an expression. The
result of that expression is the result of the **read()** operand. This is a
**non-portable extension**.
11. **maxibase()**: The max allowable **ibase**. This is a **non-portable
extension**.
12. **maxobase()**: The max allowable **obase**. This is a **non-portable
extension**.
13. **maxscale()**: The max allowable **scale**. This is a **non-portable
extension**.
14. **rand()**: A pseudo-random integer between **0** (inclusive) and
**BC_RAND_MAX** (inclusive). Using this operand will change the value of
**seed**. This is a **non-portable extension**.
15. **irand(E)**: A pseudo-random integer between **0** (inclusive) and the
value of **E** (exclusive). If **E** is negative or is a non-integer
(**E**'s *scale* is not **0**), an error is raised, and bc(1) resets (see
the **RESET** section) while **seed** remains unchanged. If **E** is larger
than **BC_RAND_MAX**, the higher bound is honored by generating several
pseudo-random integers, multiplying them by appropriate powers of
**BC_RAND_MAX+1**, and adding them together. Thus, the size of integer that
can be generated with this operand is unbounded. Using this operand will
change the value of **seed**, unless the value of **E** is **0** or **1**.
In that case, **0** is returned, and **seed** is *not* changed. This is a
**non-portable extension**.
16. **maxrand()**: The max integer returned by **rand()**. This is a
**non-portable extension**.
The integers generated by **rand()** and **irand(E)** are guaranteed to be as
unbiased as possible, subject to the limitations of the pseudo-random number
generator.
**Note**: The values returned by the pseudo-random number generator with
**rand()** and **irand(E)** are guaranteed to *NOT* be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator. However,
they *are* guaranteed to be reproducible with identical **seed** values. This
means that the pseudo-random values from bc(1) should only be used where a
reproducible stream of pseudo-random numbers is *ESSENTIAL*. In any other case,
use a non-seeded pseudo-random number generator.
## Numbers
Numbers are strings made up of digits, uppercase letters, and at most **1**
period for a radix. Numbers can have up to **BC_NUM_MAX** digits. Uppercase
letters are equal to **9** + their position in the alphabet (i.e., **A** equals
**10**, or **9+1**). If a digit or letter makes no sense with the current value
of **ibase**, they are set to the value of the highest valid digit in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **Z** alone always equals decimal
**35**.
In addition, bc(1) accepts numbers in scientific notation. These have the form
**\<number\>e\<integer\>**. The exponent (the portion after the **e**) must be
an integer. An example is **1.89237e9**, which is equal to **1892370000**.
Negative exponents are also allowed, so **4.2890e-3** is equal to **0.0042890**.
Using scientific notation is an error or warning if the **-s** or **-w**,
respectively, command-line options (or equivalents) are given.
**WARNING**: Both the number and the exponent in scientific notation are
interpreted according to the current **ibase**, but the number is still
multiplied by **10\^exponent** regardless of the current **ibase**. For example,
if **ibase** is **16** and bc(1) is given the number string **FFeA**, the
resulting decimal number will be **2550000000000**, and if bc(1) is given the
number string **10e-4**, the resulting decimal number will be **0.0016**.
Accepting input as scientific notation is a **non-portable extension**.
## Operators
The following arithmetic and logical operators can be used. They are listed in
order of decreasing precedence. Operators in the same group have the same
precedence.
**++** **--**
: Type: Prefix and Postfix
Associativity: None
Description: **increment**, **decrement**
**-** **!**
: Type: Prefix
Associativity: None
Description: **negation**, **boolean not**
**\$**
: Type: Postfix
Associativity: None
Description: **truncation**
**\@**
: Type: Binary
Associativity: Right
Description: **set precision**
**\^**
: Type: Binary
Associativity: Right
Description: **power**
**\*** **/** **%**
: Type: Binary
Associativity: Left
Description: **multiply**, **divide**, **modulus**
**+** **-**
: Type: Binary
Associativity: Left
Description: **add**, **subtract**
**\<\<** **\>\>**
: Type: Binary
Associativity: Left
Description: **shift left**, **shift right**
**=** **\<\<=** **\>\>=** **+=** **-=** **\*=** **/=** **%=** **\^=** **\@=**
: Type: Binary
Associativity: Right
Description: **assignment**
**==** **\<=** **\>=** **!=** **\<** **\>**
: Type: Binary
Associativity: Left
Description: **relational**
**&&**
: Type: Binary
Associativity: Left
Description: **boolean and**
**||**
: Type: Binary
Associativity: Left
Description: **boolean or**
The operators will be described in more detail below.
**++** **--**
: The prefix and postfix **increment** and **decrement** operators behave
exactly like they would in C. They require a named expression (see the
*Named Expressions* subsection) as an operand.
The prefix versions of these operators are more efficient; use them where
possible.
**-**
: The **negation** operator returns **0** if a user attempts to negate any
expression with the value **0**. Otherwise, a copy of the expression with
its sign flipped is returned.
**!**
: The **boolean not** operator returns **1** if the expression is **0**, or
**0** otherwise.
This is a **non-portable extension**.
**\$**
: The **truncation** operator returns a copy of the given expression with all
of its *scale* removed.
This is a **non-portable extension**.
**\@**
: The **set precision** operator takes two expressions and returns a copy of
the first with its *scale* equal to the value of the second expression. That
could either mean that the number is returned without change (if the
*scale* of the first expression matches the value of the second
expression), extended (if it is less), or truncated (if it is more).
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**\^**
: The **power** operator (not the **exclusive or** operator, as it would be in
C) takes two expressions and raises the first to the power of the value of
the second. The *scale* of the result is equal to **scale**.
The second expression must be an integer (no *scale*), and if it is
negative, the first value must be non-zero.
**\***
: The **multiply** operator takes two expressions, multiplies them, and
returns the product. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result is
equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The **divide** operator takes two expressions, divides them, and returns the
quotient. The *scale* of the result shall be the value of **scale**.
The second expression must be non-zero.
**%**
: The **modulus** operator takes two expressions, **a** and **b**, and
evaluates them by 1) Computing **a/b** to current **scale** and 2) Using the
result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The second expression must be non-zero.
**+**
: The **add** operator takes two expressions, **a** and **b**, and returns the
sum, with a *scale* equal to the max of the *scale*s of **a** and **b**.
**-**
: The **subtract** operator takes two expressions, **a** and **b**, and
returns the difference, with a *scale* equal to the max of the *scale*s of
**a** and **b**.
**\<\<**
: The **left shift** operator takes two expressions, **a** and **b**, and
returns a copy of the value of **a** with its decimal point moved **b**
places to the right.
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**\>\>**
: The **right shift** operator takes two expressions, **a** and **b**, and
returns a copy of the value of **a** with its decimal point moved **b**
places to the left.
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**=** **\<\<=** **\>\>=** **+=** **-=** **\*=** **/=** **%=** **\^=** **\@=**
: The **assignment** operators take two expressions, **a** and **b** where
**a** is a named expression (see the *Named Expressions* subsection).
For **=**, **b** is copied and the result is assigned to **a**. For all
others, **a** and **b** are applied as operands to the corresponding
arithmetic operator and the result is assigned to **a**.
The **assignment** operators that correspond to operators that are
extensions are themselves **non-portable extensions**.
**==** **\<=** **\>=** **!=** **\<** **\>**
: The **relational** operators compare two expressions, **a** and **b**, and
if the relation holds, according to C language semantics, the result is
**1**. Otherwise, it is **0**.
Note that unlike in C, these operators have a lower precedence than the
**assignment** operators, which means that **a=b\>c** is interpreted as
**(a=b)\>c**.
Also, unlike the [standard][1] requires, these operators can appear anywhere
any other expressions can be used. This allowance is a
**non-portable extension**.
**&&**
: The **boolean and** operator takes two expressions and returns **1** if both
expressions are non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
**||**
: The **boolean or** operator takes two expressions and returns **1** if one
of the expressions is non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
## Statements
The following items are statements:
1. **E**
2. **{** **S** **;** ... **;** **S** **}**
3. **if** **(** **E** **)** **S**
4. **if** **(** **E** **)** **S** **else** **S**
5. **while** **(** **E** **)** **S**
6. **for** **(** **E** **;** **E** **;** **E** **)** **S**
7. An empty statement
8. **break**
9. **continue**
10. **quit**
11. **halt**
12. **limits**
13. A string of characters, enclosed in double quotes
14. **print** **E** **,** ... **,** **E**
15. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
Numbers 4, 9, 11, 12, 14, and 15 are **non-portable extensions**.
Also, as a **non-portable extension**, any or all of the expressions in the
header of a for loop may be omitted. If the condition (second expression) is
omitted, it is assumed to be a constant **1**.
The **break** statement causes a loop to stop iterating and resume execution
immediately following a loop. This is only allowed in loops.
The **continue** statement causes a loop iteration to stop early and returns to
the start of the loop, including testing the loop condition. This is only
allowed in loops.
The **if** **else** statement does the same thing as in C.
The **quit** statement causes bc(1) to quit, even if it is on a branch that will
not be executed (it is a compile-time command).
The **halt** statement causes bc(1) to quit, if it is executed. (Unlike **quit**
if it is on a branch of an **if** statement that is not executed, bc(1) does not
quit.)
The **limits** statement prints the limits that this bc(1) is subject to. This
is like the **quit** statement in that it is a compile-time command.
An expression by itself is evaluated and printed, followed by a newline.
Both scientific notation and engineering notation are available for printing the
results of expressions. Scientific notation is activated by assigning **0** to
**obase**, and engineering notation is activated by assigning **1** to
**obase**. To deactivate them, just assign a different value to **obase**.
Scientific notation and engineering notation are disabled if bc(1) is run with
either the **-s** or **-w** command-line options (or equivalents).
Printing numbers in scientific notation and/or engineering notation is a
**non-portable extension**.
## Print Statement
The "expressions" in a **print** statement may also be strings. If they are, there
are backslash escape sequences that are interpreted specially. What those
sequences are, and what they cause to be printed, are shown below:
-------- -------
**\\a** **\\a**
**\\b** **\\b**
**\\\\** **\\**
**\\e** **\\**
**\\f** **\\f**
**\\n** **\\n**
**\\q** **"**
**\\r** **\\r**
**\\t** **\\t**
-------- -------
Any other character following a backslash causes the backslash and character to
be printed as-is.
Any non-string expression in a print statement shall be assigned to **last**,
like any other expression that is printed.
## Order of Evaluation
All expressions in a statment are evaluated left to right, except as necessary
to maintain order of operations. This means, for example, assuming that **i** is
equal to **0**, in the expression
a[i++] = i++
the first (or 0th) element of **a** is set to **1**, and **i** is equal to **2**
at the end of the expression.
This includes function arguments. Thus, assuming **i** is equal to **0**, this
means that in the expression
x(i++, i++)
the first argument passed to **x()** is **0**, and the second argument is **1**,
while **i** is equal to **2** before the function starts executing.
# FUNCTIONS
Function definitions are as follows:
```
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
```
Any **I** in the parameter list or **auto** list may be replaced with **I[]** to
make a parameter or **auto** var an array, and any **I** in the parameter list
may be replaced with **\*I[]** to make a parameter an array reference. Callers
of functions that take array references should not put an asterisk in the call;
they must be called with just **I[]** like normal array parameters and will be
automatically converted into references.
As a **non-portable extension**, the opening brace of a **define** statement may
appear on the next line.
As a **non-portable extension**, the return statement may also be in one of the
following forms:
1. **return**
2. **return** **(** **)**
3. **return** **E**
The first two, or not specifying a **return** statement, is equivalent to
**return (0)**, unless the function is a **void** function (see the *Void
Functions* subsection below).
## Void Functions
Functions can also be **void** functions, defined as follows:
```
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
```
They can only be used as standalone expressions, where such an expression would
be printed alone, except in a print statement.
Void functions can only use the first two **return** statements listed above.
They can also omit the return statement entirely.
The word "void" is not treated as a keyword; it is still possible to have
variables, arrays, and functions named **void**. The word "void" is only
treated specially right after the **define** keyword.
This is a **non-portable extension**.
## Array References
For any array in the parameter list, if the array is declared in the form
```
*I[]
```
it is a **reference**. Any changes to the array in the function are reflected,
when the function returns, to the array that was passed in.
Other than this, all function arguments are passed by value.
This is a **non-portable extension**.
# LIBRARY
All of the functions below, including the functions in the extended math
library (see the *Extended Library* subsection below), are available when the
**-l** or **--mathlib** command-line flags are given, except that the extended
math library is not available when the **-s** option, the **-w** option, or
equivalents are given.
## Standard Library
The [standard][1] defines the following functions for the math library:
**s(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**c(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a(x)**
: Returns the arctangent of **x**, in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l(x)**
: Returns the natural logarithm of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**e(x)**
: Returns the mathematical constant **e** raised to the power of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**j(x, n)**
: Returns the bessel integer order **n** (truncated) of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
## Extended Library
The extended library is *not* loaded when the **-s**/**--standard** or
**-w**/**--warn** options are given since they are not part of the library
defined by the [standard][1].
The extended library is a **non-portable extension**.
**p(x, y)**
: Calculates **x** to the power of **y**, even if **y** is not an integer, and
returns the result to the current **scale**.
It is an error if **y** is negative and **x** is **0**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**r(x, p)**
: Returns **x** rounded to **p** decimal places according to the rounding mode
[round half away from **0**][3].
**ceil(x, p)**
: Returns **x** rounded to **p** decimal places according to the rounding mode
[round away from **0**][6].
**f(x)**
: Returns the factorial of the truncated absolute value of **x**.
**perm(n, k)**
: Returns the permutation of the truncated absolute value of **n** of the
truncated absolute value of **k**, if **k \<= n**. If not, it returns **0**.
**comb(n, k)**
: Returns the combination of the truncated absolute value of **n** of the
truncated absolute value of **k**, if **k \<= n**. If not, it returns **0**.
**l2(x)**
: Returns the logarithm base **2** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l10(x)**
: Returns the logarithm base **10** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**log(x, b)**
: Returns the logarithm base **b** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**cbrt(x)**
: Returns the cube root of **x**.
**root(x, n)**
: Calculates the truncated value of **n**, **r**, and returns the **r**th root
of **x** to the current **scale**.
If **r** is **0** or negative, this raises an error and causes bc(1) to
reset (see the **RESET** section). It also raises an error and causes bc(1)
to reset if **r** is even and **x** is negative.
**pi(p)**
: Returns **pi** to **p** decimal places.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**t(x)**
: Returns the tangent of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a2(y, x)**
: Returns the arctangent of **y/x**, in radians. If both **y** and **x** are
equal to **0**, it raises an error and causes bc(1) to reset (see the
**RESET** section). Otherwise, if **x** is greater than **0**, it returns
**a(y/x)**. If **x** is less than **0**, and **y** is greater than or equal
to **0**, it returns **a(y/x)+pi**. If **x** is less than **0**, and **y**
is less than **0**, it returns **a(y/x)-pi**. If **x** is equal to **0**,
and **y** is greater than **0**, it returns **pi/2**. If **x** is equal to
**0**, and **y** is less than **0**, it returns **-pi/2**.
This function is the same as the **atan2()** function in many programming
languages.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**sin(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is an alias of **s(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**cos(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is an alias of **c(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**tan(x)**
: Returns the tangent of **x**, which is assumed to be in radians.
If **x** is equal to **1** or **-1**, this raises an error and causes bc(1)
to reset (see the **RESET** section).
This is an alias of **t(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**atan(x)**
: Returns the arctangent of **x**, in radians.
This is an alias of **a(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**atan2(y, x)**
: Returns the arctangent of **y/x**, in radians. If both **y** and **x** are
equal to **0**, it raises an error and causes bc(1) to reset (see the
**RESET** section). Otherwise, if **x** is greater than **0**, it returns
**a(y/x)**. If **x** is less than **0**, and **y** is greater than or equal
to **0**, it returns **a(y/x)+pi**. If **x** is less than **0**, and **y**
is less than **0**, it returns **a(y/x)-pi**. If **x** is equal to **0**,
and **y** is greater than **0**, it returns **pi/2**. If **x** is equal to
**0**, and **y** is less than **0**, it returns **-pi/2**.
This function is the same as the **atan2()** function in many programming
languages.
This is an alias of **a2(y, x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**r2d(x)**
: Converts **x** from radians to degrees and returns the result.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**d2r(x)**
: Converts **x** from degrees to radians and returns the result.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**frand(p)**
: Generates a pseudo-random number between **0** (inclusive) and **1**
(exclusive) with the number of decimal digits after the decimal point equal
to the truncated absolute value of **p**. If **p** is not **0**, then
calling this function will change the value of **seed**. If **p** is **0**,
then **0** is returned, and **seed** is *not* changed.
**ifrand(i, p)**
: Generates a pseudo-random number that is between **0** (inclusive) and the
truncated absolute value of **i** (exclusive) with the number of decimal
digits after the decimal point equal to the truncated absolute value of
**p**. If the absolute value of **i** is greater than or equal to **2**, and
**p** is not **0**, then calling this function will change the value of
**seed**; otherwise, **0** is returned and **seed** is not changed.
**srand(x)**
: Returns **x** with its sign flipped with probability **0.5**. In other
words, it randomizes the sign of **x**.
**brand()**
: Returns a random boolean value (either **0** or **1**).
**ubytes(x)**
: Returns the numbers of unsigned integer bytes required to hold the truncated
absolute value of **x**.
**sbytes(x)**
: Returns the numbers of signed, two's-complement integer bytes required to
hold the truncated value of **x**.
**hex(x)**
: Outputs the hexadecimal (base **16**) representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**binary(x)**
: Outputs the binary (base **2**) representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output(x, b)**
: Outputs the base **b** representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in as few power of two bytes as possible. Both outputs are
split into bytes separated by spaces.
If **x** is not an integer or is negative, an error message is printed
instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in as few power of two bytes as possible. Both
outputs are split into bytes separated by spaces.
If **x** is not an integer, an error message is printed instead, but bc(1)
is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uintn(x, n)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **n** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **n** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**intn(x, n)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **n** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **n** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint8(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **1** byte. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **1** byte, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int8(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **1** byte. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **1** byte, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint16(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **2** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **2** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int16(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **2** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **2** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint32(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **4** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **4** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int32(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **4** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **4** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint64(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **8** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **8** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int64(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **8** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **8** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**hex_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in hexadecimal using **n** bytes. Not all of the value will
be output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**binary_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in binary using **n** bytes. Not all of the value will be
output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in the current **obase** (see the **SYNTAX** section) using
**n** bytes. Not all of the value will be output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output_byte(x, i)**
: Outputs byte **i** of the truncated absolute value of **x**, where **0** is
the least significant byte and **number_of_bytes - 1** is the most
significant byte.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
## Transcendental Functions
All transcendental functions can return slightly inaccurate results (up to 1
[ULP][4]). This is unavoidable, and [this article][5] explains why it is
impossible and unnecessary to calculate exact results for the transcendental
functions.
Because of the possible inaccuracy, I recommend that users call those functions
with the precision (**scale**) set to at least 1 higher than is necessary. If
exact results are *absolutely* required, users can double the precision
(**scale**) and then truncate.
The transcendental functions in the standard math library are:
* **s(x)**
* **c(x)**
* **a(x)**
* **l(x)**
* **e(x)**
* **j(x, n)**
The transcendental functions in the extended math library are:
* **l2(x)**
* **l10(x)**
* **log(x, b)**
* **pi(p)**
* **t(x)**
* **a2(y, x)**
* **sin(x)**
* **cos(x)**
* **tan(x)**
* **atan(x)**
* **atan2(y, x)**
* **r2d(x)**
* **d2r(x)**
# RESET
When bc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any functions that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
functions returned) is skipped.
Thus, when bc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
Note that this reset behavior is different from the GNU bc(1), which attempts to
start executing the statement right after the one that caused an error.
# PERFORMANCE
Most bc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This bc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **BC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **BC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**BC_BASE_DIGS**.
The actual values of **BC_LONG_BIT** and **BC_BASE_DIGS** can be queried with
the **limits** statement.
In addition, this bc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **BC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on bc(1):
**BC_LONG_BIT**
: The number of bits in the **long** type in the environment where bc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**BC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **BC_LONG_BIT**.
**BC_BASE_POW**
: The max decimal number that each large integer can store (see
**BC_BASE_DIGS**) plus **1**. Depends on **BC_BASE_DIGS**.
**BC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **BC_LONG_BIT**.
**BC_BASE_MAX**
: The maximum output base. Set at **BC_BASE_POW**.
**BC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**BC_SCALE_MAX**
: The maximum **scale**. Set at **BC_OVERFLOW_MAX-1**.
**BC_STRING_MAX**
: The maximum length of strings. Set at **BC_OVERFLOW_MAX-1**.
**BC_NAME_MAX**
: The maximum length of identifiers. Set at **BC_OVERFLOW_MAX-1**.
**BC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **BC_OVERFLOW_MAX-1**.
**BC_RAND_MAX**
: The maximum integer (inclusive) returned by the **rand()** operand. Set at
**2\^BC_LONG_BIT-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**BC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
The actual values can be queried with the **limits** statement.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
bc(1) recognizes the following environment variables:
**POSIXLY_CORRECT**
: If this variable exists (no matter the contents), bc(1) behaves as if
the **-s** option was given.
**BC_ENV_ARGS**
: This is another way to give command-line arguments to bc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **BC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
The code that parses **BC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some bc file.bc"** will be correctly parsed, but the string
**"/home/gavin/some \"bc\" file.bc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **BC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**BC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), bc(1) will output
lines to that length, including the backslash (**\\**). The default line
length is **70**.
# EXIT STATUS
bc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, using a negative number as a bound for the pseudo-random number
generator, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**), places (**\@**), left shift (**\<\<**), and right shift (**\>\>**)
operators and their corresponding assignment operators.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, using a token where it is invalid,
giving an invalid expression, giving an invalid print statement, giving an
invalid function definition, attempting to assign to an expression that is
not a named expression (see the *Named Expressions* subsection of the
**SYNTAX** section), giving an invalid **auto** list, having a duplicate
**auto**/function parameter, failing to find the end of a code block,
attempting to return a value from a **void** function, attempting to use a
variable as a reference, and using any extensions when the option **-s** or
any equivalents were given.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a **void** function call as a value in an expression.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (bc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, bc(1) always exits
and returns **4**, no matter what mode bc(1) is in.
The other statuses will only be returned when bc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since bc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Per the [standard][1], bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, bc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, bc(1) turns
on "TTY mode."
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause bc(1) to stop execution of the current input. If
bc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If bc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If bc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to bc(1) as it is executing a file, it
can seem as though bc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause bc(1) to clean up and exit, and it uses the
default handler for all other signals.
# SEE ALSO
dc(1)
# STANDARDS
bc(1) is compliant with the [IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1]
specification. The flags **-efghiqsvVw**, all long options, and the extensions
noted above are extensions to that specification.
Note that the specification explicitly says that bc(1) only accepts numbers that
use a period (**.**) as a radix point, regardless of the value of
**LC_NUMERIC**.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHORS
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
[2]: https://www.gnu.org/software/bc/
[3]: https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero
[4]: https://en.wikipedia.org/wiki/Unit_in_the_last_place
[5]: https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT
[6]: https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero
diff --git a/contrib/bc/manuals/bc/HP.1 b/contrib/bc/manuals/bc/HP.1
index 617987fbf743..06a46ba5629a 100644
--- a/contrib/bc/manuals/bc/HP.1
+++ b/contrib/bc/manuals/bc/HP.1
@@ -1,2018 +1,2031 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "BC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "BC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH NAME
.PP
bc - arbitrary-precision decimal arithmetic language and calculator
.SH SYNOPSIS
.PP
\f[B]bc\f[R] [\f[B]-ghilPqsvVw\f[R]] [\f[B]\[en]global-stacks\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]mathlib\f[R]] [\f[B]\[en]no-prompt\f[R]]
[\f[B]\[en]quiet\f[R]] [\f[B]\[en]standard\f[R]] [\f[B]\[en]warn\f[R]]
[\f[B]\[en]version\f[R]] [\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
bc(1) is an interactive processor for a language first standardized in
1991 by POSIX.
(The current standard is
here (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).)
The language provides unlimited precision decimal arithmetic and is
somewhat C-like, but there are differences.
Such differences will be noted in this document.
.PP
After parsing and handling options, this bc(1) reads any files given on
the command line and executes them before reading from \f[B]stdin\f[R].
.SH OPTIONS
.PP
The following are the options that bc(1) accepts.
.TP
\f[B]-g\f[R], \f[B]\[en]global-stacks\f[R]
Turns the globals \f[B]ibase\f[R], \f[B]obase\f[R], \f[B]scale\f[R], and
\f[B]seed\f[R] into stacks.
.RS
.PP
This has the effect that a copy of the current value of all four are
pushed onto a stack for every function call, as well as popped when
every function returns.
This means that functions can assign to any and all of those globals
without worrying that the change will affect other functions.
Thus, a hypothetical function named \f[B]output(x,b)\f[R] that simply
printed \f[B]x\f[R] in base \f[B]b\f[R] could be written like this:
.IP
.nf
\f[C]
define void output(x, b) {
obase=b
x
}
\f[R]
.fi
.PP
instead of like this:
.IP
.nf
\f[C]
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
\f[R]
.fi
.PP
This makes writing functions much easier.
.PP
(\f[B]Note\f[R]: the function \f[B]output(x,b)\f[R] exists in the
extended math library.
See the \f[B]LIBRARY\f[R] section.)
.PP
However, since using this flag means that functions cannot set
\f[B]ibase\f[R], \f[B]obase\f[R], \f[B]scale\f[R], or \f[B]seed\f[R]
globally, functions that are made to do so cannot work anymore.
There are two possible use cases for that, and each has a solution.
.PP
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases.
Examples:
.IP
.nf
\f[C]
alias d2o=\[dq]bc -e ibase=A -e obase=8\[dq]
alias h2b=\[dq]bc -e ibase=G -e obase=2\[dq]
\f[R]
.fi
.PP
Second, if the purpose of a function is to set \f[B]ibase\f[R],
\f[B]obase\f[R], \f[B]scale\f[R], or \f[B]seed\f[R] globally for any
other purpose, it could be split into one to four functions (based on
how many globals it sets) and each of those functions could return the
desired value for a global.
.PP
For functions that set \f[B]seed\f[R], the value assigned to
\f[B]seed\f[R] is not propagated to parent functions.
This means that the sequence of pseudo-random numbers that they see will
not be the same sequence of pseudo-random numbers that any parent sees.
This is only the case once \f[B]seed\f[R] has been set.
.PP
If a function desires to not affect the sequence of pseudo-random
numbers of its parents, but wants to use the same \f[B]seed\f[R], it can
use the following line:
.IP
.nf
\f[C]
seed = seed
\f[R]
.fi
.PP
If the behavior of this option is desired for every run of bc(1), then
users could make sure to define \f[B]BC_ENV_ARGS\f[R] and include this
option (see the \f[B]ENVIRONMENT VARIABLES\f[R] section for more
details).
.PP
If \f[B]-s\f[R], \f[B]-w\f[R], or any equivalents are used, this option
is ignored.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-l\f[R], \f[B]\[en]mathlib\f[R]
Sets \f[B]scale\f[R] (see the \f[B]SYNTAX\f[R] section) to \f[B]20\f[R]
and loads the included math library and the extended math library before
running any code, including any expressions or files specified on the
command line.
.RS
.PP
To learn what is in the libraries, see the \f[B]LIBRARY\f[R] section.
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
This option is a no-op.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-q\f[R], \f[B]\[en]quiet\f[R]
This option is for compatibility with the GNU
bc(1) (https://www.gnu.org/software/bc/); it is a no-op.
Without this option, GNU bc(1) prints a copyright header.
This bc(1) only prints the copyright header if one or more of the
\f[B]-v\f[R], \f[B]-V\f[R], or \f[B]\[en]version\f[R] options are given.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-s\f[R], \f[B]\[en]standard\f[R]
Process exactly the language defined by the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
and error if any extensions are used.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-w\f[R], \f[B]\[en]warn\f[R]
Like \f[B]-s\f[R] and \f[B]\[en]standard\f[R], except that warnings (and
not errors) are printed for non-standard extensions and execution
continues normally.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]BC_ENV_ARGS\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]bc >&-\f[R], it will quit with an error.
This is done so that bc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]bc 2>&-\f[R], it will quit with an error.
This is done so that bc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
The syntax for bc(1) programs is mostly C-like, with some differences.
This bc(1) follows the POSIX
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
which is a much more thorough resource for the language this bc(1)
accepts.
This section is meant to be a summary and a listing of all the
extensions to the standard.
.PP
In the sections below, \f[B]E\f[R] means expression, \f[B]S\f[R] means
statement, and \f[B]I\f[R] means identifier.
.PP
Identifiers (\f[B]I\f[R]) start with a lowercase letter and can be
followed by any number (up to \f[B]BC_NAME_MAX-1\f[R]) of lowercase
letters (\f[B]a-z\f[R]), digits (\f[B]0-9\f[R]), and underscores
(\f[B]_\f[R]).
The regex is \f[B][a-z][a-z0-9_]*\f[R].
Identifiers with more than one character (letter) are a
\f[B]non-portable extension\f[R].
.PP
\f[B]ibase\f[R] is a global variable determining how to interpret
constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
If the \f[B]-s\f[R] (\f[B]\[en]standard\f[R]) and \f[B]-w\f[R]
(\f[B]\[en]warn\f[R]) flags were not given on the command line, the max
allowable value for \f[B]ibase\f[R] is \f[B]36\f[R].
Otherwise, it is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in bc(1)
programs with the \f[B]maxibase()\f[R] built-in function.
.PP
\f[B]obase\f[R] is a global variable determining how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]BC_BASE_MAX\f[R] and
can be queried in bc(1) programs with the \f[B]maxobase()\f[R] built-in
function.
The min allowable value for \f[B]obase\f[R] is \f[B]0\f[R].
If \f[B]obase\f[R] is \f[B]0\f[R], values are output in scientific
notation, and if \f[B]obase\f[R] is \f[B]1\f[R], values are output in
engineering notation.
Otherwise, values are output in the specified base.
.PP
Outputting in scientific and engineering notations are \f[B]non-portable
extensions\f[R].
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a global variable that sets the precision of any operations, with
exceptions.
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] is \f[B]BC_SCALE_MAX\f[R]
and can be queried in bc(1) programs with the \f[B]maxscale()\f[R]
built-in function.
.PP
bc(1) has both \f[I]global\f[R] variables and \f[I]local\f[R] variables.
All \f[I]local\f[R] variables are local to the function; they are
parameters or are introduced in the \f[B]auto\f[R] list of a function
(see the \f[B]FUNCTIONS\f[R] section).
If a variable is accessed which is not a parameter or in the
\f[B]auto\f[R] list, it is assumed to be \f[I]global\f[R].
If a parent function has a \f[I]local\f[R] variable version of a
variable that a child function considers \f[I]global\f[R], the value of
that \f[I]global\f[R] variable in the child function is the value of the
variable in the parent function, not the value of the actual
\f[I]global\f[R] variable.
.PP
All of the above applies to arrays as well.
.PP
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence
operator is an assignment operator \f[I]and\f[R] the expression is
notsurrounded by parentheses.
.PP
The value that is printed is also assigned to the special variable
\f[B]last\f[R].
A single dot (\f[B].\f[R]) may also be used as a synonym for
\f[B]last\f[R].
These are \f[B]non-portable extensions\f[R].
.PP
Either semicolons or newlines may separate statements.
.SS Comments
.PP
There are two kinds of comments:
.IP "1." 3
Block comments are enclosed in \f[B]/*\f[R] and \f[B]*/\f[R].
.IP "2." 3
Line comments go from \f[B]#\f[R] until, and not including, the next
newline.
This is a \f[B]non-portable extension\f[R].
.SS Named Expressions
.PP
The following are named expressions in bc(1):
.IP "1." 3
Variables: \f[B]I\f[R]
.IP "2." 3
Array Elements: \f[B]I[E]\f[R]
.IP "3." 3
\f[B]ibase\f[R]
.IP "4." 3
\f[B]obase\f[R]
.IP "5." 3
\f[B]scale\f[R]
.IP "6." 3
\f[B]seed\f[R]
.IP "7." 3
\f[B]last\f[R] or a single dot (\f[B].\f[R])
.PP
Numbers 6 and 7 are \f[B]non-portable extensions\f[R].
.PP
The meaning of \f[B]seed\f[R] is dependent on the current pseudo-random
number generator but is guaranteed to not change except for new major
versions.
.PP
The \f[I]scale\f[R] and sign of the value may be significant.
.PP
If a previously used \f[B]seed\f[R] value is assigned to \f[B]seed\f[R]
and used again, the pseudo-random number generator is guaranteed to
produce the same sequence of pseudo-random numbers as it did when the
\f[B]seed\f[R] value was previously used.
.PP
The exact value assigned to \f[B]seed\f[R] is not guaranteed to be
returned if \f[B]seed\f[R] is queried again immediately.
However, if \f[B]seed\f[R] \f[I]does\f[R] return a different value, both
values, when assigned to \f[B]seed\f[R], are guaranteed to produce the
same sequence of pseudo-random numbers.
This means that certain values assigned to \f[B]seed\f[R] will
\f[I]not\f[R] produce unique sequences of pseudo-random numbers.
The value of \f[B]seed\f[R] will change after any use of the
\f[B]rand()\f[R] and \f[B]irand(E)\f[R] operands (see the
\f[I]Operands\f[R] subsection below), except if the parameter passed to
\f[B]irand(E)\f[R] is \f[B]0\f[R], \f[B]1\f[R], or negative.
.PP
There is no limit to the length (number of significant decimal digits)
or \f[I]scale\f[R] of the value that can be assigned to \f[B]seed\f[R].
.PP
Variables and arrays do not interfere; users can have arrays named the
same as variables.
This also applies to functions (see the \f[B]FUNCTIONS\f[R] section), so
a user can have a variable, array, and function that all have the same
name, and they will not shadow each other, whether inside of functions
or not.
.PP
Named expressions are required as the operand of
\f[B]increment\f[R]/\f[B]decrement\f[R] operators and as the left side
of \f[B]assignment\f[R] operators (see the \f[I]Operators\f[R]
subsection).
.SS Operands
.PP
The following are valid operands in bc(1):
.IP " 1." 4
Numbers (see the \f[I]Numbers\f[R] subsection below).
.IP " 2." 4
Array indices (\f[B]I[E]\f[R]).
.IP " 3." 4
\f[B](E)\f[R]: The value of \f[B]E\f[R] (used to change precedence).
.IP " 4." 4
\f[B]sqrt(E)\f[R]: The square root of \f[B]E\f[R].
\f[B]E\f[R] must be non-negative.
.IP " 5." 4
\f[B]length(E)\f[R]: The number of significant decimal digits in
\f[B]E\f[R].
.IP " 6." 4
\f[B]length(I[])\f[R]: The number of elements in the array \f[B]I\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 7." 4
\f[B]scale(E)\f[R]: The \f[I]scale\f[R] of \f[B]E\f[R].
.IP " 8." 4
\f[B]abs(E)\f[R]: The absolute value of \f[B]E\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 9." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a non-\f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.IP "10." 4
\f[B]read()\f[R]: Reads a line from \f[B]stdin\f[R] and uses that as an
expression.
The result of that expression is the result of the \f[B]read()\f[R]
operand.
This is a \f[B]non-portable extension\f[R].
.IP "11." 4
\f[B]maxibase()\f[R]: The max allowable \f[B]ibase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "12." 4
\f[B]maxobase()\f[R]: The max allowable \f[B]obase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "13." 4
\f[B]maxscale()\f[R]: The max allowable \f[B]scale\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "14." 4
\f[B]rand()\f[R]: A pseudo-random integer between \f[B]0\f[R]
(inclusive) and \f[B]BC_RAND_MAX\f[R] (inclusive).
Using this operand will change the value of \f[B]seed\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "15." 4
\f[B]irand(E)\f[R]: A pseudo-random integer between \f[B]0\f[R]
(inclusive) and the value of \f[B]E\f[R] (exclusive).
If \f[B]E\f[R] is negative or is a non-integer (\f[B]E\f[R]\[cq]s
\f[I]scale\f[R] is not \f[B]0\f[R]), an error is raised, and bc(1)
resets (see the \f[B]RESET\f[R] section) while \f[B]seed\f[R] remains
unchanged.
If \f[B]E\f[R] is larger than \f[B]BC_RAND_MAX\f[R], the higher bound is
honored by generating several pseudo-random integers, multiplying them
by appropriate powers of \f[B]BC_RAND_MAX+1\f[R], and adding them
together.
Thus, the size of integer that can be generated with this operand is
unbounded.
Using this operand will change the value of \f[B]seed\f[R], unless the
value of \f[B]E\f[R] is \f[B]0\f[R] or \f[B]1\f[R].
In that case, \f[B]0\f[R] is returned, and \f[B]seed\f[R] is
\f[I]not\f[R] changed.
This is a \f[B]non-portable extension\f[R].
.IP "16." 4
\f[B]maxrand()\f[R]: The max integer returned by \f[B]rand()\f[R].
This is a \f[B]non-portable extension\f[R].
.PP
The integers generated by \f[B]rand()\f[R] and \f[B]irand(E)\f[R] are
guaranteed to be as unbiased as possible, subject to the limitations of
the pseudo-random number generator.
.PP
\f[B]Note\f[R]: The values returned by the pseudo-random number
generator with \f[B]rand()\f[R] and \f[B]irand(E)\f[R] are guaranteed to
\f[I]NOT\f[R] be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator.
However, they \f[I]are\f[R] guaranteed to be reproducible with identical
\f[B]seed\f[R] values.
This means that the pseudo-random values from bc(1) should only be used
where a reproducible stream of pseudo-random numbers is
\f[I]ESSENTIAL\f[R].
In any other case, use a non-seeded pseudo-random number generator.
.SS Numbers
.PP
Numbers are strings made up of digits, uppercase letters, and at most
\f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]BC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]Z\f[R] alone always equals decimal \f[B]35\f[R].
.PP
In addition, bc(1) accepts numbers in scientific notation.
These have the form \f[B]<number>e<integer>\f[R].
The exponent (the portion after the \f[B]e\f[R]) must be an integer.
An example is \f[B]1.89237e9\f[R], which is equal to
\f[B]1892370000\f[R].
Negative exponents are also allowed, so \f[B]4.2890e-3\f[R] is equal to
\f[B]0.0042890\f[R].
.PP
Using scientific notation is an error or warning if the \f[B]-s\f[R] or
\f[B]-w\f[R], respectively, command-line options (or equivalents) are
given.
.PP
\f[B]WARNING\f[R]: Both the number and the exponent in scientific
notation are interpreted according to the current \f[B]ibase\f[R], but
the number is still multiplied by \f[B]10\[ha]exponent\f[R] regardless
of the current \f[B]ibase\f[R].
For example, if \f[B]ibase\f[R] is \f[B]16\f[R] and bc(1) is given the
number string \f[B]FFeA\f[R], the resulting decimal number will be
\f[B]2550000000000\f[R], and if bc(1) is given the number string
\f[B]10e-4\f[R], the resulting decimal number will be \f[B]0.0016\f[R].
.PP
Accepting input as scientific notation is a \f[B]non-portable
extension\f[R].
.SS Operators
.PP
The following arithmetic and logical operators can be used.
They are listed in order of decreasing precedence.
Operators in the same group have the same precedence.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
Type: Prefix and Postfix
.RS
.PP
Associativity: None
.PP
Description: \f[B]increment\f[R], \f[B]decrement\f[R]
.RE
.TP
\f[B]-\f[R] \f[B]!\f[R]
Type: Prefix
.RS
.PP
Associativity: None
.PP
Description: \f[B]negation\f[R], \f[B]boolean not\f[R]
.RE
.TP
\f[B]$\f[R]
Type: Postfix
.RS
.PP
Associativity: None
.PP
Description: \f[B]truncation\f[R]
.RE
.TP
\f[B]\[at]\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]set precision\f[R]
.RE
.TP
\f[B]\[ha]\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]power\f[R]
.RE
.TP
\f[B]*\f[R] \f[B]/\f[R] \f[B]%\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]multiply\f[R], \f[B]divide\f[R], \f[B]modulus\f[R]
.RE
.TP
\f[B]+\f[R] \f[B]-\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]add\f[R], \f[B]subtract\f[R]
.RE
.TP
\f[B]<<\f[R] \f[B]>>\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]shift left\f[R], \f[B]shift right\f[R]
.RE
.TP
\f[B]=\f[R] \f[B]<<=\f[R] \f[B]>>=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R] \f[B]\[at]=\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]assignment\f[R]
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]relational\f[R]
.RE
.TP
\f[B]&&\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean and\f[R]
.RE
.TP
\f[B]||\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean or\f[R]
.RE
.PP
The operators will be described in more detail below.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
The prefix and postfix \f[B]increment\f[R] and \f[B]decrement\f[R]
operators behave exactly like they would in C.
They require a named expression (see the \f[I]Named Expressions\f[R]
subsection) as an operand.
.RS
.PP
The prefix versions of these operators are more efficient; use them
where possible.
.RE
.TP
\f[B]-\f[R]
The \f[B]negation\f[R] operator returns \f[B]0\f[R] if a user attempts
to negate any expression with the value \f[B]0\f[R].
Otherwise, a copy of the expression with its sign flipped is returned.
.TP
\f[B]!\f[R]
The \f[B]boolean not\f[R] operator returns \f[B]1\f[R] if the expression
is \f[B]0\f[R], or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]$\f[R]
The \f[B]truncation\f[R] operator returns a copy of the given expression
with all of its \f[I]scale\f[R] removed.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[at]\f[R]
The \f[B]set precision\f[R] operator takes two expressions and returns a
copy of the first with its \f[I]scale\f[R] equal to the value of the
second expression.
That could either mean that the number is returned without change (if
the \f[I]scale\f[R] of the first expression matches the value of the
second expression), extended (if it is less), or truncated (if it is
more).
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]) and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The \f[B]power\f[R] operator (not the \f[B]exclusive or\f[R] operator,
as it would be in C) takes two expressions and raises the first to the
power of the value of the second.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]), and if it
is negative, the first value must be non-zero.
.RE
.TP
\f[B]*\f[R]
The \f[B]multiply\f[R] operator takes two expressions, multiplies them,
and returns the product.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The \f[B]divide\f[R] operator takes two expressions, divides them, and
returns the quotient.
The \f[I]scale\f[R] of the result shall be the value of \f[B]scale\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]%\f[R]
The \f[B]modulus\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and evaluates them by 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R] and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]+\f[R]
The \f[B]add\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the sum, with a \f[I]scale\f[R] equal to the
max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]-\f[R]
The \f[B]subtract\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the difference, with a \f[I]scale\f[R] equal to
the max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]<<\f[R]
The \f[B]left shift\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns a copy of the value of \f[B]a\f[R] with its
decimal point moved \f[B]b\f[R] places to the right.
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]) and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]>>\f[R]
The \f[B]right shift\f[R] operator takes two expressions, \f[B]a\f[R]
and \f[B]b\f[R], and returns a copy of the value of \f[B]a\f[R] with its
decimal point moved \f[B]b\f[R] places to the left.
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]) and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]=\f[R] \f[B]<<=\f[R] \f[B]>>=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R] \f[B]\[at]=\f[R]
The \f[B]assignment\f[R] operators take two expressions, \f[B]a\f[R] and
\f[B]b\f[R] where \f[B]a\f[R] is a named expression (see the \f[I]Named
Expressions\f[R] subsection).
.RS
.PP
For \f[B]=\f[R], \f[B]b\f[R] is copied and the result is assigned to
\f[B]a\f[R].
For all others, \f[B]a\f[R] and \f[B]b\f[R] are applied as operands to
the corresponding arithmetic operator and the result is assigned to
\f[B]a\f[R].
.PP
The \f[B]assignment\f[R] operators that correspond to operators that are
extensions are themselves \f[B]non-portable extensions\f[R].
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
The \f[B]relational\f[R] operators compare two expressions, \f[B]a\f[R]
and \f[B]b\f[R], and if the relation holds, according to C language
semantics, the result is \f[B]1\f[R].
Otherwise, it is \f[B]0\f[R].
.RS
.PP
Note that unlike in C, these operators have a lower precedence than the
\f[B]assignment\f[R] operators, which means that \f[B]a=b>c\f[R] is
interpreted as \f[B](a=b)>c\f[R].
.PP
Also, unlike the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
requires, these operators can appear anywhere any other expressions can
be used.
This allowance is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]&&\f[R]
The \f[B]boolean and\f[R] operator takes two expressions and returns
\f[B]1\f[R] if both expressions are non-zero, \f[B]0\f[R] otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]||\f[R]
The \f[B]boolean or\f[R] operator takes two expressions and returns
\f[B]1\f[R] if one of the expressions is non-zero, \f[B]0\f[R]
otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Statements
.PP
The following items are statements:
.IP " 1." 4
\f[B]E\f[R]
.IP " 2." 4
\f[B]{\f[R] \f[B]S\f[R] \f[B];\f[R] \&... \f[B];\f[R] \f[B]S\f[R]
\f[B]}\f[R]
.IP " 3." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 4." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
\f[B]else\f[R] \f[B]S\f[R]
.IP " 5." 4
\f[B]while\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 6." 4
\f[B]for\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B];\f[R] \f[B]E\f[R]
\f[B];\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 7." 4
An empty statement
.IP " 8." 4
\f[B]break\f[R]
.IP " 9." 4
\f[B]continue\f[R]
.IP "10." 4
\f[B]quit\f[R]
.IP "11." 4
\f[B]halt\f[R]
.IP "12." 4
\f[B]limits\f[R]
.IP "13." 4
A string of characters, enclosed in double quotes
.IP "14." 4
\f[B]print\f[R] \f[B]E\f[R] \f[B],\f[R] \&... \f[B],\f[R] \f[B]E\f[R]
.IP "15." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a \f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.PP
Numbers 4, 9, 11, 12, 14, and 15 are \f[B]non-portable extensions\f[R].
.PP
Also, as a \f[B]non-portable extension\f[R], any or all of the
expressions in the header of a for loop may be omitted.
If the condition (second expression) is omitted, it is assumed to be a
constant \f[B]1\f[R].
.PP
The \f[B]break\f[R] statement causes a loop to stop iterating and resume
execution immediately following a loop.
This is only allowed in loops.
.PP
The \f[B]continue\f[R] statement causes a loop iteration to stop early
and returns to the start of the loop, including testing the loop
condition.
This is only allowed in loops.
.PP
The \f[B]if\f[R] \f[B]else\f[R] statement does the same thing as in C.
.PP
The \f[B]quit\f[R] statement causes bc(1) to quit, even if it is on a
branch that will not be executed (it is a compile-time command).
.PP
The \f[B]halt\f[R] statement causes bc(1) to quit, if it is executed.
(Unlike \f[B]quit\f[R] if it is on a branch of an \f[B]if\f[R] statement
that is not executed, bc(1) does not quit.)
.PP
The \f[B]limits\f[R] statement prints the limits that this bc(1) is
subject to.
This is like the \f[B]quit\f[R] statement in that it is a compile-time
command.
.PP
An expression by itself is evaluated and printed, followed by a newline.
.PP
Both scientific notation and engineering notation are available for
printing the results of expressions.
Scientific notation is activated by assigning \f[B]0\f[R] to
\f[B]obase\f[R], and engineering notation is activated by assigning
\f[B]1\f[R] to \f[B]obase\f[R].
To deactivate them, just assign a different value to \f[B]obase\f[R].
.PP
Scientific notation and engineering notation are disabled if bc(1) is
run with either the \f[B]-s\f[R] or \f[B]-w\f[R] command-line options
(or equivalents).
.PP
Printing numbers in scientific notation and/or engineering notation is a
\f[B]non-portable extension\f[R].
.SS Print Statement
.PP
The \[lq]expressions\[rq] in a \f[B]print\f[R] statement may also be
strings.
If they are, there are backslash escape sequences that are interpreted
specially.
What those sequences are, and what they cause to be printed, are shown
below:
.PP
.TS
tab(@);
l l.
T{
\f[B]\[rs]a\f[R]
T}@T{
\f[B]\[rs]a\f[R]
T}
T{
\f[B]\[rs]b\f[R]
T}@T{
\f[B]\[rs]b\f[R]
T}
T{
\f[B]\[rs]\[rs]\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]e\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]f\f[R]
T}@T{
\f[B]\[rs]f\f[R]
T}
T{
\f[B]\[rs]n\f[R]
T}@T{
\f[B]\[rs]n\f[R]
T}
T{
\f[B]\[rs]q\f[R]
T}@T{
\f[B]\[dq]\f[R]
T}
T{
\f[B]\[rs]r\f[R]
T}@T{
\f[B]\[rs]r\f[R]
T}
T{
\f[B]\[rs]t\f[R]
T}@T{
\f[B]\[rs]t\f[R]
T}
.TE
.PP
Any other character following a backslash causes the backslash and
character to be printed as-is.
.PP
Any non-string expression in a print statement shall be assigned to
\f[B]last\f[R], like any other expression that is printed.
.SS Order of Evaluation
.PP
All expressions in a statment are evaluated left to right, except as
necessary to maintain order of operations.
This means, for example, assuming that \f[B]i\f[R] is equal to
\f[B]0\f[R], in the expression
.IP
.nf
\f[C]
a[i++] = i++
\f[R]
.fi
.PP
the first (or 0th) element of \f[B]a\f[R] is set to \f[B]1\f[R], and
\f[B]i\f[R] is equal to \f[B]2\f[R] at the end of the expression.
.PP
This includes function arguments.
Thus, assuming \f[B]i\f[R] is equal to \f[B]0\f[R], this means that in
the expression
.IP
.nf
\f[C]
x(i++, i++)
\f[R]
.fi
.PP
the first argument passed to \f[B]x()\f[R] is \f[B]0\f[R], and the
second argument is \f[B]1\f[R], while \f[B]i\f[R] is equal to
\f[B]2\f[R] before the function starts executing.
.SH FUNCTIONS
.PP
Function definitions are as follows:
.IP
.nf
\f[C]
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
\f[R]
.fi
.PP
Any \f[B]I\f[R] in the parameter list or \f[B]auto\f[R] list may be
replaced with \f[B]I[]\f[R] to make a parameter or \f[B]auto\f[R] var an
array, and any \f[B]I\f[R] in the parameter list may be replaced with
\f[B]*I[]\f[R] to make a parameter an array reference.
Callers of functions that take array references should not put an
asterisk in the call; they must be called with just \f[B]I[]\f[R] like
normal array parameters and will be automatically converted into
references.
.PP
As a \f[B]non-portable extension\f[R], the opening brace of a
\f[B]define\f[R] statement may appear on the next line.
.PP
As a \f[B]non-portable extension\f[R], the return statement may also be
in one of the following forms:
.IP "1." 3
\f[B]return\f[R]
.IP "2." 3
\f[B]return\f[R] \f[B](\f[R] \f[B])\f[R]
.IP "3." 3
\f[B]return\f[R] \f[B]E\f[R]
.PP
The first two, or not specifying a \f[B]return\f[R] statement, is
equivalent to \f[B]return (0)\f[R], unless the function is a
\f[B]void\f[R] function (see the \f[I]Void Functions\f[R] subsection
below).
.SS Void Functions
.PP
Functions can also be \f[B]void\f[R] functions, defined as follows:
.IP
.nf
\f[C]
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
\f[R]
.fi
.PP
They can only be used as standalone expressions, where such an
expression would be printed alone, except in a print statement.
.PP
Void functions can only use the first two \f[B]return\f[R] statements
listed above.
They can also omit the return statement entirely.
.PP
The word \[lq]void\[rq] is not treated as a keyword; it is still
possible to have variables, arrays, and functions named \f[B]void\f[R].
The word \[lq]void\[rq] is only treated specially right after the
\f[B]define\f[R] keyword.
.PP
This is a \f[B]non-portable extension\f[R].
.SS Array References
.PP
For any array in the parameter list, if the array is declared in the
form
.IP
.nf
\f[C]
*I[]
\f[R]
.fi
.PP
it is a \f[B]reference\f[R].
Any changes to the array in the function are reflected, when the
function returns, to the array that was passed in.
.PP
Other than this, all function arguments are passed by value.
.PP
This is a \f[B]non-portable extension\f[R].
.SH LIBRARY
.PP
All of the functions below, including the functions in the extended math
library (see the \f[I]Extended Library\f[R] subsection below), are
available when the \f[B]-l\f[R] or \f[B]\[en]mathlib\f[R] command-line
flags are given, except that the extended math library is not available
when the \f[B]-s\f[R] option, the \f[B]-w\f[R] option, or equivalents
are given.
.SS Standard Library
.PP
The
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
defines the following functions for the math library:
.TP
\f[B]s(x)\f[R]
Returns the sine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]c(x)\f[R]
Returns the cosine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]a(x)\f[R]
Returns the arctangent of \f[B]x\f[R], in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]l(x)\f[R]
Returns the natural logarithm of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]e(x)\f[R]
Returns the mathematical constant \f[B]e\f[R] raised to the power of
\f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]j(x, n)\f[R]
Returns the bessel integer order \f[B]n\f[R] (truncated) of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.SS Extended Library
.PP
The extended library is \f[I]not\f[R] loaded when the
\f[B]-s\f[R]/\f[B]\[en]standard\f[R] or \f[B]-w\f[R]/\f[B]\[en]warn\f[R]
options are given since they are not part of the library defined by the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).
.PP
The extended library is a \f[B]non-portable extension\f[R].
.TP
\f[B]p(x, y)\f[R]
Calculates \f[B]x\f[R] to the power of \f[B]y\f[R], even if \f[B]y\f[R]
is not an integer, and returns the result to the current
\f[B]scale\f[R].
.RS
.PP
It is an error if \f[B]y\f[R] is negative and \f[B]x\f[R] is
\f[B]0\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]r(x, p)\f[R]
Returns \f[B]x\f[R] rounded to \f[B]p\f[R] decimal places according to
the rounding mode round half away from
\f[B]0\f[R] (https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero).
.TP
\f[B]ceil(x, p)\f[R]
Returns \f[B]x\f[R] rounded to \f[B]p\f[R] decimal places according to
the rounding mode round away from
\f[B]0\f[R] (https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero).
.TP
\f[B]f(x)\f[R]
Returns the factorial of the truncated absolute value of \f[B]x\f[R].
.TP
\f[B]perm(n, k)\f[R]
Returns the permutation of the truncated absolute value of \f[B]n\f[R]
of the truncated absolute value of \f[B]k\f[R], if \f[B]k <= n\f[R].
If not, it returns \f[B]0\f[R].
.TP
\f[B]comb(n, k)\f[R]
Returns the combination of the truncated absolute value of \f[B]n\f[R]
of the truncated absolute value of \f[B]k\f[R], if \f[B]k <= n\f[R].
If not, it returns \f[B]0\f[R].
.TP
\f[B]l2(x)\f[R]
Returns the logarithm base \f[B]2\f[R] of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]l10(x)\f[R]
Returns the logarithm base \f[B]10\f[R] of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]log(x, b)\f[R]
Returns the logarithm base \f[B]b\f[R] of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]cbrt(x)\f[R]
Returns the cube root of \f[B]x\f[R].
.TP
\f[B]root(x, n)\f[R]
Calculates the truncated value of \f[B]n\f[R], \f[B]r\f[R], and returns
the \f[B]r\f[R]th root of \f[B]x\f[R] to the current \f[B]scale\f[R].
.RS
.PP
If \f[B]r\f[R] is \f[B]0\f[R] or negative, this raises an error and
causes bc(1) to reset (see the \f[B]RESET\f[R] section).
It also raises an error and causes bc(1) to reset if \f[B]r\f[R] is even
and \f[B]x\f[R] is negative.
.RE
.TP
\f[B]pi(p)\f[R]
Returns \f[B]pi\f[R] to \f[B]p\f[R] decimal places.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]t(x)\f[R]
Returns the tangent of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]a2(y, x)\f[R]
Returns the arctangent of \f[B]y/x\f[R], in radians.
If both \f[B]y\f[R] and \f[B]x\f[R] are equal to \f[B]0\f[R], it raises
an error and causes bc(1) to reset (see the \f[B]RESET\f[R] section).
Otherwise, if \f[B]x\f[R] is greater than \f[B]0\f[R], it returns
\f[B]a(y/x)\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is greater than
or equal to \f[B]0\f[R], it returns \f[B]a(y/x)+pi\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]a(y/x)-pi\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is greater than
\f[B]0\f[R], it returns \f[B]pi/2\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]-pi/2\f[R].
.RS
.PP
This function is the same as the \f[B]atan2()\f[R] function in many
programming languages.
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]sin(x)\f[R]
Returns the sine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is an alias of \f[B]s(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]cos(x)\f[R]
Returns the cosine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is an alias of \f[B]c(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]tan(x)\f[R]
Returns the tangent of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
If \f[B]x\f[R] is equal to \f[B]1\f[R] or \f[B]-1\f[R], this raises an
error and causes bc(1) to reset (see the \f[B]RESET\f[R] section).
.PP
This is an alias of \f[B]t(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]atan(x)\f[R]
Returns the arctangent of \f[B]x\f[R], in radians.
.RS
.PP
This is an alias of \f[B]a(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]atan2(y, x)\f[R]
Returns the arctangent of \f[B]y/x\f[R], in radians.
If both \f[B]y\f[R] and \f[B]x\f[R] are equal to \f[B]0\f[R], it raises
an error and causes bc(1) to reset (see the \f[B]RESET\f[R] section).
Otherwise, if \f[B]x\f[R] is greater than \f[B]0\f[R], it returns
\f[B]a(y/x)\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is greater than
or equal to \f[B]0\f[R], it returns \f[B]a(y/x)+pi\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]a(y/x)-pi\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is greater than
\f[B]0\f[R], it returns \f[B]pi/2\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]-pi/2\f[R].
.RS
.PP
This function is the same as the \f[B]atan2()\f[R] function in many
programming languages.
.PP
This is an alias of \f[B]a2(y, x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]r2d(x)\f[R]
Converts \f[B]x\f[R] from radians to degrees and returns the result.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]d2r(x)\f[R]
Converts \f[B]x\f[R] from degrees to radians and returns the result.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]frand(p)\f[R]
Generates a pseudo-random number between \f[B]0\f[R] (inclusive) and
\f[B]1\f[R] (exclusive) with the number of decimal digits after the
decimal point equal to the truncated absolute value of \f[B]p\f[R].
If \f[B]p\f[R] is not \f[B]0\f[R], then calling this function will
change the value of \f[B]seed\f[R].
If \f[B]p\f[R] is \f[B]0\f[R], then \f[B]0\f[R] is returned, and
\f[B]seed\f[R] is \f[I]not\f[R] changed.
.TP
\f[B]ifrand(i, p)\f[R]
Generates a pseudo-random number that is between \f[B]0\f[R] (inclusive)
and the truncated absolute value of \f[B]i\f[R] (exclusive) with the
number of decimal digits after the decimal point equal to the truncated
absolute value of \f[B]p\f[R].
If the absolute value of \f[B]i\f[R] is greater than or equal to
\f[B]2\f[R], and \f[B]p\f[R] is not \f[B]0\f[R], then calling this
function will change the value of \f[B]seed\f[R]; otherwise, \f[B]0\f[R]
is returned and \f[B]seed\f[R] is not changed.
.TP
\f[B]srand(x)\f[R]
Returns \f[B]x\f[R] with its sign flipped with probability
\f[B]0.5\f[R].
In other words, it randomizes the sign of \f[B]x\f[R].
.TP
\f[B]brand()\f[R]
Returns a random boolean value (either \f[B]0\f[R] or \f[B]1\f[R]).
.TP
\f[B]ubytes(x)\f[R]
Returns the numbers of unsigned integer bytes required to hold the
truncated absolute value of \f[B]x\f[R].
.TP
\f[B]sbytes(x)\f[R]
Returns the numbers of signed, two\[cq]s-complement integer bytes
required to hold the truncated value of \f[B]x\f[R].
.TP
\f[B]hex(x)\f[R]
Outputs the hexadecimal (base \f[B]16\f[R]) representation of
\f[B]x\f[R].
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]binary(x)\f[R]
Outputs the binary (base \f[B]2\f[R]) representation of \f[B]x\f[R].
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]output(x, b)\f[R]
Outputs the base \f[B]b\f[R] representation of \f[B]x\f[R].
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in as few power of two bytes as possible.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or is negative, an error message is
printed instead, but bc(1) is not reset (see the \f[B]RESET\f[R]
section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in as few power of two bytes as
possible.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, an error message is printed instead,
but bc(1) is not reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uintn(x, n)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]n\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]n\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]intn(x, n)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]n\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]n\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint8(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]1\f[R] byte.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]1\f[R] byte, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int8(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]1\f[R] byte.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]1\f[R] byte, an
error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint16(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]2\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]2\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int16(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]2\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]2\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint32(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]4\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]4\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int32(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]4\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]4\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint64(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]8\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]8\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int64(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]8\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]8\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]hex_uint(x, n)\f[R]
Outputs the representation of the truncated absolute value of
\f[B]x\f[R] as an unsigned integer in hexadecimal using \f[B]n\f[R]
bytes.
Not all of the value will be output if \f[B]n\f[R] is too small.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]binary_uint(x, n)\f[R]
Outputs the representation of the truncated absolute value of
\f[B]x\f[R] as an unsigned integer in binary using \f[B]n\f[R] bytes.
Not all of the value will be output if \f[B]n\f[R] is too small.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]output_uint(x, n)\f[R]
Outputs the representation of the truncated absolute value of
\f[B]x\f[R] as an unsigned integer in the current \f[B]obase\f[R] (see
the \f[B]SYNTAX\f[R] section) using \f[B]n\f[R] bytes.
Not all of the value will be output if \f[B]n\f[R] is too small.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]output_byte(x, i)\f[R]
Outputs byte \f[B]i\f[R] of the truncated absolute value of \f[B]x\f[R],
where \f[B]0\f[R] is the least significant byte and \f[B]number_of_bytes
- 1\f[R] is the most significant byte.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.SS Transcendental Functions
.PP
All transcendental functions can return slightly inaccurate results (up
to 1 ULP (https://en.wikipedia.org/wiki/Unit_in_the_last_place)).
This is unavoidable, and this
article (https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT) explains
why it is impossible and unnecessary to calculate exact results for the
transcendental functions.
.PP
Because of the possible inaccuracy, I recommend that users call those
functions with the precision (\f[B]scale\f[R]) set to at least 1 higher
than is necessary.
If exact results are \f[I]absolutely\f[R] required, users can double the
precision (\f[B]scale\f[R]) and then truncate.
.PP
The transcendental functions in the standard math library are:
.IP \[bu] 2
\f[B]s(x)\f[R]
.IP \[bu] 2
\f[B]c(x)\f[R]
.IP \[bu] 2
\f[B]a(x)\f[R]
.IP \[bu] 2
\f[B]l(x)\f[R]
.IP \[bu] 2
\f[B]e(x)\f[R]
.IP \[bu] 2
\f[B]j(x, n)\f[R]
.PP
The transcendental functions in the extended math library are:
.IP \[bu] 2
\f[B]l2(x)\f[R]
.IP \[bu] 2
\f[B]l10(x)\f[R]
.IP \[bu] 2
\f[B]log(x, b)\f[R]
.IP \[bu] 2
\f[B]pi(p)\f[R]
.IP \[bu] 2
\f[B]t(x)\f[R]
.IP \[bu] 2
\f[B]a2(y, x)\f[R]
.IP \[bu] 2
\f[B]sin(x)\f[R]
.IP \[bu] 2
\f[B]cos(x)\f[R]
.IP \[bu] 2
\f[B]tan(x)\f[R]
.IP \[bu] 2
\f[B]atan(x)\f[R]
.IP \[bu] 2
\f[B]atan2(y, x)\f[R]
.IP \[bu] 2
\f[B]r2d(x)\f[R]
.IP \[bu] 2
\f[B]d2r(x)\f[R]
.SH RESET
.PP
When bc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any functions that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all functions returned) is skipped.
.PP
Thus, when bc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.PP
Note that this reset behavior is different from the GNU bc(1), which
attempts to start executing the statement right after the one that
caused an error.
.SH PERFORMANCE
.PP
Most bc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This bc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]BC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]BC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]BC_BASE_DIGS\f[R].
.PP
The actual values of \f[B]BC_LONG_BIT\f[R] and \f[B]BC_BASE_DIGS\f[R]
can be queried with the \f[B]limits\f[R] statement.
.PP
In addition, this bc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]BC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on bc(1):
.TP
\f[B]BC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
bc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]BC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]BC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]BC_BASE_DIGS\f[R].
.TP
\f[B]BC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]BC_BASE_POW\f[R].
.TP
\f[B]BC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]BC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_RAND_MAX\f[R]
The maximum integer (inclusive) returned by the \f[B]rand()\f[R]
operand.
Set at \f[B]2\[ha]BC_LONG_BIT-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]BC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
The actual values can be queried with the \f[B]limits\f[R] statement.
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
bc(1) recognizes the following environment variables:
.TP
\f[B]POSIXLY_CORRECT\f[R]
If this variable exists (no matter the contents), bc(1) behaves as if
the \f[B]-s\f[R] option was given.
.TP
\f[B]BC_ENV_ARGS\f[R]
This is another way to give command-line arguments to bc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]BC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
.RS
.PP
The code that parses \f[B]BC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some bc file.bc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]bc\[dq] file.bc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]BC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]BC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), bc(1) will output lines to that length,
including the backslash (\f[B]\[rs]\f[R]).
The default line length is \f[B]70\f[R].
.SH EXIT STATUS
.PP
bc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, using a negative number as a bound for the
pseudo-random number generator, attempting to convert a negative number
to a hardware integer, overflow when converting a number to a hardware
integer, and attempting to use a non-integer where an integer is
required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]), places (\f[B]\[at]\f[R]), left shift
(\f[B]<<\f[R]), and right shift (\f[B]>>\f[R]) operators and their
corresponding assignment operators.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, using a token
where it is invalid, giving an invalid expression, giving an invalid
print statement, giving an invalid function definition, attempting to
assign to an expression that is not a named expression (see the
\f[I]Named Expressions\f[R] subsection of the \f[B]SYNTAX\f[R] section),
giving an invalid \f[B]auto\f[R] list, having a duplicate
\f[B]auto\f[R]/function parameter, failing to find the end of a code
block, attempting to return a value from a \f[B]void\f[R] function,
attempting to use a variable as a reference, and using any extensions
when the option \f[B]-s\f[R] or any equivalents were given.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a \f[B]void\f[R] function call as a value in an
expression.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (bc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, bc(1)
always exits and returns \f[B]4\f[R], no matter what mode bc(1) is in.
.PP
The other statuses will only be returned when bc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
bc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Per the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, bc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, bc(1) turns on \[lq]TTY mode.\[rq]
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause bc(1) to stop execution of the
current input.
If bc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If bc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If bc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to bc(1) as it is
executing a file, it can seem as though bc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause bc(1) to clean up and
exit, and it uses the default handler for all other signals.
.SH LOCALES
.PP
This bc(1) ships with support for adding error messages for different
locales and thus, supports \f[B]LC_MESSAGES\f[R].
.SH SEE ALSO
.PP
dc(1)
.SH STANDARDS
.PP
bc(1) is compliant with the IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
The flags \f[B]-efghiqsvVw\f[R], all long options, and the extensions
noted above are extensions to that specification.
.PP
Note that the specification explicitly says that bc(1) only accepts
numbers that use a period (\f[B].\f[R]) as a radix point, regardless of
the value of \f[B]LC_NUMERIC\f[R].
.PP
This bc(1) supports error messages for different locales, and thus, it
supports \f[B]LC_MESSAGES\f[R].
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHORS
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/bc/HP.1.md b/contrib/bc/manuals/bc/HP.1.md
index 71bc1ff72c09..7919854a4b5e 100644
--- a/contrib/bc/manuals/bc/HP.1.md
+++ b/contrib/bc/manuals/bc/HP.1.md
@@ -1,1673 +1,1682 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# NAME
bc - arbitrary-precision decimal arithmetic language and calculator
# SYNOPSIS
**bc** [**-ghilPqsvVw**] [**--global-stacks**] [**--help**] [**--interactive**] [**--mathlib**] [**--no-prompt**] [**--quiet**] [**--standard**] [**--warn**] [**--version**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...]
[*file*...]
# DESCRIPTION
bc(1) is an interactive processor for a language first standardized in 1991 by
POSIX. (The current standard is [here][1].) The language provides unlimited
precision decimal arithmetic and is somewhat C-like, but there are differences.
Such differences will be noted in this document.
After parsing and handling options, this bc(1) reads any files given on the
command line and executes them before reading from **stdin**.
# OPTIONS
The following are the options that bc(1) accepts.
**-g**, **--global-stacks**
: Turns the globals **ibase**, **obase**, **scale**, and **seed** into stacks.
This has the effect that a copy of the current value of all four are pushed
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
(**Note**: the function **output(x,b)** exists in the extended math library.
See the **LIBRARY** section.)
However, since using this flag means that functions cannot set **ibase**,
**obase**, **scale**, or **seed** globally, functions that are made to do so
cannot work anymore. There are two possible use cases for that, and each has
a solution.
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o="bc -e ibase=A -e obase=8"
alias h2b="bc -e ibase=G -e obase=2"
Second, if the purpose of a function is to set **ibase**, **obase**,
**scale**, or **seed** globally for any other purpose, it could be split
into one to four functions (based on how many globals it sets) and each of
those functions could return the desired value for a global.
For functions that set **seed**, the value assigned to **seed** is not
propagated to parent functions. This means that the sequence of
pseudo-random numbers that they see will not be the same sequence of
pseudo-random numbers that any parent sees. This is only the case once
**seed** has been set.
If a function desires to not affect the sequence of pseudo-random numbers
of its parents, but wants to use the same **seed**, it can use the following
line:
seed = seed
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
**-h**, **--help**
: Prints a usage message and quits.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-l**, **--mathlib**
: Sets **scale** (see the **SYNTAX** section) to **20** and loads the included
math library and the extended math library before running any code,
including any expressions or files specified on the command line.
To learn what is in the libraries, see the **LIBRARY** section.
**-P**, **--no-prompt**
: This option is a no-op.
This is a **non-portable extension**.
**-q**, **--quiet**
: This option is for compatibility with the [GNU bc(1)][2]; it is a no-op.
Without this option, GNU bc(1) prints a copyright header. This bc(1) only
prints the copyright header if one or more of the **-v**, **-V**, or
**--version** options are given.
This is a **non-portable extension**.
**-s**, **--standard**
: Process exactly the language defined by the [standard][1] and error if any
extensions are used.
This is a **non-portable extension**.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
This is a **non-portable extension**.
**-w**, **--warn**
: Like **-s** and **--standard**, except that warnings (and not errors) are
printed for non-standard extensions and execution continues normally.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **BC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **bc <file> >&-**, it will quit with an error. This
is done so that bc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **bc <file> 2>&-**, it will quit with an error. This
is done so that bc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
The syntax for bc(1) programs is mostly C-like, with some differences. This
bc(1) follows the [POSIX standard][1], which is a much more thorough resource
for the language this bc(1) accepts. This section is meant to be a summary and a
listing of all the extensions to the standard.
In the sections below, **E** means expression, **S** means statement, and **I**
means identifier.
Identifiers (**I**) start with a lowercase letter and can be followed by any
number (up to **BC_NAME_MAX-1**) of lowercase letters (**a-z**), digits
(**0-9**), and underscores (**\_**). The regex is **\[a-z\]\[a-z0-9\_\]\***.
Identifiers with more than one character (letter) are a
**non-portable extension**.
**ibase** is a global variable determining how to interpret constant numbers. It
is the "input" base, or the number base used for interpreting input numbers.
**ibase** is initially **10**. If the **-s** (**--standard**) and **-w**
(**--warn**) flags were not given on the command line, the max allowable value
for **ibase** is **36**. Otherwise, it is **16**. The min allowable value for
**ibase** is **2**. The max allowable value for **ibase** can be queried in
bc(1) programs with the **maxibase()** built-in function.
**obase** is a global variable determining how to output results. It is the
"output" base, or the number base used for outputting numbers. **obase** is
initially **10**. The max allowable value for **obase** is **BC_BASE_MAX** and
can be queried in bc(1) programs with the **maxobase()** built-in function. The
min allowable value for **obase** is **0**. If **obase** is **0**, values are
output in scientific notation, and if **obase** is **1**, values are output in
engineering notation. Otherwise, values are output in the specified base.
Outputting in scientific and engineering notations are **non-portable
extensions**.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a global variable that
sets the precision of any operations, with exceptions. **scale** is initially
**0**. **scale** cannot be negative. The max allowable value for **scale** is
**BC_SCALE_MAX** and can be queried in bc(1) programs with the **maxscale()**
built-in function.
bc(1) has both *global* variables and *local* variables. All *local*
variables are local to the function; they are parameters or are introduced in
the **auto** list of a function (see the **FUNCTIONS** section). If a variable
is accessed which is not a parameter or in the **auto** list, it is assumed to
be *global*. If a parent function has a *local* variable version of a variable
that a child function considers *global*, the value of that *global* variable in
the child function is the value of the variable in the parent function, not the
value of the actual *global* variable.
All of the above applies to arrays as well.
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence operator is an
assignment operator *and* the expression is notsurrounded by parentheses.
The value that is printed is also assigned to the special variable **last**. A
single dot (**.**) may also be used as a synonym for **last**. These are
**non-portable extensions**.
Either semicolons or newlines may separate statements.
## Comments
There are two kinds of comments:
1. Block comments are enclosed in **/\*** and **\*/**.
2. Line comments go from **#** until, and not including, the next newline. This
is a **non-portable extension**.
## Named Expressions
The following are named expressions in bc(1):
1. Variables: **I**
2. Array Elements: **I[E]**
3. **ibase**
4. **obase**
5. **scale**
6. **seed**
7. **last** or a single dot (**.**)
Numbers 6 and 7 are **non-portable extensions**.
The meaning of **seed** is dependent on the current pseudo-random number
generator but is guaranteed to not change except for new major versions.
The *scale* and sign of the value may be significant.
If a previously used **seed** value is assigned to **seed** and used again, the
pseudo-random number generator is guaranteed to produce the same sequence of
pseudo-random numbers as it did when the **seed** value was previously used.
The exact value assigned to **seed** is not guaranteed to be returned if
**seed** is queried again immediately. However, if **seed** *does* return a
different value, both values, when assigned to **seed**, are guaranteed to
produce the same sequence of pseudo-random numbers. This means that certain
values assigned to **seed** will *not* produce unique sequences of pseudo-random
numbers. The value of **seed** will change after any use of the **rand()** and
**irand(E)** operands (see the *Operands* subsection below), except if the
parameter passed to **irand(E)** is **0**, **1**, or negative.
There is no limit to the length (number of significant decimal digits) or
*scale* of the value that can be assigned to **seed**.
Variables and arrays do not interfere; users can have arrays named the same as
variables. This also applies to functions (see the **FUNCTIONS** section), so a
user can have a variable, array, and function that all have the same name, and
they will not shadow each other, whether inside of functions or not.
Named expressions are required as the operand of **increment**/**decrement**
operators and as the left side of **assignment** operators (see the *Operators*
subsection).
## Operands
The following are valid operands in bc(1):
1. Numbers (see the *Numbers* subsection below).
2. Array indices (**I[E]**).
3. **(E)**: The value of **E** (used to change precedence).
4. **sqrt(E)**: The square root of **E**. **E** must be non-negative.
5. **length(E)**: The number of significant decimal digits in **E**.
6. **length(I[])**: The number of elements in the array **I**. This is a
**non-portable extension**.
7. **scale(E)**: The *scale* of **E**.
8. **abs(E)**: The absolute value of **E**. This is a **non-portable
extension**.
9. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a non-**void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
10. **read()**: Reads a line from **stdin** and uses that as an expression. The
result of that expression is the result of the **read()** operand. This is a
**non-portable extension**.
11. **maxibase()**: The max allowable **ibase**. This is a **non-portable
extension**.
12. **maxobase()**: The max allowable **obase**. This is a **non-portable
extension**.
13. **maxscale()**: The max allowable **scale**. This is a **non-portable
extension**.
14. **rand()**: A pseudo-random integer between **0** (inclusive) and
**BC_RAND_MAX** (inclusive). Using this operand will change the value of
**seed**. This is a **non-portable extension**.
15. **irand(E)**: A pseudo-random integer between **0** (inclusive) and the
value of **E** (exclusive). If **E** is negative or is a non-integer
(**E**'s *scale* is not **0**), an error is raised, and bc(1) resets (see
the **RESET** section) while **seed** remains unchanged. If **E** is larger
than **BC_RAND_MAX**, the higher bound is honored by generating several
pseudo-random integers, multiplying them by appropriate powers of
**BC_RAND_MAX+1**, and adding them together. Thus, the size of integer that
can be generated with this operand is unbounded. Using this operand will
change the value of **seed**, unless the value of **E** is **0** or **1**.
In that case, **0** is returned, and **seed** is *not* changed. This is a
**non-portable extension**.
16. **maxrand()**: The max integer returned by **rand()**. This is a
**non-portable extension**.
The integers generated by **rand()** and **irand(E)** are guaranteed to be as
unbiased as possible, subject to the limitations of the pseudo-random number
generator.
**Note**: The values returned by the pseudo-random number generator with
**rand()** and **irand(E)** are guaranteed to *NOT* be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator. However,
they *are* guaranteed to be reproducible with identical **seed** values. This
means that the pseudo-random values from bc(1) should only be used where a
reproducible stream of pseudo-random numbers is *ESSENTIAL*. In any other case,
use a non-seeded pseudo-random number generator.
## Numbers
Numbers are strings made up of digits, uppercase letters, and at most **1**
period for a radix. Numbers can have up to **BC_NUM_MAX** digits. Uppercase
letters are equal to **9** + their position in the alphabet (i.e., **A** equals
**10**, or **9+1**). If a digit or letter makes no sense with the current value
of **ibase**, they are set to the value of the highest valid digit in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **Z** alone always equals decimal
**35**.
In addition, bc(1) accepts numbers in scientific notation. These have the form
**\<number\>e\<integer\>**. The exponent (the portion after the **e**) must be
an integer. An example is **1.89237e9**, which is equal to **1892370000**.
Negative exponents are also allowed, so **4.2890e-3** is equal to **0.0042890**.
Using scientific notation is an error or warning if the **-s** or **-w**,
respectively, command-line options (or equivalents) are given.
**WARNING**: Both the number and the exponent in scientific notation are
interpreted according to the current **ibase**, but the number is still
multiplied by **10\^exponent** regardless of the current **ibase**. For example,
if **ibase** is **16** and bc(1) is given the number string **FFeA**, the
resulting decimal number will be **2550000000000**, and if bc(1) is given the
number string **10e-4**, the resulting decimal number will be **0.0016**.
Accepting input as scientific notation is a **non-portable extension**.
## Operators
The following arithmetic and logical operators can be used. They are listed in
order of decreasing precedence. Operators in the same group have the same
precedence.
**++** **--**
: Type: Prefix and Postfix
Associativity: None
Description: **increment**, **decrement**
**-** **!**
: Type: Prefix
Associativity: None
Description: **negation**, **boolean not**
**\$**
: Type: Postfix
Associativity: None
Description: **truncation**
**\@**
: Type: Binary
Associativity: Right
Description: **set precision**
**\^**
: Type: Binary
Associativity: Right
Description: **power**
**\*** **/** **%**
: Type: Binary
Associativity: Left
Description: **multiply**, **divide**, **modulus**
**+** **-**
: Type: Binary
Associativity: Left
Description: **add**, **subtract**
**\<\<** **\>\>**
: Type: Binary
Associativity: Left
Description: **shift left**, **shift right**
**=** **\<\<=** **\>\>=** **+=** **-=** **\*=** **/=** **%=** **\^=** **\@=**
: Type: Binary
Associativity: Right
Description: **assignment**
**==** **\<=** **\>=** **!=** **\<** **\>**
: Type: Binary
Associativity: Left
Description: **relational**
**&&**
: Type: Binary
Associativity: Left
Description: **boolean and**
**||**
: Type: Binary
Associativity: Left
Description: **boolean or**
The operators will be described in more detail below.
**++** **--**
: The prefix and postfix **increment** and **decrement** operators behave
exactly like they would in C. They require a named expression (see the
*Named Expressions* subsection) as an operand.
The prefix versions of these operators are more efficient; use them where
possible.
**-**
: The **negation** operator returns **0** if a user attempts to negate any
expression with the value **0**. Otherwise, a copy of the expression with
its sign flipped is returned.
**!**
: The **boolean not** operator returns **1** if the expression is **0**, or
**0** otherwise.
This is a **non-portable extension**.
**\$**
: The **truncation** operator returns a copy of the given expression with all
of its *scale* removed.
This is a **non-portable extension**.
**\@**
: The **set precision** operator takes two expressions and returns a copy of
the first with its *scale* equal to the value of the second expression. That
could either mean that the number is returned without change (if the
*scale* of the first expression matches the value of the second
expression), extended (if it is less), or truncated (if it is more).
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**\^**
: The **power** operator (not the **exclusive or** operator, as it would be in
C) takes two expressions and raises the first to the power of the value of
the second. The *scale* of the result is equal to **scale**.
The second expression must be an integer (no *scale*), and if it is
negative, the first value must be non-zero.
**\***
: The **multiply** operator takes two expressions, multiplies them, and
returns the product. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result is
equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The **divide** operator takes two expressions, divides them, and returns the
quotient. The *scale* of the result shall be the value of **scale**.
The second expression must be non-zero.
**%**
: The **modulus** operator takes two expressions, **a** and **b**, and
evaluates them by 1) Computing **a/b** to current **scale** and 2) Using the
result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The second expression must be non-zero.
**+**
: The **add** operator takes two expressions, **a** and **b**, and returns the
sum, with a *scale* equal to the max of the *scale*s of **a** and **b**.
**-**
: The **subtract** operator takes two expressions, **a** and **b**, and
returns the difference, with a *scale* equal to the max of the *scale*s of
**a** and **b**.
**\<\<**
: The **left shift** operator takes two expressions, **a** and **b**, and
returns a copy of the value of **a** with its decimal point moved **b**
places to the right.
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**\>\>**
: The **right shift** operator takes two expressions, **a** and **b**, and
returns a copy of the value of **a** with its decimal point moved **b**
places to the left.
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**=** **\<\<=** **\>\>=** **+=** **-=** **\*=** **/=** **%=** **\^=** **\@=**
: The **assignment** operators take two expressions, **a** and **b** where
**a** is a named expression (see the *Named Expressions* subsection).
For **=**, **b** is copied and the result is assigned to **a**. For all
others, **a** and **b** are applied as operands to the corresponding
arithmetic operator and the result is assigned to **a**.
The **assignment** operators that correspond to operators that are
extensions are themselves **non-portable extensions**.
**==** **\<=** **\>=** **!=** **\<** **\>**
: The **relational** operators compare two expressions, **a** and **b**, and
if the relation holds, according to C language semantics, the result is
**1**. Otherwise, it is **0**.
Note that unlike in C, these operators have a lower precedence than the
**assignment** operators, which means that **a=b\>c** is interpreted as
**(a=b)\>c**.
Also, unlike the [standard][1] requires, these operators can appear anywhere
any other expressions can be used. This allowance is a
**non-portable extension**.
**&&**
: The **boolean and** operator takes two expressions and returns **1** if both
expressions are non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
**||**
: The **boolean or** operator takes two expressions and returns **1** if one
of the expressions is non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
## Statements
The following items are statements:
1. **E**
2. **{** **S** **;** ... **;** **S** **}**
3. **if** **(** **E** **)** **S**
4. **if** **(** **E** **)** **S** **else** **S**
5. **while** **(** **E** **)** **S**
6. **for** **(** **E** **;** **E** **;** **E** **)** **S**
7. An empty statement
8. **break**
9. **continue**
10. **quit**
11. **halt**
12. **limits**
13. A string of characters, enclosed in double quotes
14. **print** **E** **,** ... **,** **E**
15. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
Numbers 4, 9, 11, 12, 14, and 15 are **non-portable extensions**.
Also, as a **non-portable extension**, any or all of the expressions in the
header of a for loop may be omitted. If the condition (second expression) is
omitted, it is assumed to be a constant **1**.
The **break** statement causes a loop to stop iterating and resume execution
immediately following a loop. This is only allowed in loops.
The **continue** statement causes a loop iteration to stop early and returns to
the start of the loop, including testing the loop condition. This is only
allowed in loops.
The **if** **else** statement does the same thing as in C.
The **quit** statement causes bc(1) to quit, even if it is on a branch that will
not be executed (it is a compile-time command).
The **halt** statement causes bc(1) to quit, if it is executed. (Unlike **quit**
if it is on a branch of an **if** statement that is not executed, bc(1) does not
quit.)
The **limits** statement prints the limits that this bc(1) is subject to. This
is like the **quit** statement in that it is a compile-time command.
An expression by itself is evaluated and printed, followed by a newline.
Both scientific notation and engineering notation are available for printing the
results of expressions. Scientific notation is activated by assigning **0** to
**obase**, and engineering notation is activated by assigning **1** to
**obase**. To deactivate them, just assign a different value to **obase**.
Scientific notation and engineering notation are disabled if bc(1) is run with
either the **-s** or **-w** command-line options (or equivalents).
Printing numbers in scientific notation and/or engineering notation is a
**non-portable extension**.
## Print Statement
The "expressions" in a **print** statement may also be strings. If they are, there
are backslash escape sequences that are interpreted specially. What those
sequences are, and what they cause to be printed, are shown below:
-------- -------
**\\a** **\\a**
**\\b** **\\b**
**\\\\** **\\**
**\\e** **\\**
**\\f** **\\f**
**\\n** **\\n**
**\\q** **"**
**\\r** **\\r**
**\\t** **\\t**
-------- -------
Any other character following a backslash causes the backslash and character to
be printed as-is.
Any non-string expression in a print statement shall be assigned to **last**,
like any other expression that is printed.
## Order of Evaluation
All expressions in a statment are evaluated left to right, except as necessary
to maintain order of operations. This means, for example, assuming that **i** is
equal to **0**, in the expression
a[i++] = i++
the first (or 0th) element of **a** is set to **1**, and **i** is equal to **2**
at the end of the expression.
This includes function arguments. Thus, assuming **i** is equal to **0**, this
means that in the expression
x(i++, i++)
the first argument passed to **x()** is **0**, and the second argument is **1**,
while **i** is equal to **2** before the function starts executing.
# FUNCTIONS
Function definitions are as follows:
```
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
```
Any **I** in the parameter list or **auto** list may be replaced with **I[]** to
make a parameter or **auto** var an array, and any **I** in the parameter list
may be replaced with **\*I[]** to make a parameter an array reference. Callers
of functions that take array references should not put an asterisk in the call;
they must be called with just **I[]** like normal array parameters and will be
automatically converted into references.
As a **non-portable extension**, the opening brace of a **define** statement may
appear on the next line.
As a **non-portable extension**, the return statement may also be in one of the
following forms:
1. **return**
2. **return** **(** **)**
3. **return** **E**
The first two, or not specifying a **return** statement, is equivalent to
**return (0)**, unless the function is a **void** function (see the *Void
Functions* subsection below).
## Void Functions
Functions can also be **void** functions, defined as follows:
```
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
```
They can only be used as standalone expressions, where such an expression would
be printed alone, except in a print statement.
Void functions can only use the first two **return** statements listed above.
They can also omit the return statement entirely.
The word "void" is not treated as a keyword; it is still possible to have
variables, arrays, and functions named **void**. The word "void" is only
treated specially right after the **define** keyword.
This is a **non-portable extension**.
## Array References
For any array in the parameter list, if the array is declared in the form
```
*I[]
```
it is a **reference**. Any changes to the array in the function are reflected,
when the function returns, to the array that was passed in.
Other than this, all function arguments are passed by value.
This is a **non-portable extension**.
# LIBRARY
All of the functions below, including the functions in the extended math
library (see the *Extended Library* subsection below), are available when the
**-l** or **--mathlib** command-line flags are given, except that the extended
math library is not available when the **-s** option, the **-w** option, or
equivalents are given.
## Standard Library
The [standard][1] defines the following functions for the math library:
**s(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**c(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a(x)**
: Returns the arctangent of **x**, in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l(x)**
: Returns the natural logarithm of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**e(x)**
: Returns the mathematical constant **e** raised to the power of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**j(x, n)**
: Returns the bessel integer order **n** (truncated) of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
## Extended Library
The extended library is *not* loaded when the **-s**/**--standard** or
**-w**/**--warn** options are given since they are not part of the library
defined by the [standard][1].
The extended library is a **non-portable extension**.
**p(x, y)**
: Calculates **x** to the power of **y**, even if **y** is not an integer, and
returns the result to the current **scale**.
It is an error if **y** is negative and **x** is **0**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**r(x, p)**
: Returns **x** rounded to **p** decimal places according to the rounding mode
[round half away from **0**][3].
**ceil(x, p)**
: Returns **x** rounded to **p** decimal places according to the rounding mode
[round away from **0**][6].
**f(x)**
: Returns the factorial of the truncated absolute value of **x**.
**perm(n, k)**
: Returns the permutation of the truncated absolute value of **n** of the
truncated absolute value of **k**, if **k \<= n**. If not, it returns **0**.
**comb(n, k)**
: Returns the combination of the truncated absolute value of **n** of the
truncated absolute value of **k**, if **k \<= n**. If not, it returns **0**.
**l2(x)**
: Returns the logarithm base **2** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l10(x)**
: Returns the logarithm base **10** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**log(x, b)**
: Returns the logarithm base **b** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**cbrt(x)**
: Returns the cube root of **x**.
**root(x, n)**
: Calculates the truncated value of **n**, **r**, and returns the **r**th root
of **x** to the current **scale**.
If **r** is **0** or negative, this raises an error and causes bc(1) to
reset (see the **RESET** section). It also raises an error and causes bc(1)
to reset if **r** is even and **x** is negative.
**pi(p)**
: Returns **pi** to **p** decimal places.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**t(x)**
: Returns the tangent of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a2(y, x)**
: Returns the arctangent of **y/x**, in radians. If both **y** and **x** are
equal to **0**, it raises an error and causes bc(1) to reset (see the
**RESET** section). Otherwise, if **x** is greater than **0**, it returns
**a(y/x)**. If **x** is less than **0**, and **y** is greater than or equal
to **0**, it returns **a(y/x)+pi**. If **x** is less than **0**, and **y**
is less than **0**, it returns **a(y/x)-pi**. If **x** is equal to **0**,
and **y** is greater than **0**, it returns **pi/2**. If **x** is equal to
**0**, and **y** is less than **0**, it returns **-pi/2**.
This function is the same as the **atan2()** function in many programming
languages.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**sin(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is an alias of **s(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**cos(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is an alias of **c(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**tan(x)**
: Returns the tangent of **x**, which is assumed to be in radians.
If **x** is equal to **1** or **-1**, this raises an error and causes bc(1)
to reset (see the **RESET** section).
This is an alias of **t(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**atan(x)**
: Returns the arctangent of **x**, in radians.
This is an alias of **a(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**atan2(y, x)**
: Returns the arctangent of **y/x**, in radians. If both **y** and **x** are
equal to **0**, it raises an error and causes bc(1) to reset (see the
**RESET** section). Otherwise, if **x** is greater than **0**, it returns
**a(y/x)**. If **x** is less than **0**, and **y** is greater than or equal
to **0**, it returns **a(y/x)+pi**. If **x** is less than **0**, and **y**
is less than **0**, it returns **a(y/x)-pi**. If **x** is equal to **0**,
and **y** is greater than **0**, it returns **pi/2**. If **x** is equal to
**0**, and **y** is less than **0**, it returns **-pi/2**.
This function is the same as the **atan2()** function in many programming
languages.
This is an alias of **a2(y, x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**r2d(x)**
: Converts **x** from radians to degrees and returns the result.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**d2r(x)**
: Converts **x** from degrees to radians and returns the result.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**frand(p)**
: Generates a pseudo-random number between **0** (inclusive) and **1**
(exclusive) with the number of decimal digits after the decimal point equal
to the truncated absolute value of **p**. If **p** is not **0**, then
calling this function will change the value of **seed**. If **p** is **0**,
then **0** is returned, and **seed** is *not* changed.
**ifrand(i, p)**
: Generates a pseudo-random number that is between **0** (inclusive) and the
truncated absolute value of **i** (exclusive) with the number of decimal
digits after the decimal point equal to the truncated absolute value of
**p**. If the absolute value of **i** is greater than or equal to **2**, and
**p** is not **0**, then calling this function will change the value of
**seed**; otherwise, **0** is returned and **seed** is not changed.
**srand(x)**
: Returns **x** with its sign flipped with probability **0.5**. In other
words, it randomizes the sign of **x**.
**brand()**
: Returns a random boolean value (either **0** or **1**).
**ubytes(x)**
: Returns the numbers of unsigned integer bytes required to hold the truncated
absolute value of **x**.
**sbytes(x)**
: Returns the numbers of signed, two's-complement integer bytes required to
hold the truncated value of **x**.
**hex(x)**
: Outputs the hexadecimal (base **16**) representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**binary(x)**
: Outputs the binary (base **2**) representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output(x, b)**
: Outputs the base **b** representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in as few power of two bytes as possible. Both outputs are
split into bytes separated by spaces.
If **x** is not an integer or is negative, an error message is printed
instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in as few power of two bytes as possible. Both
outputs are split into bytes separated by spaces.
If **x** is not an integer, an error message is printed instead, but bc(1)
is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uintn(x, n)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **n** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **n** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**intn(x, n)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **n** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **n** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint8(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **1** byte. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **1** byte, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int8(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **1** byte. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **1** byte, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint16(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **2** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **2** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int16(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **2** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **2** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint32(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **4** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **4** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int32(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **4** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **4** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint64(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **8** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **8** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int64(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **8** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **8** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**hex_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in hexadecimal using **n** bytes. Not all of the value will
be output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**binary_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in binary using **n** bytes. Not all of the value will be
output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in the current **obase** (see the **SYNTAX** section) using
**n** bytes. Not all of the value will be output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output_byte(x, i)**
: Outputs byte **i** of the truncated absolute value of **x**, where **0** is
the least significant byte and **number_of_bytes - 1** is the most
significant byte.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
## Transcendental Functions
All transcendental functions can return slightly inaccurate results (up to 1
[ULP][4]). This is unavoidable, and [this article][5] explains why it is
impossible and unnecessary to calculate exact results for the transcendental
functions.
Because of the possible inaccuracy, I recommend that users call those functions
with the precision (**scale**) set to at least 1 higher than is necessary. If
exact results are *absolutely* required, users can double the precision
(**scale**) and then truncate.
The transcendental functions in the standard math library are:
* **s(x)**
* **c(x)**
* **a(x)**
* **l(x)**
* **e(x)**
* **j(x, n)**
The transcendental functions in the extended math library are:
* **l2(x)**
* **l10(x)**
* **log(x, b)**
* **pi(p)**
* **t(x)**
* **a2(y, x)**
* **sin(x)**
* **cos(x)**
* **tan(x)**
* **atan(x)**
* **atan2(y, x)**
* **r2d(x)**
* **d2r(x)**
# RESET
When bc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any functions that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
functions returned) is skipped.
Thus, when bc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
Note that this reset behavior is different from the GNU bc(1), which attempts to
start executing the statement right after the one that caused an error.
# PERFORMANCE
Most bc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This bc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **BC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **BC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**BC_BASE_DIGS**.
The actual values of **BC_LONG_BIT** and **BC_BASE_DIGS** can be queried with
the **limits** statement.
In addition, this bc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **BC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on bc(1):
**BC_LONG_BIT**
: The number of bits in the **long** type in the environment where bc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**BC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **BC_LONG_BIT**.
**BC_BASE_POW**
: The max decimal number that each large integer can store (see
**BC_BASE_DIGS**) plus **1**. Depends on **BC_BASE_DIGS**.
**BC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **BC_LONG_BIT**.
**BC_BASE_MAX**
: The maximum output base. Set at **BC_BASE_POW**.
**BC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**BC_SCALE_MAX**
: The maximum **scale**. Set at **BC_OVERFLOW_MAX-1**.
**BC_STRING_MAX**
: The maximum length of strings. Set at **BC_OVERFLOW_MAX-1**.
**BC_NAME_MAX**
: The maximum length of identifiers. Set at **BC_OVERFLOW_MAX-1**.
**BC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **BC_OVERFLOW_MAX-1**.
**BC_RAND_MAX**
: The maximum integer (inclusive) returned by the **rand()** operand. Set at
**2\^BC_LONG_BIT-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**BC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
The actual values can be queried with the **limits** statement.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
bc(1) recognizes the following environment variables:
**POSIXLY_CORRECT**
: If this variable exists (no matter the contents), bc(1) behaves as if
the **-s** option was given.
**BC_ENV_ARGS**
: This is another way to give command-line arguments to bc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **BC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
The code that parses **BC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some bc file.bc"** will be correctly parsed, but the string
**"/home/gavin/some \"bc\" file.bc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **BC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**BC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), bc(1) will output
lines to that length, including the backslash (**\\**). The default line
length is **70**.
# EXIT STATUS
bc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, using a negative number as a bound for the pseudo-random number
generator, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**), places (**\@**), left shift (**\<\<**), and right shift (**\>\>**)
operators and their corresponding assignment operators.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, using a token where it is invalid,
giving an invalid expression, giving an invalid print statement, giving an
invalid function definition, attempting to assign to an expression that is
not a named expression (see the *Named Expressions* subsection of the
**SYNTAX** section), giving an invalid **auto** list, having a duplicate
**auto**/function parameter, failing to find the end of a code block,
attempting to return a value from a **void** function, attempting to use a
variable as a reference, and using any extensions when the option **-s** or
any equivalents were given.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a **void** function call as a value in an expression.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (bc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, bc(1) always exits
and returns **4**, no matter what mode bc(1) is in.
The other statuses will only be returned when bc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since bc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Per the [standard][1], bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, bc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, bc(1) turns
on "TTY mode."
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause bc(1) to stop execution of the current input. If
bc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If bc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If bc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to bc(1) as it is executing a file, it
can seem as though bc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause bc(1) to clean up and exit, and it uses the
default handler for all other signals.
# LOCALES
This bc(1) ships with support for adding error messages for different locales
and thus, supports **LC_MESSAGES**.
# SEE ALSO
dc(1)
# STANDARDS
bc(1) is compliant with the [IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1]
specification. The flags **-efghiqsvVw**, all long options, and the extensions
noted above are extensions to that specification.
Note that the specification explicitly says that bc(1) only accepts numbers that
use a period (**.**) as a radix point, regardless of the value of
**LC_NUMERIC**.
This bc(1) supports error messages for different locales, and thus, it supports
**LC_MESSAGES**.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHORS
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
[2]: https://www.gnu.org/software/bc/
[3]: https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero
[4]: https://en.wikipedia.org/wiki/Unit_in_the_last_place
[5]: https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT
[6]: https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero
diff --git a/contrib/bc/manuals/bc/N.1 b/contrib/bc/manuals/bc/N.1
index 70e8a4945a2b..0b94f9562d91 100644
--- a/contrib/bc/manuals/bc/N.1
+++ b/contrib/bc/manuals/bc/N.1
@@ -1,2038 +1,2051 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "BC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "BC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH NAME
.PP
bc - arbitrary-precision decimal arithmetic language and calculator
.SH SYNOPSIS
.PP
\f[B]bc\f[R] [\f[B]-ghilPqsvVw\f[R]] [\f[B]\[en]global-stacks\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]mathlib\f[R]] [\f[B]\[en]no-prompt\f[R]]
[\f[B]\[en]quiet\f[R]] [\f[B]\[en]standard\f[R]] [\f[B]\[en]warn\f[R]]
[\f[B]\[en]version\f[R]] [\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
bc(1) is an interactive processor for a language first standardized in
1991 by POSIX.
(The current standard is
here (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).)
The language provides unlimited precision decimal arithmetic and is
somewhat C-like, but there are differences.
Such differences will be noted in this document.
.PP
After parsing and handling options, this bc(1) reads any files given on
the command line and executes them before reading from \f[B]stdin\f[R].
.PP
This bc(1) is a drop-in replacement for \f[I]any\f[R] bc(1), including
(and especially) the GNU bc(1).
It also has many extensions and extra features beyond other
implementations.
.SH OPTIONS
.PP
The following are the options that bc(1) accepts.
.TP
\f[B]-g\f[R], \f[B]\[en]global-stacks\f[R]
Turns the globals \f[B]ibase\f[R], \f[B]obase\f[R], \f[B]scale\f[R], and
\f[B]seed\f[R] into stacks.
.RS
.PP
This has the effect that a copy of the current value of all four are
pushed onto a stack for every function call, as well as popped when
every function returns.
This means that functions can assign to any and all of those globals
without worrying that the change will affect other functions.
Thus, a hypothetical function named \f[B]output(x,b)\f[R] that simply
printed \f[B]x\f[R] in base \f[B]b\f[R] could be written like this:
.IP
.nf
\f[C]
define void output(x, b) {
obase=b
x
}
\f[R]
.fi
.PP
instead of like this:
.IP
.nf
\f[C]
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
\f[R]
.fi
.PP
This makes writing functions much easier.
.PP
(\f[B]Note\f[R]: the function \f[B]output(x,b)\f[R] exists in the
extended math library.
See the \f[B]LIBRARY\f[R] section.)
.PP
However, since using this flag means that functions cannot set
\f[B]ibase\f[R], \f[B]obase\f[R], \f[B]scale\f[R], or \f[B]seed\f[R]
globally, functions that are made to do so cannot work anymore.
There are two possible use cases for that, and each has a solution.
.PP
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases.
Examples:
.IP
.nf
\f[C]
alias d2o=\[dq]bc -e ibase=A -e obase=8\[dq]
alias h2b=\[dq]bc -e ibase=G -e obase=2\[dq]
\f[R]
.fi
.PP
Second, if the purpose of a function is to set \f[B]ibase\f[R],
\f[B]obase\f[R], \f[B]scale\f[R], or \f[B]seed\f[R] globally for any
other purpose, it could be split into one to four functions (based on
how many globals it sets) and each of those functions could return the
desired value for a global.
.PP
For functions that set \f[B]seed\f[R], the value assigned to
\f[B]seed\f[R] is not propagated to parent functions.
This means that the sequence of pseudo-random numbers that they see will
not be the same sequence of pseudo-random numbers that any parent sees.
This is only the case once \f[B]seed\f[R] has been set.
.PP
If a function desires to not affect the sequence of pseudo-random
numbers of its parents, but wants to use the same \f[B]seed\f[R], it can
use the following line:
.IP
.nf
\f[C]
seed = seed
\f[R]
.fi
.PP
If the behavior of this option is desired for every run of bc(1), then
users could make sure to define \f[B]BC_ENV_ARGS\f[R] and include this
option (see the \f[B]ENVIRONMENT VARIABLES\f[R] section for more
details).
.PP
If \f[B]-s\f[R], \f[B]-w\f[R], or any equivalents are used, this option
is ignored.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-l\f[R], \f[B]\[en]mathlib\f[R]
Sets \f[B]scale\f[R] (see the \f[B]SYNTAX\f[R] section) to \f[B]20\f[R]
and loads the included math library and the extended math library before
running any code, including any expressions or files specified on the
command line.
.RS
.PP
To learn what is in the libraries, see the \f[B]LIBRARY\f[R] section.
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
Disables the prompt in TTY mode.
(The prompt is only enabled in TTY mode.
See the \f[B]TTY MODE\f[R] section) This is mostly for those users that
do not want a prompt or are not used to having them in bc(1).
Most of those users would want to put this option in
\f[B]BC_ENV_ARGS\f[R] (see the \f[B]ENVIRONMENT VARIABLES\f[R] section).
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-q\f[R], \f[B]\[en]quiet\f[R]
This option is for compatibility with the GNU
bc(1) (https://www.gnu.org/software/bc/); it is a no-op.
Without this option, GNU bc(1) prints a copyright header.
This bc(1) only prints the copyright header if one or more of the
\f[B]-v\f[R], \f[B]-V\f[R], or \f[B]\[en]version\f[R] options are given.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-s\f[R], \f[B]\[en]standard\f[R]
Process exactly the language defined by the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
and error if any extensions are used.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-w\f[R], \f[B]\[en]warn\f[R]
Like \f[B]-s\f[R] and \f[B]\[en]standard\f[R], except that warnings (and
not errors) are printed for non-standard extensions and execution
continues normally.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]BC_ENV_ARGS\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]bc >&-\f[R], it will quit with an error.
This is done so that bc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]bc 2>&-\f[R], it will quit with an error.
This is done so that bc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
The syntax for bc(1) programs is mostly C-like, with some differences.
This bc(1) follows the POSIX
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
which is a much more thorough resource for the language this bc(1)
accepts.
This section is meant to be a summary and a listing of all the
extensions to the standard.
.PP
In the sections below, \f[B]E\f[R] means expression, \f[B]S\f[R] means
statement, and \f[B]I\f[R] means identifier.
.PP
Identifiers (\f[B]I\f[R]) start with a lowercase letter and can be
followed by any number (up to \f[B]BC_NAME_MAX-1\f[R]) of lowercase
letters (\f[B]a-z\f[R]), digits (\f[B]0-9\f[R]), and underscores
(\f[B]_\f[R]).
The regex is \f[B][a-z][a-z0-9_]*\f[R].
Identifiers with more than one character (letter) are a
\f[B]non-portable extension\f[R].
.PP
\f[B]ibase\f[R] is a global variable determining how to interpret
constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
If the \f[B]-s\f[R] (\f[B]\[en]standard\f[R]) and \f[B]-w\f[R]
(\f[B]\[en]warn\f[R]) flags were not given on the command line, the max
allowable value for \f[B]ibase\f[R] is \f[B]36\f[R].
Otherwise, it is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in bc(1)
programs with the \f[B]maxibase()\f[R] built-in function.
.PP
\f[B]obase\f[R] is a global variable determining how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]BC_BASE_MAX\f[R] and
can be queried in bc(1) programs with the \f[B]maxobase()\f[R] built-in
function.
The min allowable value for \f[B]obase\f[R] is \f[B]0\f[R].
If \f[B]obase\f[R] is \f[B]0\f[R], values are output in scientific
notation, and if \f[B]obase\f[R] is \f[B]1\f[R], values are output in
engineering notation.
Otherwise, values are output in the specified base.
.PP
Outputting in scientific and engineering notations are \f[B]non-portable
extensions\f[R].
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a global variable that sets the precision of any operations, with
exceptions.
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] is \f[B]BC_SCALE_MAX\f[R]
and can be queried in bc(1) programs with the \f[B]maxscale()\f[R]
built-in function.
.PP
bc(1) has both \f[I]global\f[R] variables and \f[I]local\f[R] variables.
All \f[I]local\f[R] variables are local to the function; they are
parameters or are introduced in the \f[B]auto\f[R] list of a function
(see the \f[B]FUNCTIONS\f[R] section).
If a variable is accessed which is not a parameter or in the
\f[B]auto\f[R] list, it is assumed to be \f[I]global\f[R].
If a parent function has a \f[I]local\f[R] variable version of a
variable that a child function considers \f[I]global\f[R], the value of
that \f[I]global\f[R] variable in the child function is the value of the
variable in the parent function, not the value of the actual
\f[I]global\f[R] variable.
.PP
All of the above applies to arrays as well.
.PP
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence
operator is an assignment operator \f[I]and\f[R] the expression is
notsurrounded by parentheses.
.PP
The value that is printed is also assigned to the special variable
\f[B]last\f[R].
A single dot (\f[B].\f[R]) may also be used as a synonym for
\f[B]last\f[R].
These are \f[B]non-portable extensions\f[R].
.PP
Either semicolons or newlines may separate statements.
.SS Comments
.PP
There are two kinds of comments:
.IP "1." 3
Block comments are enclosed in \f[B]/*\f[R] and \f[B]*/\f[R].
.IP "2." 3
Line comments go from \f[B]#\f[R] until, and not including, the next
newline.
This is a \f[B]non-portable extension\f[R].
.SS Named Expressions
.PP
The following are named expressions in bc(1):
.IP "1." 3
Variables: \f[B]I\f[R]
.IP "2." 3
Array Elements: \f[B]I[E]\f[R]
.IP "3." 3
\f[B]ibase\f[R]
.IP "4." 3
\f[B]obase\f[R]
.IP "5." 3
\f[B]scale\f[R]
.IP "6." 3
\f[B]seed\f[R]
.IP "7." 3
\f[B]last\f[R] or a single dot (\f[B].\f[R])
.PP
Numbers 6 and 7 are \f[B]non-portable extensions\f[R].
.PP
The meaning of \f[B]seed\f[R] is dependent on the current pseudo-random
number generator but is guaranteed to not change except for new major
versions.
.PP
The \f[I]scale\f[R] and sign of the value may be significant.
.PP
If a previously used \f[B]seed\f[R] value is assigned to \f[B]seed\f[R]
and used again, the pseudo-random number generator is guaranteed to
produce the same sequence of pseudo-random numbers as it did when the
\f[B]seed\f[R] value was previously used.
.PP
The exact value assigned to \f[B]seed\f[R] is not guaranteed to be
returned if \f[B]seed\f[R] is queried again immediately.
However, if \f[B]seed\f[R] \f[I]does\f[R] return a different value, both
values, when assigned to \f[B]seed\f[R], are guaranteed to produce the
same sequence of pseudo-random numbers.
This means that certain values assigned to \f[B]seed\f[R] will
\f[I]not\f[R] produce unique sequences of pseudo-random numbers.
The value of \f[B]seed\f[R] will change after any use of the
\f[B]rand()\f[R] and \f[B]irand(E)\f[R] operands (see the
\f[I]Operands\f[R] subsection below), except if the parameter passed to
\f[B]irand(E)\f[R] is \f[B]0\f[R], \f[B]1\f[R], or negative.
.PP
There is no limit to the length (number of significant decimal digits)
or \f[I]scale\f[R] of the value that can be assigned to \f[B]seed\f[R].
.PP
Variables and arrays do not interfere; users can have arrays named the
same as variables.
This also applies to functions (see the \f[B]FUNCTIONS\f[R] section), so
a user can have a variable, array, and function that all have the same
name, and they will not shadow each other, whether inside of functions
or not.
.PP
Named expressions are required as the operand of
\f[B]increment\f[R]/\f[B]decrement\f[R] operators and as the left side
of \f[B]assignment\f[R] operators (see the \f[I]Operators\f[R]
subsection).
.SS Operands
.PP
The following are valid operands in bc(1):
.IP " 1." 4
Numbers (see the \f[I]Numbers\f[R] subsection below).
.IP " 2." 4
Array indices (\f[B]I[E]\f[R]).
.IP " 3." 4
\f[B](E)\f[R]: The value of \f[B]E\f[R] (used to change precedence).
.IP " 4." 4
\f[B]sqrt(E)\f[R]: The square root of \f[B]E\f[R].
\f[B]E\f[R] must be non-negative.
.IP " 5." 4
\f[B]length(E)\f[R]: The number of significant decimal digits in
\f[B]E\f[R].
.IP " 6." 4
\f[B]length(I[])\f[R]: The number of elements in the array \f[B]I\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 7." 4
\f[B]scale(E)\f[R]: The \f[I]scale\f[R] of \f[B]E\f[R].
.IP " 8." 4
\f[B]abs(E)\f[R]: The absolute value of \f[B]E\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 9." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a non-\f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.IP "10." 4
\f[B]read()\f[R]: Reads a line from \f[B]stdin\f[R] and uses that as an
expression.
The result of that expression is the result of the \f[B]read()\f[R]
operand.
This is a \f[B]non-portable extension\f[R].
.IP "11." 4
\f[B]maxibase()\f[R]: The max allowable \f[B]ibase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "12." 4
\f[B]maxobase()\f[R]: The max allowable \f[B]obase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "13." 4
\f[B]maxscale()\f[R]: The max allowable \f[B]scale\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "14." 4
\f[B]rand()\f[R]: A pseudo-random integer between \f[B]0\f[R]
(inclusive) and \f[B]BC_RAND_MAX\f[R] (inclusive).
Using this operand will change the value of \f[B]seed\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "15." 4
\f[B]irand(E)\f[R]: A pseudo-random integer between \f[B]0\f[R]
(inclusive) and the value of \f[B]E\f[R] (exclusive).
If \f[B]E\f[R] is negative or is a non-integer (\f[B]E\f[R]\[cq]s
\f[I]scale\f[R] is not \f[B]0\f[R]), an error is raised, and bc(1)
resets (see the \f[B]RESET\f[R] section) while \f[B]seed\f[R] remains
unchanged.
If \f[B]E\f[R] is larger than \f[B]BC_RAND_MAX\f[R], the higher bound is
honored by generating several pseudo-random integers, multiplying them
by appropriate powers of \f[B]BC_RAND_MAX+1\f[R], and adding them
together.
Thus, the size of integer that can be generated with this operand is
unbounded.
Using this operand will change the value of \f[B]seed\f[R], unless the
value of \f[B]E\f[R] is \f[B]0\f[R] or \f[B]1\f[R].
In that case, \f[B]0\f[R] is returned, and \f[B]seed\f[R] is
\f[I]not\f[R] changed.
This is a \f[B]non-portable extension\f[R].
.IP "16." 4
\f[B]maxrand()\f[R]: The max integer returned by \f[B]rand()\f[R].
This is a \f[B]non-portable extension\f[R].
.PP
The integers generated by \f[B]rand()\f[R] and \f[B]irand(E)\f[R] are
guaranteed to be as unbiased as possible, subject to the limitations of
the pseudo-random number generator.
.PP
\f[B]Note\f[R]: The values returned by the pseudo-random number
generator with \f[B]rand()\f[R] and \f[B]irand(E)\f[R] are guaranteed to
\f[I]NOT\f[R] be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator.
However, they \f[I]are\f[R] guaranteed to be reproducible with identical
\f[B]seed\f[R] values.
This means that the pseudo-random values from bc(1) should only be used
where a reproducible stream of pseudo-random numbers is
\f[I]ESSENTIAL\f[R].
In any other case, use a non-seeded pseudo-random number generator.
.SS Numbers
.PP
Numbers are strings made up of digits, uppercase letters, and at most
\f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]BC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]Z\f[R] alone always equals decimal \f[B]35\f[R].
.PP
In addition, bc(1) accepts numbers in scientific notation.
These have the form \f[B]<number>e<integer>\f[R].
The exponent (the portion after the \f[B]e\f[R]) must be an integer.
An example is \f[B]1.89237e9\f[R], which is equal to
\f[B]1892370000\f[R].
Negative exponents are also allowed, so \f[B]4.2890e-3\f[R] is equal to
\f[B]0.0042890\f[R].
.PP
Using scientific notation is an error or warning if the \f[B]-s\f[R] or
\f[B]-w\f[R], respectively, command-line options (or equivalents) are
given.
.PP
\f[B]WARNING\f[R]: Both the number and the exponent in scientific
notation are interpreted according to the current \f[B]ibase\f[R], but
the number is still multiplied by \f[B]10\[ha]exponent\f[R] regardless
of the current \f[B]ibase\f[R].
For example, if \f[B]ibase\f[R] is \f[B]16\f[R] and bc(1) is given the
number string \f[B]FFeA\f[R], the resulting decimal number will be
\f[B]2550000000000\f[R], and if bc(1) is given the number string
\f[B]10e-4\f[R], the resulting decimal number will be \f[B]0.0016\f[R].
.PP
Accepting input as scientific notation is a \f[B]non-portable
extension\f[R].
.SS Operators
.PP
The following arithmetic and logical operators can be used.
They are listed in order of decreasing precedence.
Operators in the same group have the same precedence.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
Type: Prefix and Postfix
.RS
.PP
Associativity: None
.PP
Description: \f[B]increment\f[R], \f[B]decrement\f[R]
.RE
.TP
\f[B]-\f[R] \f[B]!\f[R]
Type: Prefix
.RS
.PP
Associativity: None
.PP
Description: \f[B]negation\f[R], \f[B]boolean not\f[R]
.RE
.TP
\f[B]$\f[R]
Type: Postfix
.RS
.PP
Associativity: None
.PP
Description: \f[B]truncation\f[R]
.RE
.TP
\f[B]\[at]\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]set precision\f[R]
.RE
.TP
\f[B]\[ha]\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]power\f[R]
.RE
.TP
\f[B]*\f[R] \f[B]/\f[R] \f[B]%\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]multiply\f[R], \f[B]divide\f[R], \f[B]modulus\f[R]
.RE
.TP
\f[B]+\f[R] \f[B]-\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]add\f[R], \f[B]subtract\f[R]
.RE
.TP
\f[B]<<\f[R] \f[B]>>\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]shift left\f[R], \f[B]shift right\f[R]
.RE
.TP
\f[B]=\f[R] \f[B]<<=\f[R] \f[B]>>=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R] \f[B]\[at]=\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]assignment\f[R]
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]relational\f[R]
.RE
.TP
\f[B]&&\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean and\f[R]
.RE
.TP
\f[B]||\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean or\f[R]
.RE
.PP
The operators will be described in more detail below.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
The prefix and postfix \f[B]increment\f[R] and \f[B]decrement\f[R]
operators behave exactly like they would in C.
They require a named expression (see the \f[I]Named Expressions\f[R]
subsection) as an operand.
.RS
.PP
The prefix versions of these operators are more efficient; use them
where possible.
.RE
.TP
\f[B]-\f[R]
The \f[B]negation\f[R] operator returns \f[B]0\f[R] if a user attempts
to negate any expression with the value \f[B]0\f[R].
Otherwise, a copy of the expression with its sign flipped is returned.
.TP
\f[B]!\f[R]
The \f[B]boolean not\f[R] operator returns \f[B]1\f[R] if the expression
is \f[B]0\f[R], or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]$\f[R]
The \f[B]truncation\f[R] operator returns a copy of the given expression
with all of its \f[I]scale\f[R] removed.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[at]\f[R]
The \f[B]set precision\f[R] operator takes two expressions and returns a
copy of the first with its \f[I]scale\f[R] equal to the value of the
second expression.
That could either mean that the number is returned without change (if
the \f[I]scale\f[R] of the first expression matches the value of the
second expression), extended (if it is less), or truncated (if it is
more).
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]) and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The \f[B]power\f[R] operator (not the \f[B]exclusive or\f[R] operator,
as it would be in C) takes two expressions and raises the first to the
power of the value of the second.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]), and if it
is negative, the first value must be non-zero.
.RE
.TP
\f[B]*\f[R]
The \f[B]multiply\f[R] operator takes two expressions, multiplies them,
and returns the product.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The \f[B]divide\f[R] operator takes two expressions, divides them, and
returns the quotient.
The \f[I]scale\f[R] of the result shall be the value of \f[B]scale\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]%\f[R]
The \f[B]modulus\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and evaluates them by 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R] and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]+\f[R]
The \f[B]add\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the sum, with a \f[I]scale\f[R] equal to the
max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]-\f[R]
The \f[B]subtract\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the difference, with a \f[I]scale\f[R] equal to
the max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]<<\f[R]
The \f[B]left shift\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns a copy of the value of \f[B]a\f[R] with its
decimal point moved \f[B]b\f[R] places to the right.
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]) and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]>>\f[R]
The \f[B]right shift\f[R] operator takes two expressions, \f[B]a\f[R]
and \f[B]b\f[R], and returns a copy of the value of \f[B]a\f[R] with its
decimal point moved \f[B]b\f[R] places to the left.
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]) and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]=\f[R] \f[B]<<=\f[R] \f[B]>>=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R] \f[B]\[at]=\f[R]
The \f[B]assignment\f[R] operators take two expressions, \f[B]a\f[R] and
\f[B]b\f[R] where \f[B]a\f[R] is a named expression (see the \f[I]Named
Expressions\f[R] subsection).
.RS
.PP
For \f[B]=\f[R], \f[B]b\f[R] is copied and the result is assigned to
\f[B]a\f[R].
For all others, \f[B]a\f[R] and \f[B]b\f[R] are applied as operands to
the corresponding arithmetic operator and the result is assigned to
\f[B]a\f[R].
.PP
The \f[B]assignment\f[R] operators that correspond to operators that are
extensions are themselves \f[B]non-portable extensions\f[R].
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
The \f[B]relational\f[R] operators compare two expressions, \f[B]a\f[R]
and \f[B]b\f[R], and if the relation holds, according to C language
semantics, the result is \f[B]1\f[R].
Otherwise, it is \f[B]0\f[R].
.RS
.PP
Note that unlike in C, these operators have a lower precedence than the
\f[B]assignment\f[R] operators, which means that \f[B]a=b>c\f[R] is
interpreted as \f[B](a=b)>c\f[R].
.PP
Also, unlike the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
requires, these operators can appear anywhere any other expressions can
be used.
This allowance is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]&&\f[R]
The \f[B]boolean and\f[R] operator takes two expressions and returns
\f[B]1\f[R] if both expressions are non-zero, \f[B]0\f[R] otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]||\f[R]
The \f[B]boolean or\f[R] operator takes two expressions and returns
\f[B]1\f[R] if one of the expressions is non-zero, \f[B]0\f[R]
otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Statements
.PP
The following items are statements:
.IP " 1." 4
\f[B]E\f[R]
.IP " 2." 4
\f[B]{\f[R] \f[B]S\f[R] \f[B];\f[R] \&... \f[B];\f[R] \f[B]S\f[R]
\f[B]}\f[R]
.IP " 3." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 4." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
\f[B]else\f[R] \f[B]S\f[R]
.IP " 5." 4
\f[B]while\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 6." 4
\f[B]for\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B];\f[R] \f[B]E\f[R]
\f[B];\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 7." 4
An empty statement
.IP " 8." 4
\f[B]break\f[R]
.IP " 9." 4
\f[B]continue\f[R]
.IP "10." 4
\f[B]quit\f[R]
.IP "11." 4
\f[B]halt\f[R]
.IP "12." 4
\f[B]limits\f[R]
.IP "13." 4
A string of characters, enclosed in double quotes
.IP "14." 4
\f[B]print\f[R] \f[B]E\f[R] \f[B],\f[R] \&... \f[B],\f[R] \f[B]E\f[R]
.IP "15." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a \f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.PP
Numbers 4, 9, 11, 12, 14, and 15 are \f[B]non-portable extensions\f[R].
.PP
Also, as a \f[B]non-portable extension\f[R], any or all of the
expressions in the header of a for loop may be omitted.
If the condition (second expression) is omitted, it is assumed to be a
constant \f[B]1\f[R].
.PP
The \f[B]break\f[R] statement causes a loop to stop iterating and resume
execution immediately following a loop.
This is only allowed in loops.
.PP
The \f[B]continue\f[R] statement causes a loop iteration to stop early
and returns to the start of the loop, including testing the loop
condition.
This is only allowed in loops.
.PP
The \f[B]if\f[R] \f[B]else\f[R] statement does the same thing as in C.
.PP
The \f[B]quit\f[R] statement causes bc(1) to quit, even if it is on a
branch that will not be executed (it is a compile-time command).
.PP
The \f[B]halt\f[R] statement causes bc(1) to quit, if it is executed.
(Unlike \f[B]quit\f[R] if it is on a branch of an \f[B]if\f[R] statement
that is not executed, bc(1) does not quit.)
.PP
The \f[B]limits\f[R] statement prints the limits that this bc(1) is
subject to.
This is like the \f[B]quit\f[R] statement in that it is a compile-time
command.
.PP
An expression by itself is evaluated and printed, followed by a newline.
.PP
Both scientific notation and engineering notation are available for
printing the results of expressions.
Scientific notation is activated by assigning \f[B]0\f[R] to
\f[B]obase\f[R], and engineering notation is activated by assigning
\f[B]1\f[R] to \f[B]obase\f[R].
To deactivate them, just assign a different value to \f[B]obase\f[R].
.PP
Scientific notation and engineering notation are disabled if bc(1) is
run with either the \f[B]-s\f[R] or \f[B]-w\f[R] command-line options
(or equivalents).
.PP
Printing numbers in scientific notation and/or engineering notation is a
\f[B]non-portable extension\f[R].
.SS Print Statement
.PP
The \[lq]expressions\[rq] in a \f[B]print\f[R] statement may also be
strings.
If they are, there are backslash escape sequences that are interpreted
specially.
What those sequences are, and what they cause to be printed, are shown
below:
.PP
.TS
tab(@);
l l.
T{
\f[B]\[rs]a\f[R]
T}@T{
\f[B]\[rs]a\f[R]
T}
T{
\f[B]\[rs]b\f[R]
T}@T{
\f[B]\[rs]b\f[R]
T}
T{
\f[B]\[rs]\[rs]\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]e\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]f\f[R]
T}@T{
\f[B]\[rs]f\f[R]
T}
T{
\f[B]\[rs]n\f[R]
T}@T{
\f[B]\[rs]n\f[R]
T}
T{
\f[B]\[rs]q\f[R]
T}@T{
\f[B]\[dq]\f[R]
T}
T{
\f[B]\[rs]r\f[R]
T}@T{
\f[B]\[rs]r\f[R]
T}
T{
\f[B]\[rs]t\f[R]
T}@T{
\f[B]\[rs]t\f[R]
T}
.TE
.PP
Any other character following a backslash causes the backslash and
character to be printed as-is.
.PP
Any non-string expression in a print statement shall be assigned to
\f[B]last\f[R], like any other expression that is printed.
.SS Order of Evaluation
.PP
All expressions in a statment are evaluated left to right, except as
necessary to maintain order of operations.
This means, for example, assuming that \f[B]i\f[R] is equal to
\f[B]0\f[R], in the expression
.IP
.nf
\f[C]
a[i++] = i++
\f[R]
.fi
.PP
the first (or 0th) element of \f[B]a\f[R] is set to \f[B]1\f[R], and
\f[B]i\f[R] is equal to \f[B]2\f[R] at the end of the expression.
.PP
This includes function arguments.
Thus, assuming \f[B]i\f[R] is equal to \f[B]0\f[R], this means that in
the expression
.IP
.nf
\f[C]
x(i++, i++)
\f[R]
.fi
.PP
the first argument passed to \f[B]x()\f[R] is \f[B]0\f[R], and the
second argument is \f[B]1\f[R], while \f[B]i\f[R] is equal to
\f[B]2\f[R] before the function starts executing.
.SH FUNCTIONS
.PP
Function definitions are as follows:
.IP
.nf
\f[C]
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
\f[R]
.fi
.PP
Any \f[B]I\f[R] in the parameter list or \f[B]auto\f[R] list may be
replaced with \f[B]I[]\f[R] to make a parameter or \f[B]auto\f[R] var an
array, and any \f[B]I\f[R] in the parameter list may be replaced with
\f[B]*I[]\f[R] to make a parameter an array reference.
Callers of functions that take array references should not put an
asterisk in the call; they must be called with just \f[B]I[]\f[R] like
normal array parameters and will be automatically converted into
references.
.PP
As a \f[B]non-portable extension\f[R], the opening brace of a
\f[B]define\f[R] statement may appear on the next line.
.PP
As a \f[B]non-portable extension\f[R], the return statement may also be
in one of the following forms:
.IP "1." 3
\f[B]return\f[R]
.IP "2." 3
\f[B]return\f[R] \f[B](\f[R] \f[B])\f[R]
.IP "3." 3
\f[B]return\f[R] \f[B]E\f[R]
.PP
The first two, or not specifying a \f[B]return\f[R] statement, is
equivalent to \f[B]return (0)\f[R], unless the function is a
\f[B]void\f[R] function (see the \f[I]Void Functions\f[R] subsection
below).
.SS Void Functions
.PP
Functions can also be \f[B]void\f[R] functions, defined as follows:
.IP
.nf
\f[C]
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
\f[R]
.fi
.PP
They can only be used as standalone expressions, where such an
expression would be printed alone, except in a print statement.
.PP
Void functions can only use the first two \f[B]return\f[R] statements
listed above.
They can also omit the return statement entirely.
.PP
The word \[lq]void\[rq] is not treated as a keyword; it is still
possible to have variables, arrays, and functions named \f[B]void\f[R].
The word \[lq]void\[rq] is only treated specially right after the
\f[B]define\f[R] keyword.
.PP
This is a \f[B]non-portable extension\f[R].
.SS Array References
.PP
For any array in the parameter list, if the array is declared in the
form
.IP
.nf
\f[C]
*I[]
\f[R]
.fi
.PP
it is a \f[B]reference\f[R].
Any changes to the array in the function are reflected, when the
function returns, to the array that was passed in.
.PP
Other than this, all function arguments are passed by value.
.PP
This is a \f[B]non-portable extension\f[R].
.SH LIBRARY
.PP
All of the functions below, including the functions in the extended math
library (see the \f[I]Extended Library\f[R] subsection below), are
available when the \f[B]-l\f[R] or \f[B]\[en]mathlib\f[R] command-line
flags are given, except that the extended math library is not available
when the \f[B]-s\f[R] option, the \f[B]-w\f[R] option, or equivalents
are given.
.SS Standard Library
.PP
The
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
defines the following functions for the math library:
.TP
\f[B]s(x)\f[R]
Returns the sine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]c(x)\f[R]
Returns the cosine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]a(x)\f[R]
Returns the arctangent of \f[B]x\f[R], in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]l(x)\f[R]
Returns the natural logarithm of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]e(x)\f[R]
Returns the mathematical constant \f[B]e\f[R] raised to the power of
\f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]j(x, n)\f[R]
Returns the bessel integer order \f[B]n\f[R] (truncated) of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.SS Extended Library
.PP
The extended library is \f[I]not\f[R] loaded when the
\f[B]-s\f[R]/\f[B]\[en]standard\f[R] or \f[B]-w\f[R]/\f[B]\[en]warn\f[R]
options are given since they are not part of the library defined by the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).
.PP
The extended library is a \f[B]non-portable extension\f[R].
.TP
\f[B]p(x, y)\f[R]
Calculates \f[B]x\f[R] to the power of \f[B]y\f[R], even if \f[B]y\f[R]
is not an integer, and returns the result to the current
\f[B]scale\f[R].
.RS
.PP
It is an error if \f[B]y\f[R] is negative and \f[B]x\f[R] is
\f[B]0\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]r(x, p)\f[R]
Returns \f[B]x\f[R] rounded to \f[B]p\f[R] decimal places according to
the rounding mode round half away from
\f[B]0\f[R] (https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero).
.TP
\f[B]ceil(x, p)\f[R]
Returns \f[B]x\f[R] rounded to \f[B]p\f[R] decimal places according to
the rounding mode round away from
\f[B]0\f[R] (https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero).
.TP
\f[B]f(x)\f[R]
Returns the factorial of the truncated absolute value of \f[B]x\f[R].
.TP
\f[B]perm(n, k)\f[R]
Returns the permutation of the truncated absolute value of \f[B]n\f[R]
of the truncated absolute value of \f[B]k\f[R], if \f[B]k <= n\f[R].
If not, it returns \f[B]0\f[R].
.TP
\f[B]comb(n, k)\f[R]
Returns the combination of the truncated absolute value of \f[B]n\f[R]
of the truncated absolute value of \f[B]k\f[R], if \f[B]k <= n\f[R].
If not, it returns \f[B]0\f[R].
.TP
\f[B]l2(x)\f[R]
Returns the logarithm base \f[B]2\f[R] of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]l10(x)\f[R]
Returns the logarithm base \f[B]10\f[R] of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]log(x, b)\f[R]
Returns the logarithm base \f[B]b\f[R] of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]cbrt(x)\f[R]
Returns the cube root of \f[B]x\f[R].
.TP
\f[B]root(x, n)\f[R]
Calculates the truncated value of \f[B]n\f[R], \f[B]r\f[R], and returns
the \f[B]r\f[R]th root of \f[B]x\f[R] to the current \f[B]scale\f[R].
.RS
.PP
If \f[B]r\f[R] is \f[B]0\f[R] or negative, this raises an error and
causes bc(1) to reset (see the \f[B]RESET\f[R] section).
It also raises an error and causes bc(1) to reset if \f[B]r\f[R] is even
and \f[B]x\f[R] is negative.
.RE
.TP
\f[B]pi(p)\f[R]
Returns \f[B]pi\f[R] to \f[B]p\f[R] decimal places.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]t(x)\f[R]
Returns the tangent of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]a2(y, x)\f[R]
Returns the arctangent of \f[B]y/x\f[R], in radians.
If both \f[B]y\f[R] and \f[B]x\f[R] are equal to \f[B]0\f[R], it raises
an error and causes bc(1) to reset (see the \f[B]RESET\f[R] section).
Otherwise, if \f[B]x\f[R] is greater than \f[B]0\f[R], it returns
\f[B]a(y/x)\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is greater than
or equal to \f[B]0\f[R], it returns \f[B]a(y/x)+pi\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]a(y/x)-pi\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is greater than
\f[B]0\f[R], it returns \f[B]pi/2\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]-pi/2\f[R].
.RS
.PP
This function is the same as the \f[B]atan2()\f[R] function in many
programming languages.
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]sin(x)\f[R]
Returns the sine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is an alias of \f[B]s(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]cos(x)\f[R]
Returns the cosine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is an alias of \f[B]c(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]tan(x)\f[R]
Returns the tangent of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
If \f[B]x\f[R] is equal to \f[B]1\f[R] or \f[B]-1\f[R], this raises an
error and causes bc(1) to reset (see the \f[B]RESET\f[R] section).
.PP
This is an alias of \f[B]t(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]atan(x)\f[R]
Returns the arctangent of \f[B]x\f[R], in radians.
.RS
.PP
This is an alias of \f[B]a(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]atan2(y, x)\f[R]
Returns the arctangent of \f[B]y/x\f[R], in radians.
If both \f[B]y\f[R] and \f[B]x\f[R] are equal to \f[B]0\f[R], it raises
an error and causes bc(1) to reset (see the \f[B]RESET\f[R] section).
Otherwise, if \f[B]x\f[R] is greater than \f[B]0\f[R], it returns
\f[B]a(y/x)\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is greater than
or equal to \f[B]0\f[R], it returns \f[B]a(y/x)+pi\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]a(y/x)-pi\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is greater than
\f[B]0\f[R], it returns \f[B]pi/2\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]-pi/2\f[R].
.RS
.PP
This function is the same as the \f[B]atan2()\f[R] function in many
programming languages.
.PP
This is an alias of \f[B]a2(y, x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]r2d(x)\f[R]
Converts \f[B]x\f[R] from radians to degrees and returns the result.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]d2r(x)\f[R]
Converts \f[B]x\f[R] from degrees to radians and returns the result.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]frand(p)\f[R]
Generates a pseudo-random number between \f[B]0\f[R] (inclusive) and
\f[B]1\f[R] (exclusive) with the number of decimal digits after the
decimal point equal to the truncated absolute value of \f[B]p\f[R].
If \f[B]p\f[R] is not \f[B]0\f[R], then calling this function will
change the value of \f[B]seed\f[R].
If \f[B]p\f[R] is \f[B]0\f[R], then \f[B]0\f[R] is returned, and
\f[B]seed\f[R] is \f[I]not\f[R] changed.
.TP
\f[B]ifrand(i, p)\f[R]
Generates a pseudo-random number that is between \f[B]0\f[R] (inclusive)
and the truncated absolute value of \f[B]i\f[R] (exclusive) with the
number of decimal digits after the decimal point equal to the truncated
absolute value of \f[B]p\f[R].
If the absolute value of \f[B]i\f[R] is greater than or equal to
\f[B]2\f[R], and \f[B]p\f[R] is not \f[B]0\f[R], then calling this
function will change the value of \f[B]seed\f[R]; otherwise, \f[B]0\f[R]
is returned and \f[B]seed\f[R] is not changed.
.TP
\f[B]srand(x)\f[R]
Returns \f[B]x\f[R] with its sign flipped with probability
\f[B]0.5\f[R].
In other words, it randomizes the sign of \f[B]x\f[R].
.TP
\f[B]brand()\f[R]
Returns a random boolean value (either \f[B]0\f[R] or \f[B]1\f[R]).
.TP
\f[B]ubytes(x)\f[R]
Returns the numbers of unsigned integer bytes required to hold the
truncated absolute value of \f[B]x\f[R].
.TP
\f[B]sbytes(x)\f[R]
Returns the numbers of signed, two\[cq]s-complement integer bytes
required to hold the truncated value of \f[B]x\f[R].
.TP
\f[B]hex(x)\f[R]
Outputs the hexadecimal (base \f[B]16\f[R]) representation of
\f[B]x\f[R].
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]binary(x)\f[R]
Outputs the binary (base \f[B]2\f[R]) representation of \f[B]x\f[R].
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]output(x, b)\f[R]
Outputs the base \f[B]b\f[R] representation of \f[B]x\f[R].
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in as few power of two bytes as possible.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or is negative, an error message is
printed instead, but bc(1) is not reset (see the \f[B]RESET\f[R]
section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in as few power of two bytes as
possible.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, an error message is printed instead,
but bc(1) is not reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uintn(x, n)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]n\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]n\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]intn(x, n)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]n\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]n\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint8(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]1\f[R] byte.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]1\f[R] byte, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int8(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]1\f[R] byte.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]1\f[R] byte, an
error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint16(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]2\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]2\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int16(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]2\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]2\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint32(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]4\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]4\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int32(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]4\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]4\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint64(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]8\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]8\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int64(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]8\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]8\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]hex_uint(x, n)\f[R]
Outputs the representation of the truncated absolute value of
\f[B]x\f[R] as an unsigned integer in hexadecimal using \f[B]n\f[R]
bytes.
Not all of the value will be output if \f[B]n\f[R] is too small.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]binary_uint(x, n)\f[R]
Outputs the representation of the truncated absolute value of
\f[B]x\f[R] as an unsigned integer in binary using \f[B]n\f[R] bytes.
Not all of the value will be output if \f[B]n\f[R] is too small.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]output_uint(x, n)\f[R]
Outputs the representation of the truncated absolute value of
\f[B]x\f[R] as an unsigned integer in the current \f[B]obase\f[R] (see
the \f[B]SYNTAX\f[R] section) using \f[B]n\f[R] bytes.
Not all of the value will be output if \f[B]n\f[R] is too small.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]output_byte(x, i)\f[R]
Outputs byte \f[B]i\f[R] of the truncated absolute value of \f[B]x\f[R],
where \f[B]0\f[R] is the least significant byte and \f[B]number_of_bytes
- 1\f[R] is the most significant byte.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.SS Transcendental Functions
.PP
All transcendental functions can return slightly inaccurate results (up
to 1 ULP (https://en.wikipedia.org/wiki/Unit_in_the_last_place)).
This is unavoidable, and this
article (https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT) explains
why it is impossible and unnecessary to calculate exact results for the
transcendental functions.
.PP
Because of the possible inaccuracy, I recommend that users call those
functions with the precision (\f[B]scale\f[R]) set to at least 1 higher
than is necessary.
If exact results are \f[I]absolutely\f[R] required, users can double the
precision (\f[B]scale\f[R]) and then truncate.
.PP
The transcendental functions in the standard math library are:
.IP \[bu] 2
\f[B]s(x)\f[R]
.IP \[bu] 2
\f[B]c(x)\f[R]
.IP \[bu] 2
\f[B]a(x)\f[R]
.IP \[bu] 2
\f[B]l(x)\f[R]
.IP \[bu] 2
\f[B]e(x)\f[R]
.IP \[bu] 2
\f[B]j(x, n)\f[R]
.PP
The transcendental functions in the extended math library are:
.IP \[bu] 2
\f[B]l2(x)\f[R]
.IP \[bu] 2
\f[B]l10(x)\f[R]
.IP \[bu] 2
\f[B]log(x, b)\f[R]
.IP \[bu] 2
\f[B]pi(p)\f[R]
.IP \[bu] 2
\f[B]t(x)\f[R]
.IP \[bu] 2
\f[B]a2(y, x)\f[R]
.IP \[bu] 2
\f[B]sin(x)\f[R]
.IP \[bu] 2
\f[B]cos(x)\f[R]
.IP \[bu] 2
\f[B]tan(x)\f[R]
.IP \[bu] 2
\f[B]atan(x)\f[R]
.IP \[bu] 2
\f[B]atan2(y, x)\f[R]
.IP \[bu] 2
\f[B]r2d(x)\f[R]
.IP \[bu] 2
\f[B]d2r(x)\f[R]
.SH RESET
.PP
When bc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any functions that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all functions returned) is skipped.
.PP
Thus, when bc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.PP
Note that this reset behavior is different from the GNU bc(1), which
attempts to start executing the statement right after the one that
caused an error.
.SH PERFORMANCE
.PP
Most bc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This bc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]BC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]BC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]BC_BASE_DIGS\f[R].
.PP
The actual values of \f[B]BC_LONG_BIT\f[R] and \f[B]BC_BASE_DIGS\f[R]
can be queried with the \f[B]limits\f[R] statement.
.PP
In addition, this bc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]BC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on bc(1):
.TP
\f[B]BC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
bc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]BC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]BC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]BC_BASE_DIGS\f[R].
.TP
\f[B]BC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]BC_BASE_POW\f[R].
.TP
\f[B]BC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]BC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_RAND_MAX\f[R]
The maximum integer (inclusive) returned by the \f[B]rand()\f[R]
operand.
Set at \f[B]2\[ha]BC_LONG_BIT-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]BC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
The actual values can be queried with the \f[B]limits\f[R] statement.
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
bc(1) recognizes the following environment variables:
.TP
\f[B]POSIXLY_CORRECT\f[R]
If this variable exists (no matter the contents), bc(1) behaves as if
the \f[B]-s\f[R] option was given.
.TP
\f[B]BC_ENV_ARGS\f[R]
This is another way to give command-line arguments to bc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]BC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
.RS
.PP
The code that parses \f[B]BC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some bc file.bc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]bc\[dq] file.bc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]BC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]BC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), bc(1) will output lines to that length,
including the backslash (\f[B]\[rs]\f[R]).
The default line length is \f[B]70\f[R].
.SH EXIT STATUS
.PP
bc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, using a negative number as a bound for the
pseudo-random number generator, attempting to convert a negative number
to a hardware integer, overflow when converting a number to a hardware
integer, and attempting to use a non-integer where an integer is
required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]), places (\f[B]\[at]\f[R]), left shift
(\f[B]<<\f[R]), and right shift (\f[B]>>\f[R]) operators and their
corresponding assignment operators.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, using a token
where it is invalid, giving an invalid expression, giving an invalid
print statement, giving an invalid function definition, attempting to
assign to an expression that is not a named expression (see the
\f[I]Named Expressions\f[R] subsection of the \f[B]SYNTAX\f[R] section),
giving an invalid \f[B]auto\f[R] list, having a duplicate
\f[B]auto\f[R]/function parameter, failing to find the end of a code
block, attempting to return a value from a \f[B]void\f[R] function,
attempting to use a variable as a reference, and using any extensions
when the option \f[B]-s\f[R] or any equivalents were given.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a \f[B]void\f[R] function call as a value in an
expression.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (bc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, bc(1)
always exits and returns \f[B]4\f[R], no matter what mode bc(1) is in.
.PP
The other statuses will only be returned when bc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
bc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Per the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, bc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, bc(1) turns on \[lq]TTY mode.\[rq]
.PP
TTY mode is required for history to be enabled (see the \f[B]COMMAND
LINE HISTORY\f[R] section).
It is also required to enable special handling for \f[B]SIGINT\f[R]
signals.
.PP
The prompt is enabled in TTY mode.
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause bc(1) to stop execution of the
current input.
If bc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If bc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If bc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to bc(1) as it is
executing a file, it can seem as though bc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause bc(1) to clean up and
exit, and it uses the default handler for all other signals.
The one exception is \f[B]SIGHUP\f[R]; in that case, when bc(1) is in
TTY mode, a \f[B]SIGHUP\f[R] will cause bc(1) to clean up and exit.
.SH COMMAND LINE HISTORY
.PP
bc(1) supports interactive command-line editing.
If bc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), history is
enabled.
Previous lines can be recalled and edited with the arrow keys.
.PP
\f[B]Note\f[R]: tabs are converted to 8 spaces.
.SH SEE ALSO
.PP
dc(1)
.SH STANDARDS
.PP
bc(1) is compliant with the IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
The flags \f[B]-efghiqsvVw\f[R], all long options, and the extensions
noted above are extensions to that specification.
.PP
Note that the specification explicitly says that bc(1) only accepts
numbers that use a period (\f[B].\f[R]) as a radix point, regardless of
the value of \f[B]LC_NUMERIC\f[R].
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHORS
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/bc/N.1.md b/contrib/bc/manuals/bc/N.1.md
index 7d7d008fc31c..0a34edb66f2a 100644
--- a/contrib/bc/manuals/bc/N.1.md
+++ b/contrib/bc/manuals/bc/N.1.md
@@ -1,1688 +1,1697 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# NAME
bc - arbitrary-precision decimal arithmetic language and calculator
# SYNOPSIS
**bc** [**-ghilPqsvVw**] [**--global-stacks**] [**--help**] [**--interactive**] [**--mathlib**] [**--no-prompt**] [**--quiet**] [**--standard**] [**--warn**] [**--version**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...]
[*file*...]
# DESCRIPTION
bc(1) is an interactive processor for a language first standardized in 1991 by
POSIX. (The current standard is [here][1].) The language provides unlimited
precision decimal arithmetic and is somewhat C-like, but there are differences.
Such differences will be noted in this document.
After parsing and handling options, this bc(1) reads any files given on the
command line and executes them before reading from **stdin**.
This bc(1) is a drop-in replacement for *any* bc(1), including (and
especially) the GNU bc(1). It also has many extensions and extra features beyond
other implementations.
# OPTIONS
The following are the options that bc(1) accepts.
**-g**, **--global-stacks**
: Turns the globals **ibase**, **obase**, **scale**, and **seed** into stacks.
This has the effect that a copy of the current value of all four are pushed
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
(**Note**: the function **output(x,b)** exists in the extended math library.
See the **LIBRARY** section.)
However, since using this flag means that functions cannot set **ibase**,
**obase**, **scale**, or **seed** globally, functions that are made to do so
cannot work anymore. There are two possible use cases for that, and each has
a solution.
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o="bc -e ibase=A -e obase=8"
alias h2b="bc -e ibase=G -e obase=2"
Second, if the purpose of a function is to set **ibase**, **obase**,
**scale**, or **seed** globally for any other purpose, it could be split
into one to four functions (based on how many globals it sets) and each of
those functions could return the desired value for a global.
For functions that set **seed**, the value assigned to **seed** is not
propagated to parent functions. This means that the sequence of
pseudo-random numbers that they see will not be the same sequence of
pseudo-random numbers that any parent sees. This is only the case once
**seed** has been set.
If a function desires to not affect the sequence of pseudo-random numbers
of its parents, but wants to use the same **seed**, it can use the following
line:
seed = seed
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
**-h**, **--help**
: Prints a usage message and quits.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-l**, **--mathlib**
: Sets **scale** (see the **SYNTAX** section) to **20** and loads the included
math library and the extended math library before running any code,
including any expressions or files specified on the command line.
To learn what is in the libraries, see the **LIBRARY** section.
**-P**, **--no-prompt**
: Disables the prompt in TTY mode. (The prompt is only enabled in TTY mode.
See the **TTY MODE** section) This is mostly for those users that do not
want a prompt or are not used to having them in bc(1). Most of those users
would want to put this option in **BC_ENV_ARGS** (see the
**ENVIRONMENT VARIABLES** section).
This is a **non-portable extension**.
**-q**, **--quiet**
: This option is for compatibility with the [GNU bc(1)][2]; it is a no-op.
Without this option, GNU bc(1) prints a copyright header. This bc(1) only
prints the copyright header if one or more of the **-v**, **-V**, or
**--version** options are given.
This is a **non-portable extension**.
**-s**, **--standard**
: Process exactly the language defined by the [standard][1] and error if any
extensions are used.
This is a **non-portable extension**.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
This is a **non-portable extension**.
**-w**, **--warn**
: Like **-s** and **--standard**, except that warnings (and not errors) are
printed for non-standard extensions and execution continues normally.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **BC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **bc <file> >&-**, it will quit with an error. This
is done so that bc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **bc <file> 2>&-**, it will quit with an error. This
is done so that bc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
The syntax for bc(1) programs is mostly C-like, with some differences. This
bc(1) follows the [POSIX standard][1], which is a much more thorough resource
for the language this bc(1) accepts. This section is meant to be a summary and a
listing of all the extensions to the standard.
In the sections below, **E** means expression, **S** means statement, and **I**
means identifier.
Identifiers (**I**) start with a lowercase letter and can be followed by any
number (up to **BC_NAME_MAX-1**) of lowercase letters (**a-z**), digits
(**0-9**), and underscores (**\_**). The regex is **\[a-z\]\[a-z0-9\_\]\***.
Identifiers with more than one character (letter) are a
**non-portable extension**.
**ibase** is a global variable determining how to interpret constant numbers. It
is the "input" base, or the number base used for interpreting input numbers.
**ibase** is initially **10**. If the **-s** (**--standard**) and **-w**
(**--warn**) flags were not given on the command line, the max allowable value
for **ibase** is **36**. Otherwise, it is **16**. The min allowable value for
**ibase** is **2**. The max allowable value for **ibase** can be queried in
bc(1) programs with the **maxibase()** built-in function.
**obase** is a global variable determining how to output results. It is the
"output" base, or the number base used for outputting numbers. **obase** is
initially **10**. The max allowable value for **obase** is **BC_BASE_MAX** and
can be queried in bc(1) programs with the **maxobase()** built-in function. The
min allowable value for **obase** is **0**. If **obase** is **0**, values are
output in scientific notation, and if **obase** is **1**, values are output in
engineering notation. Otherwise, values are output in the specified base.
Outputting in scientific and engineering notations are **non-portable
extensions**.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a global variable that
sets the precision of any operations, with exceptions. **scale** is initially
**0**. **scale** cannot be negative. The max allowable value for **scale** is
**BC_SCALE_MAX** and can be queried in bc(1) programs with the **maxscale()**
built-in function.
bc(1) has both *global* variables and *local* variables. All *local*
variables are local to the function; they are parameters or are introduced in
the **auto** list of a function (see the **FUNCTIONS** section). If a variable
is accessed which is not a parameter or in the **auto** list, it is assumed to
be *global*. If a parent function has a *local* variable version of a variable
that a child function considers *global*, the value of that *global* variable in
the child function is the value of the variable in the parent function, not the
value of the actual *global* variable.
All of the above applies to arrays as well.
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence operator is an
assignment operator *and* the expression is notsurrounded by parentheses.
The value that is printed is also assigned to the special variable **last**. A
single dot (**.**) may also be used as a synonym for **last**. These are
**non-portable extensions**.
Either semicolons or newlines may separate statements.
## Comments
There are two kinds of comments:
1. Block comments are enclosed in **/\*** and **\*/**.
2. Line comments go from **#** until, and not including, the next newline. This
is a **non-portable extension**.
## Named Expressions
The following are named expressions in bc(1):
1. Variables: **I**
2. Array Elements: **I[E]**
3. **ibase**
4. **obase**
5. **scale**
6. **seed**
7. **last** or a single dot (**.**)
Numbers 6 and 7 are **non-portable extensions**.
The meaning of **seed** is dependent on the current pseudo-random number
generator but is guaranteed to not change except for new major versions.
The *scale* and sign of the value may be significant.
If a previously used **seed** value is assigned to **seed** and used again, the
pseudo-random number generator is guaranteed to produce the same sequence of
pseudo-random numbers as it did when the **seed** value was previously used.
The exact value assigned to **seed** is not guaranteed to be returned if
**seed** is queried again immediately. However, if **seed** *does* return a
different value, both values, when assigned to **seed**, are guaranteed to
produce the same sequence of pseudo-random numbers. This means that certain
values assigned to **seed** will *not* produce unique sequences of pseudo-random
numbers. The value of **seed** will change after any use of the **rand()** and
**irand(E)** operands (see the *Operands* subsection below), except if the
parameter passed to **irand(E)** is **0**, **1**, or negative.
There is no limit to the length (number of significant decimal digits) or
*scale* of the value that can be assigned to **seed**.
Variables and arrays do not interfere; users can have arrays named the same as
variables. This also applies to functions (see the **FUNCTIONS** section), so a
user can have a variable, array, and function that all have the same name, and
they will not shadow each other, whether inside of functions or not.
Named expressions are required as the operand of **increment**/**decrement**
operators and as the left side of **assignment** operators (see the *Operators*
subsection).
## Operands
The following are valid operands in bc(1):
1. Numbers (see the *Numbers* subsection below).
2. Array indices (**I[E]**).
3. **(E)**: The value of **E** (used to change precedence).
4. **sqrt(E)**: The square root of **E**. **E** must be non-negative.
5. **length(E)**: The number of significant decimal digits in **E**.
6. **length(I[])**: The number of elements in the array **I**. This is a
**non-portable extension**.
7. **scale(E)**: The *scale* of **E**.
8. **abs(E)**: The absolute value of **E**. This is a **non-portable
extension**.
9. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a non-**void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
10. **read()**: Reads a line from **stdin** and uses that as an expression. The
result of that expression is the result of the **read()** operand. This is a
**non-portable extension**.
11. **maxibase()**: The max allowable **ibase**. This is a **non-portable
extension**.
12. **maxobase()**: The max allowable **obase**. This is a **non-portable
extension**.
13. **maxscale()**: The max allowable **scale**. This is a **non-portable
extension**.
14. **rand()**: A pseudo-random integer between **0** (inclusive) and
**BC_RAND_MAX** (inclusive). Using this operand will change the value of
**seed**. This is a **non-portable extension**.
15. **irand(E)**: A pseudo-random integer between **0** (inclusive) and the
value of **E** (exclusive). If **E** is negative or is a non-integer
(**E**'s *scale* is not **0**), an error is raised, and bc(1) resets (see
the **RESET** section) while **seed** remains unchanged. If **E** is larger
than **BC_RAND_MAX**, the higher bound is honored by generating several
pseudo-random integers, multiplying them by appropriate powers of
**BC_RAND_MAX+1**, and adding them together. Thus, the size of integer that
can be generated with this operand is unbounded. Using this operand will
change the value of **seed**, unless the value of **E** is **0** or **1**.
In that case, **0** is returned, and **seed** is *not* changed. This is a
**non-portable extension**.
16. **maxrand()**: The max integer returned by **rand()**. This is a
**non-portable extension**.
The integers generated by **rand()** and **irand(E)** are guaranteed to be as
unbiased as possible, subject to the limitations of the pseudo-random number
generator.
**Note**: The values returned by the pseudo-random number generator with
**rand()** and **irand(E)** are guaranteed to *NOT* be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator. However,
they *are* guaranteed to be reproducible with identical **seed** values. This
means that the pseudo-random values from bc(1) should only be used where a
reproducible stream of pseudo-random numbers is *ESSENTIAL*. In any other case,
use a non-seeded pseudo-random number generator.
## Numbers
Numbers are strings made up of digits, uppercase letters, and at most **1**
period for a radix. Numbers can have up to **BC_NUM_MAX** digits. Uppercase
letters are equal to **9** + their position in the alphabet (i.e., **A** equals
**10**, or **9+1**). If a digit or letter makes no sense with the current value
of **ibase**, they are set to the value of the highest valid digit in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **Z** alone always equals decimal
**35**.
In addition, bc(1) accepts numbers in scientific notation. These have the form
**\<number\>e\<integer\>**. The exponent (the portion after the **e**) must be
an integer. An example is **1.89237e9**, which is equal to **1892370000**.
Negative exponents are also allowed, so **4.2890e-3** is equal to **0.0042890**.
Using scientific notation is an error or warning if the **-s** or **-w**,
respectively, command-line options (or equivalents) are given.
**WARNING**: Both the number and the exponent in scientific notation are
interpreted according to the current **ibase**, but the number is still
multiplied by **10\^exponent** regardless of the current **ibase**. For example,
if **ibase** is **16** and bc(1) is given the number string **FFeA**, the
resulting decimal number will be **2550000000000**, and if bc(1) is given the
number string **10e-4**, the resulting decimal number will be **0.0016**.
Accepting input as scientific notation is a **non-portable extension**.
## Operators
The following arithmetic and logical operators can be used. They are listed in
order of decreasing precedence. Operators in the same group have the same
precedence.
**++** **--**
: Type: Prefix and Postfix
Associativity: None
Description: **increment**, **decrement**
**-** **!**
: Type: Prefix
Associativity: None
Description: **negation**, **boolean not**
**\$**
: Type: Postfix
Associativity: None
Description: **truncation**
**\@**
: Type: Binary
Associativity: Right
Description: **set precision**
**\^**
: Type: Binary
Associativity: Right
Description: **power**
**\*** **/** **%**
: Type: Binary
Associativity: Left
Description: **multiply**, **divide**, **modulus**
**+** **-**
: Type: Binary
Associativity: Left
Description: **add**, **subtract**
**\<\<** **\>\>**
: Type: Binary
Associativity: Left
Description: **shift left**, **shift right**
**=** **\<\<=** **\>\>=** **+=** **-=** **\*=** **/=** **%=** **\^=** **\@=**
: Type: Binary
Associativity: Right
Description: **assignment**
**==** **\<=** **\>=** **!=** **\<** **\>**
: Type: Binary
Associativity: Left
Description: **relational**
**&&**
: Type: Binary
Associativity: Left
Description: **boolean and**
**||**
: Type: Binary
Associativity: Left
Description: **boolean or**
The operators will be described in more detail below.
**++** **--**
: The prefix and postfix **increment** and **decrement** operators behave
exactly like they would in C. They require a named expression (see the
*Named Expressions* subsection) as an operand.
The prefix versions of these operators are more efficient; use them where
possible.
**-**
: The **negation** operator returns **0** if a user attempts to negate any
expression with the value **0**. Otherwise, a copy of the expression with
its sign flipped is returned.
**!**
: The **boolean not** operator returns **1** if the expression is **0**, or
**0** otherwise.
This is a **non-portable extension**.
**\$**
: The **truncation** operator returns a copy of the given expression with all
of its *scale* removed.
This is a **non-portable extension**.
**\@**
: The **set precision** operator takes two expressions and returns a copy of
the first with its *scale* equal to the value of the second expression. That
could either mean that the number is returned without change (if the
*scale* of the first expression matches the value of the second
expression), extended (if it is less), or truncated (if it is more).
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**\^**
: The **power** operator (not the **exclusive or** operator, as it would be in
C) takes two expressions and raises the first to the power of the value of
the second. The *scale* of the result is equal to **scale**.
The second expression must be an integer (no *scale*), and if it is
negative, the first value must be non-zero.
**\***
: The **multiply** operator takes two expressions, multiplies them, and
returns the product. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result is
equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The **divide** operator takes two expressions, divides them, and returns the
quotient. The *scale* of the result shall be the value of **scale**.
The second expression must be non-zero.
**%**
: The **modulus** operator takes two expressions, **a** and **b**, and
evaluates them by 1) Computing **a/b** to current **scale** and 2) Using the
result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The second expression must be non-zero.
**+**
: The **add** operator takes two expressions, **a** and **b**, and returns the
sum, with a *scale* equal to the max of the *scale*s of **a** and **b**.
**-**
: The **subtract** operator takes two expressions, **a** and **b**, and
returns the difference, with a *scale* equal to the max of the *scale*s of
**a** and **b**.
**\<\<**
: The **left shift** operator takes two expressions, **a** and **b**, and
returns a copy of the value of **a** with its decimal point moved **b**
places to the right.
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**\>\>**
: The **right shift** operator takes two expressions, **a** and **b**, and
returns a copy of the value of **a** with its decimal point moved **b**
places to the left.
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**=** **\<\<=** **\>\>=** **+=** **-=** **\*=** **/=** **%=** **\^=** **\@=**
: The **assignment** operators take two expressions, **a** and **b** where
**a** is a named expression (see the *Named Expressions* subsection).
For **=**, **b** is copied and the result is assigned to **a**. For all
others, **a** and **b** are applied as operands to the corresponding
arithmetic operator and the result is assigned to **a**.
The **assignment** operators that correspond to operators that are
extensions are themselves **non-portable extensions**.
**==** **\<=** **\>=** **!=** **\<** **\>**
: The **relational** operators compare two expressions, **a** and **b**, and
if the relation holds, according to C language semantics, the result is
**1**. Otherwise, it is **0**.
Note that unlike in C, these operators have a lower precedence than the
**assignment** operators, which means that **a=b\>c** is interpreted as
**(a=b)\>c**.
Also, unlike the [standard][1] requires, these operators can appear anywhere
any other expressions can be used. This allowance is a
**non-portable extension**.
**&&**
: The **boolean and** operator takes two expressions and returns **1** if both
expressions are non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
**||**
: The **boolean or** operator takes two expressions and returns **1** if one
of the expressions is non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
## Statements
The following items are statements:
1. **E**
2. **{** **S** **;** ... **;** **S** **}**
3. **if** **(** **E** **)** **S**
4. **if** **(** **E** **)** **S** **else** **S**
5. **while** **(** **E** **)** **S**
6. **for** **(** **E** **;** **E** **;** **E** **)** **S**
7. An empty statement
8. **break**
9. **continue**
10. **quit**
11. **halt**
12. **limits**
13. A string of characters, enclosed in double quotes
14. **print** **E** **,** ... **,** **E**
15. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
Numbers 4, 9, 11, 12, 14, and 15 are **non-portable extensions**.
Also, as a **non-portable extension**, any or all of the expressions in the
header of a for loop may be omitted. If the condition (second expression) is
omitted, it is assumed to be a constant **1**.
The **break** statement causes a loop to stop iterating and resume execution
immediately following a loop. This is only allowed in loops.
The **continue** statement causes a loop iteration to stop early and returns to
the start of the loop, including testing the loop condition. This is only
allowed in loops.
The **if** **else** statement does the same thing as in C.
The **quit** statement causes bc(1) to quit, even if it is on a branch that will
not be executed (it is a compile-time command).
The **halt** statement causes bc(1) to quit, if it is executed. (Unlike **quit**
if it is on a branch of an **if** statement that is not executed, bc(1) does not
quit.)
The **limits** statement prints the limits that this bc(1) is subject to. This
is like the **quit** statement in that it is a compile-time command.
An expression by itself is evaluated and printed, followed by a newline.
Both scientific notation and engineering notation are available for printing the
results of expressions. Scientific notation is activated by assigning **0** to
**obase**, and engineering notation is activated by assigning **1** to
**obase**. To deactivate them, just assign a different value to **obase**.
Scientific notation and engineering notation are disabled if bc(1) is run with
either the **-s** or **-w** command-line options (or equivalents).
Printing numbers in scientific notation and/or engineering notation is a
**non-portable extension**.
## Print Statement
The "expressions" in a **print** statement may also be strings. If they are, there
are backslash escape sequences that are interpreted specially. What those
sequences are, and what they cause to be printed, are shown below:
-------- -------
**\\a** **\\a**
**\\b** **\\b**
**\\\\** **\\**
**\\e** **\\**
**\\f** **\\f**
**\\n** **\\n**
**\\q** **"**
**\\r** **\\r**
**\\t** **\\t**
-------- -------
Any other character following a backslash causes the backslash and character to
be printed as-is.
Any non-string expression in a print statement shall be assigned to **last**,
like any other expression that is printed.
## Order of Evaluation
All expressions in a statment are evaluated left to right, except as necessary
to maintain order of operations. This means, for example, assuming that **i** is
equal to **0**, in the expression
a[i++] = i++
the first (or 0th) element of **a** is set to **1**, and **i** is equal to **2**
at the end of the expression.
This includes function arguments. Thus, assuming **i** is equal to **0**, this
means that in the expression
x(i++, i++)
the first argument passed to **x()** is **0**, and the second argument is **1**,
while **i** is equal to **2** before the function starts executing.
# FUNCTIONS
Function definitions are as follows:
```
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
```
Any **I** in the parameter list or **auto** list may be replaced with **I[]** to
make a parameter or **auto** var an array, and any **I** in the parameter list
may be replaced with **\*I[]** to make a parameter an array reference. Callers
of functions that take array references should not put an asterisk in the call;
they must be called with just **I[]** like normal array parameters and will be
automatically converted into references.
As a **non-portable extension**, the opening brace of a **define** statement may
appear on the next line.
As a **non-portable extension**, the return statement may also be in one of the
following forms:
1. **return**
2. **return** **(** **)**
3. **return** **E**
The first two, or not specifying a **return** statement, is equivalent to
**return (0)**, unless the function is a **void** function (see the *Void
Functions* subsection below).
## Void Functions
Functions can also be **void** functions, defined as follows:
```
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
```
They can only be used as standalone expressions, where such an expression would
be printed alone, except in a print statement.
Void functions can only use the first two **return** statements listed above.
They can also omit the return statement entirely.
The word "void" is not treated as a keyword; it is still possible to have
variables, arrays, and functions named **void**. The word "void" is only
treated specially right after the **define** keyword.
This is a **non-portable extension**.
## Array References
For any array in the parameter list, if the array is declared in the form
```
*I[]
```
it is a **reference**. Any changes to the array in the function are reflected,
when the function returns, to the array that was passed in.
Other than this, all function arguments are passed by value.
This is a **non-portable extension**.
# LIBRARY
All of the functions below, including the functions in the extended math
library (see the *Extended Library* subsection below), are available when the
**-l** or **--mathlib** command-line flags are given, except that the extended
math library is not available when the **-s** option, the **-w** option, or
equivalents are given.
## Standard Library
The [standard][1] defines the following functions for the math library:
**s(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**c(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a(x)**
: Returns the arctangent of **x**, in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l(x)**
: Returns the natural logarithm of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**e(x)**
: Returns the mathematical constant **e** raised to the power of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**j(x, n)**
: Returns the bessel integer order **n** (truncated) of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
## Extended Library
The extended library is *not* loaded when the **-s**/**--standard** or
**-w**/**--warn** options are given since they are not part of the library
defined by the [standard][1].
The extended library is a **non-portable extension**.
**p(x, y)**
: Calculates **x** to the power of **y**, even if **y** is not an integer, and
returns the result to the current **scale**.
It is an error if **y** is negative and **x** is **0**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**r(x, p)**
: Returns **x** rounded to **p** decimal places according to the rounding mode
[round half away from **0**][3].
**ceil(x, p)**
: Returns **x** rounded to **p** decimal places according to the rounding mode
[round away from **0**][6].
**f(x)**
: Returns the factorial of the truncated absolute value of **x**.
**perm(n, k)**
: Returns the permutation of the truncated absolute value of **n** of the
truncated absolute value of **k**, if **k \<= n**. If not, it returns **0**.
**comb(n, k)**
: Returns the combination of the truncated absolute value of **n** of the
truncated absolute value of **k**, if **k \<= n**. If not, it returns **0**.
**l2(x)**
: Returns the logarithm base **2** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l10(x)**
: Returns the logarithm base **10** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**log(x, b)**
: Returns the logarithm base **b** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**cbrt(x)**
: Returns the cube root of **x**.
**root(x, n)**
: Calculates the truncated value of **n**, **r**, and returns the **r**th root
of **x** to the current **scale**.
If **r** is **0** or negative, this raises an error and causes bc(1) to
reset (see the **RESET** section). It also raises an error and causes bc(1)
to reset if **r** is even and **x** is negative.
**pi(p)**
: Returns **pi** to **p** decimal places.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**t(x)**
: Returns the tangent of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a2(y, x)**
: Returns the arctangent of **y/x**, in radians. If both **y** and **x** are
equal to **0**, it raises an error and causes bc(1) to reset (see the
**RESET** section). Otherwise, if **x** is greater than **0**, it returns
**a(y/x)**. If **x** is less than **0**, and **y** is greater than or equal
to **0**, it returns **a(y/x)+pi**. If **x** is less than **0**, and **y**
is less than **0**, it returns **a(y/x)-pi**. If **x** is equal to **0**,
and **y** is greater than **0**, it returns **pi/2**. If **x** is equal to
**0**, and **y** is less than **0**, it returns **-pi/2**.
This function is the same as the **atan2()** function in many programming
languages.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**sin(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is an alias of **s(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**cos(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is an alias of **c(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**tan(x)**
: Returns the tangent of **x**, which is assumed to be in radians.
If **x** is equal to **1** or **-1**, this raises an error and causes bc(1)
to reset (see the **RESET** section).
This is an alias of **t(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**atan(x)**
: Returns the arctangent of **x**, in radians.
This is an alias of **a(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**atan2(y, x)**
: Returns the arctangent of **y/x**, in radians. If both **y** and **x** are
equal to **0**, it raises an error and causes bc(1) to reset (see the
**RESET** section). Otherwise, if **x** is greater than **0**, it returns
**a(y/x)**. If **x** is less than **0**, and **y** is greater than or equal
to **0**, it returns **a(y/x)+pi**. If **x** is less than **0**, and **y**
is less than **0**, it returns **a(y/x)-pi**. If **x** is equal to **0**,
and **y** is greater than **0**, it returns **pi/2**. If **x** is equal to
**0**, and **y** is less than **0**, it returns **-pi/2**.
This function is the same as the **atan2()** function in many programming
languages.
This is an alias of **a2(y, x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**r2d(x)**
: Converts **x** from radians to degrees and returns the result.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**d2r(x)**
: Converts **x** from degrees to radians and returns the result.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**frand(p)**
: Generates a pseudo-random number between **0** (inclusive) and **1**
(exclusive) with the number of decimal digits after the decimal point equal
to the truncated absolute value of **p**. If **p** is not **0**, then
calling this function will change the value of **seed**. If **p** is **0**,
then **0** is returned, and **seed** is *not* changed.
**ifrand(i, p)**
: Generates a pseudo-random number that is between **0** (inclusive) and the
truncated absolute value of **i** (exclusive) with the number of decimal
digits after the decimal point equal to the truncated absolute value of
**p**. If the absolute value of **i** is greater than or equal to **2**, and
**p** is not **0**, then calling this function will change the value of
**seed**; otherwise, **0** is returned and **seed** is not changed.
**srand(x)**
: Returns **x** with its sign flipped with probability **0.5**. In other
words, it randomizes the sign of **x**.
**brand()**
: Returns a random boolean value (either **0** or **1**).
**ubytes(x)**
: Returns the numbers of unsigned integer bytes required to hold the truncated
absolute value of **x**.
**sbytes(x)**
: Returns the numbers of signed, two's-complement integer bytes required to
hold the truncated value of **x**.
**hex(x)**
: Outputs the hexadecimal (base **16**) representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**binary(x)**
: Outputs the binary (base **2**) representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output(x, b)**
: Outputs the base **b** representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in as few power of two bytes as possible. Both outputs are
split into bytes separated by spaces.
If **x** is not an integer or is negative, an error message is printed
instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in as few power of two bytes as possible. Both
outputs are split into bytes separated by spaces.
If **x** is not an integer, an error message is printed instead, but bc(1)
is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uintn(x, n)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **n** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **n** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**intn(x, n)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **n** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **n** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint8(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **1** byte. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **1** byte, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int8(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **1** byte. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **1** byte, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint16(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **2** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **2** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int16(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **2** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **2** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint32(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **4** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **4** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int32(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **4** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **4** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint64(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **8** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **8** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int64(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **8** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **8** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**hex_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in hexadecimal using **n** bytes. Not all of the value will
be output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**binary_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in binary using **n** bytes. Not all of the value will be
output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in the current **obase** (see the **SYNTAX** section) using
**n** bytes. Not all of the value will be output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output_byte(x, i)**
: Outputs byte **i** of the truncated absolute value of **x**, where **0** is
the least significant byte and **number_of_bytes - 1** is the most
significant byte.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
## Transcendental Functions
All transcendental functions can return slightly inaccurate results (up to 1
[ULP][4]). This is unavoidable, and [this article][5] explains why it is
impossible and unnecessary to calculate exact results for the transcendental
functions.
Because of the possible inaccuracy, I recommend that users call those functions
with the precision (**scale**) set to at least 1 higher than is necessary. If
exact results are *absolutely* required, users can double the precision
(**scale**) and then truncate.
The transcendental functions in the standard math library are:
* **s(x)**
* **c(x)**
* **a(x)**
* **l(x)**
* **e(x)**
* **j(x, n)**
The transcendental functions in the extended math library are:
* **l2(x)**
* **l10(x)**
* **log(x, b)**
* **pi(p)**
* **t(x)**
* **a2(y, x)**
* **sin(x)**
* **cos(x)**
* **tan(x)**
* **atan(x)**
* **atan2(y, x)**
* **r2d(x)**
* **d2r(x)**
# RESET
When bc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any functions that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
functions returned) is skipped.
Thus, when bc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
Note that this reset behavior is different from the GNU bc(1), which attempts to
start executing the statement right after the one that caused an error.
# PERFORMANCE
Most bc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This bc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **BC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **BC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**BC_BASE_DIGS**.
The actual values of **BC_LONG_BIT** and **BC_BASE_DIGS** can be queried with
the **limits** statement.
In addition, this bc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **BC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on bc(1):
**BC_LONG_BIT**
: The number of bits in the **long** type in the environment where bc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**BC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **BC_LONG_BIT**.
**BC_BASE_POW**
: The max decimal number that each large integer can store (see
**BC_BASE_DIGS**) plus **1**. Depends on **BC_BASE_DIGS**.
**BC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **BC_LONG_BIT**.
**BC_BASE_MAX**
: The maximum output base. Set at **BC_BASE_POW**.
**BC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**BC_SCALE_MAX**
: The maximum **scale**. Set at **BC_OVERFLOW_MAX-1**.
**BC_STRING_MAX**
: The maximum length of strings. Set at **BC_OVERFLOW_MAX-1**.
**BC_NAME_MAX**
: The maximum length of identifiers. Set at **BC_OVERFLOW_MAX-1**.
**BC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **BC_OVERFLOW_MAX-1**.
**BC_RAND_MAX**
: The maximum integer (inclusive) returned by the **rand()** operand. Set at
**2\^BC_LONG_BIT-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**BC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
The actual values can be queried with the **limits** statement.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
bc(1) recognizes the following environment variables:
**POSIXLY_CORRECT**
: If this variable exists (no matter the contents), bc(1) behaves as if
the **-s** option was given.
**BC_ENV_ARGS**
: This is another way to give command-line arguments to bc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **BC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
The code that parses **BC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some bc file.bc"** will be correctly parsed, but the string
**"/home/gavin/some \"bc\" file.bc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **BC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**BC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), bc(1) will output
lines to that length, including the backslash (**\\**). The default line
length is **70**.
# EXIT STATUS
bc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, using a negative number as a bound for the pseudo-random number
generator, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**), places (**\@**), left shift (**\<\<**), and right shift (**\>\>**)
operators and their corresponding assignment operators.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, using a token where it is invalid,
giving an invalid expression, giving an invalid print statement, giving an
invalid function definition, attempting to assign to an expression that is
not a named expression (see the *Named Expressions* subsection of the
**SYNTAX** section), giving an invalid **auto** list, having a duplicate
**auto**/function parameter, failing to find the end of a code block,
attempting to return a value from a **void** function, attempting to use a
variable as a reference, and using any extensions when the option **-s** or
any equivalents were given.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a **void** function call as a value in an expression.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (bc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, bc(1) always exits
and returns **4**, no matter what mode bc(1) is in.
The other statuses will only be returned when bc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since bc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Per the [standard][1], bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, bc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, bc(1) turns
on "TTY mode."
TTY mode is required for history to be enabled (see the **COMMAND LINE HISTORY**
section). It is also required to enable special handling for **SIGINT** signals.
The prompt is enabled in TTY mode.
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause bc(1) to stop execution of the current input. If
bc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If bc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If bc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to bc(1) as it is executing a file, it
can seem as though bc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause bc(1) to clean up and exit, and it uses the
default handler for all other signals. The one exception is **SIGHUP**; in that
case, when bc(1) is in TTY mode, a **SIGHUP** will cause bc(1) to clean up and
exit.
# COMMAND LINE HISTORY
bc(1) supports interactive command-line editing. If bc(1) is in TTY mode (see
the **TTY MODE** section), history is enabled. Previous lines can be recalled
and edited with the arrow keys.
**Note**: tabs are converted to 8 spaces.
# SEE ALSO
dc(1)
# STANDARDS
bc(1) is compliant with the [IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1]
specification. The flags **-efghiqsvVw**, all long options, and the extensions
noted above are extensions to that specification.
Note that the specification explicitly says that bc(1) only accepts numbers that
use a period (**.**) as a radix point, regardless of the value of
**LC_NUMERIC**.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHORS
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
[2]: https://www.gnu.org/software/bc/
[3]: https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero
[4]: https://en.wikipedia.org/wiki/Unit_in_the_last_place
[5]: https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT
[6]: https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero
diff --git a/contrib/bc/manuals/bc/NP.1 b/contrib/bc/manuals/bc/NP.1
index 0e45d6dcab62..a89f6ec17271 100644
--- a/contrib/bc/manuals/bc/NP.1
+++ b/contrib/bc/manuals/bc/NP.1
@@ -1,2031 +1,2044 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "BC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "BC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH NAME
.PP
bc - arbitrary-precision decimal arithmetic language and calculator
.SH SYNOPSIS
.PP
\f[B]bc\f[R] [\f[B]-ghilPqsvVw\f[R]] [\f[B]\[en]global-stacks\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]mathlib\f[R]] [\f[B]\[en]no-prompt\f[R]]
[\f[B]\[en]quiet\f[R]] [\f[B]\[en]standard\f[R]] [\f[B]\[en]warn\f[R]]
[\f[B]\[en]version\f[R]] [\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
bc(1) is an interactive processor for a language first standardized in
1991 by POSIX.
(The current standard is
here (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).)
The language provides unlimited precision decimal arithmetic and is
somewhat C-like, but there are differences.
Such differences will be noted in this document.
.PP
After parsing and handling options, this bc(1) reads any files given on
the command line and executes them before reading from \f[B]stdin\f[R].
.PP
This bc(1) is a drop-in replacement for \f[I]any\f[R] bc(1), including
(and especially) the GNU bc(1).
It also has many extensions and extra features beyond other
implementations.
.SH OPTIONS
.PP
The following are the options that bc(1) accepts.
.TP
\f[B]-g\f[R], \f[B]\[en]global-stacks\f[R]
Turns the globals \f[B]ibase\f[R], \f[B]obase\f[R], \f[B]scale\f[R], and
\f[B]seed\f[R] into stacks.
.RS
.PP
This has the effect that a copy of the current value of all four are
pushed onto a stack for every function call, as well as popped when
every function returns.
This means that functions can assign to any and all of those globals
without worrying that the change will affect other functions.
Thus, a hypothetical function named \f[B]output(x,b)\f[R] that simply
printed \f[B]x\f[R] in base \f[B]b\f[R] could be written like this:
.IP
.nf
\f[C]
define void output(x, b) {
obase=b
x
}
\f[R]
.fi
.PP
instead of like this:
.IP
.nf
\f[C]
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
\f[R]
.fi
.PP
This makes writing functions much easier.
.PP
(\f[B]Note\f[R]: the function \f[B]output(x,b)\f[R] exists in the
extended math library.
See the \f[B]LIBRARY\f[R] section.)
.PP
However, since using this flag means that functions cannot set
\f[B]ibase\f[R], \f[B]obase\f[R], \f[B]scale\f[R], or \f[B]seed\f[R]
globally, functions that are made to do so cannot work anymore.
There are two possible use cases for that, and each has a solution.
.PP
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases.
Examples:
.IP
.nf
\f[C]
alias d2o=\[dq]bc -e ibase=A -e obase=8\[dq]
alias h2b=\[dq]bc -e ibase=G -e obase=2\[dq]
\f[R]
.fi
.PP
Second, if the purpose of a function is to set \f[B]ibase\f[R],
\f[B]obase\f[R], \f[B]scale\f[R], or \f[B]seed\f[R] globally for any
other purpose, it could be split into one to four functions (based on
how many globals it sets) and each of those functions could return the
desired value for a global.
.PP
For functions that set \f[B]seed\f[R], the value assigned to
\f[B]seed\f[R] is not propagated to parent functions.
This means that the sequence of pseudo-random numbers that they see will
not be the same sequence of pseudo-random numbers that any parent sees.
This is only the case once \f[B]seed\f[R] has been set.
.PP
If a function desires to not affect the sequence of pseudo-random
numbers of its parents, but wants to use the same \f[B]seed\f[R], it can
use the following line:
.IP
.nf
\f[C]
seed = seed
\f[R]
.fi
.PP
If the behavior of this option is desired for every run of bc(1), then
users could make sure to define \f[B]BC_ENV_ARGS\f[R] and include this
option (see the \f[B]ENVIRONMENT VARIABLES\f[R] section for more
details).
.PP
If \f[B]-s\f[R], \f[B]-w\f[R], or any equivalents are used, this option
is ignored.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-l\f[R], \f[B]\[en]mathlib\f[R]
Sets \f[B]scale\f[R] (see the \f[B]SYNTAX\f[R] section) to \f[B]20\f[R]
and loads the included math library and the extended math library before
running any code, including any expressions or files specified on the
command line.
.RS
.PP
To learn what is in the libraries, see the \f[B]LIBRARY\f[R] section.
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
This option is a no-op.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-q\f[R], \f[B]\[en]quiet\f[R]
This option is for compatibility with the GNU
bc(1) (https://www.gnu.org/software/bc/); it is a no-op.
Without this option, GNU bc(1) prints a copyright header.
This bc(1) only prints the copyright header if one or more of the
\f[B]-v\f[R], \f[B]-V\f[R], or \f[B]\[en]version\f[R] options are given.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-s\f[R], \f[B]\[en]standard\f[R]
Process exactly the language defined by the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
and error if any extensions are used.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-w\f[R], \f[B]\[en]warn\f[R]
Like \f[B]-s\f[R] and \f[B]\[en]standard\f[R], except that warnings (and
not errors) are printed for non-standard extensions and execution
continues normally.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]BC_ENV_ARGS\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]bc >&-\f[R], it will quit with an error.
This is done so that bc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]bc 2>&-\f[R], it will quit with an error.
This is done so that bc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
The syntax for bc(1) programs is mostly C-like, with some differences.
This bc(1) follows the POSIX
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
which is a much more thorough resource for the language this bc(1)
accepts.
This section is meant to be a summary and a listing of all the
extensions to the standard.
.PP
In the sections below, \f[B]E\f[R] means expression, \f[B]S\f[R] means
statement, and \f[B]I\f[R] means identifier.
.PP
Identifiers (\f[B]I\f[R]) start with a lowercase letter and can be
followed by any number (up to \f[B]BC_NAME_MAX-1\f[R]) of lowercase
letters (\f[B]a-z\f[R]), digits (\f[B]0-9\f[R]), and underscores
(\f[B]_\f[R]).
The regex is \f[B][a-z][a-z0-9_]*\f[R].
Identifiers with more than one character (letter) are a
\f[B]non-portable extension\f[R].
.PP
\f[B]ibase\f[R] is a global variable determining how to interpret
constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
If the \f[B]-s\f[R] (\f[B]\[en]standard\f[R]) and \f[B]-w\f[R]
(\f[B]\[en]warn\f[R]) flags were not given on the command line, the max
allowable value for \f[B]ibase\f[R] is \f[B]36\f[R].
Otherwise, it is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in bc(1)
programs with the \f[B]maxibase()\f[R] built-in function.
.PP
\f[B]obase\f[R] is a global variable determining how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]BC_BASE_MAX\f[R] and
can be queried in bc(1) programs with the \f[B]maxobase()\f[R] built-in
function.
The min allowable value for \f[B]obase\f[R] is \f[B]0\f[R].
If \f[B]obase\f[R] is \f[B]0\f[R], values are output in scientific
notation, and if \f[B]obase\f[R] is \f[B]1\f[R], values are output in
engineering notation.
Otherwise, values are output in the specified base.
.PP
Outputting in scientific and engineering notations are \f[B]non-portable
extensions\f[R].
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a global variable that sets the precision of any operations, with
exceptions.
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] is \f[B]BC_SCALE_MAX\f[R]
and can be queried in bc(1) programs with the \f[B]maxscale()\f[R]
built-in function.
.PP
bc(1) has both \f[I]global\f[R] variables and \f[I]local\f[R] variables.
All \f[I]local\f[R] variables are local to the function; they are
parameters or are introduced in the \f[B]auto\f[R] list of a function
(see the \f[B]FUNCTIONS\f[R] section).
If a variable is accessed which is not a parameter or in the
\f[B]auto\f[R] list, it is assumed to be \f[I]global\f[R].
If a parent function has a \f[I]local\f[R] variable version of a
variable that a child function considers \f[I]global\f[R], the value of
that \f[I]global\f[R] variable in the child function is the value of the
variable in the parent function, not the value of the actual
\f[I]global\f[R] variable.
.PP
All of the above applies to arrays as well.
.PP
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence
operator is an assignment operator \f[I]and\f[R] the expression is
notsurrounded by parentheses.
.PP
The value that is printed is also assigned to the special variable
\f[B]last\f[R].
A single dot (\f[B].\f[R]) may also be used as a synonym for
\f[B]last\f[R].
These are \f[B]non-portable extensions\f[R].
.PP
Either semicolons or newlines may separate statements.
.SS Comments
.PP
There are two kinds of comments:
.IP "1." 3
Block comments are enclosed in \f[B]/*\f[R] and \f[B]*/\f[R].
.IP "2." 3
Line comments go from \f[B]#\f[R] until, and not including, the next
newline.
This is a \f[B]non-portable extension\f[R].
.SS Named Expressions
.PP
The following are named expressions in bc(1):
.IP "1." 3
Variables: \f[B]I\f[R]
.IP "2." 3
Array Elements: \f[B]I[E]\f[R]
.IP "3." 3
\f[B]ibase\f[R]
.IP "4." 3
\f[B]obase\f[R]
.IP "5." 3
\f[B]scale\f[R]
.IP "6." 3
\f[B]seed\f[R]
.IP "7." 3
\f[B]last\f[R] or a single dot (\f[B].\f[R])
.PP
Numbers 6 and 7 are \f[B]non-portable extensions\f[R].
.PP
The meaning of \f[B]seed\f[R] is dependent on the current pseudo-random
number generator but is guaranteed to not change except for new major
versions.
.PP
The \f[I]scale\f[R] and sign of the value may be significant.
.PP
If a previously used \f[B]seed\f[R] value is assigned to \f[B]seed\f[R]
and used again, the pseudo-random number generator is guaranteed to
produce the same sequence of pseudo-random numbers as it did when the
\f[B]seed\f[R] value was previously used.
.PP
The exact value assigned to \f[B]seed\f[R] is not guaranteed to be
returned if \f[B]seed\f[R] is queried again immediately.
However, if \f[B]seed\f[R] \f[I]does\f[R] return a different value, both
values, when assigned to \f[B]seed\f[R], are guaranteed to produce the
same sequence of pseudo-random numbers.
This means that certain values assigned to \f[B]seed\f[R] will
\f[I]not\f[R] produce unique sequences of pseudo-random numbers.
The value of \f[B]seed\f[R] will change after any use of the
\f[B]rand()\f[R] and \f[B]irand(E)\f[R] operands (see the
\f[I]Operands\f[R] subsection below), except if the parameter passed to
\f[B]irand(E)\f[R] is \f[B]0\f[R], \f[B]1\f[R], or negative.
.PP
There is no limit to the length (number of significant decimal digits)
or \f[I]scale\f[R] of the value that can be assigned to \f[B]seed\f[R].
.PP
Variables and arrays do not interfere; users can have arrays named the
same as variables.
This also applies to functions (see the \f[B]FUNCTIONS\f[R] section), so
a user can have a variable, array, and function that all have the same
name, and they will not shadow each other, whether inside of functions
or not.
.PP
Named expressions are required as the operand of
\f[B]increment\f[R]/\f[B]decrement\f[R] operators and as the left side
of \f[B]assignment\f[R] operators (see the \f[I]Operators\f[R]
subsection).
.SS Operands
.PP
The following are valid operands in bc(1):
.IP " 1." 4
Numbers (see the \f[I]Numbers\f[R] subsection below).
.IP " 2." 4
Array indices (\f[B]I[E]\f[R]).
.IP " 3." 4
\f[B](E)\f[R]: The value of \f[B]E\f[R] (used to change precedence).
.IP " 4." 4
\f[B]sqrt(E)\f[R]: The square root of \f[B]E\f[R].
\f[B]E\f[R] must be non-negative.
.IP " 5." 4
\f[B]length(E)\f[R]: The number of significant decimal digits in
\f[B]E\f[R].
.IP " 6." 4
\f[B]length(I[])\f[R]: The number of elements in the array \f[B]I\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 7." 4
\f[B]scale(E)\f[R]: The \f[I]scale\f[R] of \f[B]E\f[R].
.IP " 8." 4
\f[B]abs(E)\f[R]: The absolute value of \f[B]E\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 9." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a non-\f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.IP "10." 4
\f[B]read()\f[R]: Reads a line from \f[B]stdin\f[R] and uses that as an
expression.
The result of that expression is the result of the \f[B]read()\f[R]
operand.
This is a \f[B]non-portable extension\f[R].
.IP "11." 4
\f[B]maxibase()\f[R]: The max allowable \f[B]ibase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "12." 4
\f[B]maxobase()\f[R]: The max allowable \f[B]obase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "13." 4
\f[B]maxscale()\f[R]: The max allowable \f[B]scale\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "14." 4
\f[B]rand()\f[R]: A pseudo-random integer between \f[B]0\f[R]
(inclusive) and \f[B]BC_RAND_MAX\f[R] (inclusive).
Using this operand will change the value of \f[B]seed\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "15." 4
\f[B]irand(E)\f[R]: A pseudo-random integer between \f[B]0\f[R]
(inclusive) and the value of \f[B]E\f[R] (exclusive).
If \f[B]E\f[R] is negative or is a non-integer (\f[B]E\f[R]\[cq]s
\f[I]scale\f[R] is not \f[B]0\f[R]), an error is raised, and bc(1)
resets (see the \f[B]RESET\f[R] section) while \f[B]seed\f[R] remains
unchanged.
If \f[B]E\f[R] is larger than \f[B]BC_RAND_MAX\f[R], the higher bound is
honored by generating several pseudo-random integers, multiplying them
by appropriate powers of \f[B]BC_RAND_MAX+1\f[R], and adding them
together.
Thus, the size of integer that can be generated with this operand is
unbounded.
Using this operand will change the value of \f[B]seed\f[R], unless the
value of \f[B]E\f[R] is \f[B]0\f[R] or \f[B]1\f[R].
In that case, \f[B]0\f[R] is returned, and \f[B]seed\f[R] is
\f[I]not\f[R] changed.
This is a \f[B]non-portable extension\f[R].
.IP "16." 4
\f[B]maxrand()\f[R]: The max integer returned by \f[B]rand()\f[R].
This is a \f[B]non-portable extension\f[R].
.PP
The integers generated by \f[B]rand()\f[R] and \f[B]irand(E)\f[R] are
guaranteed to be as unbiased as possible, subject to the limitations of
the pseudo-random number generator.
.PP
\f[B]Note\f[R]: The values returned by the pseudo-random number
generator with \f[B]rand()\f[R] and \f[B]irand(E)\f[R] are guaranteed to
\f[I]NOT\f[R] be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator.
However, they \f[I]are\f[R] guaranteed to be reproducible with identical
\f[B]seed\f[R] values.
This means that the pseudo-random values from bc(1) should only be used
where a reproducible stream of pseudo-random numbers is
\f[I]ESSENTIAL\f[R].
In any other case, use a non-seeded pseudo-random number generator.
.SS Numbers
.PP
Numbers are strings made up of digits, uppercase letters, and at most
\f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]BC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]Z\f[R] alone always equals decimal \f[B]35\f[R].
.PP
In addition, bc(1) accepts numbers in scientific notation.
These have the form \f[B]<number>e<integer>\f[R].
The exponent (the portion after the \f[B]e\f[R]) must be an integer.
An example is \f[B]1.89237e9\f[R], which is equal to
\f[B]1892370000\f[R].
Negative exponents are also allowed, so \f[B]4.2890e-3\f[R] is equal to
\f[B]0.0042890\f[R].
.PP
Using scientific notation is an error or warning if the \f[B]-s\f[R] or
\f[B]-w\f[R], respectively, command-line options (or equivalents) are
given.
.PP
\f[B]WARNING\f[R]: Both the number and the exponent in scientific
notation are interpreted according to the current \f[B]ibase\f[R], but
the number is still multiplied by \f[B]10\[ha]exponent\f[R] regardless
of the current \f[B]ibase\f[R].
For example, if \f[B]ibase\f[R] is \f[B]16\f[R] and bc(1) is given the
number string \f[B]FFeA\f[R], the resulting decimal number will be
\f[B]2550000000000\f[R], and if bc(1) is given the number string
\f[B]10e-4\f[R], the resulting decimal number will be \f[B]0.0016\f[R].
.PP
Accepting input as scientific notation is a \f[B]non-portable
extension\f[R].
.SS Operators
.PP
The following arithmetic and logical operators can be used.
They are listed in order of decreasing precedence.
Operators in the same group have the same precedence.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
Type: Prefix and Postfix
.RS
.PP
Associativity: None
.PP
Description: \f[B]increment\f[R], \f[B]decrement\f[R]
.RE
.TP
\f[B]-\f[R] \f[B]!\f[R]
Type: Prefix
.RS
.PP
Associativity: None
.PP
Description: \f[B]negation\f[R], \f[B]boolean not\f[R]
.RE
.TP
\f[B]$\f[R]
Type: Postfix
.RS
.PP
Associativity: None
.PP
Description: \f[B]truncation\f[R]
.RE
.TP
\f[B]\[at]\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]set precision\f[R]
.RE
.TP
\f[B]\[ha]\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]power\f[R]
.RE
.TP
\f[B]*\f[R] \f[B]/\f[R] \f[B]%\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]multiply\f[R], \f[B]divide\f[R], \f[B]modulus\f[R]
.RE
.TP
\f[B]+\f[R] \f[B]-\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]add\f[R], \f[B]subtract\f[R]
.RE
.TP
\f[B]<<\f[R] \f[B]>>\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]shift left\f[R], \f[B]shift right\f[R]
.RE
.TP
\f[B]=\f[R] \f[B]<<=\f[R] \f[B]>>=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R] \f[B]\[at]=\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]assignment\f[R]
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]relational\f[R]
.RE
.TP
\f[B]&&\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean and\f[R]
.RE
.TP
\f[B]||\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean or\f[R]
.RE
.PP
The operators will be described in more detail below.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
The prefix and postfix \f[B]increment\f[R] and \f[B]decrement\f[R]
operators behave exactly like they would in C.
They require a named expression (see the \f[I]Named Expressions\f[R]
subsection) as an operand.
.RS
.PP
The prefix versions of these operators are more efficient; use them
where possible.
.RE
.TP
\f[B]-\f[R]
The \f[B]negation\f[R] operator returns \f[B]0\f[R] if a user attempts
to negate any expression with the value \f[B]0\f[R].
Otherwise, a copy of the expression with its sign flipped is returned.
.TP
\f[B]!\f[R]
The \f[B]boolean not\f[R] operator returns \f[B]1\f[R] if the expression
is \f[B]0\f[R], or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]$\f[R]
The \f[B]truncation\f[R] operator returns a copy of the given expression
with all of its \f[I]scale\f[R] removed.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[at]\f[R]
The \f[B]set precision\f[R] operator takes two expressions and returns a
copy of the first with its \f[I]scale\f[R] equal to the value of the
second expression.
That could either mean that the number is returned without change (if
the \f[I]scale\f[R] of the first expression matches the value of the
second expression), extended (if it is less), or truncated (if it is
more).
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]) and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The \f[B]power\f[R] operator (not the \f[B]exclusive or\f[R] operator,
as it would be in C) takes two expressions and raises the first to the
power of the value of the second.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]), and if it
is negative, the first value must be non-zero.
.RE
.TP
\f[B]*\f[R]
The \f[B]multiply\f[R] operator takes two expressions, multiplies them,
and returns the product.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The \f[B]divide\f[R] operator takes two expressions, divides them, and
returns the quotient.
The \f[I]scale\f[R] of the result shall be the value of \f[B]scale\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]%\f[R]
The \f[B]modulus\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and evaluates them by 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R] and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]+\f[R]
The \f[B]add\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the sum, with a \f[I]scale\f[R] equal to the
max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]-\f[R]
The \f[B]subtract\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the difference, with a \f[I]scale\f[R] equal to
the max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]<<\f[R]
The \f[B]left shift\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns a copy of the value of \f[B]a\f[R] with its
decimal point moved \f[B]b\f[R] places to the right.
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]) and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]>>\f[R]
The \f[B]right shift\f[R] operator takes two expressions, \f[B]a\f[R]
and \f[B]b\f[R], and returns a copy of the value of \f[B]a\f[R] with its
decimal point moved \f[B]b\f[R] places to the left.
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]) and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]=\f[R] \f[B]<<=\f[R] \f[B]>>=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R] \f[B]\[at]=\f[R]
The \f[B]assignment\f[R] operators take two expressions, \f[B]a\f[R] and
\f[B]b\f[R] where \f[B]a\f[R] is a named expression (see the \f[I]Named
Expressions\f[R] subsection).
.RS
.PP
For \f[B]=\f[R], \f[B]b\f[R] is copied and the result is assigned to
\f[B]a\f[R].
For all others, \f[B]a\f[R] and \f[B]b\f[R] are applied as operands to
the corresponding arithmetic operator and the result is assigned to
\f[B]a\f[R].
.PP
The \f[B]assignment\f[R] operators that correspond to operators that are
extensions are themselves \f[B]non-portable extensions\f[R].
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
The \f[B]relational\f[R] operators compare two expressions, \f[B]a\f[R]
and \f[B]b\f[R], and if the relation holds, according to C language
semantics, the result is \f[B]1\f[R].
Otherwise, it is \f[B]0\f[R].
.RS
.PP
Note that unlike in C, these operators have a lower precedence than the
\f[B]assignment\f[R] operators, which means that \f[B]a=b>c\f[R] is
interpreted as \f[B](a=b)>c\f[R].
.PP
Also, unlike the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
requires, these operators can appear anywhere any other expressions can
be used.
This allowance is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]&&\f[R]
The \f[B]boolean and\f[R] operator takes two expressions and returns
\f[B]1\f[R] if both expressions are non-zero, \f[B]0\f[R] otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]||\f[R]
The \f[B]boolean or\f[R] operator takes two expressions and returns
\f[B]1\f[R] if one of the expressions is non-zero, \f[B]0\f[R]
otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Statements
.PP
The following items are statements:
.IP " 1." 4
\f[B]E\f[R]
.IP " 2." 4
\f[B]{\f[R] \f[B]S\f[R] \f[B];\f[R] \&... \f[B];\f[R] \f[B]S\f[R]
\f[B]}\f[R]
.IP " 3." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 4." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
\f[B]else\f[R] \f[B]S\f[R]
.IP " 5." 4
\f[B]while\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 6." 4
\f[B]for\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B];\f[R] \f[B]E\f[R]
\f[B];\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 7." 4
An empty statement
.IP " 8." 4
\f[B]break\f[R]
.IP " 9." 4
\f[B]continue\f[R]
.IP "10." 4
\f[B]quit\f[R]
.IP "11." 4
\f[B]halt\f[R]
.IP "12." 4
\f[B]limits\f[R]
.IP "13." 4
A string of characters, enclosed in double quotes
.IP "14." 4
\f[B]print\f[R] \f[B]E\f[R] \f[B],\f[R] \&... \f[B],\f[R] \f[B]E\f[R]
.IP "15." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a \f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.PP
Numbers 4, 9, 11, 12, 14, and 15 are \f[B]non-portable extensions\f[R].
.PP
Also, as a \f[B]non-portable extension\f[R], any or all of the
expressions in the header of a for loop may be omitted.
If the condition (second expression) is omitted, it is assumed to be a
constant \f[B]1\f[R].
.PP
The \f[B]break\f[R] statement causes a loop to stop iterating and resume
execution immediately following a loop.
This is only allowed in loops.
.PP
The \f[B]continue\f[R] statement causes a loop iteration to stop early
and returns to the start of the loop, including testing the loop
condition.
This is only allowed in loops.
.PP
The \f[B]if\f[R] \f[B]else\f[R] statement does the same thing as in C.
.PP
The \f[B]quit\f[R] statement causes bc(1) to quit, even if it is on a
branch that will not be executed (it is a compile-time command).
.PP
The \f[B]halt\f[R] statement causes bc(1) to quit, if it is executed.
(Unlike \f[B]quit\f[R] if it is on a branch of an \f[B]if\f[R] statement
that is not executed, bc(1) does not quit.)
.PP
The \f[B]limits\f[R] statement prints the limits that this bc(1) is
subject to.
This is like the \f[B]quit\f[R] statement in that it is a compile-time
command.
.PP
An expression by itself is evaluated and printed, followed by a newline.
.PP
Both scientific notation and engineering notation are available for
printing the results of expressions.
Scientific notation is activated by assigning \f[B]0\f[R] to
\f[B]obase\f[R], and engineering notation is activated by assigning
\f[B]1\f[R] to \f[B]obase\f[R].
To deactivate them, just assign a different value to \f[B]obase\f[R].
.PP
Scientific notation and engineering notation are disabled if bc(1) is
run with either the \f[B]-s\f[R] or \f[B]-w\f[R] command-line options
(or equivalents).
.PP
Printing numbers in scientific notation and/or engineering notation is a
\f[B]non-portable extension\f[R].
.SS Print Statement
.PP
The \[lq]expressions\[rq] in a \f[B]print\f[R] statement may also be
strings.
If they are, there are backslash escape sequences that are interpreted
specially.
What those sequences are, and what they cause to be printed, are shown
below:
.PP
.TS
tab(@);
l l.
T{
\f[B]\[rs]a\f[R]
T}@T{
\f[B]\[rs]a\f[R]
T}
T{
\f[B]\[rs]b\f[R]
T}@T{
\f[B]\[rs]b\f[R]
T}
T{
\f[B]\[rs]\[rs]\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]e\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]f\f[R]
T}@T{
\f[B]\[rs]f\f[R]
T}
T{
\f[B]\[rs]n\f[R]
T}@T{
\f[B]\[rs]n\f[R]
T}
T{
\f[B]\[rs]q\f[R]
T}@T{
\f[B]\[dq]\f[R]
T}
T{
\f[B]\[rs]r\f[R]
T}@T{
\f[B]\[rs]r\f[R]
T}
T{
\f[B]\[rs]t\f[R]
T}@T{
\f[B]\[rs]t\f[R]
T}
.TE
.PP
Any other character following a backslash causes the backslash and
character to be printed as-is.
.PP
Any non-string expression in a print statement shall be assigned to
\f[B]last\f[R], like any other expression that is printed.
.SS Order of Evaluation
.PP
All expressions in a statment are evaluated left to right, except as
necessary to maintain order of operations.
This means, for example, assuming that \f[B]i\f[R] is equal to
\f[B]0\f[R], in the expression
.IP
.nf
\f[C]
a[i++] = i++
\f[R]
.fi
.PP
the first (or 0th) element of \f[B]a\f[R] is set to \f[B]1\f[R], and
\f[B]i\f[R] is equal to \f[B]2\f[R] at the end of the expression.
.PP
This includes function arguments.
Thus, assuming \f[B]i\f[R] is equal to \f[B]0\f[R], this means that in
the expression
.IP
.nf
\f[C]
x(i++, i++)
\f[R]
.fi
.PP
the first argument passed to \f[B]x()\f[R] is \f[B]0\f[R], and the
second argument is \f[B]1\f[R], while \f[B]i\f[R] is equal to
\f[B]2\f[R] before the function starts executing.
.SH FUNCTIONS
.PP
Function definitions are as follows:
.IP
.nf
\f[C]
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
\f[R]
.fi
.PP
Any \f[B]I\f[R] in the parameter list or \f[B]auto\f[R] list may be
replaced with \f[B]I[]\f[R] to make a parameter or \f[B]auto\f[R] var an
array, and any \f[B]I\f[R] in the parameter list may be replaced with
\f[B]*I[]\f[R] to make a parameter an array reference.
Callers of functions that take array references should not put an
asterisk in the call; they must be called with just \f[B]I[]\f[R] like
normal array parameters and will be automatically converted into
references.
.PP
As a \f[B]non-portable extension\f[R], the opening brace of a
\f[B]define\f[R] statement may appear on the next line.
.PP
As a \f[B]non-portable extension\f[R], the return statement may also be
in one of the following forms:
.IP "1." 3
\f[B]return\f[R]
.IP "2." 3
\f[B]return\f[R] \f[B](\f[R] \f[B])\f[R]
.IP "3." 3
\f[B]return\f[R] \f[B]E\f[R]
.PP
The first two, or not specifying a \f[B]return\f[R] statement, is
equivalent to \f[B]return (0)\f[R], unless the function is a
\f[B]void\f[R] function (see the \f[I]Void Functions\f[R] subsection
below).
.SS Void Functions
.PP
Functions can also be \f[B]void\f[R] functions, defined as follows:
.IP
.nf
\f[C]
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
\f[R]
.fi
.PP
They can only be used as standalone expressions, where such an
expression would be printed alone, except in a print statement.
.PP
Void functions can only use the first two \f[B]return\f[R] statements
listed above.
They can also omit the return statement entirely.
.PP
The word \[lq]void\[rq] is not treated as a keyword; it is still
possible to have variables, arrays, and functions named \f[B]void\f[R].
The word \[lq]void\[rq] is only treated specially right after the
\f[B]define\f[R] keyword.
.PP
This is a \f[B]non-portable extension\f[R].
.SS Array References
.PP
For any array in the parameter list, if the array is declared in the
form
.IP
.nf
\f[C]
*I[]
\f[R]
.fi
.PP
it is a \f[B]reference\f[R].
Any changes to the array in the function are reflected, when the
function returns, to the array that was passed in.
.PP
Other than this, all function arguments are passed by value.
.PP
This is a \f[B]non-portable extension\f[R].
.SH LIBRARY
.PP
All of the functions below, including the functions in the extended math
library (see the \f[I]Extended Library\f[R] subsection below), are
available when the \f[B]-l\f[R] or \f[B]\[en]mathlib\f[R] command-line
flags are given, except that the extended math library is not available
when the \f[B]-s\f[R] option, the \f[B]-w\f[R] option, or equivalents
are given.
.SS Standard Library
.PP
The
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
defines the following functions for the math library:
.TP
\f[B]s(x)\f[R]
Returns the sine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]c(x)\f[R]
Returns the cosine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]a(x)\f[R]
Returns the arctangent of \f[B]x\f[R], in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]l(x)\f[R]
Returns the natural logarithm of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]e(x)\f[R]
Returns the mathematical constant \f[B]e\f[R] raised to the power of
\f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]j(x, n)\f[R]
Returns the bessel integer order \f[B]n\f[R] (truncated) of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.SS Extended Library
.PP
The extended library is \f[I]not\f[R] loaded when the
\f[B]-s\f[R]/\f[B]\[en]standard\f[R] or \f[B]-w\f[R]/\f[B]\[en]warn\f[R]
options are given since they are not part of the library defined by the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).
.PP
The extended library is a \f[B]non-portable extension\f[R].
.TP
\f[B]p(x, y)\f[R]
Calculates \f[B]x\f[R] to the power of \f[B]y\f[R], even if \f[B]y\f[R]
is not an integer, and returns the result to the current
\f[B]scale\f[R].
.RS
.PP
It is an error if \f[B]y\f[R] is negative and \f[B]x\f[R] is
\f[B]0\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]r(x, p)\f[R]
Returns \f[B]x\f[R] rounded to \f[B]p\f[R] decimal places according to
the rounding mode round half away from
\f[B]0\f[R] (https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero).
.TP
\f[B]ceil(x, p)\f[R]
Returns \f[B]x\f[R] rounded to \f[B]p\f[R] decimal places according to
the rounding mode round away from
\f[B]0\f[R] (https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero).
.TP
\f[B]f(x)\f[R]
Returns the factorial of the truncated absolute value of \f[B]x\f[R].
.TP
\f[B]perm(n, k)\f[R]
Returns the permutation of the truncated absolute value of \f[B]n\f[R]
of the truncated absolute value of \f[B]k\f[R], if \f[B]k <= n\f[R].
If not, it returns \f[B]0\f[R].
.TP
\f[B]comb(n, k)\f[R]
Returns the combination of the truncated absolute value of \f[B]n\f[R]
of the truncated absolute value of \f[B]k\f[R], if \f[B]k <= n\f[R].
If not, it returns \f[B]0\f[R].
.TP
\f[B]l2(x)\f[R]
Returns the logarithm base \f[B]2\f[R] of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]l10(x)\f[R]
Returns the logarithm base \f[B]10\f[R] of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]log(x, b)\f[R]
Returns the logarithm base \f[B]b\f[R] of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]cbrt(x)\f[R]
Returns the cube root of \f[B]x\f[R].
.TP
\f[B]root(x, n)\f[R]
Calculates the truncated value of \f[B]n\f[R], \f[B]r\f[R], and returns
the \f[B]r\f[R]th root of \f[B]x\f[R] to the current \f[B]scale\f[R].
.RS
.PP
If \f[B]r\f[R] is \f[B]0\f[R] or negative, this raises an error and
causes bc(1) to reset (see the \f[B]RESET\f[R] section).
It also raises an error and causes bc(1) to reset if \f[B]r\f[R] is even
and \f[B]x\f[R] is negative.
.RE
.TP
\f[B]pi(p)\f[R]
Returns \f[B]pi\f[R] to \f[B]p\f[R] decimal places.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]t(x)\f[R]
Returns the tangent of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]a2(y, x)\f[R]
Returns the arctangent of \f[B]y/x\f[R], in radians.
If both \f[B]y\f[R] and \f[B]x\f[R] are equal to \f[B]0\f[R], it raises
an error and causes bc(1) to reset (see the \f[B]RESET\f[R] section).
Otherwise, if \f[B]x\f[R] is greater than \f[B]0\f[R], it returns
\f[B]a(y/x)\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is greater than
or equal to \f[B]0\f[R], it returns \f[B]a(y/x)+pi\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]a(y/x)-pi\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is greater than
\f[B]0\f[R], it returns \f[B]pi/2\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]-pi/2\f[R].
.RS
.PP
This function is the same as the \f[B]atan2()\f[R] function in many
programming languages.
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]sin(x)\f[R]
Returns the sine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is an alias of \f[B]s(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]cos(x)\f[R]
Returns the cosine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is an alias of \f[B]c(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]tan(x)\f[R]
Returns the tangent of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
If \f[B]x\f[R] is equal to \f[B]1\f[R] or \f[B]-1\f[R], this raises an
error and causes bc(1) to reset (see the \f[B]RESET\f[R] section).
.PP
This is an alias of \f[B]t(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]atan(x)\f[R]
Returns the arctangent of \f[B]x\f[R], in radians.
.RS
.PP
This is an alias of \f[B]a(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]atan2(y, x)\f[R]
Returns the arctangent of \f[B]y/x\f[R], in radians.
If both \f[B]y\f[R] and \f[B]x\f[R] are equal to \f[B]0\f[R], it raises
an error and causes bc(1) to reset (see the \f[B]RESET\f[R] section).
Otherwise, if \f[B]x\f[R] is greater than \f[B]0\f[R], it returns
\f[B]a(y/x)\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is greater than
or equal to \f[B]0\f[R], it returns \f[B]a(y/x)+pi\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]a(y/x)-pi\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is greater than
\f[B]0\f[R], it returns \f[B]pi/2\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]-pi/2\f[R].
.RS
.PP
This function is the same as the \f[B]atan2()\f[R] function in many
programming languages.
.PP
This is an alias of \f[B]a2(y, x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]r2d(x)\f[R]
Converts \f[B]x\f[R] from radians to degrees and returns the result.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]d2r(x)\f[R]
Converts \f[B]x\f[R] from degrees to radians and returns the result.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]frand(p)\f[R]
Generates a pseudo-random number between \f[B]0\f[R] (inclusive) and
\f[B]1\f[R] (exclusive) with the number of decimal digits after the
decimal point equal to the truncated absolute value of \f[B]p\f[R].
If \f[B]p\f[R] is not \f[B]0\f[R], then calling this function will
change the value of \f[B]seed\f[R].
If \f[B]p\f[R] is \f[B]0\f[R], then \f[B]0\f[R] is returned, and
\f[B]seed\f[R] is \f[I]not\f[R] changed.
.TP
\f[B]ifrand(i, p)\f[R]
Generates a pseudo-random number that is between \f[B]0\f[R] (inclusive)
and the truncated absolute value of \f[B]i\f[R] (exclusive) with the
number of decimal digits after the decimal point equal to the truncated
absolute value of \f[B]p\f[R].
If the absolute value of \f[B]i\f[R] is greater than or equal to
\f[B]2\f[R], and \f[B]p\f[R] is not \f[B]0\f[R], then calling this
function will change the value of \f[B]seed\f[R]; otherwise, \f[B]0\f[R]
is returned and \f[B]seed\f[R] is not changed.
.TP
\f[B]srand(x)\f[R]
Returns \f[B]x\f[R] with its sign flipped with probability
\f[B]0.5\f[R].
In other words, it randomizes the sign of \f[B]x\f[R].
.TP
\f[B]brand()\f[R]
Returns a random boolean value (either \f[B]0\f[R] or \f[B]1\f[R]).
.TP
\f[B]ubytes(x)\f[R]
Returns the numbers of unsigned integer bytes required to hold the
truncated absolute value of \f[B]x\f[R].
.TP
\f[B]sbytes(x)\f[R]
Returns the numbers of signed, two\[cq]s-complement integer bytes
required to hold the truncated value of \f[B]x\f[R].
.TP
\f[B]hex(x)\f[R]
Outputs the hexadecimal (base \f[B]16\f[R]) representation of
\f[B]x\f[R].
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]binary(x)\f[R]
Outputs the binary (base \f[B]2\f[R]) representation of \f[B]x\f[R].
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]output(x, b)\f[R]
Outputs the base \f[B]b\f[R] representation of \f[B]x\f[R].
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in as few power of two bytes as possible.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or is negative, an error message is
printed instead, but bc(1) is not reset (see the \f[B]RESET\f[R]
section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in as few power of two bytes as
possible.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, an error message is printed instead,
but bc(1) is not reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uintn(x, n)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]n\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]n\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]intn(x, n)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]n\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]n\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint8(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]1\f[R] byte.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]1\f[R] byte, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int8(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]1\f[R] byte.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]1\f[R] byte, an
error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint16(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]2\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]2\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int16(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]2\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]2\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint32(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]4\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]4\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int32(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]4\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]4\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint64(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]8\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]8\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int64(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]8\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]8\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]hex_uint(x, n)\f[R]
Outputs the representation of the truncated absolute value of
\f[B]x\f[R] as an unsigned integer in hexadecimal using \f[B]n\f[R]
bytes.
Not all of the value will be output if \f[B]n\f[R] is too small.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]binary_uint(x, n)\f[R]
Outputs the representation of the truncated absolute value of
\f[B]x\f[R] as an unsigned integer in binary using \f[B]n\f[R] bytes.
Not all of the value will be output if \f[B]n\f[R] is too small.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]output_uint(x, n)\f[R]
Outputs the representation of the truncated absolute value of
\f[B]x\f[R] as an unsigned integer in the current \f[B]obase\f[R] (see
the \f[B]SYNTAX\f[R] section) using \f[B]n\f[R] bytes.
Not all of the value will be output if \f[B]n\f[R] is too small.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]output_byte(x, i)\f[R]
Outputs byte \f[B]i\f[R] of the truncated absolute value of \f[B]x\f[R],
where \f[B]0\f[R] is the least significant byte and \f[B]number_of_bytes
- 1\f[R] is the most significant byte.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.SS Transcendental Functions
.PP
All transcendental functions can return slightly inaccurate results (up
to 1 ULP (https://en.wikipedia.org/wiki/Unit_in_the_last_place)).
This is unavoidable, and this
article (https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT) explains
why it is impossible and unnecessary to calculate exact results for the
transcendental functions.
.PP
Because of the possible inaccuracy, I recommend that users call those
functions with the precision (\f[B]scale\f[R]) set to at least 1 higher
than is necessary.
If exact results are \f[I]absolutely\f[R] required, users can double the
precision (\f[B]scale\f[R]) and then truncate.
.PP
The transcendental functions in the standard math library are:
.IP \[bu] 2
\f[B]s(x)\f[R]
.IP \[bu] 2
\f[B]c(x)\f[R]
.IP \[bu] 2
\f[B]a(x)\f[R]
.IP \[bu] 2
\f[B]l(x)\f[R]
.IP \[bu] 2
\f[B]e(x)\f[R]
.IP \[bu] 2
\f[B]j(x, n)\f[R]
.PP
The transcendental functions in the extended math library are:
.IP \[bu] 2
\f[B]l2(x)\f[R]
.IP \[bu] 2
\f[B]l10(x)\f[R]
.IP \[bu] 2
\f[B]log(x, b)\f[R]
.IP \[bu] 2
\f[B]pi(p)\f[R]
.IP \[bu] 2
\f[B]t(x)\f[R]
.IP \[bu] 2
\f[B]a2(y, x)\f[R]
.IP \[bu] 2
\f[B]sin(x)\f[R]
.IP \[bu] 2
\f[B]cos(x)\f[R]
.IP \[bu] 2
\f[B]tan(x)\f[R]
.IP \[bu] 2
\f[B]atan(x)\f[R]
.IP \[bu] 2
\f[B]atan2(y, x)\f[R]
.IP \[bu] 2
\f[B]r2d(x)\f[R]
.IP \[bu] 2
\f[B]d2r(x)\f[R]
.SH RESET
.PP
When bc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any functions that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all functions returned) is skipped.
.PP
Thus, when bc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.PP
Note that this reset behavior is different from the GNU bc(1), which
attempts to start executing the statement right after the one that
caused an error.
.SH PERFORMANCE
.PP
Most bc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This bc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]BC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]BC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]BC_BASE_DIGS\f[R].
.PP
The actual values of \f[B]BC_LONG_BIT\f[R] and \f[B]BC_BASE_DIGS\f[R]
can be queried with the \f[B]limits\f[R] statement.
.PP
In addition, this bc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]BC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on bc(1):
.TP
\f[B]BC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
bc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]BC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]BC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]BC_BASE_DIGS\f[R].
.TP
\f[B]BC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]BC_BASE_POW\f[R].
.TP
\f[B]BC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]BC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_RAND_MAX\f[R]
The maximum integer (inclusive) returned by the \f[B]rand()\f[R]
operand.
Set at \f[B]2\[ha]BC_LONG_BIT-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]BC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
The actual values can be queried with the \f[B]limits\f[R] statement.
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
bc(1) recognizes the following environment variables:
.TP
\f[B]POSIXLY_CORRECT\f[R]
If this variable exists (no matter the contents), bc(1) behaves as if
the \f[B]-s\f[R] option was given.
.TP
\f[B]BC_ENV_ARGS\f[R]
This is another way to give command-line arguments to bc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]BC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
.RS
.PP
The code that parses \f[B]BC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some bc file.bc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]bc\[dq] file.bc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]BC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]BC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), bc(1) will output lines to that length,
including the backslash (\f[B]\[rs]\f[R]).
The default line length is \f[B]70\f[R].
.SH EXIT STATUS
.PP
bc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, using a negative number as a bound for the
pseudo-random number generator, attempting to convert a negative number
to a hardware integer, overflow when converting a number to a hardware
integer, and attempting to use a non-integer where an integer is
required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]), places (\f[B]\[at]\f[R]), left shift
(\f[B]<<\f[R]), and right shift (\f[B]>>\f[R]) operators and their
corresponding assignment operators.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, using a token
where it is invalid, giving an invalid expression, giving an invalid
print statement, giving an invalid function definition, attempting to
assign to an expression that is not a named expression (see the
\f[I]Named Expressions\f[R] subsection of the \f[B]SYNTAX\f[R] section),
giving an invalid \f[B]auto\f[R] list, having a duplicate
\f[B]auto\f[R]/function parameter, failing to find the end of a code
block, attempting to return a value from a \f[B]void\f[R] function,
attempting to use a variable as a reference, and using any extensions
when the option \f[B]-s\f[R] or any equivalents were given.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a \f[B]void\f[R] function call as a value in an
expression.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (bc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, bc(1)
always exits and returns \f[B]4\f[R], no matter what mode bc(1) is in.
.PP
The other statuses will only be returned when bc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
bc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Per the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, bc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, bc(1) turns on \[lq]TTY mode.\[rq]
.PP
TTY mode is required for history to be enabled (see the \f[B]COMMAND
LINE HISTORY\f[R] section).
It is also required to enable special handling for \f[B]SIGINT\f[R]
signals.
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause bc(1) to stop execution of the
current input.
If bc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If bc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If bc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to bc(1) as it is
executing a file, it can seem as though bc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause bc(1) to clean up and
exit, and it uses the default handler for all other signals.
The one exception is \f[B]SIGHUP\f[R]; in that case, when bc(1) is in
TTY mode, a \f[B]SIGHUP\f[R] will cause bc(1) to clean up and exit.
.SH COMMAND LINE HISTORY
.PP
bc(1) supports interactive command-line editing.
If bc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), history is
enabled.
Previous lines can be recalled and edited with the arrow keys.
.PP
\f[B]Note\f[R]: tabs are converted to 8 spaces.
.SH SEE ALSO
.PP
dc(1)
.SH STANDARDS
.PP
bc(1) is compliant with the IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
The flags \f[B]-efghiqsvVw\f[R], all long options, and the extensions
noted above are extensions to that specification.
.PP
Note that the specification explicitly says that bc(1) only accepts
numbers that use a period (\f[B].\f[R]) as a radix point, regardless of
the value of \f[B]LC_NUMERIC\f[R].
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHORS
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/bc/NP.1.md b/contrib/bc/manuals/bc/NP.1.md
index b948badbf5e7..4aa6923b7494 100644
--- a/contrib/bc/manuals/bc/NP.1.md
+++ b/contrib/bc/manuals/bc/NP.1.md
@@ -1,1682 +1,1691 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# NAME
bc - arbitrary-precision decimal arithmetic language and calculator
# SYNOPSIS
**bc** [**-ghilPqsvVw**] [**--global-stacks**] [**--help**] [**--interactive**] [**--mathlib**] [**--no-prompt**] [**--quiet**] [**--standard**] [**--warn**] [**--version**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...]
[*file*...]
# DESCRIPTION
bc(1) is an interactive processor for a language first standardized in 1991 by
POSIX. (The current standard is [here][1].) The language provides unlimited
precision decimal arithmetic and is somewhat C-like, but there are differences.
Such differences will be noted in this document.
After parsing and handling options, this bc(1) reads any files given on the
command line and executes them before reading from **stdin**.
This bc(1) is a drop-in replacement for *any* bc(1), including (and
especially) the GNU bc(1). It also has many extensions and extra features beyond
other implementations.
# OPTIONS
The following are the options that bc(1) accepts.
**-g**, **--global-stacks**
: Turns the globals **ibase**, **obase**, **scale**, and **seed** into stacks.
This has the effect that a copy of the current value of all four are pushed
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
(**Note**: the function **output(x,b)** exists in the extended math library.
See the **LIBRARY** section.)
However, since using this flag means that functions cannot set **ibase**,
**obase**, **scale**, or **seed** globally, functions that are made to do so
cannot work anymore. There are two possible use cases for that, and each has
a solution.
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o="bc -e ibase=A -e obase=8"
alias h2b="bc -e ibase=G -e obase=2"
Second, if the purpose of a function is to set **ibase**, **obase**,
**scale**, or **seed** globally for any other purpose, it could be split
into one to four functions (based on how many globals it sets) and each of
those functions could return the desired value for a global.
For functions that set **seed**, the value assigned to **seed** is not
propagated to parent functions. This means that the sequence of
pseudo-random numbers that they see will not be the same sequence of
pseudo-random numbers that any parent sees. This is only the case once
**seed** has been set.
If a function desires to not affect the sequence of pseudo-random numbers
of its parents, but wants to use the same **seed**, it can use the following
line:
seed = seed
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
**-h**, **--help**
: Prints a usage message and quits.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-l**, **--mathlib**
: Sets **scale** (see the **SYNTAX** section) to **20** and loads the included
math library and the extended math library before running any code,
including any expressions or files specified on the command line.
To learn what is in the libraries, see the **LIBRARY** section.
**-P**, **--no-prompt**
: This option is a no-op.
This is a **non-portable extension**.
**-q**, **--quiet**
: This option is for compatibility with the [GNU bc(1)][2]; it is a no-op.
Without this option, GNU bc(1) prints a copyright header. This bc(1) only
prints the copyright header if one or more of the **-v**, **-V**, or
**--version** options are given.
This is a **non-portable extension**.
**-s**, **--standard**
: Process exactly the language defined by the [standard][1] and error if any
extensions are used.
This is a **non-portable extension**.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
This is a **non-portable extension**.
**-w**, **--warn**
: Like **-s** and **--standard**, except that warnings (and not errors) are
printed for non-standard extensions and execution continues normally.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **BC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **bc <file> >&-**, it will quit with an error. This
is done so that bc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **bc <file> 2>&-**, it will quit with an error. This
is done so that bc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
The syntax for bc(1) programs is mostly C-like, with some differences. This
bc(1) follows the [POSIX standard][1], which is a much more thorough resource
for the language this bc(1) accepts. This section is meant to be a summary and a
listing of all the extensions to the standard.
In the sections below, **E** means expression, **S** means statement, and **I**
means identifier.
Identifiers (**I**) start with a lowercase letter and can be followed by any
number (up to **BC_NAME_MAX-1**) of lowercase letters (**a-z**), digits
(**0-9**), and underscores (**\_**). The regex is **\[a-z\]\[a-z0-9\_\]\***.
Identifiers with more than one character (letter) are a
**non-portable extension**.
**ibase** is a global variable determining how to interpret constant numbers. It
is the "input" base, or the number base used for interpreting input numbers.
**ibase** is initially **10**. If the **-s** (**--standard**) and **-w**
(**--warn**) flags were not given on the command line, the max allowable value
for **ibase** is **36**. Otherwise, it is **16**. The min allowable value for
**ibase** is **2**. The max allowable value for **ibase** can be queried in
bc(1) programs with the **maxibase()** built-in function.
**obase** is a global variable determining how to output results. It is the
"output" base, or the number base used for outputting numbers. **obase** is
initially **10**. The max allowable value for **obase** is **BC_BASE_MAX** and
can be queried in bc(1) programs with the **maxobase()** built-in function. The
min allowable value for **obase** is **0**. If **obase** is **0**, values are
output in scientific notation, and if **obase** is **1**, values are output in
engineering notation. Otherwise, values are output in the specified base.
Outputting in scientific and engineering notations are **non-portable
extensions**.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a global variable that
sets the precision of any operations, with exceptions. **scale** is initially
**0**. **scale** cannot be negative. The max allowable value for **scale** is
**BC_SCALE_MAX** and can be queried in bc(1) programs with the **maxscale()**
built-in function.
bc(1) has both *global* variables and *local* variables. All *local*
variables are local to the function; they are parameters or are introduced in
the **auto** list of a function (see the **FUNCTIONS** section). If a variable
is accessed which is not a parameter or in the **auto** list, it is assumed to
be *global*. If a parent function has a *local* variable version of a variable
that a child function considers *global*, the value of that *global* variable in
the child function is the value of the variable in the parent function, not the
value of the actual *global* variable.
All of the above applies to arrays as well.
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence operator is an
assignment operator *and* the expression is notsurrounded by parentheses.
The value that is printed is also assigned to the special variable **last**. A
single dot (**.**) may also be used as a synonym for **last**. These are
**non-portable extensions**.
Either semicolons or newlines may separate statements.
## Comments
There are two kinds of comments:
1. Block comments are enclosed in **/\*** and **\*/**.
2. Line comments go from **#** until, and not including, the next newline. This
is a **non-portable extension**.
## Named Expressions
The following are named expressions in bc(1):
1. Variables: **I**
2. Array Elements: **I[E]**
3. **ibase**
4. **obase**
5. **scale**
6. **seed**
7. **last** or a single dot (**.**)
Numbers 6 and 7 are **non-portable extensions**.
The meaning of **seed** is dependent on the current pseudo-random number
generator but is guaranteed to not change except for new major versions.
The *scale* and sign of the value may be significant.
If a previously used **seed** value is assigned to **seed** and used again, the
pseudo-random number generator is guaranteed to produce the same sequence of
pseudo-random numbers as it did when the **seed** value was previously used.
The exact value assigned to **seed** is not guaranteed to be returned if
**seed** is queried again immediately. However, if **seed** *does* return a
different value, both values, when assigned to **seed**, are guaranteed to
produce the same sequence of pseudo-random numbers. This means that certain
values assigned to **seed** will *not* produce unique sequences of pseudo-random
numbers. The value of **seed** will change after any use of the **rand()** and
**irand(E)** operands (see the *Operands* subsection below), except if the
parameter passed to **irand(E)** is **0**, **1**, or negative.
There is no limit to the length (number of significant decimal digits) or
*scale* of the value that can be assigned to **seed**.
Variables and arrays do not interfere; users can have arrays named the same as
variables. This also applies to functions (see the **FUNCTIONS** section), so a
user can have a variable, array, and function that all have the same name, and
they will not shadow each other, whether inside of functions or not.
Named expressions are required as the operand of **increment**/**decrement**
operators and as the left side of **assignment** operators (see the *Operators*
subsection).
## Operands
The following are valid operands in bc(1):
1. Numbers (see the *Numbers* subsection below).
2. Array indices (**I[E]**).
3. **(E)**: The value of **E** (used to change precedence).
4. **sqrt(E)**: The square root of **E**. **E** must be non-negative.
5. **length(E)**: The number of significant decimal digits in **E**.
6. **length(I[])**: The number of elements in the array **I**. This is a
**non-portable extension**.
7. **scale(E)**: The *scale* of **E**.
8. **abs(E)**: The absolute value of **E**. This is a **non-portable
extension**.
9. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a non-**void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
10. **read()**: Reads a line from **stdin** and uses that as an expression. The
result of that expression is the result of the **read()** operand. This is a
**non-portable extension**.
11. **maxibase()**: The max allowable **ibase**. This is a **non-portable
extension**.
12. **maxobase()**: The max allowable **obase**. This is a **non-portable
extension**.
13. **maxscale()**: The max allowable **scale**. This is a **non-portable
extension**.
14. **rand()**: A pseudo-random integer between **0** (inclusive) and
**BC_RAND_MAX** (inclusive). Using this operand will change the value of
**seed**. This is a **non-portable extension**.
15. **irand(E)**: A pseudo-random integer between **0** (inclusive) and the
value of **E** (exclusive). If **E** is negative or is a non-integer
(**E**'s *scale* is not **0**), an error is raised, and bc(1) resets (see
the **RESET** section) while **seed** remains unchanged. If **E** is larger
than **BC_RAND_MAX**, the higher bound is honored by generating several
pseudo-random integers, multiplying them by appropriate powers of
**BC_RAND_MAX+1**, and adding them together. Thus, the size of integer that
can be generated with this operand is unbounded. Using this operand will
change the value of **seed**, unless the value of **E** is **0** or **1**.
In that case, **0** is returned, and **seed** is *not* changed. This is a
**non-portable extension**.
16. **maxrand()**: The max integer returned by **rand()**. This is a
**non-portable extension**.
The integers generated by **rand()** and **irand(E)** are guaranteed to be as
unbiased as possible, subject to the limitations of the pseudo-random number
generator.
**Note**: The values returned by the pseudo-random number generator with
**rand()** and **irand(E)** are guaranteed to *NOT* be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator. However,
they *are* guaranteed to be reproducible with identical **seed** values. This
means that the pseudo-random values from bc(1) should only be used where a
reproducible stream of pseudo-random numbers is *ESSENTIAL*. In any other case,
use a non-seeded pseudo-random number generator.
## Numbers
Numbers are strings made up of digits, uppercase letters, and at most **1**
period for a radix. Numbers can have up to **BC_NUM_MAX** digits. Uppercase
letters are equal to **9** + their position in the alphabet (i.e., **A** equals
**10**, or **9+1**). If a digit or letter makes no sense with the current value
of **ibase**, they are set to the value of the highest valid digit in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **Z** alone always equals decimal
**35**.
In addition, bc(1) accepts numbers in scientific notation. These have the form
**\<number\>e\<integer\>**. The exponent (the portion after the **e**) must be
an integer. An example is **1.89237e9**, which is equal to **1892370000**.
Negative exponents are also allowed, so **4.2890e-3** is equal to **0.0042890**.
Using scientific notation is an error or warning if the **-s** or **-w**,
respectively, command-line options (or equivalents) are given.
**WARNING**: Both the number and the exponent in scientific notation are
interpreted according to the current **ibase**, but the number is still
multiplied by **10\^exponent** regardless of the current **ibase**. For example,
if **ibase** is **16** and bc(1) is given the number string **FFeA**, the
resulting decimal number will be **2550000000000**, and if bc(1) is given the
number string **10e-4**, the resulting decimal number will be **0.0016**.
Accepting input as scientific notation is a **non-portable extension**.
## Operators
The following arithmetic and logical operators can be used. They are listed in
order of decreasing precedence. Operators in the same group have the same
precedence.
**++** **--**
: Type: Prefix and Postfix
Associativity: None
Description: **increment**, **decrement**
**-** **!**
: Type: Prefix
Associativity: None
Description: **negation**, **boolean not**
**\$**
: Type: Postfix
Associativity: None
Description: **truncation**
**\@**
: Type: Binary
Associativity: Right
Description: **set precision**
**\^**
: Type: Binary
Associativity: Right
Description: **power**
**\*** **/** **%**
: Type: Binary
Associativity: Left
Description: **multiply**, **divide**, **modulus**
**+** **-**
: Type: Binary
Associativity: Left
Description: **add**, **subtract**
**\<\<** **\>\>**
: Type: Binary
Associativity: Left
Description: **shift left**, **shift right**
**=** **\<\<=** **\>\>=** **+=** **-=** **\*=** **/=** **%=** **\^=** **\@=**
: Type: Binary
Associativity: Right
Description: **assignment**
**==** **\<=** **\>=** **!=** **\<** **\>**
: Type: Binary
Associativity: Left
Description: **relational**
**&&**
: Type: Binary
Associativity: Left
Description: **boolean and**
**||**
: Type: Binary
Associativity: Left
Description: **boolean or**
The operators will be described in more detail below.
**++** **--**
: The prefix and postfix **increment** and **decrement** operators behave
exactly like they would in C. They require a named expression (see the
*Named Expressions* subsection) as an operand.
The prefix versions of these operators are more efficient; use them where
possible.
**-**
: The **negation** operator returns **0** if a user attempts to negate any
expression with the value **0**. Otherwise, a copy of the expression with
its sign flipped is returned.
**!**
: The **boolean not** operator returns **1** if the expression is **0**, or
**0** otherwise.
This is a **non-portable extension**.
**\$**
: The **truncation** operator returns a copy of the given expression with all
of its *scale* removed.
This is a **non-portable extension**.
**\@**
: The **set precision** operator takes two expressions and returns a copy of
the first with its *scale* equal to the value of the second expression. That
could either mean that the number is returned without change (if the
*scale* of the first expression matches the value of the second
expression), extended (if it is less), or truncated (if it is more).
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**\^**
: The **power** operator (not the **exclusive or** operator, as it would be in
C) takes two expressions and raises the first to the power of the value of
the second. The *scale* of the result is equal to **scale**.
The second expression must be an integer (no *scale*), and if it is
negative, the first value must be non-zero.
**\***
: The **multiply** operator takes two expressions, multiplies them, and
returns the product. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result is
equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The **divide** operator takes two expressions, divides them, and returns the
quotient. The *scale* of the result shall be the value of **scale**.
The second expression must be non-zero.
**%**
: The **modulus** operator takes two expressions, **a** and **b**, and
evaluates them by 1) Computing **a/b** to current **scale** and 2) Using the
result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The second expression must be non-zero.
**+**
: The **add** operator takes two expressions, **a** and **b**, and returns the
sum, with a *scale* equal to the max of the *scale*s of **a** and **b**.
**-**
: The **subtract** operator takes two expressions, **a** and **b**, and
returns the difference, with a *scale* equal to the max of the *scale*s of
**a** and **b**.
**\<\<**
: The **left shift** operator takes two expressions, **a** and **b**, and
returns a copy of the value of **a** with its decimal point moved **b**
places to the right.
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**\>\>**
: The **right shift** operator takes two expressions, **a** and **b**, and
returns a copy of the value of **a** with its decimal point moved **b**
places to the left.
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**=** **\<\<=** **\>\>=** **+=** **-=** **\*=** **/=** **%=** **\^=** **\@=**
: The **assignment** operators take two expressions, **a** and **b** where
**a** is a named expression (see the *Named Expressions* subsection).
For **=**, **b** is copied and the result is assigned to **a**. For all
others, **a** and **b** are applied as operands to the corresponding
arithmetic operator and the result is assigned to **a**.
The **assignment** operators that correspond to operators that are
extensions are themselves **non-portable extensions**.
**==** **\<=** **\>=** **!=** **\<** **\>**
: The **relational** operators compare two expressions, **a** and **b**, and
if the relation holds, according to C language semantics, the result is
**1**. Otherwise, it is **0**.
Note that unlike in C, these operators have a lower precedence than the
**assignment** operators, which means that **a=b\>c** is interpreted as
**(a=b)\>c**.
Also, unlike the [standard][1] requires, these operators can appear anywhere
any other expressions can be used. This allowance is a
**non-portable extension**.
**&&**
: The **boolean and** operator takes two expressions and returns **1** if both
expressions are non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
**||**
: The **boolean or** operator takes two expressions and returns **1** if one
of the expressions is non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
## Statements
The following items are statements:
1. **E**
2. **{** **S** **;** ... **;** **S** **}**
3. **if** **(** **E** **)** **S**
4. **if** **(** **E** **)** **S** **else** **S**
5. **while** **(** **E** **)** **S**
6. **for** **(** **E** **;** **E** **;** **E** **)** **S**
7. An empty statement
8. **break**
9. **continue**
10. **quit**
11. **halt**
12. **limits**
13. A string of characters, enclosed in double quotes
14. **print** **E** **,** ... **,** **E**
15. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
Numbers 4, 9, 11, 12, 14, and 15 are **non-portable extensions**.
Also, as a **non-portable extension**, any or all of the expressions in the
header of a for loop may be omitted. If the condition (second expression) is
omitted, it is assumed to be a constant **1**.
The **break** statement causes a loop to stop iterating and resume execution
immediately following a loop. This is only allowed in loops.
The **continue** statement causes a loop iteration to stop early and returns to
the start of the loop, including testing the loop condition. This is only
allowed in loops.
The **if** **else** statement does the same thing as in C.
The **quit** statement causes bc(1) to quit, even if it is on a branch that will
not be executed (it is a compile-time command).
The **halt** statement causes bc(1) to quit, if it is executed. (Unlike **quit**
if it is on a branch of an **if** statement that is not executed, bc(1) does not
quit.)
The **limits** statement prints the limits that this bc(1) is subject to. This
is like the **quit** statement in that it is a compile-time command.
An expression by itself is evaluated and printed, followed by a newline.
Both scientific notation and engineering notation are available for printing the
results of expressions. Scientific notation is activated by assigning **0** to
**obase**, and engineering notation is activated by assigning **1** to
**obase**. To deactivate them, just assign a different value to **obase**.
Scientific notation and engineering notation are disabled if bc(1) is run with
either the **-s** or **-w** command-line options (or equivalents).
Printing numbers in scientific notation and/or engineering notation is a
**non-portable extension**.
## Print Statement
The "expressions" in a **print** statement may also be strings. If they are, there
are backslash escape sequences that are interpreted specially. What those
sequences are, and what they cause to be printed, are shown below:
-------- -------
**\\a** **\\a**
**\\b** **\\b**
**\\\\** **\\**
**\\e** **\\**
**\\f** **\\f**
**\\n** **\\n**
**\\q** **"**
**\\r** **\\r**
**\\t** **\\t**
-------- -------
Any other character following a backslash causes the backslash and character to
be printed as-is.
Any non-string expression in a print statement shall be assigned to **last**,
like any other expression that is printed.
## Order of Evaluation
All expressions in a statment are evaluated left to right, except as necessary
to maintain order of operations. This means, for example, assuming that **i** is
equal to **0**, in the expression
a[i++] = i++
the first (or 0th) element of **a** is set to **1**, and **i** is equal to **2**
at the end of the expression.
This includes function arguments. Thus, assuming **i** is equal to **0**, this
means that in the expression
x(i++, i++)
the first argument passed to **x()** is **0**, and the second argument is **1**,
while **i** is equal to **2** before the function starts executing.
# FUNCTIONS
Function definitions are as follows:
```
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
```
Any **I** in the parameter list or **auto** list may be replaced with **I[]** to
make a parameter or **auto** var an array, and any **I** in the parameter list
may be replaced with **\*I[]** to make a parameter an array reference. Callers
of functions that take array references should not put an asterisk in the call;
they must be called with just **I[]** like normal array parameters and will be
automatically converted into references.
As a **non-portable extension**, the opening brace of a **define** statement may
appear on the next line.
As a **non-portable extension**, the return statement may also be in one of the
following forms:
1. **return**
2. **return** **(** **)**
3. **return** **E**
The first two, or not specifying a **return** statement, is equivalent to
**return (0)**, unless the function is a **void** function (see the *Void
Functions* subsection below).
## Void Functions
Functions can also be **void** functions, defined as follows:
```
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
```
They can only be used as standalone expressions, where such an expression would
be printed alone, except in a print statement.
Void functions can only use the first two **return** statements listed above.
They can also omit the return statement entirely.
The word "void" is not treated as a keyword; it is still possible to have
variables, arrays, and functions named **void**. The word "void" is only
treated specially right after the **define** keyword.
This is a **non-portable extension**.
## Array References
For any array in the parameter list, if the array is declared in the form
```
*I[]
```
it is a **reference**. Any changes to the array in the function are reflected,
when the function returns, to the array that was passed in.
Other than this, all function arguments are passed by value.
This is a **non-portable extension**.
# LIBRARY
All of the functions below, including the functions in the extended math
library (see the *Extended Library* subsection below), are available when the
**-l** or **--mathlib** command-line flags are given, except that the extended
math library is not available when the **-s** option, the **-w** option, or
equivalents are given.
## Standard Library
The [standard][1] defines the following functions for the math library:
**s(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**c(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a(x)**
: Returns the arctangent of **x**, in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l(x)**
: Returns the natural logarithm of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**e(x)**
: Returns the mathematical constant **e** raised to the power of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**j(x, n)**
: Returns the bessel integer order **n** (truncated) of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
## Extended Library
The extended library is *not* loaded when the **-s**/**--standard** or
**-w**/**--warn** options are given since they are not part of the library
defined by the [standard][1].
The extended library is a **non-portable extension**.
**p(x, y)**
: Calculates **x** to the power of **y**, even if **y** is not an integer, and
returns the result to the current **scale**.
It is an error if **y** is negative and **x** is **0**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**r(x, p)**
: Returns **x** rounded to **p** decimal places according to the rounding mode
[round half away from **0**][3].
**ceil(x, p)**
: Returns **x** rounded to **p** decimal places according to the rounding mode
[round away from **0**][6].
**f(x)**
: Returns the factorial of the truncated absolute value of **x**.
**perm(n, k)**
: Returns the permutation of the truncated absolute value of **n** of the
truncated absolute value of **k**, if **k \<= n**. If not, it returns **0**.
**comb(n, k)**
: Returns the combination of the truncated absolute value of **n** of the
truncated absolute value of **k**, if **k \<= n**. If not, it returns **0**.
**l2(x)**
: Returns the logarithm base **2** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l10(x)**
: Returns the logarithm base **10** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**log(x, b)**
: Returns the logarithm base **b** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**cbrt(x)**
: Returns the cube root of **x**.
**root(x, n)**
: Calculates the truncated value of **n**, **r**, and returns the **r**th root
of **x** to the current **scale**.
If **r** is **0** or negative, this raises an error and causes bc(1) to
reset (see the **RESET** section). It also raises an error and causes bc(1)
to reset if **r** is even and **x** is negative.
**pi(p)**
: Returns **pi** to **p** decimal places.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**t(x)**
: Returns the tangent of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a2(y, x)**
: Returns the arctangent of **y/x**, in radians. If both **y** and **x** are
equal to **0**, it raises an error and causes bc(1) to reset (see the
**RESET** section). Otherwise, if **x** is greater than **0**, it returns
**a(y/x)**. If **x** is less than **0**, and **y** is greater than or equal
to **0**, it returns **a(y/x)+pi**. If **x** is less than **0**, and **y**
is less than **0**, it returns **a(y/x)-pi**. If **x** is equal to **0**,
and **y** is greater than **0**, it returns **pi/2**. If **x** is equal to
**0**, and **y** is less than **0**, it returns **-pi/2**.
This function is the same as the **atan2()** function in many programming
languages.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**sin(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is an alias of **s(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**cos(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is an alias of **c(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**tan(x)**
: Returns the tangent of **x**, which is assumed to be in radians.
If **x** is equal to **1** or **-1**, this raises an error and causes bc(1)
to reset (see the **RESET** section).
This is an alias of **t(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**atan(x)**
: Returns the arctangent of **x**, in radians.
This is an alias of **a(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**atan2(y, x)**
: Returns the arctangent of **y/x**, in radians. If both **y** and **x** are
equal to **0**, it raises an error and causes bc(1) to reset (see the
**RESET** section). Otherwise, if **x** is greater than **0**, it returns
**a(y/x)**. If **x** is less than **0**, and **y** is greater than or equal
to **0**, it returns **a(y/x)+pi**. If **x** is less than **0**, and **y**
is less than **0**, it returns **a(y/x)-pi**. If **x** is equal to **0**,
and **y** is greater than **0**, it returns **pi/2**. If **x** is equal to
**0**, and **y** is less than **0**, it returns **-pi/2**.
This function is the same as the **atan2()** function in many programming
languages.
This is an alias of **a2(y, x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**r2d(x)**
: Converts **x** from radians to degrees and returns the result.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**d2r(x)**
: Converts **x** from degrees to radians and returns the result.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**frand(p)**
: Generates a pseudo-random number between **0** (inclusive) and **1**
(exclusive) with the number of decimal digits after the decimal point equal
to the truncated absolute value of **p**. If **p** is not **0**, then
calling this function will change the value of **seed**. If **p** is **0**,
then **0** is returned, and **seed** is *not* changed.
**ifrand(i, p)**
: Generates a pseudo-random number that is between **0** (inclusive) and the
truncated absolute value of **i** (exclusive) with the number of decimal
digits after the decimal point equal to the truncated absolute value of
**p**. If the absolute value of **i** is greater than or equal to **2**, and
**p** is not **0**, then calling this function will change the value of
**seed**; otherwise, **0** is returned and **seed** is not changed.
**srand(x)**
: Returns **x** with its sign flipped with probability **0.5**. In other
words, it randomizes the sign of **x**.
**brand()**
: Returns a random boolean value (either **0** or **1**).
**ubytes(x)**
: Returns the numbers of unsigned integer bytes required to hold the truncated
absolute value of **x**.
**sbytes(x)**
: Returns the numbers of signed, two's-complement integer bytes required to
hold the truncated value of **x**.
**hex(x)**
: Outputs the hexadecimal (base **16**) representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**binary(x)**
: Outputs the binary (base **2**) representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output(x, b)**
: Outputs the base **b** representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in as few power of two bytes as possible. Both outputs are
split into bytes separated by spaces.
If **x** is not an integer or is negative, an error message is printed
instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in as few power of two bytes as possible. Both
outputs are split into bytes separated by spaces.
If **x** is not an integer, an error message is printed instead, but bc(1)
is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uintn(x, n)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **n** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **n** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**intn(x, n)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **n** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **n** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint8(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **1** byte. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **1** byte, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int8(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **1** byte. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **1** byte, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint16(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **2** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **2** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int16(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **2** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **2** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint32(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **4** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **4** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int32(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **4** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **4** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint64(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **8** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **8** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int64(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **8** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **8** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**hex_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in hexadecimal using **n** bytes. Not all of the value will
be output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**binary_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in binary using **n** bytes. Not all of the value will be
output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in the current **obase** (see the **SYNTAX** section) using
**n** bytes. Not all of the value will be output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output_byte(x, i)**
: Outputs byte **i** of the truncated absolute value of **x**, where **0** is
the least significant byte and **number_of_bytes - 1** is the most
significant byte.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
## Transcendental Functions
All transcendental functions can return slightly inaccurate results (up to 1
[ULP][4]). This is unavoidable, and [this article][5] explains why it is
impossible and unnecessary to calculate exact results for the transcendental
functions.
Because of the possible inaccuracy, I recommend that users call those functions
with the precision (**scale**) set to at least 1 higher than is necessary. If
exact results are *absolutely* required, users can double the precision
(**scale**) and then truncate.
The transcendental functions in the standard math library are:
* **s(x)**
* **c(x)**
* **a(x)**
* **l(x)**
* **e(x)**
* **j(x, n)**
The transcendental functions in the extended math library are:
* **l2(x)**
* **l10(x)**
* **log(x, b)**
* **pi(p)**
* **t(x)**
* **a2(y, x)**
* **sin(x)**
* **cos(x)**
* **tan(x)**
* **atan(x)**
* **atan2(y, x)**
* **r2d(x)**
* **d2r(x)**
# RESET
When bc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any functions that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
functions returned) is skipped.
Thus, when bc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
Note that this reset behavior is different from the GNU bc(1), which attempts to
start executing the statement right after the one that caused an error.
# PERFORMANCE
Most bc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This bc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **BC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **BC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**BC_BASE_DIGS**.
The actual values of **BC_LONG_BIT** and **BC_BASE_DIGS** can be queried with
the **limits** statement.
In addition, this bc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **BC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on bc(1):
**BC_LONG_BIT**
: The number of bits in the **long** type in the environment where bc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**BC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **BC_LONG_BIT**.
**BC_BASE_POW**
: The max decimal number that each large integer can store (see
**BC_BASE_DIGS**) plus **1**. Depends on **BC_BASE_DIGS**.
**BC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **BC_LONG_BIT**.
**BC_BASE_MAX**
: The maximum output base. Set at **BC_BASE_POW**.
**BC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**BC_SCALE_MAX**
: The maximum **scale**. Set at **BC_OVERFLOW_MAX-1**.
**BC_STRING_MAX**
: The maximum length of strings. Set at **BC_OVERFLOW_MAX-1**.
**BC_NAME_MAX**
: The maximum length of identifiers. Set at **BC_OVERFLOW_MAX-1**.
**BC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **BC_OVERFLOW_MAX-1**.
**BC_RAND_MAX**
: The maximum integer (inclusive) returned by the **rand()** operand. Set at
**2\^BC_LONG_BIT-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**BC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
The actual values can be queried with the **limits** statement.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
bc(1) recognizes the following environment variables:
**POSIXLY_CORRECT**
: If this variable exists (no matter the contents), bc(1) behaves as if
the **-s** option was given.
**BC_ENV_ARGS**
: This is another way to give command-line arguments to bc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **BC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
The code that parses **BC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some bc file.bc"** will be correctly parsed, but the string
**"/home/gavin/some \"bc\" file.bc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **BC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**BC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), bc(1) will output
lines to that length, including the backslash (**\\**). The default line
length is **70**.
# EXIT STATUS
bc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, using a negative number as a bound for the pseudo-random number
generator, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**), places (**\@**), left shift (**\<\<**), and right shift (**\>\>**)
operators and their corresponding assignment operators.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, using a token where it is invalid,
giving an invalid expression, giving an invalid print statement, giving an
invalid function definition, attempting to assign to an expression that is
not a named expression (see the *Named Expressions* subsection of the
**SYNTAX** section), giving an invalid **auto** list, having a duplicate
**auto**/function parameter, failing to find the end of a code block,
attempting to return a value from a **void** function, attempting to use a
variable as a reference, and using any extensions when the option **-s** or
any equivalents were given.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a **void** function call as a value in an expression.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (bc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, bc(1) always exits
and returns **4**, no matter what mode bc(1) is in.
The other statuses will only be returned when bc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since bc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Per the [standard][1], bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, bc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, bc(1) turns
on "TTY mode."
TTY mode is required for history to be enabled (see the **COMMAND LINE HISTORY**
section). It is also required to enable special handling for **SIGINT** signals.
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause bc(1) to stop execution of the current input. If
bc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If bc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If bc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to bc(1) as it is executing a file, it
can seem as though bc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause bc(1) to clean up and exit, and it uses the
default handler for all other signals. The one exception is **SIGHUP**; in that
case, when bc(1) is in TTY mode, a **SIGHUP** will cause bc(1) to clean up and
exit.
# COMMAND LINE HISTORY
bc(1) supports interactive command-line editing. If bc(1) is in TTY mode (see
the **TTY MODE** section), history is enabled. Previous lines can be recalled
and edited with the arrow keys.
**Note**: tabs are converted to 8 spaces.
# SEE ALSO
dc(1)
# STANDARDS
bc(1) is compliant with the [IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1]
specification. The flags **-efghiqsvVw**, all long options, and the extensions
noted above are extensions to that specification.
Note that the specification explicitly says that bc(1) only accepts numbers that
use a period (**.**) as a radix point, regardless of the value of
**LC_NUMERIC**.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHORS
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
[2]: https://www.gnu.org/software/bc/
[3]: https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero
[4]: https://en.wikipedia.org/wiki/Unit_in_the_last_place
[5]: https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT
[6]: https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero
diff --git a/contrib/bc/manuals/bc/P.1 b/contrib/bc/manuals/bc/P.1
index 24fd54bcfecc..dc59aa11d961 100644
--- a/contrib/bc/manuals/bc/P.1
+++ b/contrib/bc/manuals/bc/P.1
@@ -1,2038 +1,2051 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "BC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "BC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH NAME
.PP
bc - arbitrary-precision decimal arithmetic language and calculator
.SH SYNOPSIS
.PP
\f[B]bc\f[R] [\f[B]-ghilPqsvVw\f[R]] [\f[B]\[en]global-stacks\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]mathlib\f[R]] [\f[B]\[en]no-prompt\f[R]]
[\f[B]\[en]quiet\f[R]] [\f[B]\[en]standard\f[R]] [\f[B]\[en]warn\f[R]]
[\f[B]\[en]version\f[R]] [\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
bc(1) is an interactive processor for a language first standardized in
1991 by POSIX.
(The current standard is
here (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).)
The language provides unlimited precision decimal arithmetic and is
somewhat C-like, but there are differences.
Such differences will be noted in this document.
.PP
After parsing and handling options, this bc(1) reads any files given on
the command line and executes them before reading from \f[B]stdin\f[R].
.PP
This bc(1) is a drop-in replacement for \f[I]any\f[R] bc(1), including
(and especially) the GNU bc(1).
It also has many extensions and extra features beyond other
implementations.
.SH OPTIONS
.PP
The following are the options that bc(1) accepts.
.TP
\f[B]-g\f[R], \f[B]\[en]global-stacks\f[R]
Turns the globals \f[B]ibase\f[R], \f[B]obase\f[R], \f[B]scale\f[R], and
\f[B]seed\f[R] into stacks.
.RS
.PP
This has the effect that a copy of the current value of all four are
pushed onto a stack for every function call, as well as popped when
every function returns.
This means that functions can assign to any and all of those globals
without worrying that the change will affect other functions.
Thus, a hypothetical function named \f[B]output(x,b)\f[R] that simply
printed \f[B]x\f[R] in base \f[B]b\f[R] could be written like this:
.IP
.nf
\f[C]
define void output(x, b) {
obase=b
x
}
\f[R]
.fi
.PP
instead of like this:
.IP
.nf
\f[C]
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
\f[R]
.fi
.PP
This makes writing functions much easier.
.PP
(\f[B]Note\f[R]: the function \f[B]output(x,b)\f[R] exists in the
extended math library.
See the \f[B]LIBRARY\f[R] section.)
.PP
However, since using this flag means that functions cannot set
\f[B]ibase\f[R], \f[B]obase\f[R], \f[B]scale\f[R], or \f[B]seed\f[R]
globally, functions that are made to do so cannot work anymore.
There are two possible use cases for that, and each has a solution.
.PP
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases.
Examples:
.IP
.nf
\f[C]
alias d2o=\[dq]bc -e ibase=A -e obase=8\[dq]
alias h2b=\[dq]bc -e ibase=G -e obase=2\[dq]
\f[R]
.fi
.PP
Second, if the purpose of a function is to set \f[B]ibase\f[R],
\f[B]obase\f[R], \f[B]scale\f[R], or \f[B]seed\f[R] globally for any
other purpose, it could be split into one to four functions (based on
how many globals it sets) and each of those functions could return the
desired value for a global.
.PP
For functions that set \f[B]seed\f[R], the value assigned to
\f[B]seed\f[R] is not propagated to parent functions.
This means that the sequence of pseudo-random numbers that they see will
not be the same sequence of pseudo-random numbers that any parent sees.
This is only the case once \f[B]seed\f[R] has been set.
.PP
If a function desires to not affect the sequence of pseudo-random
numbers of its parents, but wants to use the same \f[B]seed\f[R], it can
use the following line:
.IP
.nf
\f[C]
seed = seed
\f[R]
.fi
.PP
If the behavior of this option is desired for every run of bc(1), then
users could make sure to define \f[B]BC_ENV_ARGS\f[R] and include this
option (see the \f[B]ENVIRONMENT VARIABLES\f[R] section for more
details).
.PP
If \f[B]-s\f[R], \f[B]-w\f[R], or any equivalents are used, this option
is ignored.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-l\f[R], \f[B]\[en]mathlib\f[R]
Sets \f[B]scale\f[R] (see the \f[B]SYNTAX\f[R] section) to \f[B]20\f[R]
and loads the included math library and the extended math library before
running any code, including any expressions or files specified on the
command line.
.RS
.PP
To learn what is in the libraries, see the \f[B]LIBRARY\f[R] section.
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
This option is a no-op.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-q\f[R], \f[B]\[en]quiet\f[R]
This option is for compatibility with the GNU
bc(1) (https://www.gnu.org/software/bc/); it is a no-op.
Without this option, GNU bc(1) prints a copyright header.
This bc(1) only prints the copyright header if one or more of the
\f[B]-v\f[R], \f[B]-V\f[R], or \f[B]\[en]version\f[R] options are given.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-s\f[R], \f[B]\[en]standard\f[R]
Process exactly the language defined by the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
and error if any extensions are used.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-w\f[R], \f[B]\[en]warn\f[R]
Like \f[B]-s\f[R] and \f[B]\[en]standard\f[R], except that warnings (and
not errors) are printed for non-standard extensions and execution
continues normally.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]BC_ENV_ARGS\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, bc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]BC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, bc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, bc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]bc >&-\f[R], it will quit with an error.
This is done so that bc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other bc(1) implementations, this bc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]bc 2>&-\f[R], it will quit with an error.
This is done so that bc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other bc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
The syntax for bc(1) programs is mostly C-like, with some differences.
This bc(1) follows the POSIX
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
which is a much more thorough resource for the language this bc(1)
accepts.
This section is meant to be a summary and a listing of all the
extensions to the standard.
.PP
In the sections below, \f[B]E\f[R] means expression, \f[B]S\f[R] means
statement, and \f[B]I\f[R] means identifier.
.PP
Identifiers (\f[B]I\f[R]) start with a lowercase letter and can be
followed by any number (up to \f[B]BC_NAME_MAX-1\f[R]) of lowercase
letters (\f[B]a-z\f[R]), digits (\f[B]0-9\f[R]), and underscores
(\f[B]_\f[R]).
The regex is \f[B][a-z][a-z0-9_]*\f[R].
Identifiers with more than one character (letter) are a
\f[B]non-portable extension\f[R].
.PP
\f[B]ibase\f[R] is a global variable determining how to interpret
constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
If the \f[B]-s\f[R] (\f[B]\[en]standard\f[R]) and \f[B]-w\f[R]
(\f[B]\[en]warn\f[R]) flags were not given on the command line, the max
allowable value for \f[B]ibase\f[R] is \f[B]36\f[R].
Otherwise, it is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in bc(1)
programs with the \f[B]maxibase()\f[R] built-in function.
.PP
\f[B]obase\f[R] is a global variable determining how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]BC_BASE_MAX\f[R] and
can be queried in bc(1) programs with the \f[B]maxobase()\f[R] built-in
function.
The min allowable value for \f[B]obase\f[R] is \f[B]0\f[R].
If \f[B]obase\f[R] is \f[B]0\f[R], values are output in scientific
notation, and if \f[B]obase\f[R] is \f[B]1\f[R], values are output in
engineering notation.
Otherwise, values are output in the specified base.
.PP
Outputting in scientific and engineering notations are \f[B]non-portable
extensions\f[R].
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a global variable that sets the precision of any operations, with
exceptions.
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] is \f[B]BC_SCALE_MAX\f[R]
and can be queried in bc(1) programs with the \f[B]maxscale()\f[R]
built-in function.
.PP
bc(1) has both \f[I]global\f[R] variables and \f[I]local\f[R] variables.
All \f[I]local\f[R] variables are local to the function; they are
parameters or are introduced in the \f[B]auto\f[R] list of a function
(see the \f[B]FUNCTIONS\f[R] section).
If a variable is accessed which is not a parameter or in the
\f[B]auto\f[R] list, it is assumed to be \f[I]global\f[R].
If a parent function has a \f[I]local\f[R] variable version of a
variable that a child function considers \f[I]global\f[R], the value of
that \f[I]global\f[R] variable in the child function is the value of the
variable in the parent function, not the value of the actual
\f[I]global\f[R] variable.
.PP
All of the above applies to arrays as well.
.PP
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence
operator is an assignment operator \f[I]and\f[R] the expression is
notsurrounded by parentheses.
.PP
The value that is printed is also assigned to the special variable
\f[B]last\f[R].
A single dot (\f[B].\f[R]) may also be used as a synonym for
\f[B]last\f[R].
These are \f[B]non-portable extensions\f[R].
.PP
Either semicolons or newlines may separate statements.
.SS Comments
.PP
There are two kinds of comments:
.IP "1." 3
Block comments are enclosed in \f[B]/*\f[R] and \f[B]*/\f[R].
.IP "2." 3
Line comments go from \f[B]#\f[R] until, and not including, the next
newline.
This is a \f[B]non-portable extension\f[R].
.SS Named Expressions
.PP
The following are named expressions in bc(1):
.IP "1." 3
Variables: \f[B]I\f[R]
.IP "2." 3
Array Elements: \f[B]I[E]\f[R]
.IP "3." 3
\f[B]ibase\f[R]
.IP "4." 3
\f[B]obase\f[R]
.IP "5." 3
\f[B]scale\f[R]
.IP "6." 3
\f[B]seed\f[R]
.IP "7." 3
\f[B]last\f[R] or a single dot (\f[B].\f[R])
.PP
Numbers 6 and 7 are \f[B]non-portable extensions\f[R].
.PP
The meaning of \f[B]seed\f[R] is dependent on the current pseudo-random
number generator but is guaranteed to not change except for new major
versions.
.PP
The \f[I]scale\f[R] and sign of the value may be significant.
.PP
If a previously used \f[B]seed\f[R] value is assigned to \f[B]seed\f[R]
and used again, the pseudo-random number generator is guaranteed to
produce the same sequence of pseudo-random numbers as it did when the
\f[B]seed\f[R] value was previously used.
.PP
The exact value assigned to \f[B]seed\f[R] is not guaranteed to be
returned if \f[B]seed\f[R] is queried again immediately.
However, if \f[B]seed\f[R] \f[I]does\f[R] return a different value, both
values, when assigned to \f[B]seed\f[R], are guaranteed to produce the
same sequence of pseudo-random numbers.
This means that certain values assigned to \f[B]seed\f[R] will
\f[I]not\f[R] produce unique sequences of pseudo-random numbers.
The value of \f[B]seed\f[R] will change after any use of the
\f[B]rand()\f[R] and \f[B]irand(E)\f[R] operands (see the
\f[I]Operands\f[R] subsection below), except if the parameter passed to
\f[B]irand(E)\f[R] is \f[B]0\f[R], \f[B]1\f[R], or negative.
.PP
There is no limit to the length (number of significant decimal digits)
or \f[I]scale\f[R] of the value that can be assigned to \f[B]seed\f[R].
.PP
Variables and arrays do not interfere; users can have arrays named the
same as variables.
This also applies to functions (see the \f[B]FUNCTIONS\f[R] section), so
a user can have a variable, array, and function that all have the same
name, and they will not shadow each other, whether inside of functions
or not.
.PP
Named expressions are required as the operand of
\f[B]increment\f[R]/\f[B]decrement\f[R] operators and as the left side
of \f[B]assignment\f[R] operators (see the \f[I]Operators\f[R]
subsection).
.SS Operands
.PP
The following are valid operands in bc(1):
.IP " 1." 4
Numbers (see the \f[I]Numbers\f[R] subsection below).
.IP " 2." 4
Array indices (\f[B]I[E]\f[R]).
.IP " 3." 4
\f[B](E)\f[R]: The value of \f[B]E\f[R] (used to change precedence).
.IP " 4." 4
\f[B]sqrt(E)\f[R]: The square root of \f[B]E\f[R].
\f[B]E\f[R] must be non-negative.
.IP " 5." 4
\f[B]length(E)\f[R]: The number of significant decimal digits in
\f[B]E\f[R].
.IP " 6." 4
\f[B]length(I[])\f[R]: The number of elements in the array \f[B]I\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 7." 4
\f[B]scale(E)\f[R]: The \f[I]scale\f[R] of \f[B]E\f[R].
.IP " 8." 4
\f[B]abs(E)\f[R]: The absolute value of \f[B]E\f[R].
This is a \f[B]non-portable extension\f[R].
.IP " 9." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a non-\f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.IP "10." 4
\f[B]read()\f[R]: Reads a line from \f[B]stdin\f[R] and uses that as an
expression.
The result of that expression is the result of the \f[B]read()\f[R]
operand.
This is a \f[B]non-portable extension\f[R].
.IP "11." 4
\f[B]maxibase()\f[R]: The max allowable \f[B]ibase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "12." 4
\f[B]maxobase()\f[R]: The max allowable \f[B]obase\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "13." 4
\f[B]maxscale()\f[R]: The max allowable \f[B]scale\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "14." 4
\f[B]rand()\f[R]: A pseudo-random integer between \f[B]0\f[R]
(inclusive) and \f[B]BC_RAND_MAX\f[R] (inclusive).
Using this operand will change the value of \f[B]seed\f[R].
This is a \f[B]non-portable extension\f[R].
.IP "15." 4
\f[B]irand(E)\f[R]: A pseudo-random integer between \f[B]0\f[R]
(inclusive) and the value of \f[B]E\f[R] (exclusive).
If \f[B]E\f[R] is negative or is a non-integer (\f[B]E\f[R]\[cq]s
\f[I]scale\f[R] is not \f[B]0\f[R]), an error is raised, and bc(1)
resets (see the \f[B]RESET\f[R] section) while \f[B]seed\f[R] remains
unchanged.
If \f[B]E\f[R] is larger than \f[B]BC_RAND_MAX\f[R], the higher bound is
honored by generating several pseudo-random integers, multiplying them
by appropriate powers of \f[B]BC_RAND_MAX+1\f[R], and adding them
together.
Thus, the size of integer that can be generated with this operand is
unbounded.
Using this operand will change the value of \f[B]seed\f[R], unless the
value of \f[B]E\f[R] is \f[B]0\f[R] or \f[B]1\f[R].
In that case, \f[B]0\f[R] is returned, and \f[B]seed\f[R] is
\f[I]not\f[R] changed.
This is a \f[B]non-portable extension\f[R].
.IP "16." 4
\f[B]maxrand()\f[R]: The max integer returned by \f[B]rand()\f[R].
This is a \f[B]non-portable extension\f[R].
.PP
The integers generated by \f[B]rand()\f[R] and \f[B]irand(E)\f[R] are
guaranteed to be as unbiased as possible, subject to the limitations of
the pseudo-random number generator.
.PP
\f[B]Note\f[R]: The values returned by the pseudo-random number
generator with \f[B]rand()\f[R] and \f[B]irand(E)\f[R] are guaranteed to
\f[I]NOT\f[R] be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator.
However, they \f[I]are\f[R] guaranteed to be reproducible with identical
\f[B]seed\f[R] values.
This means that the pseudo-random values from bc(1) should only be used
where a reproducible stream of pseudo-random numbers is
\f[I]ESSENTIAL\f[R].
In any other case, use a non-seeded pseudo-random number generator.
.SS Numbers
.PP
Numbers are strings made up of digits, uppercase letters, and at most
\f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]BC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]Z\f[R] alone always equals decimal \f[B]35\f[R].
.PP
In addition, bc(1) accepts numbers in scientific notation.
These have the form \f[B]<number>e<integer>\f[R].
The exponent (the portion after the \f[B]e\f[R]) must be an integer.
An example is \f[B]1.89237e9\f[R], which is equal to
\f[B]1892370000\f[R].
Negative exponents are also allowed, so \f[B]4.2890e-3\f[R] is equal to
\f[B]0.0042890\f[R].
.PP
Using scientific notation is an error or warning if the \f[B]-s\f[R] or
\f[B]-w\f[R], respectively, command-line options (or equivalents) are
given.
.PP
\f[B]WARNING\f[R]: Both the number and the exponent in scientific
notation are interpreted according to the current \f[B]ibase\f[R], but
the number is still multiplied by \f[B]10\[ha]exponent\f[R] regardless
of the current \f[B]ibase\f[R].
For example, if \f[B]ibase\f[R] is \f[B]16\f[R] and bc(1) is given the
number string \f[B]FFeA\f[R], the resulting decimal number will be
\f[B]2550000000000\f[R], and if bc(1) is given the number string
\f[B]10e-4\f[R], the resulting decimal number will be \f[B]0.0016\f[R].
.PP
Accepting input as scientific notation is a \f[B]non-portable
extension\f[R].
.SS Operators
.PP
The following arithmetic and logical operators can be used.
They are listed in order of decreasing precedence.
Operators in the same group have the same precedence.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
Type: Prefix and Postfix
.RS
.PP
Associativity: None
.PP
Description: \f[B]increment\f[R], \f[B]decrement\f[R]
.RE
.TP
\f[B]-\f[R] \f[B]!\f[R]
Type: Prefix
.RS
.PP
Associativity: None
.PP
Description: \f[B]negation\f[R], \f[B]boolean not\f[R]
.RE
.TP
\f[B]$\f[R]
Type: Postfix
.RS
.PP
Associativity: None
.PP
Description: \f[B]truncation\f[R]
.RE
.TP
\f[B]\[at]\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]set precision\f[R]
.RE
.TP
\f[B]\[ha]\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]power\f[R]
.RE
.TP
\f[B]*\f[R] \f[B]/\f[R] \f[B]%\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]multiply\f[R], \f[B]divide\f[R], \f[B]modulus\f[R]
.RE
.TP
\f[B]+\f[R] \f[B]-\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]add\f[R], \f[B]subtract\f[R]
.RE
.TP
\f[B]<<\f[R] \f[B]>>\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]shift left\f[R], \f[B]shift right\f[R]
.RE
.TP
\f[B]=\f[R] \f[B]<<=\f[R] \f[B]>>=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R] \f[B]\[at]=\f[R]
Type: Binary
.RS
.PP
Associativity: Right
.PP
Description: \f[B]assignment\f[R]
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]relational\f[R]
.RE
.TP
\f[B]&&\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean and\f[R]
.RE
.TP
\f[B]||\f[R]
Type: Binary
.RS
.PP
Associativity: Left
.PP
Description: \f[B]boolean or\f[R]
.RE
.PP
The operators will be described in more detail below.
.TP
\f[B]++\f[R] \f[B]\[en]\f[R]
The prefix and postfix \f[B]increment\f[R] and \f[B]decrement\f[R]
operators behave exactly like they would in C.
They require a named expression (see the \f[I]Named Expressions\f[R]
subsection) as an operand.
.RS
.PP
The prefix versions of these operators are more efficient; use them
where possible.
.RE
.TP
\f[B]-\f[R]
The \f[B]negation\f[R] operator returns \f[B]0\f[R] if a user attempts
to negate any expression with the value \f[B]0\f[R].
Otherwise, a copy of the expression with its sign flipped is returned.
.TP
\f[B]!\f[R]
The \f[B]boolean not\f[R] operator returns \f[B]1\f[R] if the expression
is \f[B]0\f[R], or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]$\f[R]
The \f[B]truncation\f[R] operator returns a copy of the given expression
with all of its \f[I]scale\f[R] removed.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[at]\f[R]
The \f[B]set precision\f[R] operator takes two expressions and returns a
copy of the first with its \f[I]scale\f[R] equal to the value of the
second expression.
That could either mean that the number is returned without change (if
the \f[I]scale\f[R] of the first expression matches the value of the
second expression), extended (if it is less), or truncated (if it is
more).
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]) and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The \f[B]power\f[R] operator (not the \f[B]exclusive or\f[R] operator,
as it would be in C) takes two expressions and raises the first to the
power of the value of the second.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]), and if it
is negative, the first value must be non-zero.
.RE
.TP
\f[B]*\f[R]
The \f[B]multiply\f[R] operator takes two expressions, multiplies them,
and returns the product.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The \f[B]divide\f[R] operator takes two expressions, divides them, and
returns the quotient.
The \f[I]scale\f[R] of the result shall be the value of \f[B]scale\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]%\f[R]
The \f[B]modulus\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and evaluates them by 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R] and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.RS
.PP
The second expression must be non-zero.
.RE
.TP
\f[B]+\f[R]
The \f[B]add\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the sum, with a \f[I]scale\f[R] equal to the
max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]-\f[R]
The \f[B]subtract\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns the difference, with a \f[I]scale\f[R] equal to
the max of the \f[I]scale\f[R]s of \f[B]a\f[R] and \f[B]b\f[R].
.TP
\f[B]<<\f[R]
The \f[B]left shift\f[R] operator takes two expressions, \f[B]a\f[R] and
\f[B]b\f[R], and returns a copy of the value of \f[B]a\f[R] with its
decimal point moved \f[B]b\f[R] places to the right.
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]) and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]>>\f[R]
The \f[B]right shift\f[R] operator takes two expressions, \f[B]a\f[R]
and \f[B]b\f[R], and returns a copy of the value of \f[B]a\f[R] with its
decimal point moved \f[B]b\f[R] places to the left.
.RS
.PP
The second expression must be an integer (no \f[I]scale\f[R]) and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]=\f[R] \f[B]<<=\f[R] \f[B]>>=\f[R] \f[B]+=\f[R] \f[B]-=\f[R] \f[B]*=\f[R] \f[B]/=\f[R] \f[B]%=\f[R] \f[B]\[ha]=\f[R] \f[B]\[at]=\f[R]
The \f[B]assignment\f[R] operators take two expressions, \f[B]a\f[R] and
\f[B]b\f[R] where \f[B]a\f[R] is a named expression (see the \f[I]Named
Expressions\f[R] subsection).
.RS
.PP
For \f[B]=\f[R], \f[B]b\f[R] is copied and the result is assigned to
\f[B]a\f[R].
For all others, \f[B]a\f[R] and \f[B]b\f[R] are applied as operands to
the corresponding arithmetic operator and the result is assigned to
\f[B]a\f[R].
.PP
The \f[B]assignment\f[R] operators that correspond to operators that are
extensions are themselves \f[B]non-portable extensions\f[R].
.RE
.TP
\f[B]==\f[R] \f[B]<=\f[R] \f[B]>=\f[R] \f[B]!=\f[R] \f[B]<\f[R] \f[B]>\f[R]
The \f[B]relational\f[R] operators compare two expressions, \f[B]a\f[R]
and \f[B]b\f[R], and if the relation holds, according to C language
semantics, the result is \f[B]1\f[R].
Otherwise, it is \f[B]0\f[R].
.RS
.PP
Note that unlike in C, these operators have a lower precedence than the
\f[B]assignment\f[R] operators, which means that \f[B]a=b>c\f[R] is
interpreted as \f[B](a=b)>c\f[R].
.PP
Also, unlike the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
requires, these operators can appear anywhere any other expressions can
be used.
This allowance is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]&&\f[R]
The \f[B]boolean and\f[R] operator takes two expressions and returns
\f[B]1\f[R] if both expressions are non-zero, \f[B]0\f[R] otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]||\f[R]
The \f[B]boolean or\f[R] operator takes two expressions and returns
\f[B]1\f[R] if one of the expressions is non-zero, \f[B]0\f[R]
otherwise.
.RS
.PP
This is \f[I]not\f[R] a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Statements
.PP
The following items are statements:
.IP " 1." 4
\f[B]E\f[R]
.IP " 2." 4
\f[B]{\f[R] \f[B]S\f[R] \f[B];\f[R] \&... \f[B];\f[R] \f[B]S\f[R]
\f[B]}\f[R]
.IP " 3." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 4." 4
\f[B]if\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
\f[B]else\f[R] \f[B]S\f[R]
.IP " 5." 4
\f[B]while\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 6." 4
\f[B]for\f[R] \f[B](\f[R] \f[B]E\f[R] \f[B];\f[R] \f[B]E\f[R]
\f[B];\f[R] \f[B]E\f[R] \f[B])\f[R] \f[B]S\f[R]
.IP " 7." 4
An empty statement
.IP " 8." 4
\f[B]break\f[R]
.IP " 9." 4
\f[B]continue\f[R]
.IP "10." 4
\f[B]quit\f[R]
.IP "11." 4
\f[B]halt\f[R]
.IP "12." 4
\f[B]limits\f[R]
.IP "13." 4
A string of characters, enclosed in double quotes
.IP "14." 4
\f[B]print\f[R] \f[B]E\f[R] \f[B],\f[R] \&... \f[B],\f[R] \f[B]E\f[R]
.IP "15." 4
\f[B]I()\f[R], \f[B]I(E)\f[R], \f[B]I(E, E)\f[R], and so on, where
\f[B]I\f[R] is an identifier for a \f[B]void\f[R] function (see the
\f[I]Void Functions\f[R] subsection of the \f[B]FUNCTIONS\f[R] section).
The \f[B]E\f[R] argument(s) may also be arrays of the form
\f[B]I[]\f[R], which will automatically be turned into array references
(see the \f[I]Array References\f[R] subsection of the
\f[B]FUNCTIONS\f[R] section) if the corresponding parameter in the
function definition is an array reference.
.PP
Numbers 4, 9, 11, 12, 14, and 15 are \f[B]non-portable extensions\f[R].
.PP
Also, as a \f[B]non-portable extension\f[R], any or all of the
expressions in the header of a for loop may be omitted.
If the condition (second expression) is omitted, it is assumed to be a
constant \f[B]1\f[R].
.PP
The \f[B]break\f[R] statement causes a loop to stop iterating and resume
execution immediately following a loop.
This is only allowed in loops.
.PP
The \f[B]continue\f[R] statement causes a loop iteration to stop early
and returns to the start of the loop, including testing the loop
condition.
This is only allowed in loops.
.PP
The \f[B]if\f[R] \f[B]else\f[R] statement does the same thing as in C.
.PP
The \f[B]quit\f[R] statement causes bc(1) to quit, even if it is on a
branch that will not be executed (it is a compile-time command).
.PP
The \f[B]halt\f[R] statement causes bc(1) to quit, if it is executed.
(Unlike \f[B]quit\f[R] if it is on a branch of an \f[B]if\f[R] statement
that is not executed, bc(1) does not quit.)
.PP
The \f[B]limits\f[R] statement prints the limits that this bc(1) is
subject to.
This is like the \f[B]quit\f[R] statement in that it is a compile-time
command.
.PP
An expression by itself is evaluated and printed, followed by a newline.
.PP
Both scientific notation and engineering notation are available for
printing the results of expressions.
Scientific notation is activated by assigning \f[B]0\f[R] to
\f[B]obase\f[R], and engineering notation is activated by assigning
\f[B]1\f[R] to \f[B]obase\f[R].
To deactivate them, just assign a different value to \f[B]obase\f[R].
.PP
Scientific notation and engineering notation are disabled if bc(1) is
run with either the \f[B]-s\f[R] or \f[B]-w\f[R] command-line options
(or equivalents).
.PP
Printing numbers in scientific notation and/or engineering notation is a
\f[B]non-portable extension\f[R].
.SS Print Statement
.PP
The \[lq]expressions\[rq] in a \f[B]print\f[R] statement may also be
strings.
If they are, there are backslash escape sequences that are interpreted
specially.
What those sequences are, and what they cause to be printed, are shown
below:
.PP
.TS
tab(@);
l l.
T{
\f[B]\[rs]a\f[R]
T}@T{
\f[B]\[rs]a\f[R]
T}
T{
\f[B]\[rs]b\f[R]
T}@T{
\f[B]\[rs]b\f[R]
T}
T{
\f[B]\[rs]\[rs]\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]e\f[R]
T}@T{
\f[B]\[rs]\f[R]
T}
T{
\f[B]\[rs]f\f[R]
T}@T{
\f[B]\[rs]f\f[R]
T}
T{
\f[B]\[rs]n\f[R]
T}@T{
\f[B]\[rs]n\f[R]
T}
T{
\f[B]\[rs]q\f[R]
T}@T{
\f[B]\[dq]\f[R]
T}
T{
\f[B]\[rs]r\f[R]
T}@T{
\f[B]\[rs]r\f[R]
T}
T{
\f[B]\[rs]t\f[R]
T}@T{
\f[B]\[rs]t\f[R]
T}
.TE
.PP
Any other character following a backslash causes the backslash and
character to be printed as-is.
.PP
Any non-string expression in a print statement shall be assigned to
\f[B]last\f[R], like any other expression that is printed.
.SS Order of Evaluation
.PP
All expressions in a statment are evaluated left to right, except as
necessary to maintain order of operations.
This means, for example, assuming that \f[B]i\f[R] is equal to
\f[B]0\f[R], in the expression
.IP
.nf
\f[C]
a[i++] = i++
\f[R]
.fi
.PP
the first (or 0th) element of \f[B]a\f[R] is set to \f[B]1\f[R], and
\f[B]i\f[R] is equal to \f[B]2\f[R] at the end of the expression.
.PP
This includes function arguments.
Thus, assuming \f[B]i\f[R] is equal to \f[B]0\f[R], this means that in
the expression
.IP
.nf
\f[C]
x(i++, i++)
\f[R]
.fi
.PP
the first argument passed to \f[B]x()\f[R] is \f[B]0\f[R], and the
second argument is \f[B]1\f[R], while \f[B]i\f[R] is equal to
\f[B]2\f[R] before the function starts executing.
.SH FUNCTIONS
.PP
Function definitions are as follows:
.IP
.nf
\f[C]
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
\f[R]
.fi
.PP
Any \f[B]I\f[R] in the parameter list or \f[B]auto\f[R] list may be
replaced with \f[B]I[]\f[R] to make a parameter or \f[B]auto\f[R] var an
array, and any \f[B]I\f[R] in the parameter list may be replaced with
\f[B]*I[]\f[R] to make a parameter an array reference.
Callers of functions that take array references should not put an
asterisk in the call; they must be called with just \f[B]I[]\f[R] like
normal array parameters and will be automatically converted into
references.
.PP
As a \f[B]non-portable extension\f[R], the opening brace of a
\f[B]define\f[R] statement may appear on the next line.
.PP
As a \f[B]non-portable extension\f[R], the return statement may also be
in one of the following forms:
.IP "1." 3
\f[B]return\f[R]
.IP "2." 3
\f[B]return\f[R] \f[B](\f[R] \f[B])\f[R]
.IP "3." 3
\f[B]return\f[R] \f[B]E\f[R]
.PP
The first two, or not specifying a \f[B]return\f[R] statement, is
equivalent to \f[B]return (0)\f[R], unless the function is a
\f[B]void\f[R] function (see the \f[I]Void Functions\f[R] subsection
below).
.SS Void Functions
.PP
Functions can also be \f[B]void\f[R] functions, defined as follows:
.IP
.nf
\f[C]
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
\f[R]
.fi
.PP
They can only be used as standalone expressions, where such an
expression would be printed alone, except in a print statement.
.PP
Void functions can only use the first two \f[B]return\f[R] statements
listed above.
They can also omit the return statement entirely.
.PP
The word \[lq]void\[rq] is not treated as a keyword; it is still
possible to have variables, arrays, and functions named \f[B]void\f[R].
The word \[lq]void\[rq] is only treated specially right after the
\f[B]define\f[R] keyword.
.PP
This is a \f[B]non-portable extension\f[R].
.SS Array References
.PP
For any array in the parameter list, if the array is declared in the
form
.IP
.nf
\f[C]
*I[]
\f[R]
.fi
.PP
it is a \f[B]reference\f[R].
Any changes to the array in the function are reflected, when the
function returns, to the array that was passed in.
.PP
Other than this, all function arguments are passed by value.
.PP
This is a \f[B]non-portable extension\f[R].
.SH LIBRARY
.PP
All of the functions below, including the functions in the extended math
library (see the \f[I]Extended Library\f[R] subsection below), are
available when the \f[B]-l\f[R] or \f[B]\[en]mathlib\f[R] command-line
flags are given, except that the extended math library is not available
when the \f[B]-s\f[R] option, the \f[B]-w\f[R] option, or equivalents
are given.
.SS Standard Library
.PP
The
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
defines the following functions for the math library:
.TP
\f[B]s(x)\f[R]
Returns the sine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]c(x)\f[R]
Returns the cosine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]a(x)\f[R]
Returns the arctangent of \f[B]x\f[R], in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]l(x)\f[R]
Returns the natural logarithm of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]e(x)\f[R]
Returns the mathematical constant \f[B]e\f[R] raised to the power of
\f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]j(x, n)\f[R]
Returns the bessel integer order \f[B]n\f[R] (truncated) of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.SS Extended Library
.PP
The extended library is \f[I]not\f[R] loaded when the
\f[B]-s\f[R]/\f[B]\[en]standard\f[R] or \f[B]-w\f[R]/\f[B]\[en]warn\f[R]
options are given since they are not part of the library defined by the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html).
.PP
The extended library is a \f[B]non-portable extension\f[R].
.TP
\f[B]p(x, y)\f[R]
Calculates \f[B]x\f[R] to the power of \f[B]y\f[R], even if \f[B]y\f[R]
is not an integer, and returns the result to the current
\f[B]scale\f[R].
.RS
.PP
It is an error if \f[B]y\f[R] is negative and \f[B]x\f[R] is
\f[B]0\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]r(x, p)\f[R]
Returns \f[B]x\f[R] rounded to \f[B]p\f[R] decimal places according to
the rounding mode round half away from
\f[B]0\f[R] (https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero).
.TP
\f[B]ceil(x, p)\f[R]
Returns \f[B]x\f[R] rounded to \f[B]p\f[R] decimal places according to
the rounding mode round away from
\f[B]0\f[R] (https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero).
.TP
\f[B]f(x)\f[R]
Returns the factorial of the truncated absolute value of \f[B]x\f[R].
.TP
\f[B]perm(n, k)\f[R]
Returns the permutation of the truncated absolute value of \f[B]n\f[R]
of the truncated absolute value of \f[B]k\f[R], if \f[B]k <= n\f[R].
If not, it returns \f[B]0\f[R].
.TP
\f[B]comb(n, k)\f[R]
Returns the combination of the truncated absolute value of \f[B]n\f[R]
of the truncated absolute value of \f[B]k\f[R], if \f[B]k <= n\f[R].
If not, it returns \f[B]0\f[R].
.TP
\f[B]l2(x)\f[R]
Returns the logarithm base \f[B]2\f[R] of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]l10(x)\f[R]
Returns the logarithm base \f[B]10\f[R] of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]log(x, b)\f[R]
Returns the logarithm base \f[B]b\f[R] of \f[B]x\f[R].
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]cbrt(x)\f[R]
Returns the cube root of \f[B]x\f[R].
.TP
\f[B]root(x, n)\f[R]
Calculates the truncated value of \f[B]n\f[R], \f[B]r\f[R], and returns
the \f[B]r\f[R]th root of \f[B]x\f[R] to the current \f[B]scale\f[R].
.RS
.PP
If \f[B]r\f[R] is \f[B]0\f[R] or negative, this raises an error and
causes bc(1) to reset (see the \f[B]RESET\f[R] section).
It also raises an error and causes bc(1) to reset if \f[B]r\f[R] is even
and \f[B]x\f[R] is negative.
.RE
.TP
\f[B]pi(p)\f[R]
Returns \f[B]pi\f[R] to \f[B]p\f[R] decimal places.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]t(x)\f[R]
Returns the tangent of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]a2(y, x)\f[R]
Returns the arctangent of \f[B]y/x\f[R], in radians.
If both \f[B]y\f[R] and \f[B]x\f[R] are equal to \f[B]0\f[R], it raises
an error and causes bc(1) to reset (see the \f[B]RESET\f[R] section).
Otherwise, if \f[B]x\f[R] is greater than \f[B]0\f[R], it returns
\f[B]a(y/x)\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is greater than
or equal to \f[B]0\f[R], it returns \f[B]a(y/x)+pi\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]a(y/x)-pi\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is greater than
\f[B]0\f[R], it returns \f[B]pi/2\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]-pi/2\f[R].
.RS
.PP
This function is the same as the \f[B]atan2()\f[R] function in many
programming languages.
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]sin(x)\f[R]
Returns the sine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is an alias of \f[B]s(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]cos(x)\f[R]
Returns the cosine of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
This is an alias of \f[B]c(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]tan(x)\f[R]
Returns the tangent of \f[B]x\f[R], which is assumed to be in radians.
.RS
.PP
If \f[B]x\f[R] is equal to \f[B]1\f[R] or \f[B]-1\f[R], this raises an
error and causes bc(1) to reset (see the \f[B]RESET\f[R] section).
.PP
This is an alias of \f[B]t(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]atan(x)\f[R]
Returns the arctangent of \f[B]x\f[R], in radians.
.RS
.PP
This is an alias of \f[B]a(x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]atan2(y, x)\f[R]
Returns the arctangent of \f[B]y/x\f[R], in radians.
If both \f[B]y\f[R] and \f[B]x\f[R] are equal to \f[B]0\f[R], it raises
an error and causes bc(1) to reset (see the \f[B]RESET\f[R] section).
Otherwise, if \f[B]x\f[R] is greater than \f[B]0\f[R], it returns
\f[B]a(y/x)\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is greater than
or equal to \f[B]0\f[R], it returns \f[B]a(y/x)+pi\f[R].
If \f[B]x\f[R] is less than \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]a(y/x)-pi\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is greater than
\f[B]0\f[R], it returns \f[B]pi/2\f[R].
If \f[B]x\f[R] is equal to \f[B]0\f[R], and \f[B]y\f[R] is less than
\f[B]0\f[R], it returns \f[B]-pi/2\f[R].
.RS
.PP
This function is the same as the \f[B]atan2()\f[R] function in many
programming languages.
.PP
This is an alias of \f[B]a2(y, x)\f[R].
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]r2d(x)\f[R]
Converts \f[B]x\f[R] from radians to degrees and returns the result.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]d2r(x)\f[R]
Converts \f[B]x\f[R] from degrees to radians and returns the result.
.RS
.PP
This is a transcendental function (see the \f[I]Transcendental
Functions\f[R] subsection below).
.RE
.TP
\f[B]frand(p)\f[R]
Generates a pseudo-random number between \f[B]0\f[R] (inclusive) and
\f[B]1\f[R] (exclusive) with the number of decimal digits after the
decimal point equal to the truncated absolute value of \f[B]p\f[R].
If \f[B]p\f[R] is not \f[B]0\f[R], then calling this function will
change the value of \f[B]seed\f[R].
If \f[B]p\f[R] is \f[B]0\f[R], then \f[B]0\f[R] is returned, and
\f[B]seed\f[R] is \f[I]not\f[R] changed.
.TP
\f[B]ifrand(i, p)\f[R]
Generates a pseudo-random number that is between \f[B]0\f[R] (inclusive)
and the truncated absolute value of \f[B]i\f[R] (exclusive) with the
number of decimal digits after the decimal point equal to the truncated
absolute value of \f[B]p\f[R].
If the absolute value of \f[B]i\f[R] is greater than or equal to
\f[B]2\f[R], and \f[B]p\f[R] is not \f[B]0\f[R], then calling this
function will change the value of \f[B]seed\f[R]; otherwise, \f[B]0\f[R]
is returned and \f[B]seed\f[R] is not changed.
.TP
\f[B]srand(x)\f[R]
Returns \f[B]x\f[R] with its sign flipped with probability
\f[B]0.5\f[R].
In other words, it randomizes the sign of \f[B]x\f[R].
.TP
\f[B]brand()\f[R]
Returns a random boolean value (either \f[B]0\f[R] or \f[B]1\f[R]).
.TP
\f[B]ubytes(x)\f[R]
Returns the numbers of unsigned integer bytes required to hold the
truncated absolute value of \f[B]x\f[R].
.TP
\f[B]sbytes(x)\f[R]
Returns the numbers of signed, two\[cq]s-complement integer bytes
required to hold the truncated value of \f[B]x\f[R].
.TP
\f[B]hex(x)\f[R]
Outputs the hexadecimal (base \f[B]16\f[R]) representation of
\f[B]x\f[R].
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]binary(x)\f[R]
Outputs the binary (base \f[B]2\f[R]) representation of \f[B]x\f[R].
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]output(x, b)\f[R]
Outputs the base \f[B]b\f[R] representation of \f[B]x\f[R].
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in as few power of two bytes as possible.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or is negative, an error message is
printed instead, but bc(1) is not reset (see the \f[B]RESET\f[R]
section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in as few power of two bytes as
possible.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, an error message is printed instead,
but bc(1) is not reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uintn(x, n)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]n\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]n\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]intn(x, n)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]n\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]n\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint8(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]1\f[R] byte.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]1\f[R] byte, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int8(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]1\f[R] byte.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]1\f[R] byte, an
error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint16(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]2\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]2\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int16(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]2\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]2\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint32(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]4\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]4\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int32(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]4\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]4\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]uint64(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
an unsigned integer in \f[B]8\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer, is negative, or cannot fit into
\f[B]8\f[R] bytes, an error message is printed instead, but bc(1) is not
reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]int64(x)\f[R]
Outputs the representation, in binary and hexadecimal, of \f[B]x\f[R] as
a signed, two\[cq]s-complement integer in \f[B]8\f[R] bytes.
Both outputs are split into bytes separated by spaces.
.RS
.PP
If \f[B]x\f[R] is not an integer or cannot fit into \f[B]8\f[R] bytes,
an error message is printed instead, but bc(1) is not reset (see the
\f[B]RESET\f[R] section).
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]hex_uint(x, n)\f[R]
Outputs the representation of the truncated absolute value of
\f[B]x\f[R] as an unsigned integer in hexadecimal using \f[B]n\f[R]
bytes.
Not all of the value will be output if \f[B]n\f[R] is too small.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]binary_uint(x, n)\f[R]
Outputs the representation of the truncated absolute value of
\f[B]x\f[R] as an unsigned integer in binary using \f[B]n\f[R] bytes.
Not all of the value will be output if \f[B]n\f[R] is too small.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]output_uint(x, n)\f[R]
Outputs the representation of the truncated absolute value of
\f[B]x\f[R] as an unsigned integer in the current \f[B]obase\f[R] (see
the \f[B]SYNTAX\f[R] section) using \f[B]n\f[R] bytes.
Not all of the value will be output if \f[B]n\f[R] is too small.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.TP
\f[B]output_byte(x, i)\f[R]
Outputs byte \f[B]i\f[R] of the truncated absolute value of \f[B]x\f[R],
where \f[B]0\f[R] is the least significant byte and \f[B]number_of_bytes
- 1\f[R] is the most significant byte.
.RS
.PP
This is a \f[B]void\f[R] function (see the \f[I]Void Functions\f[R]
subsection of the \f[B]FUNCTIONS\f[R] section).
.RE
.SS Transcendental Functions
.PP
All transcendental functions can return slightly inaccurate results (up
to 1 ULP (https://en.wikipedia.org/wiki/Unit_in_the_last_place)).
This is unavoidable, and this
article (https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT) explains
why it is impossible and unnecessary to calculate exact results for the
transcendental functions.
.PP
Because of the possible inaccuracy, I recommend that users call those
functions with the precision (\f[B]scale\f[R]) set to at least 1 higher
than is necessary.
If exact results are \f[I]absolutely\f[R] required, users can double the
precision (\f[B]scale\f[R]) and then truncate.
.PP
The transcendental functions in the standard math library are:
.IP \[bu] 2
\f[B]s(x)\f[R]
.IP \[bu] 2
\f[B]c(x)\f[R]
.IP \[bu] 2
\f[B]a(x)\f[R]
.IP \[bu] 2
\f[B]l(x)\f[R]
.IP \[bu] 2
\f[B]e(x)\f[R]
.IP \[bu] 2
\f[B]j(x, n)\f[R]
.PP
The transcendental functions in the extended math library are:
.IP \[bu] 2
\f[B]l2(x)\f[R]
.IP \[bu] 2
\f[B]l10(x)\f[R]
.IP \[bu] 2
\f[B]log(x, b)\f[R]
.IP \[bu] 2
\f[B]pi(p)\f[R]
.IP \[bu] 2
\f[B]t(x)\f[R]
.IP \[bu] 2
\f[B]a2(y, x)\f[R]
.IP \[bu] 2
\f[B]sin(x)\f[R]
.IP \[bu] 2
\f[B]cos(x)\f[R]
.IP \[bu] 2
\f[B]tan(x)\f[R]
.IP \[bu] 2
\f[B]atan(x)\f[R]
.IP \[bu] 2
\f[B]atan2(y, x)\f[R]
.IP \[bu] 2
\f[B]r2d(x)\f[R]
.IP \[bu] 2
\f[B]d2r(x)\f[R]
.SH RESET
.PP
When bc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any functions that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all functions returned) is skipped.
.PP
Thus, when bc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.PP
Note that this reset behavior is different from the GNU bc(1), which
attempts to start executing the statement right after the one that
caused an error.
.SH PERFORMANCE
.PP
Most bc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This bc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]BC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]BC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]BC_BASE_DIGS\f[R].
.PP
The actual values of \f[B]BC_LONG_BIT\f[R] and \f[B]BC_BASE_DIGS\f[R]
can be queried with the \f[B]limits\f[R] statement.
.PP
In addition, this bc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]BC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on bc(1):
.TP
\f[B]BC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
bc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]BC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]BC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]BC_BASE_DIGS\f[R].
.TP
\f[B]BC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]BC_BASE_POW\f[R].
.TP
\f[B]BC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]BC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_RAND_MAX\f[R]
The maximum integer (inclusive) returned by the \f[B]rand()\f[R]
operand.
Set at \f[B]2\[ha]BC_LONG_BIT-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]BC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
The actual values can be queried with the \f[B]limits\f[R] statement.
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
bc(1) recognizes the following environment variables:
.TP
\f[B]POSIXLY_CORRECT\f[R]
If this variable exists (no matter the contents), bc(1) behaves as if
the \f[B]-s\f[R] option was given.
.TP
\f[B]BC_ENV_ARGS\f[R]
This is another way to give command-line arguments to bc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]BC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
.RS
.PP
The code that parses \f[B]BC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some bc file.bc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]bc\[dq] file.bc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]BC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]BC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), bc(1) will output lines to that length,
including the backslash (\f[B]\[rs]\f[R]).
The default line length is \f[B]70\f[R].
.SH EXIT STATUS
.PP
bc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, using a negative number as a bound for the
pseudo-random number generator, attempting to convert a negative number
to a hardware integer, overflow when converting a number to a hardware
integer, and attempting to use a non-integer where an integer is
required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]), places (\f[B]\[at]\f[R]), left shift
(\f[B]<<\f[R]), and right shift (\f[B]>>\f[R]) operators and their
corresponding assignment operators.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, using a token
where it is invalid, giving an invalid expression, giving an invalid
print statement, giving an invalid function definition, attempting to
assign to an expression that is not a named expression (see the
\f[I]Named Expressions\f[R] subsection of the \f[B]SYNTAX\f[R] section),
giving an invalid \f[B]auto\f[R] list, having a duplicate
\f[B]auto\f[R]/function parameter, failing to find the end of a code
block, attempting to return a value from a \f[B]void\f[R] function,
attempting to use a variable as a reference, and using any extensions
when the option \f[B]-s\f[R] or any equivalents were given.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a \f[B]void\f[R] function call as a value in an
expression.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (bc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, bc(1)
always exits and returns \f[B]4\f[R], no matter what mode bc(1) is in.
.PP
The other statuses will only be returned when bc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
bc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Per the
standard (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, bc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, bc(1) turns on \[lq]TTY mode.\[rq]
.PP
TTY mode is required for history to be enabled (see the \f[B]COMMAND
LINE HISTORY\f[R] section).
It is also required to enable special handling for \f[B]SIGINT\f[R]
signals.
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause bc(1) to stop execution of the
current input.
If bc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If bc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If bc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to bc(1) as it is
executing a file, it can seem as though bc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause bc(1) to clean up and
exit, and it uses the default handler for all other signals.
The one exception is \f[B]SIGHUP\f[R]; in that case, when bc(1) is in
TTY mode, a \f[B]SIGHUP\f[R] will cause bc(1) to clean up and exit.
.SH COMMAND LINE HISTORY
.PP
bc(1) supports interactive command-line editing.
If bc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), history is
enabled.
Previous lines can be recalled and edited with the arrow keys.
.PP
\f[B]Note\f[R]: tabs are converted to 8 spaces.
.SH LOCALES
.PP
This bc(1) ships with support for adding error messages for different
locales and thus, supports \f[B]LC_MESSAGES\f[R].
.SH SEE ALSO
.PP
dc(1)
.SH STANDARDS
.PP
bc(1) is compliant with the IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
The flags \f[B]-efghiqsvVw\f[R], all long options, and the extensions
noted above are extensions to that specification.
.PP
Note that the specification explicitly says that bc(1) only accepts
numbers that use a period (\f[B].\f[R]) as a radix point, regardless of
the value of \f[B]LC_NUMERIC\f[R].
.PP
This bc(1) supports error messages for different locales, and thus, it
supports \f[B]LC_MESSAGES\f[R].
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHORS
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/bc/P.1.md b/contrib/bc/manuals/bc/P.1.md
index d69e83ab0fc7..7e6dcee4747d 100644
--- a/contrib/bc/manuals/bc/P.1.md
+++ b/contrib/bc/manuals/bc/P.1.md
@@ -1,1690 +1,1699 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# NAME
bc - arbitrary-precision decimal arithmetic language and calculator
# SYNOPSIS
**bc** [**-ghilPqsvVw**] [**--global-stacks**] [**--help**] [**--interactive**] [**--mathlib**] [**--no-prompt**] [**--quiet**] [**--standard**] [**--warn**] [**--version**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...]
[*file*...]
# DESCRIPTION
bc(1) is an interactive processor for a language first standardized in 1991 by
POSIX. (The current standard is [here][1].) The language provides unlimited
precision decimal arithmetic and is somewhat C-like, but there are differences.
Such differences will be noted in this document.
After parsing and handling options, this bc(1) reads any files given on the
command line and executes them before reading from **stdin**.
This bc(1) is a drop-in replacement for *any* bc(1), including (and
especially) the GNU bc(1). It also has many extensions and extra features beyond
other implementations.
# OPTIONS
The following are the options that bc(1) accepts.
**-g**, **--global-stacks**
: Turns the globals **ibase**, **obase**, **scale**, and **seed** into stacks.
This has the effect that a copy of the current value of all four are pushed
onto a stack for every function call, as well as popped when every function
returns. This means that functions can assign to any and all of those
globals without worrying that the change will affect other functions.
Thus, a hypothetical function named **output(x,b)** that simply printed
**x** in base **b** could be written like this:
define void output(x, b) {
obase=b
x
}
instead of like this:
define void output(x, b) {
auto c
c=obase
obase=b
x
obase=c
}
This makes writing functions much easier.
(**Note**: the function **output(x,b)** exists in the extended math library.
See the **LIBRARY** section.)
However, since using this flag means that functions cannot set **ibase**,
**obase**, **scale**, or **seed** globally, functions that are made to do so
cannot work anymore. There are two possible use cases for that, and each has
a solution.
First, if a function is called on startup to turn bc(1) into a number
converter, it is possible to replace that capability with various shell
aliases. Examples:
alias d2o="bc -e ibase=A -e obase=8"
alias h2b="bc -e ibase=G -e obase=2"
Second, if the purpose of a function is to set **ibase**, **obase**,
**scale**, or **seed** globally for any other purpose, it could be split
into one to four functions (based on how many globals it sets) and each of
those functions could return the desired value for a global.
For functions that set **seed**, the value assigned to **seed** is not
propagated to parent functions. This means that the sequence of
pseudo-random numbers that they see will not be the same sequence of
pseudo-random numbers that any parent sees. This is only the case once
**seed** has been set.
If a function desires to not affect the sequence of pseudo-random numbers
of its parents, but wants to use the same **seed**, it can use the following
line:
seed = seed
If the behavior of this option is desired for every run of bc(1), then users
could make sure to define **BC_ENV_ARGS** and include this option (see the
**ENVIRONMENT VARIABLES** section for more details).
If **-s**, **-w**, or any equivalents are used, this option is ignored.
This is a **non-portable extension**.
**-h**, **--help**
: Prints a usage message and quits.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-l**, **--mathlib**
: Sets **scale** (see the **SYNTAX** section) to **20** and loads the included
math library and the extended math library before running any code,
including any expressions or files specified on the command line.
To learn what is in the libraries, see the **LIBRARY** section.
**-P**, **--no-prompt**
: This option is a no-op.
This is a **non-portable extension**.
**-q**, **--quiet**
: This option is for compatibility with the [GNU bc(1)][2]; it is a no-op.
Without this option, GNU bc(1) prints a copyright header. This bc(1) only
prints the copyright header if one or more of the **-v**, **-V**, or
**--version** options are given.
This is a **non-portable extension**.
**-s**, **--standard**
: Process exactly the language defined by the [standard][1] and error if any
extensions are used.
This is a **non-portable extension**.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
This is a **non-portable extension**.
**-w**, **--warn**
: Like **-s** and **--standard**, except that warnings (and not errors) are
printed for non-standard extensions and execution continues normally.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **BC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, bc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **BC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, bc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, bc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **bc <file> >&-**, it will quit with an error. This
is done so that bc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other bc(1) implementations, this bc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **bc <file> 2>&-**, it will quit with an error. This
is done so that bc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other bc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
The syntax for bc(1) programs is mostly C-like, with some differences. This
bc(1) follows the [POSIX standard][1], which is a much more thorough resource
for the language this bc(1) accepts. This section is meant to be a summary and a
listing of all the extensions to the standard.
In the sections below, **E** means expression, **S** means statement, and **I**
means identifier.
Identifiers (**I**) start with a lowercase letter and can be followed by any
number (up to **BC_NAME_MAX-1**) of lowercase letters (**a-z**), digits
(**0-9**), and underscores (**\_**). The regex is **\[a-z\]\[a-z0-9\_\]\***.
Identifiers with more than one character (letter) are a
**non-portable extension**.
**ibase** is a global variable determining how to interpret constant numbers. It
is the "input" base, or the number base used for interpreting input numbers.
**ibase** is initially **10**. If the **-s** (**--standard**) and **-w**
(**--warn**) flags were not given on the command line, the max allowable value
for **ibase** is **36**. Otherwise, it is **16**. The min allowable value for
**ibase** is **2**. The max allowable value for **ibase** can be queried in
bc(1) programs with the **maxibase()** built-in function.
**obase** is a global variable determining how to output results. It is the
"output" base, or the number base used for outputting numbers. **obase** is
initially **10**. The max allowable value for **obase** is **BC_BASE_MAX** and
can be queried in bc(1) programs with the **maxobase()** built-in function. The
min allowable value for **obase** is **0**. If **obase** is **0**, values are
output in scientific notation, and if **obase** is **1**, values are output in
engineering notation. Otherwise, values are output in the specified base.
Outputting in scientific and engineering notations are **non-portable
extensions**.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a global variable that
sets the precision of any operations, with exceptions. **scale** is initially
**0**. **scale** cannot be negative. The max allowable value for **scale** is
**BC_SCALE_MAX** and can be queried in bc(1) programs with the **maxscale()**
built-in function.
bc(1) has both *global* variables and *local* variables. All *local*
variables are local to the function; they are parameters or are introduced in
the **auto** list of a function (see the **FUNCTIONS** section). If a variable
is accessed which is not a parameter or in the **auto** list, it is assumed to
be *global*. If a parent function has a *local* variable version of a variable
that a child function considers *global*, the value of that *global* variable in
the child function is the value of the variable in the parent function, not the
value of the actual *global* variable.
All of the above applies to arrays as well.
The value of a statement that is an expression (i.e., any of the named
expressions or operands) is printed unless the lowest precedence operator is an
assignment operator *and* the expression is notsurrounded by parentheses.
The value that is printed is also assigned to the special variable **last**. A
single dot (**.**) may also be used as a synonym for **last**. These are
**non-portable extensions**.
Either semicolons or newlines may separate statements.
## Comments
There are two kinds of comments:
1. Block comments are enclosed in **/\*** and **\*/**.
2. Line comments go from **#** until, and not including, the next newline. This
is a **non-portable extension**.
## Named Expressions
The following are named expressions in bc(1):
1. Variables: **I**
2. Array Elements: **I[E]**
3. **ibase**
4. **obase**
5. **scale**
6. **seed**
7. **last** or a single dot (**.**)
Numbers 6 and 7 are **non-portable extensions**.
The meaning of **seed** is dependent on the current pseudo-random number
generator but is guaranteed to not change except for new major versions.
The *scale* and sign of the value may be significant.
If a previously used **seed** value is assigned to **seed** and used again, the
pseudo-random number generator is guaranteed to produce the same sequence of
pseudo-random numbers as it did when the **seed** value was previously used.
The exact value assigned to **seed** is not guaranteed to be returned if
**seed** is queried again immediately. However, if **seed** *does* return a
different value, both values, when assigned to **seed**, are guaranteed to
produce the same sequence of pseudo-random numbers. This means that certain
values assigned to **seed** will *not* produce unique sequences of pseudo-random
numbers. The value of **seed** will change after any use of the **rand()** and
**irand(E)** operands (see the *Operands* subsection below), except if the
parameter passed to **irand(E)** is **0**, **1**, or negative.
There is no limit to the length (number of significant decimal digits) or
*scale* of the value that can be assigned to **seed**.
Variables and arrays do not interfere; users can have arrays named the same as
variables. This also applies to functions (see the **FUNCTIONS** section), so a
user can have a variable, array, and function that all have the same name, and
they will not shadow each other, whether inside of functions or not.
Named expressions are required as the operand of **increment**/**decrement**
operators and as the left side of **assignment** operators (see the *Operators*
subsection).
## Operands
The following are valid operands in bc(1):
1. Numbers (see the *Numbers* subsection below).
2. Array indices (**I[E]**).
3. **(E)**: The value of **E** (used to change precedence).
4. **sqrt(E)**: The square root of **E**. **E** must be non-negative.
5. **length(E)**: The number of significant decimal digits in **E**.
6. **length(I[])**: The number of elements in the array **I**. This is a
**non-portable extension**.
7. **scale(E)**: The *scale* of **E**.
8. **abs(E)**: The absolute value of **E**. This is a **non-portable
extension**.
9. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a non-**void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
10. **read()**: Reads a line from **stdin** and uses that as an expression. The
result of that expression is the result of the **read()** operand. This is a
**non-portable extension**.
11. **maxibase()**: The max allowable **ibase**. This is a **non-portable
extension**.
12. **maxobase()**: The max allowable **obase**. This is a **non-portable
extension**.
13. **maxscale()**: The max allowable **scale**. This is a **non-portable
extension**.
14. **rand()**: A pseudo-random integer between **0** (inclusive) and
**BC_RAND_MAX** (inclusive). Using this operand will change the value of
**seed**. This is a **non-portable extension**.
15. **irand(E)**: A pseudo-random integer between **0** (inclusive) and the
value of **E** (exclusive). If **E** is negative or is a non-integer
(**E**'s *scale* is not **0**), an error is raised, and bc(1) resets (see
the **RESET** section) while **seed** remains unchanged. If **E** is larger
than **BC_RAND_MAX**, the higher bound is honored by generating several
pseudo-random integers, multiplying them by appropriate powers of
**BC_RAND_MAX+1**, and adding them together. Thus, the size of integer that
can be generated with this operand is unbounded. Using this operand will
change the value of **seed**, unless the value of **E** is **0** or **1**.
In that case, **0** is returned, and **seed** is *not* changed. This is a
**non-portable extension**.
16. **maxrand()**: The max integer returned by **rand()**. This is a
**non-portable extension**.
The integers generated by **rand()** and **irand(E)** are guaranteed to be as
unbiased as possible, subject to the limitations of the pseudo-random number
generator.
**Note**: The values returned by the pseudo-random number generator with
**rand()** and **irand(E)** are guaranteed to *NOT* be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator. However,
they *are* guaranteed to be reproducible with identical **seed** values. This
means that the pseudo-random values from bc(1) should only be used where a
reproducible stream of pseudo-random numbers is *ESSENTIAL*. In any other case,
use a non-seeded pseudo-random number generator.
## Numbers
Numbers are strings made up of digits, uppercase letters, and at most **1**
period for a radix. Numbers can have up to **BC_NUM_MAX** digits. Uppercase
letters are equal to **9** + their position in the alphabet (i.e., **A** equals
**10**, or **9+1**). If a digit or letter makes no sense with the current value
of **ibase**, they are set to the value of the highest valid digit in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **Z** alone always equals decimal
**35**.
In addition, bc(1) accepts numbers in scientific notation. These have the form
**\<number\>e\<integer\>**. The exponent (the portion after the **e**) must be
an integer. An example is **1.89237e9**, which is equal to **1892370000**.
Negative exponents are also allowed, so **4.2890e-3** is equal to **0.0042890**.
Using scientific notation is an error or warning if the **-s** or **-w**,
respectively, command-line options (or equivalents) are given.
**WARNING**: Both the number and the exponent in scientific notation are
interpreted according to the current **ibase**, but the number is still
multiplied by **10\^exponent** regardless of the current **ibase**. For example,
if **ibase** is **16** and bc(1) is given the number string **FFeA**, the
resulting decimal number will be **2550000000000**, and if bc(1) is given the
number string **10e-4**, the resulting decimal number will be **0.0016**.
Accepting input as scientific notation is a **non-portable extension**.
## Operators
The following arithmetic and logical operators can be used. They are listed in
order of decreasing precedence. Operators in the same group have the same
precedence.
**++** **--**
: Type: Prefix and Postfix
Associativity: None
Description: **increment**, **decrement**
**-** **!**
: Type: Prefix
Associativity: None
Description: **negation**, **boolean not**
**\$**
: Type: Postfix
Associativity: None
Description: **truncation**
**\@**
: Type: Binary
Associativity: Right
Description: **set precision**
**\^**
: Type: Binary
Associativity: Right
Description: **power**
**\*** **/** **%**
: Type: Binary
Associativity: Left
Description: **multiply**, **divide**, **modulus**
**+** **-**
: Type: Binary
Associativity: Left
Description: **add**, **subtract**
**\<\<** **\>\>**
: Type: Binary
Associativity: Left
Description: **shift left**, **shift right**
**=** **\<\<=** **\>\>=** **+=** **-=** **\*=** **/=** **%=** **\^=** **\@=**
: Type: Binary
Associativity: Right
Description: **assignment**
**==** **\<=** **\>=** **!=** **\<** **\>**
: Type: Binary
Associativity: Left
Description: **relational**
**&&**
: Type: Binary
Associativity: Left
Description: **boolean and**
**||**
: Type: Binary
Associativity: Left
Description: **boolean or**
The operators will be described in more detail below.
**++** **--**
: The prefix and postfix **increment** and **decrement** operators behave
exactly like they would in C. They require a named expression (see the
*Named Expressions* subsection) as an operand.
The prefix versions of these operators are more efficient; use them where
possible.
**-**
: The **negation** operator returns **0** if a user attempts to negate any
expression with the value **0**. Otherwise, a copy of the expression with
its sign flipped is returned.
**!**
: The **boolean not** operator returns **1** if the expression is **0**, or
**0** otherwise.
This is a **non-portable extension**.
**\$**
: The **truncation** operator returns a copy of the given expression with all
of its *scale* removed.
This is a **non-portable extension**.
**\@**
: The **set precision** operator takes two expressions and returns a copy of
the first with its *scale* equal to the value of the second expression. That
could either mean that the number is returned without change (if the
*scale* of the first expression matches the value of the second
expression), extended (if it is less), or truncated (if it is more).
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**\^**
: The **power** operator (not the **exclusive or** operator, as it would be in
C) takes two expressions and raises the first to the power of the value of
the second. The *scale* of the result is equal to **scale**.
The second expression must be an integer (no *scale*), and if it is
negative, the first value must be non-zero.
**\***
: The **multiply** operator takes two expressions, multiplies them, and
returns the product. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result is
equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The **divide** operator takes two expressions, divides them, and returns the
quotient. The *scale* of the result shall be the value of **scale**.
The second expression must be non-zero.
**%**
: The **modulus** operator takes two expressions, **a** and **b**, and
evaluates them by 1) Computing **a/b** to current **scale** and 2) Using the
result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The second expression must be non-zero.
**+**
: The **add** operator takes two expressions, **a** and **b**, and returns the
sum, with a *scale* equal to the max of the *scale*s of **a** and **b**.
**-**
: The **subtract** operator takes two expressions, **a** and **b**, and
returns the difference, with a *scale* equal to the max of the *scale*s of
**a** and **b**.
**\<\<**
: The **left shift** operator takes two expressions, **a** and **b**, and
returns a copy of the value of **a** with its decimal point moved **b**
places to the right.
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**\>\>**
: The **right shift** operator takes two expressions, **a** and **b**, and
returns a copy of the value of **a** with its decimal point moved **b**
places to the left.
The second expression must be an integer (no *scale*) and non-negative.
This is a **non-portable extension**.
**=** **\<\<=** **\>\>=** **+=** **-=** **\*=** **/=** **%=** **\^=** **\@=**
: The **assignment** operators take two expressions, **a** and **b** where
**a** is a named expression (see the *Named Expressions* subsection).
For **=**, **b** is copied and the result is assigned to **a**. For all
others, **a** and **b** are applied as operands to the corresponding
arithmetic operator and the result is assigned to **a**.
The **assignment** operators that correspond to operators that are
extensions are themselves **non-portable extensions**.
**==** **\<=** **\>=** **!=** **\<** **\>**
: The **relational** operators compare two expressions, **a** and **b**, and
if the relation holds, according to C language semantics, the result is
**1**. Otherwise, it is **0**.
Note that unlike in C, these operators have a lower precedence than the
**assignment** operators, which means that **a=b\>c** is interpreted as
**(a=b)\>c**.
Also, unlike the [standard][1] requires, these operators can appear anywhere
any other expressions can be used. This allowance is a
**non-portable extension**.
**&&**
: The **boolean and** operator takes two expressions and returns **1** if both
expressions are non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
**||**
: The **boolean or** operator takes two expressions and returns **1** if one
of the expressions is non-zero, **0** otherwise.
This is *not* a short-circuit operator.
This is a **non-portable extension**.
## Statements
The following items are statements:
1. **E**
2. **{** **S** **;** ... **;** **S** **}**
3. **if** **(** **E** **)** **S**
4. **if** **(** **E** **)** **S** **else** **S**
5. **while** **(** **E** **)** **S**
6. **for** **(** **E** **;** **E** **;** **E** **)** **S**
7. An empty statement
8. **break**
9. **continue**
10. **quit**
11. **halt**
12. **limits**
13. A string of characters, enclosed in double quotes
14. **print** **E** **,** ... **,** **E**
15. **I()**, **I(E)**, **I(E, E)**, and so on, where **I** is an identifier for
a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section). The **E** argument(s) may also be arrays of the form
**I[]**, which will automatically be turned into array references (see the
*Array References* subsection of the **FUNCTIONS** section) if the
corresponding parameter in the function definition is an array reference.
Numbers 4, 9, 11, 12, 14, and 15 are **non-portable extensions**.
Also, as a **non-portable extension**, any or all of the expressions in the
header of a for loop may be omitted. If the condition (second expression) is
omitted, it is assumed to be a constant **1**.
The **break** statement causes a loop to stop iterating and resume execution
immediately following a loop. This is only allowed in loops.
The **continue** statement causes a loop iteration to stop early and returns to
the start of the loop, including testing the loop condition. This is only
allowed in loops.
The **if** **else** statement does the same thing as in C.
The **quit** statement causes bc(1) to quit, even if it is on a branch that will
not be executed (it is a compile-time command).
The **halt** statement causes bc(1) to quit, if it is executed. (Unlike **quit**
if it is on a branch of an **if** statement that is not executed, bc(1) does not
quit.)
The **limits** statement prints the limits that this bc(1) is subject to. This
is like the **quit** statement in that it is a compile-time command.
An expression by itself is evaluated and printed, followed by a newline.
Both scientific notation and engineering notation are available for printing the
results of expressions. Scientific notation is activated by assigning **0** to
**obase**, and engineering notation is activated by assigning **1** to
**obase**. To deactivate them, just assign a different value to **obase**.
Scientific notation and engineering notation are disabled if bc(1) is run with
either the **-s** or **-w** command-line options (or equivalents).
Printing numbers in scientific notation and/or engineering notation is a
**non-portable extension**.
## Print Statement
The "expressions" in a **print** statement may also be strings. If they are, there
are backslash escape sequences that are interpreted specially. What those
sequences are, and what they cause to be printed, are shown below:
-------- -------
**\\a** **\\a**
**\\b** **\\b**
**\\\\** **\\**
**\\e** **\\**
**\\f** **\\f**
**\\n** **\\n**
**\\q** **"**
**\\r** **\\r**
**\\t** **\\t**
-------- -------
Any other character following a backslash causes the backslash and character to
be printed as-is.
Any non-string expression in a print statement shall be assigned to **last**,
like any other expression that is printed.
## Order of Evaluation
All expressions in a statment are evaluated left to right, except as necessary
to maintain order of operations. This means, for example, assuming that **i** is
equal to **0**, in the expression
a[i++] = i++
the first (or 0th) element of **a** is set to **1**, and **i** is equal to **2**
at the end of the expression.
This includes function arguments. Thus, assuming **i** is equal to **0**, this
means that in the expression
x(i++, i++)
the first argument passed to **x()** is **0**, and the second argument is **1**,
while **i** is equal to **2** before the function starts executing.
# FUNCTIONS
Function definitions are as follows:
```
define I(I,...,I){
auto I,...,I
S;...;S
return(E)
}
```
Any **I** in the parameter list or **auto** list may be replaced with **I[]** to
make a parameter or **auto** var an array, and any **I** in the parameter list
may be replaced with **\*I[]** to make a parameter an array reference. Callers
of functions that take array references should not put an asterisk in the call;
they must be called with just **I[]** like normal array parameters and will be
automatically converted into references.
As a **non-portable extension**, the opening brace of a **define** statement may
appear on the next line.
As a **non-portable extension**, the return statement may also be in one of the
following forms:
1. **return**
2. **return** **(** **)**
3. **return** **E**
The first two, or not specifying a **return** statement, is equivalent to
**return (0)**, unless the function is a **void** function (see the *Void
Functions* subsection below).
## Void Functions
Functions can also be **void** functions, defined as follows:
```
define void I(I,...,I){
auto I,...,I
S;...;S
return
}
```
They can only be used as standalone expressions, where such an expression would
be printed alone, except in a print statement.
Void functions can only use the first two **return** statements listed above.
They can also omit the return statement entirely.
The word "void" is not treated as a keyword; it is still possible to have
variables, arrays, and functions named **void**. The word "void" is only
treated specially right after the **define** keyword.
This is a **non-portable extension**.
## Array References
For any array in the parameter list, if the array is declared in the form
```
*I[]
```
it is a **reference**. Any changes to the array in the function are reflected,
when the function returns, to the array that was passed in.
Other than this, all function arguments are passed by value.
This is a **non-portable extension**.
# LIBRARY
All of the functions below, including the functions in the extended math
library (see the *Extended Library* subsection below), are available when the
**-l** or **--mathlib** command-line flags are given, except that the extended
math library is not available when the **-s** option, the **-w** option, or
equivalents are given.
## Standard Library
The [standard][1] defines the following functions for the math library:
**s(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**c(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a(x)**
: Returns the arctangent of **x**, in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l(x)**
: Returns the natural logarithm of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**e(x)**
: Returns the mathematical constant **e** raised to the power of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**j(x, n)**
: Returns the bessel integer order **n** (truncated) of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
## Extended Library
The extended library is *not* loaded when the **-s**/**--standard** or
**-w**/**--warn** options are given since they are not part of the library
defined by the [standard][1].
The extended library is a **non-portable extension**.
**p(x, y)**
: Calculates **x** to the power of **y**, even if **y** is not an integer, and
returns the result to the current **scale**.
It is an error if **y** is negative and **x** is **0**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**r(x, p)**
: Returns **x** rounded to **p** decimal places according to the rounding mode
[round half away from **0**][3].
**ceil(x, p)**
: Returns **x** rounded to **p** decimal places according to the rounding mode
[round away from **0**][6].
**f(x)**
: Returns the factorial of the truncated absolute value of **x**.
**perm(n, k)**
: Returns the permutation of the truncated absolute value of **n** of the
truncated absolute value of **k**, if **k \<= n**. If not, it returns **0**.
**comb(n, k)**
: Returns the combination of the truncated absolute value of **n** of the
truncated absolute value of **k**, if **k \<= n**. If not, it returns **0**.
**l2(x)**
: Returns the logarithm base **2** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**l10(x)**
: Returns the logarithm base **10** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**log(x, b)**
: Returns the logarithm base **b** of **x**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**cbrt(x)**
: Returns the cube root of **x**.
**root(x, n)**
: Calculates the truncated value of **n**, **r**, and returns the **r**th root
of **x** to the current **scale**.
If **r** is **0** or negative, this raises an error and causes bc(1) to
reset (see the **RESET** section). It also raises an error and causes bc(1)
to reset if **r** is even and **x** is negative.
**pi(p)**
: Returns **pi** to **p** decimal places.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**t(x)**
: Returns the tangent of **x**, which is assumed to be in radians.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**a2(y, x)**
: Returns the arctangent of **y/x**, in radians. If both **y** and **x** are
equal to **0**, it raises an error and causes bc(1) to reset (see the
**RESET** section). Otherwise, if **x** is greater than **0**, it returns
**a(y/x)**. If **x** is less than **0**, and **y** is greater than or equal
to **0**, it returns **a(y/x)+pi**. If **x** is less than **0**, and **y**
is less than **0**, it returns **a(y/x)-pi**. If **x** is equal to **0**,
and **y** is greater than **0**, it returns **pi/2**. If **x** is equal to
**0**, and **y** is less than **0**, it returns **-pi/2**.
This function is the same as the **atan2()** function in many programming
languages.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**sin(x)**
: Returns the sine of **x**, which is assumed to be in radians.
This is an alias of **s(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**cos(x)**
: Returns the cosine of **x**, which is assumed to be in radians.
This is an alias of **c(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**tan(x)**
: Returns the tangent of **x**, which is assumed to be in radians.
If **x** is equal to **1** or **-1**, this raises an error and causes bc(1)
to reset (see the **RESET** section).
This is an alias of **t(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**atan(x)**
: Returns the arctangent of **x**, in radians.
This is an alias of **a(x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**atan2(y, x)**
: Returns the arctangent of **y/x**, in radians. If both **y** and **x** are
equal to **0**, it raises an error and causes bc(1) to reset (see the
**RESET** section). Otherwise, if **x** is greater than **0**, it returns
**a(y/x)**. If **x** is less than **0**, and **y** is greater than or equal
to **0**, it returns **a(y/x)+pi**. If **x** is less than **0**, and **y**
is less than **0**, it returns **a(y/x)-pi**. If **x** is equal to **0**,
and **y** is greater than **0**, it returns **pi/2**. If **x** is equal to
**0**, and **y** is less than **0**, it returns **-pi/2**.
This function is the same as the **atan2()** function in many programming
languages.
This is an alias of **a2(y, x)**.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**r2d(x)**
: Converts **x** from radians to degrees and returns the result.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**d2r(x)**
: Converts **x** from degrees to radians and returns the result.
This is a transcendental function (see the *Transcendental Functions*
subsection below).
**frand(p)**
: Generates a pseudo-random number between **0** (inclusive) and **1**
(exclusive) with the number of decimal digits after the decimal point equal
to the truncated absolute value of **p**. If **p** is not **0**, then
calling this function will change the value of **seed**. If **p** is **0**,
then **0** is returned, and **seed** is *not* changed.
**ifrand(i, p)**
: Generates a pseudo-random number that is between **0** (inclusive) and the
truncated absolute value of **i** (exclusive) with the number of decimal
digits after the decimal point equal to the truncated absolute value of
**p**. If the absolute value of **i** is greater than or equal to **2**, and
**p** is not **0**, then calling this function will change the value of
**seed**; otherwise, **0** is returned and **seed** is not changed.
**srand(x)**
: Returns **x** with its sign flipped with probability **0.5**. In other
words, it randomizes the sign of **x**.
**brand()**
: Returns a random boolean value (either **0** or **1**).
**ubytes(x)**
: Returns the numbers of unsigned integer bytes required to hold the truncated
absolute value of **x**.
**sbytes(x)**
: Returns the numbers of signed, two's-complement integer bytes required to
hold the truncated value of **x**.
**hex(x)**
: Outputs the hexadecimal (base **16**) representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**binary(x)**
: Outputs the binary (base **2**) representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output(x, b)**
: Outputs the base **b** representation of **x**.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in as few power of two bytes as possible. Both outputs are
split into bytes separated by spaces.
If **x** is not an integer or is negative, an error message is printed
instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in as few power of two bytes as possible. Both
outputs are split into bytes separated by spaces.
If **x** is not an integer, an error message is printed instead, but bc(1)
is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uintn(x, n)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **n** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **n** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**intn(x, n)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **n** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **n** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint8(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **1** byte. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **1** byte, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int8(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **1** byte. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **1** byte, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint16(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **2** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **2** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int16(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **2** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **2** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint32(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **4** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **4** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int32(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **4** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **4** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**uint64(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as an
unsigned integer in **8** bytes. Both outputs are split into bytes separated
by spaces.
If **x** is not an integer, is negative, or cannot fit into **8** bytes, an
error message is printed instead, but bc(1) is not reset (see the **RESET**
section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**int64(x)**
: Outputs the representation, in binary and hexadecimal, of **x** as a signed,
two's-complement integer in **8** bytes. Both outputs are split into bytes
separated by spaces.
If **x** is not an integer or cannot fit into **8** bytes, an error message
is printed instead, but bc(1) is not reset (see the **RESET** section).
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**hex_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in hexadecimal using **n** bytes. Not all of the value will
be output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**binary_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in binary using **n** bytes. Not all of the value will be
output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output_uint(x, n)**
: Outputs the representation of the truncated absolute value of **x** as an
unsigned integer in the current **obase** (see the **SYNTAX** section) using
**n** bytes. Not all of the value will be output if **n** is too small.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
**output_byte(x, i)**
: Outputs byte **i** of the truncated absolute value of **x**, where **0** is
the least significant byte and **number_of_bytes - 1** is the most
significant byte.
This is a **void** function (see the *Void Functions* subsection of the
**FUNCTIONS** section).
## Transcendental Functions
All transcendental functions can return slightly inaccurate results (up to 1
[ULP][4]). This is unavoidable, and [this article][5] explains why it is
impossible and unnecessary to calculate exact results for the transcendental
functions.
Because of the possible inaccuracy, I recommend that users call those functions
with the precision (**scale**) set to at least 1 higher than is necessary. If
exact results are *absolutely* required, users can double the precision
(**scale**) and then truncate.
The transcendental functions in the standard math library are:
* **s(x)**
* **c(x)**
* **a(x)**
* **l(x)**
* **e(x)**
* **j(x, n)**
The transcendental functions in the extended math library are:
* **l2(x)**
* **l10(x)**
* **log(x, b)**
* **pi(p)**
* **t(x)**
* **a2(y, x)**
* **sin(x)**
* **cos(x)**
* **tan(x)**
* **atan(x)**
* **atan2(y, x)**
* **r2d(x)**
* **d2r(x)**
# RESET
When bc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any functions that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
functions returned) is skipped.
Thus, when bc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
Note that this reset behavior is different from the GNU bc(1), which attempts to
start executing the statement right after the one that caused an error.
# PERFORMANCE
Most bc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This bc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **BC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **BC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**BC_BASE_DIGS**.
The actual values of **BC_LONG_BIT** and **BC_BASE_DIGS** can be queried with
the **limits** statement.
In addition, this bc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **BC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on bc(1):
**BC_LONG_BIT**
: The number of bits in the **long** type in the environment where bc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**BC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **BC_LONG_BIT**.
**BC_BASE_POW**
: The max decimal number that each large integer can store (see
**BC_BASE_DIGS**) plus **1**. Depends on **BC_BASE_DIGS**.
**BC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **BC_LONG_BIT**.
**BC_BASE_MAX**
: The maximum output base. Set at **BC_BASE_POW**.
**BC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**BC_SCALE_MAX**
: The maximum **scale**. Set at **BC_OVERFLOW_MAX-1**.
**BC_STRING_MAX**
: The maximum length of strings. Set at **BC_OVERFLOW_MAX-1**.
**BC_NAME_MAX**
: The maximum length of identifiers. Set at **BC_OVERFLOW_MAX-1**.
**BC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **BC_OVERFLOW_MAX-1**.
**BC_RAND_MAX**
: The maximum integer (inclusive) returned by the **rand()** operand. Set at
**2\^BC_LONG_BIT-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**BC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
The actual values can be queried with the **limits** statement.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
bc(1) recognizes the following environment variables:
**POSIXLY_CORRECT**
: If this variable exists (no matter the contents), bc(1) behaves as if
the **-s** option was given.
**BC_ENV_ARGS**
: This is another way to give command-line arguments to bc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **BC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time bc(1) runs.
The code that parses **BC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some bc file.bc"** will be correctly parsed, but the string
**"/home/gavin/some \"bc\" file.bc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **BC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**BC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), bc(1) will output
lines to that length, including the backslash (**\\**). The default line
length is **70**.
# EXIT STATUS
bc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, using a negative number as a bound for the pseudo-random number
generator, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**), places (**\@**), left shift (**\<\<**), and right shift (**\>\>**)
operators and their corresponding assignment operators.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, using a token where it is invalid,
giving an invalid expression, giving an invalid print statement, giving an
invalid function definition, attempting to assign to an expression that is
not a named expression (see the *Named Expressions* subsection of the
**SYNTAX** section), giving an invalid **auto** list, having a duplicate
**auto**/function parameter, failing to find the end of a code block,
attempting to return a value from a **void** function, attempting to use a
variable as a reference, and using any extensions when the option **-s** or
any equivalents were given.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, passing the wrong number of
arguments to functions, attempting to call an undefined function, and
attempting to use a **void** function call as a value in an expression.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (bc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, bc(1) always exits
and returns **4**, no matter what mode bc(1) is in.
The other statuses will only be returned when bc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since bc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow bc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Per the [standard][1], bc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, bc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, bc(1) turns
on "TTY mode."
TTY mode is required for history to be enabled (see the **COMMAND LINE HISTORY**
section). It is also required to enable special handling for **SIGINT** signals.
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause bc(1) to stop execution of the current input. If
bc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If bc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If bc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to bc(1) as it is executing a file, it
can seem as though bc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with bc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause bc(1) to clean up and exit, and it uses the
default handler for all other signals. The one exception is **SIGHUP**; in that
case, when bc(1) is in TTY mode, a **SIGHUP** will cause bc(1) to clean up and
exit.
# COMMAND LINE HISTORY
bc(1) supports interactive command-line editing. If bc(1) is in TTY mode (see
the **TTY MODE** section), history is enabled. Previous lines can be recalled
and edited with the arrow keys.
**Note**: tabs are converted to 8 spaces.
# LOCALES
This bc(1) ships with support for adding error messages for different locales
and thus, supports **LC_MESSAGES**.
# SEE ALSO
dc(1)
# STANDARDS
bc(1) is compliant with the [IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1]
specification. The flags **-efghiqsvVw**, all long options, and the extensions
noted above are extensions to that specification.
Note that the specification explicitly says that bc(1) only accepts numbers that
use a period (**.**) as a radix point, regardless of the value of
**LC_NUMERIC**.
This bc(1) supports error messages for different locales, and thus, it supports
**LC_MESSAGES**.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHORS
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
[2]: https://www.gnu.org/software/bc/
[3]: https://en.wikipedia.org/wiki/Rounding#Round_half_away_from_zero
[4]: https://en.wikipedia.org/wiki/Unit_in_the_last_place
[5]: https://people.eecs.berkeley.edu/~wkahan/LOG10HAF.TXT
[6]: https://en.wikipedia.org/wiki/Rounding#Rounding_away_from_zero
diff --git a/contrib/bc/manuals/bcl.3 b/contrib/bc/manuals/bcl.3
index 2d265a20511a..99040581a153 100644
--- a/contrib/bc/manuals/bcl.3
+++ b/contrib/bc/manuals/bcl.3
@@ -1,1365 +1,1365 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "BCL" "3" "January 2021" "Gavin D. Howard" "Libraries Manual"
+.TH "BCL" "3" "February 2021" "Gavin D. Howard" "Libraries Manual"
.SH NAME
.PP
bcl - library of arbitrary precision decimal arithmetic
.SH SYNOPSIS
.SS Use
.PP
\f[I]#include <bcl.h>\f[R]
.PP
Link with \f[I]-lbcl\f[R].
.SS Signals
.PP
This procedure will allow clients to use signals to interrupt
computations running in bcl(3).
.PP
\f[B]void bcl_handleSignal(\f[R]\f[I]void\f[R]\f[B]);\f[R]
.PP
\f[B]bool bcl_running(\f[R]\f[I]void\f[R]\f[B]);\f[R]
.SS Setup
.PP
These items allow clients to set up bcl(3).
.PP
\f[B]BclError bcl_init(\f[R]\f[I]void\f[R]\f[B]);\f[R]
.PP
\f[B]void bcl_free(\f[R]\f[I]void\f[R]\f[B]);\f[R]
.PP
\f[B]bool bcl_abortOnFatalError(\f[R]\f[I]void\f[R]\f[B]);\f[R]
.PP
\f[B]void bcl_setAbortOnFatalError(bool\f[R] \f[I]abrt\f[R]\f[B]);\f[R]
.PP
\f[B]void bcl_gc(\f[R]\f[I]void\f[R]\f[B]);\f[R]
.SS Contexts
.PP
These items will allow clients to handle contexts, which are isolated
from each other.
This allows more than one client to use bcl(3) in the same program.
.PP
\f[B]struct BclCtxt;\f[R]
.PP
\f[B]typedef struct BclCtxt* BclContext;\f[R]
.PP
\f[B]BclContext bcl_ctxt_create(\f[R]\f[I]void\f[R]\f[B]);\f[R]
.PP
\f[B]void bcl_ctxt_free(BclContext\f[R] \f[I]ctxt\f[R]\f[B]);\f[R]
.PP
\f[B]BclError bcl_pushContext(BclContext\f[R] \f[I]ctxt\f[R]\f[B]);\f[R]
.PP
\f[B]void bcl_popContext(\f[R]\f[I]void\f[R]\f[B]);\f[R]
.PP
\f[B]BclContext bcl_context(\f[R]\f[I]void\f[R]\f[B]);\f[R]
.PP
\f[B]void bcl_ctxt_freeNums(BclContext\f[R] \f[I]ctxt\f[R]\f[B]);\f[R]
.PP
\f[B]size_t bcl_ctxt_scale(BclContext\f[R] \f[I]ctxt\f[R]\f[B]);\f[R]
.PP
\f[B]void bcl_ctxt_setScale(BclContext\f[R] \f[I]ctxt\f[R]\f[B],
size_t\f[R] \f[I]scale\f[R]\f[B]);\f[R]
.PP
\f[B]size_t bcl_ctxt_ibase(BclContext\f[R] \f[I]ctxt\f[R]\f[B]);\f[R]
.PP
\f[B]void bcl_ctxt_setIbase(BclContext\f[R] \f[I]ctxt\f[R]\f[B],
size_t\f[R] \f[I]ibase\f[R]\f[B]);\f[R]
.PP
\f[B]size_t bcl_ctxt_obase(BclContext\f[R] \f[I]ctxt\f[R]\f[B]);\f[R]
.PP
\f[B]void bcl_ctxt_setObase(BclContext\f[R] \f[I]ctxt\f[R]\f[B],
size_t\f[R] \f[I]obase\f[R]\f[B]);\f[R]
.SS Errors
.PP
These items allow clients to handle errors.
.PP
\f[B]typedef enum BclError BclError;\f[R]
.PP
\f[B]BclError bcl_err(BclNumber\f[R] \f[I]n\f[R]\f[B]);\f[R]
.SS Numbers
.PP
These items allow clients to manipulate and query the
arbitrary-precision numbers managed by bcl(3).
.PP
\f[B]typedef struct { size_t i; } BclNumber;\f[R]
.PP
\f[B]BclNumber bcl_num_create(\f[R]\f[I]void\f[R]\f[B]);\f[R]
.PP
\f[B]void bcl_num_free(BclNumber\f[R] \f[I]n\f[R]\f[B]);\f[R]
.PP
\f[B]bool bcl_num_neg(BclNumber\f[R] \f[I]n\f[R]\f[B]);\f[R]
.PP
\f[B]void bcl_num_setNeg(BclNumber\f[R] \f[I]n\f[R]\f[B], bool\f[R]
\f[I]neg\f[R]\f[B]);\f[R]
.PP
\f[B]size_t bcl_num_scale(BclNumber\f[R] \f[I]n\f[R]\f[B]);\f[R]
.PP
\f[B]BclError bcl_num_setScale(BclNumber\f[R] \f[I]n\f[R]\f[B],
size_t\f[R] \f[I]scale\f[R]\f[B]);\f[R]
.PP
\f[B]size_t bcl_num_len(BclNumber\f[R] \f[I]n\f[R]\f[B]);\f[R]
.SS Conversion
.PP
These items allow clients to convert numbers into and from strings and
integers.
.PP
\f[B]BclNumber bcl_parse(const char *restrict\f[R]
\f[I]val\f[R]\f[B]);\f[R]
.PP
\f[B]char* bcl_string(BclNumber\f[R] \f[I]n\f[R]\f[B]);\f[R]
.PP
\f[B]BclError bcl_bigdig(BclNumber\f[R] \f[I]n\f[R]\f[B], BclBigDig
*\f[R]\f[I]result\f[R]\f[B]);\f[R]
.PP
\f[B]BclNumber bcl_bigdig2num(BclBigDig\f[R] \f[I]val\f[R]\f[B]);\f[R]
.SS Math
.PP
These items allow clients to run math on numbers.
.PP
\f[B]BclNumber bcl_add(BclNumber\f[R] \f[I]a\f[R]\f[B], BclNumber\f[R]
\f[I]b\f[R]\f[B]);\f[R]
.PP
\f[B]BclNumber bcl_sub(BclNumber\f[R] \f[I]a\f[R]\f[B], BclNumber\f[R]
\f[I]b\f[R]\f[B]);\f[R]
.PP
\f[B]BclNumber bcl_mul(BclNumber\f[R] \f[I]a\f[R]\f[B], BclNumber\f[R]
\f[I]b\f[R]\f[B]);\f[R]
.PP
\f[B]BclNumber bcl_div(BclNumber\f[R] \f[I]a\f[R]\f[B], BclNumber\f[R]
\f[I]b\f[R]\f[B]);\f[R]
.PP
\f[B]BclNumber bcl_mod(BclNumber\f[R] \f[I]a\f[R]\f[B], BclNumber\f[R]
\f[I]b\f[R]\f[B]);\f[R]
.PP
\f[B]BclNumber bcl_pow(BclNumber\f[R] \f[I]a\f[R]\f[B], BclNumber\f[R]
\f[I]b\f[R]\f[B]);\f[R]
.PP
\f[B]BclNumber bcl_lshift(BclNumber\f[R] \f[I]a\f[R]\f[B],
BclNumber\f[R] \f[I]b\f[R]\f[B]);\f[R]
.PP
\f[B]BclNumber bcl_rshift(BclNumber\f[R] \f[I]a\f[R]\f[B],
BclNumber\f[R] \f[I]b\f[R]\f[B]);\f[R]
.PP
\f[B]BclNumber bcl_sqrt(BclNumber\f[R] \f[I]a\f[R]\f[B]);\f[R]
.PP
\f[B]BclError bcl_divmod(BclNumber\f[R] \f[I]a\f[R]\f[B], BclNumber\f[R]
\f[I]b\f[R]\f[B], BclNumber *\f[R]\f[I]c\f[R]\f[B], BclNumber
*\f[R]\f[I]d\f[R]\f[B]);\f[R]
.PP
\f[B]BclNumber bcl_modexp(BclNumber\f[R] \f[I]a\f[R]\f[B],
BclNumber\f[R] \f[I]b\f[R]\f[B], BclNumber\f[R] \f[I]c\f[R]\f[B]);\f[R]
.SS Miscellaneous
.PP
These items are miscellaneous.
.PP
\f[B]void bcl_zero(BclNumber\f[R] \f[I]n\f[R]\f[B]);\f[R]
.PP
\f[B]void bcl_one(BclNumber\f[R] \f[I]n\f[R]\f[B]);\f[R]
.PP
\f[B]ssize_t bcl_cmp(BclNumber\f[R] \f[I]a\f[R]\f[B], BclNumber\f[R]
\f[I]b\f[R]\f[B]);\f[R]
.PP
\f[B]BclError bcl_copy(BclNumber\f[R] \f[I]d\f[R]\f[B], BclNumber\f[R]
\f[I]s\f[R]\f[B]);\f[R]
.PP
\f[B]BclNumber bcl_dup(BclNumber\f[R] \f[I]s\f[R]\f[B]);\f[R]
.SS Pseudo-Random Number Generator
.PP
These items allow clients to manipulate the seeded pseudo-random number
generator in bcl(3).
.PP
\f[B]#define BCL_SEED_ULONGS\f[R]
.PP
\f[B]#define BCL_SEED_SIZE\f[R]
.PP
\f[B]typedef unsigned long BclBigDig;\f[R]
.PP
\f[B]typedef unsigned long BclRandInt;\f[R]
.PP
\f[B]BclNumber bcl_irand(BclNumber\f[R] \f[I]a\f[R]\f[B]);\f[R]
.PP
\f[B]BclNumber bcl_frand(size_t\f[R] \f[I]places\f[R]\f[B]);\f[R]
.PP
\f[B]BclNumber bcl_ifrand(BclNumber\f[R] \f[I]a\f[R]\f[B], size_t\f[R]
\f[I]places\f[R]\f[B]);\f[R]
.PP
\f[B]BclError bcl_rand_seedWithNum(BclNumber\f[R]
\f[I]n\f[R]\f[B]);\f[R]
.PP
\f[B]BclError bcl_rand_seed(unsigned char\f[R]
\f[I]seed\f[R]\f[B][\f[R]\f[I]BC_SEED_SIZE\f[R]\f[B]]);\f[R]
.PP
\f[B]void bcl_rand_reseed(\f[R]\f[I]void\f[R]\f[B]);\f[R]
.PP
\f[B]BclNumber bcl_rand_seed2num(\f[R]\f[I]void\f[R]\f[B]);\f[R]
.PP
\f[B]BclRandInt bcl_rand_int(\f[R]\f[I]void\f[R]\f[B]);\f[R]
.PP
\f[B]BclRandInt bcl_rand_bounded(BclRandInt\f[R]
\f[I]bound\f[R]\f[B]);\f[R]
.SH DESCRIPTION
.PP
bcl(3) is a library that implements arbitrary-precision decimal math, as
standardized by
POSIX (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
in bc(1).
.PP
bcl(3) is async-signal-safe if
\f[B]bcl_handleSignal(\f[R]\f[I]void\f[R]\f[B])\f[R] is used properly.
(See the \f[B]SIGNAL HANDLING\f[R] section.)
.PP
All of the items in its interface are described below.
See the documentation for each function for what each function can
return.
.SS Signals
.TP
\f[B]void bcl_handleSignal(\f[R]\f[I]void\f[R]\f[B])\f[R]
An async-signal-safe function that can be called from a signal handler.
If called from a signal handler on the same thread as any executing
bcl(3) functions, it will interrupt the functions and force them to
return early.
It is undefined behavior if this function is called from a thread that
is \f[I]not\f[R] executing any bcl(3) functions while any bcl(3)
functions are executing.
.RS
.PP
If execution \f[I]is\f[R] interrupted,
\f[B]bcl_handleSignal(\f[R]\f[I]void\f[R]\f[B])\f[R] does \f[I]not\f[R]
return to its caller.
.PP
See the \f[B]SIGNAL HANDLING\f[R] section.
.RE
.TP
\f[B]bool bcl_running(\f[R]\f[I]void\f[R]\f[B])\f[R]
An async-signal-safe function that can be called from a signal handler.
It will return \f[B]true\f[R] if any bcl(3) procedures are running,
which means it is safe to call
\f[B]bcl_handleSignal(\f[R]\f[I]void\f[R]\f[B])\f[R].
Otherwise, it returns \f[B]false\f[R].
.RS
.PP
See the \f[B]SIGNAL HANDLING\f[R] section.
.RE
.SS Setup
.TP
\f[B]BclError bcl_init(\f[R]\f[I]void\f[R]\f[B])\f[R]
Initializes this library.
This function can be called multiple times, but each call must be
matched by a call to \f[B]bcl_free(\f[R]\f[I]void\f[R]\f[B])\f[R].
This is to make it possible for multiple libraries and applications to
initialize bcl(3) without problem.
.RS
.PP
If there was no error, \f[B]BCL_ERROR_NONE\f[R] is returned.
Otherwise, this function can return:
.IP \[bu] 2
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
.PP
This function must be the first one clients call.
Calling any other function without calling this one first is undefined
behavior.
.RE
.TP
\f[B]void bcl_free(\f[R]\f[I]void\f[R]\f[B])\f[R]
Decrements bcl(3)\[cq]s reference count and frees the data associated
with it if the reference count is \f[B]0\f[R].
.RS
.PP
This function must be the last one clients call.
Calling this function before calling any other function is undefined
behavior.
.RE
.TP
\f[B]bool bcl_abortOnFatalError(\f[R]\f[I]void\f[R]\f[B])\f[R]
Queries and returns the current state of calling \f[B]abort()\f[R] on
fatal errors.
If \f[B]true\f[R] is returned, bcl(3) will cause a \f[B]SIGABRT\f[R] if
a fatal error occurs.
.RS
.PP
If activated, clients do not need to check for fatal errors.
.RE
.TP
\f[B]void bcl_setAbortOnFatalError(bool\f[R] \f[I]abrt\f[R]\f[B])\f[R]
Sets the state of calling \f[B]abort()\f[R] on fatal errors.
If \f[I]abrt\f[R] is \f[B]false\f[R], bcl(3) will not cause a
\f[B]SIGABRT\f[R] on fatal errors after the call.
If \f[I]abrt\f[R] is \f[B]true\f[R], bcl(3) will cause a
\f[B]SIGABRT\f[R] on fatal errors after the call.
.RS
.PP
If activated, clients do not need to check for fatal errors.
.RE
.TP
\f[B]void bcl_gc(\f[R]\f[I]void\f[R]\f[B])\f[R]
Garbage collects cached instances of arbitrary-precision numbers.
This only frees the memory of numbers that are \f[I]not\f[R] in use, so
it is safe to call at any time.
.SS Contexts
.PP
All procedures that take a \f[B]BclContext\f[R] parameter a require a
valid context as an argument.
.TP
\f[B]struct BclCtxt\f[R]
A forward declaration for a hidden \f[B]struct\f[R] type.
Clients cannot access the internals of the \f[B]struct\f[R] type
directly.
All interactions with the type are done through pointers.
See \f[B]BclContext\f[R] below.
.TP
\f[B]BclContext\f[R]
A typedef to a pointer of \f[B]struct BclCtxt\f[R].
This is the only handle clients can get to \f[B]struct BclCtxt\f[R].
.RS
.PP
A \f[B]BclContext\f[R] contains the values \f[B]scale\f[R],
\f[B]ibase\f[R], and \f[B]obase\f[R], as well as a list of numbers.
.PP
\f[B]scale\f[R] is a value used to control how many decimal places
calculations should use.
A value of \f[B]0\f[R] means that calculations are done on integers
only, where applicable, and a value of 20, for example, means that all
applicable calculations return results with 20 decimal places.
The default is \f[B]0\f[R].
.PP
\f[B]ibase\f[R] is a value used to control the input base.
The minimum \f[B]ibase\f[R] is \f[B]2\f[R], and the maximum is
\f[B]36\f[R].
If \f[B]ibase\f[R] is \f[B]2\f[R], numbers are parsed as though they are
in binary, and any digits larger than \f[B]1\f[R] are clamped.
Likewise, a value of \f[B]10\f[R] means that numbers are parsed as
though they are decimal, and any larger digits are clamped.
The default is \f[B]10\f[R].
.PP
\f[B]obase\f[R] is a value used to control the output base.
The minimum \f[B]obase\f[R] is \f[B]0\f[R] and the maximum is
\f[B]BC_BASE_MAX\f[R] (see the \f[B]LIMITS\f[R] section).
.PP
Numbers created in one context are not valid in another context.
It is undefined behavior to use a number created in a different context.
Contexts are meant to isolate the numbers used by different clients in
the same application.
.RE
.TP
\f[B]BclContext bcl_ctxt_create(\f[R]\f[I]void\f[R]\f[B])\f[R]
Creates a context and returns it.
Returns \f[B]NULL\f[R] if there was an error.
.TP
\f[B]void bcl_ctxt_free(BclContext\f[R] \f[I]ctxt\f[R]\f[B])\f[R]
Frees \f[I]ctxt\f[R], after which it is no longer valid.
It is undefined behavior to attempt to use an invalid context.
.TP
\f[B]BclError bcl_pushContext(BclContext\f[R] \f[I]ctxt\f[R]\f[B])\f[R]
Pushes \f[I]ctxt\f[R] onto bcl(3)\[cq]s stack of contexts.
\f[I]ctxt\f[R] must have been created with
\f[B]bcl_ctxt_create(\f[R]\f[I]void\f[R]\f[B])\f[R].
.RS
.PP
If there was no error, \f[B]BCL_ERROR_NONE\f[R] is returned.
Otherwise, this function can return:
.IP \[bu] 2
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
.PP
There \f[I]must\f[R] be a valid context to do any arithmetic.
.RE
.TP
\f[B]void bcl_popContext(\f[R]\f[I]void\f[R]\f[B])\f[R]
Pops the current context off of the stack, if one exists.
.TP
\f[B]BclContext bcl_context(\f[R]\f[I]void\f[R]\f[B])\f[R]
Returns the current context, or \f[B]NULL\f[R] if no context exists.
.TP
\f[B]void bcl_ctxt_freeNums(BclContext\f[R] \f[I]ctxt\f[R]\f[B])\f[R]
Frees all numbers in use that are associated with \f[I]ctxt\f[R].
It is undefined behavior to attempt to use a number associated with
\f[I]ctxt\f[R] after calling this procedure unless such numbers have
been created with \f[B]bcl_num_create(\f[R]\f[I]void\f[R]\f[B])\f[R]
after calling this procedure.
.TP
\f[B]size_t bcl_ctxt_scale(BclContext\f[R] \f[I]ctxt\f[R]\f[B])\f[R]
Returns the \f[B]scale\f[R] for given context.
.TP
\f[B]void bcl_ctxt_setScale(BclContext\f[R] \f[I]ctxt\f[R]\f[B], size_t\f[R] \f[I]scale\f[R]\f[B])\f[R]
Sets the \f[B]scale\f[R] for the given context to the argument
\f[I]scale\f[R].
.TP
\f[B]size_t bcl_ctxt_ibase(BclContext\f[R] \f[I]ctxt\f[R]\f[B])\f[R]
Returns the \f[B]ibase\f[R] for the given context.
.TP
\f[B]void bcl_ctxt_setIbase(BclContext\f[R] \f[I]ctxt\f[R]\f[B], size_t\f[R] \f[I]ibase\f[R]\f[B])\f[R]
Sets the \f[B]ibase\f[R] for the given context to the argument
\f[I]ibase\f[R].
If the argument \f[I]ibase\f[R] is invalid, it clamped, so an
\f[I]ibase\f[R] of \f[B]0\f[R] or \f[B]1\f[R] is clamped to \f[B]2\f[R],
and any values above \f[B]36\f[R] are clamped to \f[B]36\f[R].
.TP
\f[B]size_t bcl_ctxt_obase(BclContext\f[R] \f[I]ctxt\f[R]\f[B])\f[R]
Returns the \f[B]obase\f[R] for the given context.
.TP
\f[B]void bcl_ctxt_setObase(BclContext\f[R] \f[I]ctxt\f[R]\f[B], size_t\f[R] \f[I]obase\f[R]\f[B])\f[R]
Sets the \f[B]obase\f[R] for the given context to the argument
\f[I]obase\f[R].
.SS Errors
.TP
\f[B]BclError\f[R]
An \f[B]enum\f[R] of possible error codes.
See the \f[B]ERRORS\f[R] section for a complete listing the codes.
.TP
\f[B]BclError bcl_err(BclNumber\f[R] \f[I]n\f[R]\f[B])\f[R]
Checks for errors in a \f[B]BclNumber\f[R].
All functions that can return a \f[B]BclNumber\f[R] can encode an error
in the number, and this function will return the error, if any.
If there was no error, it will return \f[B]BCL_ERROR_NONE\f[R].
.RS
.PP
There must be a valid current context.
.RE
.SS Numbers
.PP
All procedures in this section require a valid current context.
.TP
\f[B]BclNumber\f[R]
A handle to an arbitrary-precision number.
The actual number type is not exposed; the \f[B]BclNumber\f[R] handle is
the only way clients can refer to instances of arbitrary-precision
numbers.
.TP
\f[B]BclNumber bcl_num_create(\f[R]\f[I]void\f[R]\f[B])\f[R]
Creates and returns a \f[B]BclNumber\f[R].
.RS
.PP
bcl(3) will encode an error in the return value, if there was one.
The error can be queried with \f[B]bcl_err(BclNumber)\f[R].
Possible errors include:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
.RE
.TP
\f[B]void bcl_num_free(BclNumber\f[R] \f[I]n\f[R]\f[B])\f[R]
Frees \f[I]n\f[R].
It is undefined behavior to use \f[I]n\f[R] after calling this function.
.TP
\f[B]bool bcl_num_neg(BclNumber\f[R] \f[I]n\f[R]\f[B])\f[R]
Returns \f[B]true\f[R] if \f[I]n\f[R] is negative, \f[B]false\f[R]
otherwise.
.TP
\f[B]void bcl_num_setNeg(BclNumber\f[R] \f[I]n\f[R]\f[B], bool\f[R] \f[I]neg\f[R]\f[B])\f[R]
Sets \f[I]n\f[R]\[cq]s sign to \f[I]neg\f[R], where \f[B]true\f[R] is
negative, and \f[B]false\f[R] is positive.
.TP
\f[B]size_t bcl_num_scale(BclNumber\f[R] \f[I]n\f[R]\f[B])\f[R]
Returns the \f[I]scale\f[R] of \f[I]n\f[R].
.RS
.PP
The \f[I]scale\f[R] of a number is the number of decimal places it has
after the radix (decimal point).
.RE
.TP
\f[B]BclError bcl_num_setScale(BclNumber\f[R] \f[I]n\f[R]\f[B], size_t\f[R] \f[I]scale\f[R]\f[B])\f[R]
Sets the \f[I]scale\f[R] of \f[I]n\f[R] to the argument \f[I]scale\f[R].
If the argument \f[I]scale\f[R] is greater than the \f[I]scale\f[R] of
\f[I]n\f[R], \f[I]n\f[R] is extended.
If the argument \f[I]scale\f[R] is less than the \f[I]scale\f[R] of
\f[I]n\f[R], \f[I]n\f[R] is truncated.
.RS
.PP
If there was no error, \f[B]BCL_ERROR_NONE\f[R] is returned.
Otherwise, this function can return:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_NUM\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
.RE
.TP
\f[B]size_t bcl_num_len(BclNumber\f[R] \f[I]n\f[R]\f[B])\f[R]
Returns the number of \f[I]significant decimal digits\f[R] in
\f[I]n\f[R].
.SS Conversion
.PP
All procedures in this section require a valid current context.
.PP
All procedures in this section consume the given \f[B]BclNumber\f[R]
arguments that are not given to pointer arguments.
See the \f[B]Consumption and Propagation\f[R] subsection below.
.TP
\f[B]BclNumber bcl_parse(const char *restrict\f[R] \f[I]val\f[R]\f[B])\f[R]
Parses a number string according to the current context\[cq]s
\f[B]ibase\f[R] and returns the resulting number.
.RS
.PP
\f[I]val\f[R] must be non-\f[B]NULL\f[R] and a valid string.
See \f[B]BCL_ERROR_PARSE_INVALID_STR\f[R] in the \f[B]ERRORS\f[R]
section for more information.
.PP
bcl(3) will encode an error in the return value, if there was one.
The error can be queried with \f[B]bcl_err(BclNumber)\f[R].
Possible errors include:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_NUM\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_PARSE_INVALID_STR\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
.RE
.TP
\f[B]char* bcl_string(BclNumber\f[R] \f[I]n\f[R]\f[B])\f[R]
Returns a string representation of \f[I]n\f[R] according the the current
context\[cq]s \f[B]ibase\f[R].
The string is dynamically allocated and must be freed by the caller.
.RS
.PP
\f[I]n\f[R] is consumed; it cannot be used after the call.
See the \f[B]Consumption and Propagation\f[R] subsection below.
.RE
.TP
\f[B]BclError bcl_bigdig(BclNumber\f[R] \f[I]n\f[R]\f[B], BclBigDig *\f[R]\f[I]result\f[R]\f[B])\f[R]
Converts \f[I]n\f[R] into a \f[B]BclBigDig\f[R] and returns the result
in the space pointed to by \f[I]result\f[R].
.RS
.PP
\f[I]a\f[R] must be smaller than \f[B]BC_OVERFLOW_MAX\f[R].
See the \f[B]LIMITS\f[R] section.
.PP
If there was no error, \f[B]BCL_ERROR_NONE\f[R] is returned.
Otherwise, this function can return:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_NUM\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_MATH_OVERFLOW\f[R]
.PP
\f[I]n\f[R] is consumed; it cannot be used after the call.
See the \f[B]Consumption and Propagation\f[R] subsection below.
.RE
.TP
\f[B]BclNumber bcl_bigdig2num(BclBigDig\f[R] \f[I]val\f[R]\f[B])\f[R]
Creates a \f[B]BclNumber\f[R] from \f[I]val\f[R].
.RS
.PP
bcl(3) will encode an error in the return value, if there was one.
The error can be queried with \f[B]bcl_err(BclNumber)\f[R].
Possible errors include:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
.RE
.SS Math
.PP
All procedures in this section require a valid current context.
.PP
All procedures in this section can return the following errors:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_NUM\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
.TP
\f[B]BclNumber bcl_add(BclNumber\f[R] \f[I]a\f[R]\f[B], BclNumber\f[R] \f[I]b\f[R]\f[B])\f[R]
Adds \f[I]a\f[R] and \f[I]b\f[R] and returns the result.
The \f[I]scale\f[R] of the result is the max of the \f[I]scale\f[R]s of
\f[I]a\f[R] and \f[I]b\f[R].
.RS
.PP
\f[I]a\f[R] and \f[I]b\f[R] are consumed; they cannot be used after the
call.
See the \f[B]Consumption and Propagation\f[R] subsection below.
.PP
\f[I]a\f[R] and \f[I]b\f[R] can be the same number.
.PP
bcl(3) will encode an error in the return value, if there was one.
The error can be queried with \f[B]bcl_err(BclNumber)\f[R].
Possible errors include:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_NUM\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
.RE
.TP
\f[B]BclNumber bcl_sub(BclNumber\f[R] \f[I]a\f[R]\f[B], BclNumber\f[R] \f[I]b\f[R]\f[B])\f[R]
Subtracts \f[I]b\f[R] from \f[I]a\f[R] and returns the result.
The \f[I]scale\f[R] of the result is the max of the \f[I]scale\f[R]s of
\f[I]a\f[R] and \f[I]b\f[R].
.RS
.PP
\f[I]a\f[R] and \f[I]b\f[R] are consumed; they cannot be used after the
call.
See the \f[B]Consumption and Propagation\f[R] subsection below.
.PP
\f[I]a\f[R] and \f[I]b\f[R] can be the same number.
.PP
bcl(3) will encode an error in the return value, if there was one.
The error can be queried with \f[B]bcl_err(BclNumber)\f[R].
Possible errors include:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_NUM\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
.RE
.TP
\f[B]BclNumber bcl_mul(BclNumber\f[R] \f[I]a\f[R]\f[B], BclNumber\f[R] \f[I]b\f[R]\f[B])\f[R]
Multiplies \f[I]a\f[R] and \f[I]b\f[R] and returns the result.
If \f[I]ascale\f[R] is the \f[I]scale\f[R] of \f[I]a\f[R] and
\f[I]bscale\f[R] is the \f[I]scale\f[R] of \f[I]b\f[R], the
\f[I]scale\f[R] of the result is equal to
\f[B]min(ascale+bscale,max(scale,ascale,bscale))\f[R], where
\f[B]min()\f[R] and \f[B]max()\f[R] return the obvious values.
.RS
.PP
\f[I]a\f[R] and \f[I]b\f[R] are consumed; they cannot be used after the
call.
See the \f[B]Consumption and Propagation\f[R] subsection below.
.PP
\f[I]a\f[R] and \f[I]b\f[R] can be the same number.
.PP
bcl(3) will encode an error in the return value, if there was one.
The error can be queried with \f[B]bcl_err(BclNumber)\f[R].
Possible errors include:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_NUM\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
.RE
.TP
\f[B]BclNumber bcl_div(BclNumber\f[R] \f[I]a\f[R]\f[B], BclNumber\f[R] \f[I]b\f[R]\f[B])\f[R]
Divides \f[I]a\f[R] by \f[I]b\f[R] and returns the result.
The \f[I]scale\f[R] of the result is the \f[I]scale\f[R] of the current
context.
.RS
.PP
\f[I]b\f[R] cannot be \f[B]0\f[R].
.PP
\f[I]a\f[R] and \f[I]b\f[R] are consumed; they cannot be used after the
call.
See the \f[B]Consumption and Propagation\f[R] subsection below.
.PP
\f[I]a\f[R] and \f[I]b\f[R] can be the same number.
.PP
bcl(3) will encode an error in the return value, if there was one.
The error can be queried with \f[B]bcl_err(BclNumber)\f[R].
Possible errors include:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_NUM\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_MATH_DIVIDE_BY_ZERO\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
.RE
.TP
\f[B]BclNumber bcl_mod(BclNumber\f[R] \f[I]a\f[R]\f[B], BclNumber\f[R] \f[I]b\f[R]\f[B])\f[R]
Divides \f[I]a\f[R] by \f[I]b\f[R] to the \f[I]scale\f[R] of the current
context, computes the modulus \f[B]a-(a/b)*b\f[R], and returns the
modulus.
.RS
.PP
\f[I]b\f[R] cannot be \f[B]0\f[R].
.PP
\f[I]a\f[R] and \f[I]b\f[R] are consumed; they cannot be used after the
call.
See the \f[B]Consumption and Propagation\f[R] subsection below.
.PP
\f[I]a\f[R] and \f[I]b\f[R] can be the same number.
.PP
bcl(3) will encode an error in the return value, if there was one.
The error can be queried with \f[B]bcl_err(BclNumber)\f[R].
Possible errors include:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_NUM\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_MATH_DIVIDE_BY_ZERO\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
.RE
.TP
\f[B]BclNumber bcl_pow(BclNumber\f[R] \f[I]a\f[R]\f[B], BclNumber\f[R] \f[I]b\f[R]\f[B])\f[R]
Calculates \f[I]a\f[R] to the power of \f[I]b\f[R] to the
\f[I]scale\f[R] of the current context.
\f[I]b\f[R] must be an integer, but can be negative.
If it is negative, \f[I]a\f[R] must be non-zero.
.RS
.PP
\f[I]b\f[R] must be an integer.
If \f[I]b\f[R] is negative, \f[I]a\f[R] must not be \f[B]0\f[R].
.PP
\f[I]a\f[R] must be smaller than \f[B]BC_OVERFLOW_MAX\f[R].
See the \f[B]LIMITS\f[R] section.
.PP
\f[I]a\f[R] and \f[I]b\f[R] are consumed; they cannot be used after the
call.
See the \f[B]Consumption and Propagation\f[R] subsection below.
.PP
\f[I]a\f[R] and \f[I]b\f[R] can be the same number.
.PP
bcl(3) will encode an error in the return value, if there was one.
The error can be queried with \f[B]bcl_err(BclNumber)\f[R].
Possible errors include:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_NUM\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_MATH_NON_INTEGER\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_MATH_OVERFLOW\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_MATH_DIVIDE_BY_ZERO\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
.RE
.TP
\f[B]BclNumber bcl_lshift(BclNumber\f[R] \f[I]a\f[R]\f[B], BclNumber\f[R] \f[I]b\f[R]\f[B])\f[R]
Shifts \f[I]a\f[R] left (moves the radix right) by \f[I]b\f[R] places
and returns the result.
This is done in decimal.
\f[I]b\f[R] must be an integer.
.RS
.PP
\f[I]b\f[R] must be an integer.
.PP
\f[I]a\f[R] and \f[I]b\f[R] are consumed; they cannot be used after the
call.
See the \f[B]Consumption and Propagation\f[R] subsection below.
.PP
\f[I]a\f[R] and \f[I]b\f[R] can be the same number.
.PP
bcl(3) will encode an error in the return value, if there was one.
The error can be queried with \f[B]bcl_err(BclNumber)\f[R].
Possible errors include:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_NUM\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_MATH_NON_INTEGER\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
.RE
.TP
\f[B]BclNumber bcl_rshift(BclNumber\f[R] \f[I]a\f[R]\f[B], BclNumber\f[R] \f[I]b\f[R]\f[B])\f[R]
Shifts \f[I]a\f[R] right (moves the radix left) by \f[I]b\f[R] places
and returns the result.
This is done in decimal.
\f[I]b\f[R] must be an integer.
.RS
.PP
\f[I]b\f[R] must be an integer.
.PP
\f[I]a\f[R] and \f[I]b\f[R] are consumed; they cannot be used after the
call.
See the \f[B]Consumption and Propagation\f[R] subsection below.
.PP
\f[I]a\f[R] and \f[I]b\f[R] can be the same number.
.PP
bcl(3) will encode an error in the return value, if there was one.
The error can be queried with \f[B]bcl_err(BclNumber)\f[R].
Possible errors include:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_NUM\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_MATH_NON_INTEGER\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
.RE
.TP
\f[B]BclNumber bcl_sqrt(BclNumber\f[R] \f[I]a\f[R]\f[B])\f[R]
Calculates the square root of \f[I]a\f[R] and returns the result.
The \f[I]scale\f[R] of the result is equal to the \f[B]scale\f[R] of the
current context.
.RS
.PP
\f[I]a\f[R] cannot be negative.
.PP
\f[I]a\f[R] is consumed; it cannot be used after the call.
See the \f[B]Consumption and Propagation\f[R] subsection below.
.PP
bcl(3) will encode an error in the return value, if there was one.
The error can be queried with \f[B]bcl_err(BclNumber)\f[R].
Possible errors include:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_NUM\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_MATH_NEGATIVE\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
.RE
.TP
\f[B]BclError bcl_divmod(BclNumber\f[R] \f[I]a\f[R]\f[B], BclNumber\f[R] \f[I]b\f[R]\f[B], BclNumber *\f[R]\f[I]c\f[R]\f[B], BclNumber *\f[R]\f[I]d\f[R]\f[B])\f[R]
Divides \f[I]a\f[R] by \f[I]b\f[R] and returns the quotient in a new
number which is put into the space pointed to by \f[I]c\f[R], and puts
the modulus in a new number which is put into the space pointed to by
\f[I]d\f[R].
.RS
.PP
\f[I]b\f[R] cannot be \f[B]0\f[R].
.PP
\f[I]a\f[R] and \f[I]b\f[R] are consumed; they cannot be used after the
call.
See the \f[B]Consumption and Propagation\f[R] subsection below.
.PP
\f[I]c\f[R] and \f[I]d\f[R] cannot point to the same place, nor can they
point to the space occupied by \f[I]a\f[R] or \f[I]b\f[R].
.PP
If there was no error, \f[B]BCL_ERROR_NONE\f[R] is returned.
Otherwise, this function can return:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_NUM\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_MATH_DIVIDE_BY_ZERO\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
.RE
.TP
\f[B]BclNumber bcl_modexp(BclNumber\f[R] \f[I]a\f[R]\f[B], BclNumber\f[R] \f[I]b\f[R]\f[B], BclNumber\f[R] \f[I]c\f[R]\f[B])\f[R]
Computes a modular exponentiation where \f[I]a\f[R] is the base,
\f[I]b\f[R] is the exponent, and \f[I]c\f[R] is the modulus, and returns
the result.
The \f[I]scale\f[R] of the result is equal to the \f[B]scale\f[R] of the
current context.
.RS
.PP
\f[I]a\f[R], \f[I]b\f[R], and \f[I]c\f[R] must be integers.
\f[I]c\f[R] must not be \f[B]0\f[R].
\f[I]b\f[R] must not be negative.
.PP
\f[I]a\f[R], \f[I]b\f[R], and \f[I]c\f[R] are consumed; they cannot be
used after the call.
See the \f[B]Consumption and Propagation\f[R] subsection below.
.PP
bcl(3) will encode an error in the return value, if there was one.
The error can be queried with \f[B]bcl_err(BclNumber)\f[R].
Possible errors include:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_NUM\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_MATH_NEGATIVE\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_MATH_NON_INTEGER\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_MATH_DIVIDE_BY_ZERO\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
.RE
.SS Miscellaneous
.TP
\f[B]void bcl_zero(BclNumber\f[R] \f[I]n\f[R]\f[B])\f[R]
Sets \f[I]n\f[R] to \f[B]0\f[R].
.TP
\f[B]void bcl_one(BclNumber\f[R] \f[I]n\f[R]\f[B])\f[R]
Sets \f[I]n\f[R] to \f[B]1\f[R].
.TP
\f[B]ssize_t bcl_cmp(BclNumber\f[R] \f[I]a\f[R]\f[B], BclNumber\f[R] \f[I]b\f[R]\f[B])\f[R]
Compares \f[I]a\f[R] and \f[I]b\f[R] and returns \f[B]0\f[R] if
\f[I]a\f[R] and \f[I]b\f[R] are equal, \f[B]<0\f[R] if \f[I]a\f[R] is
less than \f[I]b\f[R], and \f[B]>0\f[R] if \f[I]a\f[R] is greater than
\f[I]b\f[R].
.TP
\f[B]BclError bcl_copy(BclNumber\f[R] \f[I]d\f[R]\f[B], BclNumber\f[R] \f[I]s\f[R]\f[B])\f[R]
Copies \f[I]s\f[R] into \f[I]d\f[R].
.RS
.PP
If there was no error, \f[B]BCL_ERROR_NONE\f[R] is returned.
Otherwise, this function can return:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_NUM\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
.RE
.TP
\f[B]BclNumber bcl_dup(BclNumber\f[R] \f[I]s\f[R]\f[B])\f[R]
Creates and returns a new \f[B]BclNumber\f[R] that is a copy of
\f[I]s\f[R].
.RS
.PP
bcl(3) will encode an error in the return value, if there was one.
The error can be queried with \f[B]bcl_err(BclNumber)\f[R].
Possible errors include:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_NUM\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
.RE
.SS Pseudo-Random Number Generator
.PP
The pseudo-random number generator in bcl(3) is a \f[I]seeded\f[R] PRNG.
Given the same seed twice, it will produce the same sequence of
pseudo-random numbers twice.
.PP
By default, bcl(3) attempts to seed the PRNG with data from
\f[B]/dev/urandom\f[R].
If that fails, it seeds itself with by calling \f[B]libc\f[R]\[cq]s
\f[B]srand(time(NULL))\f[R] and then calling \f[B]rand()\f[R] for each
byte, since \f[B]rand()\f[R] is only guaranteed to return \f[B]15\f[R]
bits.
.PP
This should provide fairly good seeding in the standard case while also
remaining fairly portable.
.PP
If necessary, the PRNG can be reseeded with one of the following
functions:
.IP \[bu] 2
\f[B]bcl_rand_seedWithNum(BclNumber)\f[R]
.IP \[bu] 2
\f[B]bcl_rand_seed(unsigned char[BC_SEED_SIZE])\f[R]
.IP \[bu] 2
\f[B]bcl_rand_reseed(\f[R]\f[I]void\f[R]\f[B])\f[R]
.PP
The following items allow clients to use the pseudo-random number
generator.
All procedures require a valid current context.
.TP
\f[B]BCL_SEED_ULONGS\f[R]
The number of \f[B]unsigned long\f[R]\[cq]s in a seed for bcl(3)\[cq]s
random number generator.
.TP
\f[B]BCL_SEED_SIZE\f[R]
The size, in \f[B]char\f[R]\[cq]s, of a seed for bcl(3)\[cq]s random
number generator.
.TP
\f[B]BclBigDig\f[R]
bcl(3)\[cq]s overflow type (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]BclRandInt\f[R]
An unsigned integer type returned by bcl(3)\[cq]s random number
generator.
.TP
\f[B]BclNumber bcl_irand(BclNumber\f[R] \f[I]a\f[R]\f[B])\f[R]
Returns a random number that is not larger than \f[I]a\f[R] in a new
number.
If \f[I]a\f[R] is \f[B]0\f[R] or \f[B]1\f[R], the new number is equal to
\f[B]0\f[R].
The bound is unlimited, so it is not bound to the size of
\f[B]BclRandInt\f[R].
This is done by generating as many random numbers as necessary,
multiplying them by certain exponents, and adding them all together.
.RS
.PP
\f[I]a\f[R] must be an integer and non-negative.
.PP
\f[I]a\f[R] is consumed; it cannot be used after the call.
See the \f[B]Consumption and Propagation\f[R] subsection below.
.PP
This procedure requires a valid current context.
.PP
bcl(3) will encode an error in the return value, if there was one.
The error can be queried with \f[B]bcl_err(BclNumber)\f[R].
Possible errors include:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_NUM\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_MATH_NEGATIVE\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_MATH_NON_INTEGER\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
.RE
.TP
\f[B]BclNumber bcl_frand(size_t\f[R] \f[I]places\f[R]\f[B])\f[R]
Returns a random number between \f[B]0\f[R] (inclusive) and \f[B]1\f[R]
(exclusive) that has \f[I]places\f[R] decimal digits after the radix
(decimal point).
There are no limits on \f[I]places\f[R].
.RS
.PP
This procedure requires a valid current context.
.PP
bcl(3) will encode an error in the return value, if there was one.
The error can be queried with \f[B]bcl_err(BclNumber)\f[R].
Possible errors include:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
.RE
.TP
\f[B]BclNumber bcl_ifrand(BclNumber\f[R] \f[I]a\f[R]\f[B], size_t\f[R] \f[I]places\f[R]\f[B])\f[R]
Returns a random number less than \f[I]a\f[R] with \f[I]places\f[R]
decimal digits after the radix (decimal point).
There are no limits on \f[I]a\f[R] or \f[I]places\f[R].
.RS
.PP
\f[I]a\f[R] must be an integer and non-negative.
.PP
\f[I]a\f[R] is consumed; it cannot be used after the call.
See the \f[B]Consumption and Propagation\f[R] subsection below.
.PP
This procedure requires a valid current context.
.PP
bcl(3) will encode an error in the return value, if there was one.
The error can be queried with \f[B]bcl_err(BclNumber)\f[R].
Possible errors include:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_NUM\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_MATH_NEGATIVE\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_MATH_NON_INTEGER\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
.RE
.TP
\f[B]BclError bcl_rand_seedWithNum(BclNumber\f[R] \f[I]n\f[R]\f[B])\f[R]
Seeds the PRNG with \f[I]n\f[R].
.RS
.PP
\f[I]n\f[R] is \f[I]not\f[R] consumed.
.PP
This procedure requires a valid current context.
.PP
If there was no error, \f[B]BCL_ERROR_NONE\f[R] is returned.
Otherwise, this function can return:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_NUM\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.PP
Note that if \f[B]bcl_rand_seed2num(\f[R]\f[I]void\f[R]\f[B])\f[R] or
\f[B]bcl_rand_seed2num_err(BclNumber)\f[R] are called right after this
function, they are not guaranteed to return a number equal to
\f[I]n\f[R].
.RE
.TP
\f[B]BclError bcl_rand_seed(unsigned char\f[R] \f[I]seed\f[R]\f[B][\f[R]\f[I]BC_SEED_SIZE\f[R]\f[B]])\f[R]
Seeds the PRNG with the bytes in \f[I]seed\f[R].
.RS
.PP
If there was no error, \f[B]BCL_ERROR_NONE\f[R] is returned.
Otherwise, this function can return:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.RE
.TP
\f[B]void bcl_rand_reseed(\f[R]\f[I]void\f[R]\f[B])\f[R]
Reseeds the PRNG with the default reseeding behavior.
First, it attempts to read data from \f[B]/dev/urandom\f[R] and falls
back to \f[B]libc\f[R]\[cq]s \f[B]rand()\f[R].
.RS
.PP
This procedure cannot fail.
.RE
.TP
\f[B]BclNumber bcl_rand_seed2num(\f[R]\f[I]void\f[R]\f[B])\f[R]
Returns the current seed of the PRNG as a \f[B]BclNumber\f[R].
.RS
.PP
This procedure requires a valid current context.
.PP
bcl(3) will encode an error in the return value, if there was one.
The error can be queried with \f[B]bcl_err(BclNumber)\f[R].
Possible errors include:
.IP \[bu] 2
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
.IP \[bu] 2
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
.RE
.TP
\f[B]BclRandInt bcl_rand_int(\f[R]\f[I]void\f[R]\f[B])\f[R]
Returns a random integer between \f[B]0\f[R] and \f[B]BC_RAND_MAX\f[R]
(inclusive).
.RS
.PP
This procedure cannot fail.
.RE
.TP
\f[B]BclRandInt bcl_rand_bounded(BclRandInt\f[R] \f[I]bound\f[R]\f[B])\f[R]
Returns a random integer between \f[B]0\f[R] and \f[I]bound\f[R]
(exclusive).
Bias is removed before returning the integer.
.RS
.PP
This procedure cannot fail.
.RE
.SS Consumption and Propagation
.PP
Some functions are listed as consuming some or all of their arguments.
This means that the arguments are freed, regardless of if there were
errors or not.
.PP
This is to enable compact code like the following:
.IP
.nf
\f[C]
BclNumber n = bcl_num_add(bcl_num_mul(a, b), bcl_num_div(c, d));
\f[R]
.fi
.PP
If arguments to those functions were not consumed, memory would be
leaked until reclaimed with \f[B]bcl_ctxt_freeNums(BclContext)\f[R].
.PP
When errors occur, they are propagated through.
The result should always be checked with \f[B]bcl_err(BclNumber)\f[R],
so the example above should properly be:
.IP
.nf
\f[C]
BclNumber n = bcl_num_add(bcl_num_mul(a, b), bcl_num_div(c, d));
if (bc_num_err(n) != BCL_ERROR_NONE) {
// Handle the error.
}
\f[R]
.fi
.SH ERRORS
.PP
Most functions in bcl(3) return, directly or indirectly, any one of the
error codes defined in \f[B]BclError\f[R].
The complete list of codes is the following:
.TP
\f[B]BCL_ERROR_NONE\f[R]
Success; no error occurred.
.TP
\f[B]BCL_ERROR_INVALID_NUM\f[R]
An invalid \f[B]BclNumber\f[R] was given as a parameter.
.TP
\f[B]BCL_ERROR_INVALID_CONTEXT\f[R]
An invalid \f[B]BclContext\f[R] is being used.
.TP
\f[B]BCL_ERROR_SIGNAL\f[R]
A signal interrupted execution.
.TP
\f[B]BCL_ERROR_MATH_NEGATIVE\f[R]
A negative number was given as an argument to a parameter that cannot
accept negative numbers, such as for square roots.
.TP
\f[B]BCL_ERROR_MATH_NON_INTEGER\f[R]
A non-integer was given as an argument to a parameter that cannot accept
non-integer numbers, such as for the second parameter of
\f[B]bcl_num_pow()\f[R].
.TP
\f[B]BCL_ERROR_MATH_OVERFLOW\f[R]
A number that would overflow its result was given as an argument, such
as for converting a \f[B]BclNumber\f[R] to a \f[B]BclBigDig\f[R].
.TP
\f[B]BCL_ERROR_MATH_DIVIDE_BY_ZERO\f[R]
A divide by zero occurred.
.TP
\f[B]BCL_ERROR_PARSE_INVALID_STR\f[R]
An invalid number string was passed to a parsing function.
.RS
.PP
A valid number string can only be one radix (period).
In addition, any lowercase ASCII letters, symbols, or non-ASCII
characters are invalid.
It is allowed for the first character to be a dash.
In that case, the number is considered to be negative.
.PP
There is one exception to the above: one lowercase \f[B]e\f[R] is
allowed in the number, after the radix, if it exists.
If the letter \f[B]e\f[R] exists, the number is considered to be in
scientific notation, where the part before the \f[B]e\f[R] is the
number, and the part after, which must be an integer, is the exponent.
There can be a dash right after the \f[B]e\f[R] to indicate a negative
exponent.
.PP
\f[B]WARNING\f[R]: Both the number and the exponent in scientific
notation are interpreted according to the current \f[B]ibase\f[R], but
the number is still multiplied by \f[B]10\[ha]exponent\f[R] regardless
of the current \f[B]ibase\f[R].
For example, if \f[B]ibase\f[R] is \f[B]16\f[R] and bcl(3) is given the
number string \f[B]FFeA\f[R], the resulting decimal number will be
\f[B]2550000000000\f[R], and if bcl(3) is given the number string
\f[B]10e-4\f[R], the resulting decimal number will be \f[B]0.0016\f[R].
.RE
.TP
\f[B]BCL_ERROR_FATAL_ALLOC_ERR\f[R]
bcl(3) failed to allocate memory.
.RS
.PP
If clients call \f[B]bcl_setAbortOnFatalError()\f[R] with an
\f[B]true\f[R] argument, this error will cause bcl(3) to throw a
\f[B]SIGABRT\f[R].
This behavior can also be turned off later by calling that same function
with a \f[B]false\f[R] argument.
By default, this behavior is off.
.PP
It is highly recommended that client libraries do \f[I]not\f[R] activate
this behavior.
.RE
.TP
\f[B]BCL_ERROR_FATAL_UNKNOWN_ERR\f[R]
An unknown error occurred.
.RS
.PP
If clients call \f[B]bcl_setAbortOnFatalError()\f[R] with an
\f[B]true\f[R] argument, this error will cause bcl(3) to throw a
\f[B]SIGABRT\f[R].
This behavior can also be turned off later by calling that same function
with a \f[B]false\f[R] argument.
By default, this behavior is off.
.PP
It is highly recommended that client libraries do \f[I]not\f[R] activate
this behavior.
.RE
.SH ATTRIBUTES
.PP
When \f[B]bcl_handleSignal(\f[R]\f[I]void\f[R]\f[B])\f[R] is used
properly, bcl(3) is async-signal-safe.
.PP
bcl(3) is \f[I]MT-Unsafe\f[R]: it is unsafe to call any functions from
more than one thread.
.SH PERFORMANCE
.PP
Most bc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
bcl(3) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]BC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]BC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]BC_BASE_DIGS\f[R].
.PP
In addition, this bcl(3) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]BC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on bcl(3):
.TP
\f[B]BC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
bcl(3) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]BC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]BC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]BC_BASE_DIGS\f[R].
.TP
\f[B]BC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]BC_LONG_BIT\f[R].
.TP
\f[B]BC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]BC_BASE_POW\f[R].
.TP
\f[B]BC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]BC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]BC_RAND_MAX\f[R]
The maximum integer (inclusive) returned by the \f[B]bcl_rand_int()\f[R]
function.
Set at \f[B]2\[ha]BC_LONG_BIT-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]BC_OVERFLOW_MAX\f[R].
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH SIGNAL HANDLING
.PP
If a signal handler calls
\f[B]bcl_handleSignal(\f[R]\f[I]void\f[R]\f[B])\f[R] from the same
thread that there are bcl(3) functions executing in, it will cause all
execution to stop as soon as possible, interrupting long-running
calculations, if necessary and cause the function that was executing to
return.
If possible, the error code \f[B]BC_ERROR_SIGNAL\f[R] is returned.
.PP
If execution \f[I]is\f[R] interrupted,
\f[B]bcl_handleSignal(\f[R]\f[I]void\f[R]\f[B])\f[R] does \f[I]not\f[R]
return to its caller.
.PP
It is undefined behavior if
\f[B]bcl_handleSignal(\f[R]\f[I]void\f[R]\f[B])\f[R] is called from a
thread that is not executing bcl(3) functions, if bcl(3) functions are
executing.
.SH SEE ALSO
.PP
bc(1) and dc(1)
.SH STANDARDS
.PP
bcl(3) is compliant with the arithmetic defined in the IEEE Std
1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification for bc(1).
.PP
Note that the specification explicitly says that bc(1) only accepts
numbers that use a period (\f[B].\f[R]) as a radix point, regardless of
the value of \f[B]LC_NUMERIC\f[R].
This is also true of bcl(3).
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHORS
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/build.md b/contrib/bc/manuals/build.md
index 47fbabdfad7f..a58da6d427ed 100644
--- a/contrib/bc/manuals/build.md
+++ b/contrib/bc/manuals/build.md
@@ -1,694 +1,710 @@
# Build
This `bc` attempts to be as portable as possible. It can be built on any
POSIX-compliant system.
To accomplish that, a POSIX-compatible, custom `configure.sh` script is used to
select build options, compiler, and compiler flags and generate a `Makefile`.
The general form of configuring, building, and installing this `bc` is as
follows:
```
[ENVIRONMENT_VARIABLE=<value>...] ./configure.sh [build_options...]
make
make install
```
To get all of the options, including any useful environment variables, use
either one of the following commands:
```
./configure.sh -h
./configure.sh --help
```
***WARNING***: even though `configure.sh` supports both option types, short and
long, it does not support handling both at the same time. Use only one type.
To learn the available `make` targets run the following command after running
the `configure.sh` script:
```
make help
```
See [Build Environment Variables][4] for a more detailed description of all
accepted environment variables and [Build Options][5] for more detail about all
accepted build options.
<a name="cross-compiling"/>
## Cross Compiling
To cross-compile this `bc`, an appropriate compiler must be present and assigned
to the environment variable `HOSTCC` or `HOST_CC` (the two are equivalent,
though `HOSTCC` is prioritized). This is in order to bootstrap core file(s), if
the architectures are not compatible (i.e., unlike i686 on x86_64). Thus, the
approach is:
```
HOSTCC="/path/to/native/compiler" ./configure.sh
make
make install
```
`HOST_CC` will work in exactly the same way.
`HOSTCFLAGS` and `HOST_CFLAGS` can be used to set compiler flags for `HOSTCC`.
(The two are equivalent, as `HOSTCC` and `HOST_CC` are.) `HOSTCFLAGS` is
prioritized over `HOST_CFLAGS`. If neither are present, `HOSTCC` (or `HOST_CC`)
uses `CFLAGS` (see [Build Environment Variables][4] for more details).
It is expected that `CC` produces code for the target system and `HOSTCC`
produces code for the host system. See [Build Environment Variables][4] for more
details.
If an emulator is necessary to run the bootstrap binaries, it can be set with
the environment variable `GEN_EMU`.
<a name="build-environment-variables"/>
## Build Environment Variables
This `bc` supports `CC`, `HOSTCC`, `HOST_CC`, `CFLAGS`, `HOSTCFLAGS`,
`HOST_CFLAGS`, `CPPFLAGS`, `LDFLAGS`, `LDLIBS`, `PREFIX`, `DESTDIR`, `BINDIR`,
`DATAROOTDIR`, `DATADIR`, `MANDIR`, `MAN1DIR`, `LOCALEDIR` `EXECSUFFIX`,
`EXECPREFIX`, `LONG_BIT`, `GEN_HOST`, and `GEN_EMU` environment variables in
`configure.sh`. Any values of those variables given to `configure.sh` will be
put into the generated Makefile.
More detail on what those environment variables do can be found in the following
sections.
### `CC`
C compiler for the target system. `CC` must be compatible with POSIX `c99`
behavior and options. However, **I encourage users to use any C99 or C11
compatible compiler they wish.**
If there is a space in the basename of the compiler, the items after the first
space are assumed to be compiler flags, and in that case, the flags are
automatically moved into CFLAGS.
Defaults to `c99`.
### `HOSTCC` or `HOST_CC`
C compiler for the host system, used only in [cross compiling][6]. Must be
compatible with POSIX `c99` behavior and options.
If there is a space in the basename of the compiler, the items after the first
space are assumed to be compiler flags, and in that case, the flags are
automatically moved into HOSTCFLAGS.
Defaults to `$CC`.
### `CFLAGS`
Command-line flags that will be passed verbatim to `CC`.
Defaults to empty.
### `HOSTCFLAGS` or `HOST_CFLAGS`
Command-line flags that will be passed verbatim to `HOSTCC` or `HOST_CC`.
Defaults to `$CFLAGS`.
### `CPPFLAGS`
Command-line flags for the C preprocessor. These are also passed verbatim to
both compilers (`CC` and `HOSTCC`); they are supported just for legacy reasons.
Defaults to empty.
### `LDFLAGS`
Command-line flags for the linker. These are also passed verbatim to both
compilers (`CC` and `HOSTCC`); they are supported just for legacy reasons.
Defaults to empty.
### `LDLIBS`
Libraries to link to. These are also passed verbatim to both compilers (`CC` and
`HOSTCC`); they are supported just for legacy reasons and for cross compiling
with different C standard libraries (like [musl][3]).
Defaults to empty.
### `PREFIX`
The prefix to install to.
Can be overridden by passing the `--prefix` option to `configure.sh`.
Defaults to `/usr/local`.
### `DESTDIR`
Path to prepend onto `PREFIX`. This is mostly for distro and package
maintainers.
This can be passed either to `configure.sh` or `make install`. If it is passed
to both, the one given to `configure.sh` takes precedence.
Defaults to empty.
### `BINDIR`
The directory to install binaries in.
Can be overridden by passing the `--bindir` option to `configure.sh`.
Defaults to `$PREFIX/bin`.
+### `INCLUDEDIR`
+
+The directory to install header files in.
+
+Can be overridden by passing the `--includedir` option to `configure.sh`.
+
+Defaults to `$PREFIX/include`.
+
+### `LIBDIR`
+
+The directory to install libraries in.
+
+Can be overridden by passing the `--libdir` option to `configure.sh`.
+
+Defaults to `$PREFIX/lib`.
+
### `DATAROOTDIR`
The root directory to install data files in.
Can be overridden by passing the `--datarootdir` option to `configure.sh`.
Defaults to `$PREFIX/share`.
### `DATADIR`
The directory to install data files in.
Can be overridden by passing the `--datadir` option to `configure.sh`.
Defaults to `$DATAROOTDIR`.
### `MANDIR`
The directory to install manpages in.
Can be overridden by passing the `--mandir` option to `configure.sh`.
Defaults to `$DATADIR/man`
### `MAN1DIR`
The directory to install Section 1 manpages in. Because both `bc` and `dc` are
Section 1 commands, this is the only relevant section directory.
Can be overridden by passing the `--man1dir` option to `configure.sh`.
Defaults to `$MANDIR/man1`.
### `LOCALEDIR`
The directory to install locales in.
Can be overridden by passing the `--localedir` option to `configure.sh`.
Defaults to `$DATAROOTDIR/locale`.
### `EXECSUFFIX`
The suffix to append onto the executable names *when installing*. This is for
packagers and distro maintainers who want this `bc` as an option, but do not
want to replace the default `bc`.
Defaults to empty.
### `EXECPREFIX`
The prefix to append onto the executable names *when building and installing*.
This is for packagers and distro maintainers who want this `bc` as an option,
but do not want to replace the default `bc`.
Defaults to empty.
### `LONG_BIT`
The number of bits in a C `long` type. This is mostly for the embedded space.
This `bc` uses `long`s internally for overflow checking. In C99, a `long` is
required to be 32 bits. For this reason, on 8-bit and 16-bit microcontrollers,
the generated code to do math with `long` types may be inefficient.
For most normal desktop systems, setting this is unnecessary, except that 32-bit
platforms with 64-bit longs may want to set it to `32`.
Defaults to the default value of `LONG_BIT` for the target platform. For
compliance with the `bc` spec, the minimum allowed value is `32`.
It is an error if the specified value is greater than the default value of
`LONG_BIT` for the target platform.
### `GEN_HOST`
Whether to use `gen/strgen.c`, instead of `gen/strgen.sh`, to produce the C
files that contain the help texts as well as the math libraries. By default,
`gen/strgen.c` is used, compiled by `$HOSTCC` and run on the host machine. Using
`gen/strgen.sh` removes the need to compile and run an executable on the host
machine since `gen/strgen.sh` is a POSIX shell script. However, `gen/lib2.bc` is
perilously close to 4095 characters, the max supported length of a string
literal in C99 (and it could be added to in the future), and `gen/strgen.sh`
generates a string literal instead of an array, as `gen/strgen.c` does. For most
production-ready compilers, this limit probably is not enforced, but it could
be. Both options are still available for this reason.
If you are sure your compiler does not have the limit and do not want to compile
and run a binary on the host machine, set this variable to "0". Any other value,
or a non-existent value, will cause the build system to compile and run
`gen/strgen.c`.
Default is "".
### `GEN_EMU`
The emulator to run bootstrap binaries under. This is only if the binaries
produced by `HOSTCC` (or `HOST_CC`) need to be run under an emulator to work.
Defaults to empty.
<a name="build-options"/>
## Build Options
This `bc` comes with several build options, all of which are enabled by default.
All options can be used with each other, with a few exceptions that will be
noted below.
**NOTE**: All long options with mandatory argumenst accept either one of the
following forms:
```
--option arg
--option=arg
```
### Library
To build the math library, use the following commands for the configure step:
```
./configure.sh -a
./configure.sh --library
```
Both commands are equivalent.
When the library is built, history, prompt, and locales are disabled, and the
functionality for `bc` and `dc` are both enabled, though the executables are
*not* built. This is because the library's options clash with the executables.
To build an optimized version of the library, users can pass optimization
options to `configure.sh` or include them in `CFLAGS`.
The library API can be found in `manuals/bcl.3.md` or `man bcl` once the library
is installed.
The library is built as `bin/libbcl.a`.
### `bc` Only
To build `bc` only (no `dc`), use any one of the following commands for the
configure step:
```
./configure.sh -b
./configure.sh --bc-only
./configure.sh -D
./configure.sh --disable-dc
```
Those commands are all equivalent.
***Warning***: It is an error to use those options if `bc` has also been
disabled (see below).
### `dc` Only
To build `dc` only (no `bc`), use either one of the following commands for the
configure step:
```
./configure.sh -d
./configure.sh --dc-only
./configure.sh -B
./configure.sh --disable-bc
```
Those commands are all equivalent.
***Warning***: It is an error to use those options if `dc` has also been
disabled (see above).
<a name="build-history"/>
### History
To disable signal handling, pass either the `-H` flag or the `--disable-history`
option to `configure.sh`, as follows:
```
./configure.sh -H
./configure.sh --disable-history
```
Both commands are equivalent.
History is automatically disabled when building for Windows or on another
platform that does not support the terminal handling that is required.
***WARNING***: Of all of the code in the `bc`, this is the only code that is not
completely portable. If the `bc` does not work on your platform, your first step
should be to retry with history disabled.
### NLS (Locale Support)
To disable locale support (use only English), pass either the `-N` flag or the
`--disable-nls` option to `configure.sh`, as follows:
```
./configure.sh -N
./configure.sh --disable-nls
```
Both commands are equivalent.
NLS (locale support) is automatically disabled when building for Windows or on
another platform that does not support the POSIX locale API or utilities.
### Prompt
By default, `bc` and `dc` print a prompt when in interactive mode. They both
have the command-line option `-P`/`--no-prompt`, which turns that off, but it
can be disabled permanently in the build by passing the `-P` flag or the
`--disable-prompt` option to `configure.sh`, as follows:
```
./configure.sh -P
./configure.sh --disable-prompt
```
Both commands are equivalent.
### Locales
By default, `bc` and `dc` do not install all locales, but only the enabled
locales. If `DESTDIR` exists and is not empty, then they will install all of
the locales that exist on the system. The `-l` flag or `--install-all-locales`
option skips all of that and just installs all of the locales that `bc` and `dc`
have, regardless. To enable that behavior, you can pass the `-l` flag or the
`--install-all-locales` option to `configure.sh`, as follows:
```
./configure.sh -l
./configure.sh --install-all-locales
```
Both commands are equivalent.
### Extra Math
This `bc` has 7 extra operators:
* `$` (truncation to integer)
* `@` (set precision)
* `@=` (set precision and assign)
* `<<` (shift number left, shifts radix right)
* `<<=` (shift number left and assign)
* `>>` (shift number right, shifts radix left)
* `>>=` (shift number right and assign)
There is no assignment version of `$` because it is a unary operator.
The assignment versions of the above operators are not available in `dc`, but
the others are, as the operators `$`, `@`, `H`, and `h`, respectively.
In addition, this `bc` has the option of outputting in scientific notation or
engineering notation. It can also take input in scientific or engineering
notation. On top of that, it has a pseudo-random number generator. (See the
full manual for more details.)
Extra operators, scientific notation, engineering notation, and the
pseudo-random number generator can be disabled by passing either the `-E` flag
or the `--disable-extra-math` option to `configure.sh`, as follows:
```
./configure.sh -E
./configure.sh --disable-extra-math
```
Both commands are equivalent.
This `bc` also has a larger library that is only enabled if extra operators and
the pseudo-random number generator are. More information about the functions can
be found in the Extended Library section of the full manual.
### Manpages
To disable installing manpages, pass either the `-M` flag or the
`--disable-man-pages` option to `configure.sh` as follows:
```
./configure.sh -M
./configure.sh --disable-man-pages
```
Both commands are equivalent.
### Karatsuba Length
The Karatsuba length is the point at which `bc` and `dc` switch from Karatsuba
multiplication to brute force, `O(n^2)` multiplication. It can be set by passing
the `-k` flag or the `--karatsuba-len` option to `configure.sh` as follows:
```
./configure.sh -k64
./configure.sh --karatsuba-len 64
```
Both commands are equivalent.
Default is `64`.
***WARNING***: The Karatsuba Length must be a **integer** greater than or equal
to `16` (to prevent stack overflow). If it is not, `configure.sh` will give an
error.
### Install Options
The relevant `autotools`-style install options are supported in `configure.sh`:
* `--prefix`
* `--bindir`
* `--datarootdir`
* `--datadir`
* `--mandir`
* `--man1dir`
* `--localedir`
An example is:
```
./configure.sh --prefix=/usr --localedir /usr/share/nls
make
make install
```
They correspond to the environment variables `$PREFIX`, `$BINDIR`,
`$DATAROOTDIR`, `$DATADIR`, `$MANDIR`, `$MAN1DIR`, and `$LOCALEDIR`,
respectively.
***WARNING***: If the option is given, the value of the corresponding
environment variable is overridden.
***WARNING***: If any long command-line options are used, the long form of all
other command-line options must be used. Mixing long and short options is not
supported.
## Optimization
The `configure.sh` script will accept an optimization level to pass to the
compiler. Because `bc` is orders of magnitude faster with optimization, I
***highly*** recommend package and distro maintainers pass the highest
optimization level available in `CC` to `configure.sh` with the `-O` flag or
`--opt` option, as follows:
```
./configure.sh -O3
./configure.sh --opt 3
```
Both commands are equivalent.
The build and install can then be run as normal:
```
make
make install
```
As usual, `configure.sh` will also accept additional `CFLAGS` on the command
line, so for SSE4 architectures, the following can add a bit more speed:
```
CFLAGS="-march=native -msse4" ./configure.sh -O3
make
make install
```
Building with link-time optimization (`-flto` in clang) can further increase the
performance. I ***highly*** recommend doing so.
I do **NOT*** recommend building with `-march=native`; doing so reduces this
`bc`'s performance.
Manual stripping is not necessary; non-debug builds are automatically stripped
in the link stage.
## Debug Builds
Debug builds (which also disable optimization if no optimization level is given
and if no extra `CFLAGS` are given) can be enabled with either the `-g` flag or
the `--debug` option, as follows:
```
./configure.sh -g
./configure.sh --debug
```
Both commands are equivalent.
The build and install can then be run as normal:
```
make
make install
```
## Stripping Binaries
By default, when `bc` and `dc` are not built in debug mode, the binaries are
stripped. Stripping can be disabled with either the `-T` or the
`--disable-strip` option, as follows:
```
./configure.sh -T
./configure.sh --disable-strip
```
Both commands are equivalent.
The build and install can then be run as normal:
```
make
make install
```
## Binary Size
When built with both calculators, all available features, and `-Os` using
`clang` and `musl`, the executable is 140.4 kb (140,386 bytes) on `x86_64`. That
isn't much for what is contained in the binary, but if necessary, it can be
reduced.
The single largest user of space is the `bc` calculator. If just `dc` is needed,
the size can be reduced to 107.6 kb (107,584 bytes).
The next largest user of space is history support. If that is not needed, size
can be reduced (for a build with both calculators) to 119.9 kb (119,866 bytes).
There are several reasons that history is a bigger user of space than `dc`
itself:
* `dc`'s lexer and parser are *tiny* compared to `bc`'s because `dc` code is
almost already in the form that it is executed in, while `bc` has to not only
adjust the form to be executable, it has to parse functions, loops, `if`
statements, and other extra features.
* `dc` does not have much extra code in the interpreter.
* History has a lot of const data for supporting `UTF-8` terminals.
* History pulls in a bunch of more code from the `libc`.
The next biggest user is extra math support. Without it, the size is reduced to
124.0 kb (123,986 bytes) with history and 107.6 kb (107,560 bytes) without
history.
The reasons why extra math support is bigger than `dc`, besides the fact that
`dc` is small already, are:
* Extra math supports adds an extra math library that takes several kilobytes of
constant data space.
* Extra math support includes support for a pseudo-random number generator,
including the code to convert a series of pseudo-random numbers into a number
of arbitrary size.
* Extra math support adds several operators.
The next biggest user is `dc`, so if just `bc` is needed, the size can be
reduced to 128.1 kb (128,096 bytes) with history and extra math support, 107.6
kb (107,576 bytes) without history and with extra math support, and 95.3 kb
(95,272 bytes) without history and without extra math support.
*Note*: all of these binary sizes were compiled using `musl` `1.2.0` as the
`libc`, making a fully static executable, with `clang` `9.0.1` (well,
`musl-clang` using `clang` `9.0.1`) as the compiler and using `-Os`
optimizations. These builds were done on an `x86_64` machine running Gentoo
Linux.
## Testing
The default test suite can be run with the following command:
```
make test
```
To test `bc` only, run the following command:
```
make test_bc
```
To test `dc` only, run the following command:
```
make test_dc
```
This `bc`, if built, assumes a working, GNU-compatible `bc`, installed on the
system and in the `PATH`, to generate some tests, unless the `-G` flag or
`--disable-generated-tests` option is given to `configure.sh`, as follows:
```
./configure.sh -G
./configure.sh --disable-generated-tests
```
After running `configure.sh`, build and run tests as follows:
```
make
make test
```
This `dc` also assumes a working, GNU-compatible `dc`, installed on the system
and in the `PATH`, to generate some tests, unless one of the above options is
given to `configure.sh`.
To generate test coverage, pass the `-c` flag or the `--coverage` option to
`configure.sh` as follows:
```
./configure.sh -c
./configure.sh --coverage
```
Both commands are equivalent.
***WARNING***: Both `bc` and `dc` must be built for test coverage. Otherwise,
`configure.sh` will give an error.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
[2]: https://www.gnu.org/software/bc/
[3]: https://www.musl-libc.org/
[4]: #build-environment-variables
[5]: #build-options
[6]: #cross-compiling
diff --git a/contrib/bc/manuals/dc.1.md.in b/contrib/bc/manuals/dc.1.md.in
index 72071df06421..b00eff17471e 100644
--- a/contrib/bc/manuals/dc.1.md.in
+++ b/contrib/bc/manuals/dc.1.md.in
@@ -1,1261 +1,1270 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# Name
dc - arbitrary-precision decimal reverse-Polish notation calculator
# SYNOPSIS
**dc** [**-hiPvVx**] [**--version**] [**--help**] [**--interactive**] [**--no-prompt**] [**--extended-register**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...] [*file*...]
# DESCRIPTION
dc(1) is an arbitrary-precision calculator. It uses a stack (reverse Polish
notation) to store numbers and results of computations. Arithmetic operations
pop arguments off of the stack and push the results.
If no files are given on the command-line as extra arguments (i.e., not as
**-f** or **--file** arguments), then dc(1) reads from **stdin**. Otherwise,
those files are processed, and dc(1) will then exit.
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where **-e** (**--expression**) and **-f** (**--file**)
arguments cause dc(1) to execute them and exit. The reason for this is that this
dc(1) allows users to set arguments in the environment variable **DC_ENV_ARGS**
(see the **ENVIRONMENT VARIABLES** section). Any expressions given on the
command-line should be used to set up a standard environment. For example, if a
user wants the **scale** always set to **10**, they can set **DC_ENV_ARGS** to
**-e 10k**, and this dc(1) will always start with a **scale** of **10**.
If users want to have dc(1) exit after processing all input from **-e** and
**-f** arguments (and their equivalents), then they can just simply add **-e q**
as the last command-line argument or define the environment variable
**DC_EXPR_EXIT**.
# OPTIONS
The following are the options that dc(1) accepts.
**-h**, **--help**
: Prints a usage message and quits.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-P**, **--no-prompt**
{{ A E H N EH EN HN EHN }}
: Disables the prompt in TTY mode. (The prompt is only enabled in TTY mode.
See the **TTY MODE** section) This is mostly for those users that do not
want a prompt or are not used to having them in dc(1). Most of those users
would want to put this option in **DC_ENV_ARGS**.
{{ end }}
{{ P EP HP NP EHP ENP HNP EHNP }}
: This option is a no-op.
{{ end }}
This is a **non-portable extension**.
**-x** **--extended-register**
: Enables extended register mode. See the *Extended Register Mode* subsection
of the **REGISTERS** section for more information.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **DC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **dc <file> >&-**, it will quit with an error. This
is done so that dc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **dc <file> 2>&-**, it will quit with an error. This
is done so that dc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
Each item in the input source code, either a number (see the **NUMBERS**
section) or a command (see the **COMMANDS** section), is processed and executed,
in order. Input is processed immediately when entered.
**ibase** is a register (see the **REGISTERS** section) that determines how to
interpret constant numbers. It is the "input" base, or the number base used for
interpreting input numbers. **ibase** is initially **10**. The max allowable
value for **ibase** is **16**. The min allowable value for **ibase** is **2**.
The max allowable value for **ibase** can be queried in dc(1) programs with the
**T** command.
**obase** is a register (see the **REGISTERS** section) that determines how to
output results. It is the "output" base, or the number base used for outputting
numbers. **obase** is initially **10**. The max allowable value for **obase** is
**DC_BASE_MAX** and can be queried with the **U** command. The min allowable
{{ A H N P HN HP NP HNP }}
value for **obase** is **0**. If **obase** is **0**, values are output in
scientific notation, and if **obase** is **1**, values are output in engineering
notation. Otherwise, values are output in the specified base.
Outputting in scientific and engineering notations are **non-portable
extensions**.
{{ end }}
{{ E EH EN EP EHN EHP ENP EHNP }}
value for **obase** is **2**. Values are output in the specified base.
{{ end }}
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a register (see the
**REGISTERS** section) that sets the precision of any operations (with
exceptions). **scale** is initially **0**. **scale** cannot be negative. The max
allowable value for **scale** can be queried in dc(1) programs with the **V**
command.
{{ A H N P HN HP NP HNP }}
**seed** is a register containing the current seed for the pseudo-random number
generator. If the current value of **seed** is queried and stored, then if it is
assigned to **seed** later, the pseudo-random number generator is guaranteed to
produce the same sequence of pseudo-random numbers that were generated after the
value of **seed** was first queried.
Multiple values assigned to **seed** can produce the same sequence of
pseudo-random numbers. Likewise, when a value is assigned to **seed**, it is not
guaranteed that querying **seed** immediately after will return the same value.
In addition, the value of **seed** will change after any call to the **'**
command or the **"** command that does not get receive a value of **0** or
**1**. The maximum integer returned by the **'** command can be queried with the
**W** command.
**Note**: The values returned by the pseudo-random number generator with the
**'** and **"** commands are guaranteed to **NOT** be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator. However,
they *are* guaranteed to be reproducible with identical **seed** values. This
-means that the pseudo-random values from bc(1) should only be used where a
+means that the pseudo-random values from dc(1) should only be used where a
reproducible stream of pseudo-random numbers is *ESSENTIAL*. In any other case,
use a non-seeded pseudo-random number generator.
The pseudo-random number generator, **seed**, and all associated operations are
**non-portable extensions**.
{{ end }}
## Comments
Comments go from **#** until, and not including, the next newline. This is a
**non-portable extension**.
# NUMBERS
Numbers are strings made up of digits, uppercase letters up to **F**, and at
most **1** period for a radix. Numbers can have up to **DC_NUM_MAX** digits.
Uppercase letters are equal to **9** + their position in the alphabet (i.e.,
**A** equals **10**, or **9+1**). If a digit or letter makes no sense with the
current value of **ibase**, they are set to the value of the highest valid digit
in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **F** alone always equals decimal
**15**.
{{ A H N P HN HP NP HNP }}
In addition, dc(1) accepts numbers in scientific notation. These have the form
**\<number\>e\<integer\>**. The exponent (the portion after the **e**) must be
an integer. An example is **1.89237e9**, which is equal to **1892370000**.
Negative exponents are also allowed, so **4.2890e_3** is equal to **0.0042890**.
**WARNING**: Both the number and the exponent in scientific notation are
interpreted according to the current **ibase**, but the number is still
multiplied by **10\^exponent** regardless of the current **ibase**. For example,
if **ibase** is **16** and dc(1) is given the number string **FFeA**, the
resulting decimal number will be **2550000000000**, and if dc(1) is given the
number string **10e_4**, the resulting decimal number will be **0.0016**.
Accepting input as scientific notation is a **non-portable extension**.
{{ end }}
# COMMANDS
The valid commands are listed below.
## Printing
These commands are used for printing.
{{ A H N P HN HP NP HNP }}
Note that both scientific notation and engineering notation are available for
printing numbers. Scientific notation is activated by assigning **0** to
**obase** using **0o**, and engineering notation is activated by assigning **1**
to **obase** using **1o**. To deactivate them, just assign a different value to
**obase**.
Printing numbers in scientific notation and/or engineering notation is a
**non-portable extension**.
{{ end }}
**p**
: Prints the value on top of the stack, whether number or string, and prints a
newline after.
This does not alter the stack.
**n**
: Prints the value on top of the stack, whether number or string, and pops it
off of the stack.
**P**
: Pops a value off the stack.
If the value is a number, it is truncated and the absolute value of the
result is printed as though **obase** is **UCHAR_MAX+1** and each digit is
interpreted as an ASCII character, making it a byte stream.
If the value is a string, it is printed without a trailing newline.
This is a **non-portable extension**.
**f**
: Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
Users should use this command when they get lost.
## Arithmetic
These are the commands used for arithmetic.
**+**
: The top two values are popped off the stack, added, and the result is pushed
onto the stack. The *scale* of the result is equal to the max *scale* of
both operands.
**-**
: The top two values are popped off the stack, subtracted, and the result is
pushed onto the stack. The *scale* of the result is equal to the max
*scale* of both operands.
**\***
: The top two values are popped off the stack, multiplied, and the result is
pushed onto the stack. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result
is equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The top two values are popped off the stack, divided, and the result is
pushed onto the stack. The *scale* of the result is equal to **scale**.
The first value popped off of the stack must be non-zero.
**%**
: The top two values are popped off the stack, remaindered, and the result is
pushed onto the stack.
Remaindering is equivalent to 1) Computing **a/b** to current **scale**, and
2) Using the result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The first value popped off of the stack must be non-zero.
**~**
: The top two values are popped off the stack, divided and remaindered, and
the results (divided first, remainder second) are pushed onto the stack.
This is equivalent to **x y / x y %** except that **x** and **y** are only
evaluated once.
The first value popped off of the stack must be non-zero.
This is a **non-portable extension**.
**\^**
: The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack. The *scale* of
the result is equal to **scale**.
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
**v**
: The top value is popped off the stack, its square root is computed, and the
result is pushed onto the stack. The *scale* of the result is equal to
**scale**.
The value popped off of the stack must be non-negative.
**\_**
: If this command *immediately* precedes a number (i.e., no spaces or other
commands), then that number is input as a negative number.
Otherwise, the top value on the stack is popped and copied, and the copy is
negated and pushed onto the stack. This behavior without a number is a
**non-portable extension**.
**b**
: The top value is popped off the stack, and if it is zero, it is pushed back
onto the stack. Otherwise, its absolute value is pushed onto the stack.
This is a **non-portable extension**.
**|**
: The top three values are popped off the stack, a modular exponentiation is
computed, and the result is pushed onto the stack.
The first value popped is used as the reduction modulus and must be an
integer and non-zero. The second value popped is used as the exponent and
must be an integer and non-negative. The third value popped is the base and
must be an integer.
This is a **non-portable extension**.
{{ A H N P HN HP NP HNP }}
**\$**
: The top value is popped off the stack and copied, and the copy is truncated
and pushed onto the stack.
This is a **non-portable extension**.
**\@**
: The top two values are popped off the stack, and the precision of the second
is set to the value of the first, whether by truncation or extension.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**H**
: The top two values are popped off the stack, and the second is shifted left
(radix shifted right) to the value of the first.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**h**
: The top two values are popped off the stack, and the second is shifted right
(radix shifted left) to the value of the first.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
{{ end }}
**G**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if they are equal, or **0** otherwise.
This is a **non-portable extension**.
**N**
: The top value is popped off of the stack, and if it a **0**, a **1** is
pushed; otherwise, a **0** is pushed.
This is a **non-portable extension**.
**(**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than the second, or **0** otherwise.
This is a **non-portable extension**.
**{**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than or equal to the second, or **0**
otherwise.
This is a **non-portable extension**.
**)**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than the second, or **0** otherwise.
This is a **non-portable extension**.
**}**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than or equal to the second, or
**0** otherwise.
This is a **non-portable extension**.
**M**
: The top two values are popped off of the stack. If they are both non-zero, a
**1** is pushed onto the stack. If either of them is zero, or both of them
are, then a **0** is pushed onto the stack.
This is like the **&&** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
**m**
: The top two values are popped off of the stack. If at least one of them is
non-zero, a **1** is pushed onto the stack. If both of them are zero, then a
**0** is pushed onto the stack.
This is like the **||** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
{{ A H N P HN HP NP HNP }}
## Pseudo-Random Number Generator
dc(1) has a built-in pseudo-random number generator. These commands query the
pseudo-random number generator. (See Parameters for more information about the
**seed** value that controls the pseudo-random number generator.)
The pseudo-random number generator is guaranteed to **NOT** be
cryptographically secure.
**'**
: Generates an integer between 0 and **DC_RAND_MAX**, inclusive (see the
**LIMITS** section).
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
This is a **non-portable extension**.
**"**
: Pops a value off of the stack, which is used as an **exclusive** upper bound
on the integer that will be generated. If the bound is negative or is a
non-integer, an error is raised, and dc(1) resets (see the **RESET**
section) while **seed** remains unchanged. If the bound is larger than
**DC_RAND_MAX**, the higher bound is honored by generating several
pseudo-random integers, multiplying them by appropriate powers of
**DC_RAND_MAX+1**, and adding them together. Thus, the size of integer that
can be generated with this command is unbounded. Using this command will
change the value of **seed**, unless the operand is **0** or **1**. In that
case, **0** is pushed onto the stack, and **seed** is *not* changed.
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
This is a **non-portable extension**.
{{ end }}
## Stack Control
These commands control the stack.
**c**
: Removes all items from ("clears") the stack.
**d**
: Copies the item on top of the stack ("duplicates") and pushes the copy onto
the stack.
**r**
: Swaps ("reverses") the two top items on the stack.
**R**
: Pops ("removes") the top value from the stack.
## Register Control
These commands control registers (see the **REGISTERS** section).
**s***r*
: Pops the value off the top of the stack and stores it into register *r*.
**l***r*
: Copies the value in register *r* and pushes it onto the stack. This does not
alter the contents of *r*.
**S***r*
: Pops the value off the top of the (main) stack and pushes it onto the stack
of register *r*. The previous value of the register becomes inaccessible.
**L***r*
: Pops the value off the top of the stack for register *r* and push it onto
the main stack. The previous value in the stack for register *r*, if any, is
now accessible via the **l***r* command.
## Parameters
{{ A H N P HN HP NP HNP }}
These commands control the values of **ibase**, **obase**, **scale**, and
**seed**. Also see the **SYNTAX** section.
{{ end }}
{{ E EH EN EP EHN EHP ENP EHNP }}
These commands control the values of **ibase**, **obase**, and **scale**. Also
see the **SYNTAX** section.
{{ end }}
**i**
: Pops the value off of the top of the stack and uses it to set **ibase**,
which must be between **2** and **16**, inclusive.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**o**
: Pops the value off of the top of the stack and uses it to set **obase**,
{{ A H N P HN HP NP HNP }}
which must be between **0** and **DC_BASE_MAX**, inclusive (see the
**LIMITS** section and the **NUMBERS** section).
{{ end }}
{{ E EH EN EP EHN EHP ENP EHNP }}
which must be between **2** and **DC_BASE_MAX**, inclusive (see the
**LIMITS** section).
{{ end }}
If the value on top of the stack has any *scale*, the *scale* is ignored.
**k**
: Pops the value off of the top of the stack and uses it to set **scale**,
which must be non-negative.
If the value on top of the stack has any *scale*, the *scale* is ignored.
{{ A H N P HN HP NP HNP }}
**j**
: Pops the value off of the top of the stack and uses it to set **seed**. The
meaning of **seed** is dependent on the current pseudo-random number
generator but is guaranteed to not change except for new major versions.
The *scale* and sign of the value may be significant.
If a previously used **seed** value is used again, the pseudo-random number
generator is guaranteed to produce the same sequence of pseudo-random
numbers as it did when the **seed** value was previously used.
The exact value assigned to **seed** is not guaranteed to be returned if the
**J** command is used. However, if **seed** *does* return a different value,
both values, when assigned to **seed**, are guaranteed to produce the same
sequence of pseudo-random numbers. This means that certain values assigned
to **seed** will not produce unique sequences of pseudo-random numbers.
There is no limit to the length (number of significant decimal digits) or
*scale* of the value that can be assigned to **seed**.
This is a **non-portable extension**.
{{ end }}
**I**
: Pushes the current value of **ibase** onto the main stack.
**O**
: Pushes the current value of **obase** onto the main stack.
**K**
: Pushes the current value of **scale** onto the main stack.
{{ A H N P HN HP NP HNP }}
**J**
: Pushes the current value of **seed** onto the main stack.
This is a **non-portable extension**.
{{ end }}
**T**
: Pushes the maximum allowable value of **ibase** onto the main stack.
This is a **non-portable extension**.
**U**
: Pushes the maximum allowable value of **obase** onto the main stack.
This is a **non-portable extension**.
**V**
: Pushes the maximum allowable value of **scale** onto the main stack.
This is a **non-portable extension**.
{{ A H N P HN HP NP HNP }}
**W**
: Pushes the maximum (inclusive) integer that can be generated with the **'**
pseudo-random number generator command.
This is a **non-portable extension**.
{{ end }}
## Strings
The following commands control strings.
dc(1) can work with both numbers and strings, and registers (see the
**REGISTERS** section) can hold both strings and numbers. dc(1) always knows
whether the contents of a register are a string or a number.
While arithmetic operations have to have numbers, and will print an error if
given a string, other commands accept strings.
Strings can also be executed as macros. For example, if the string **[1pR]** is
executed as a macro, then the code **1pR** is executed, meaning that the **1**
will be printed with a newline after and then popped from the stack.
**\[**_characters_**\]**
: Makes a string containing *characters* and pushes it onto the stack.
If there are brackets (**\[** and **\]**) in the string, then they must be
balanced. Unbalanced brackets can be escaped using a backslash (**\\**)
character.
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the (first)
backslash is not.
**a**
: The value on top of the stack is popped.
If it is a number, it is truncated and its absolute value is taken. The
result mod **UCHAR_MAX+1** is calculated. If that result is **0**, push an
empty string; otherwise, push a one-character string where the character is
the result of the mod interpreted as an ASCII character.
If it is a string, then a new string is made. If the original string is
empty, the new string is empty. If it is not, then the first character of
the original string is used to create the new string as a one-character
string. The new string is then pushed onto the stack.
This is a **non-portable extension**.
**x**
: Pops a value off of the top of the stack.
If it is a number, it is pushed back onto the stack.
If it is a string, it is executed as a macro.
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
**\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is greater than the second, then the contents of register
*r* are executed.
For example, **0 1>a** will execute the contents of register **a**, and
**1 0>a** will not.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not greater than the second (less than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is less than the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not less than the second (greater than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is equal to the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not equal to the second, then the contents of register
*r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**?**
: Reads a line from the **stdin** and executes it. This is to allow macros to
request input from users.
**q**
: During execution of a macro, this exits the execution of that macro and the
execution of the macro that executed it. If there are no macros, or only one
macro executing, dc(1) exits.
**Q**
: Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack. If the number
of levels to pop is greater than the number of executing macros, dc(1)
exits.
## Status
These commands query status of the stack or its top value.
**Z**
: Pops a value off of the stack.
If it is a number, calculates the number of significant decimal digits it
has and pushes the result.
If it is a string, pushes the number of characters the string has.
**X**
: Pops a value off of the stack.
If it is a number, pushes the *scale* of the value onto the stack.
If it is a string, pushes **0**.
**z**
: Pushes the current stack depth (before execution of this command).
## Arrays
These commands manipulate arrays.
**:***r*
: Pops the top two values off of the stack. The second value will be stored in
the array *r* (see the **REGISTERS** section), indexed by the first value.
**;***r*
: Pops the value on top of the stack and uses it as an index into the array
*r*. The selected value is then pushed onto the stack.
# REGISTERS
Registers are names that can store strings, numbers, and arrays. (Number/string
registers do not interfere with array registers.)
Each register is also its own stack, so the current register value is the top of
the stack for the register. All registers, when first referenced, have one value
(**0**) in their stack.
In non-extended register mode, a register name is just the single character that
follows any command that needs a register name. The only exception is a newline
(**'\\n'**); it is a parse error for a newline to be used as a register name.
## Extended Register Mode
Unlike most other dc(1) implentations, this dc(1) provides nearly unlimited
amounts of registers, if extended register mode is enabled.
If extended register mode is enabled (**-x** or **--extended-register**
command-line arguments are given), then normal single character registers are
used *unless* the character immediately following a command that needs a
register name is a space (according to **isspace()**) and not a newline
(**'\\n'**).
In that case, the register name is found according to the regex
**\[a-z\]\[a-z0-9\_\]\*** (like bc(1) identifiers), and it is a parse error if
the next non-space characters do not match that regex.
# RESET
When dc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any macros that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
macros returned) is skipped.
Thus, when dc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
# PERFORMANCE
Most dc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This dc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **DC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **DC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**DC_BASE_DIGS**.
In addition, this dc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **DC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on dc(1):
**DC_LONG_BIT**
: The number of bits in the **long** type in the environment where dc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**DC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **DC_LONG_BIT**.
**DC_BASE_POW**
: The max decimal number that each large integer can store (see
**DC_BASE_DIGS**) plus **1**. Depends on **DC_BASE_DIGS**.
**DC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **DC_LONG_BIT**.
**DC_BASE_MAX**
: The maximum output base. Set at **DC_BASE_POW**.
**DC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**DC_SCALE_MAX**
: The maximum **scale**. Set at **DC_OVERFLOW_MAX-1**.
**DC_STRING_MAX**
: The maximum length of strings. Set at **DC_OVERFLOW_MAX-1**.
**DC_NAME_MAX**
: The maximum length of identifiers. Set at **DC_OVERFLOW_MAX-1**.
**DC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **DC_OVERFLOW_MAX-1**.
{{ A H N P HN HP NP HNP }}
**DC_RAND_MAX**
: The maximum integer (inclusive) returned by the **'** command, if dc(1). Set
at **2\^DC_LONG_BIT-1**.
{{ end }}
Exponent
: The maximum allowable exponent (positive or negative). Set at
**DC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
dc(1) recognizes the following environment variables:
**DC_ENV_ARGS**
: This is another way to give command-line arguments to dc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **DC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs. Another use would
be to use the **-e** option to set **scale** to a value other than **0**.
The code that parses **DC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some dc file.dc"** will be correctly parsed, but the string
**"/home/gavin/some \"dc\" file.dc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
- double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
+ double quotes as the outside quotes, as in **"some 'dc' file.dc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **DC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**DC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), dc(1) will output
lines to that length, including the backslash newline combo. The default
line length is **70**.
**DC_EXPR_EXIT**
: If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the **-e** and/or
**-f** command-line options (and any equivalents).
# EXIT STATUS
dc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
{{ A H N P HN HP NP HNP }}
number, using a negative number as a bound for the pseudo-random number
generator, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**), places (**\@**), left shift (**H**), and right shift (**h**)
operators.
{{ end }}
{{ E EH EN EP EHN EHP ENP EHNP }}
number, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**) operator.
{{ end }}
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, and using a token where it is
invalid.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, and attempting an operation when
the stack has too few elements.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (dc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, dc(1) always exits
and returns **4**, no matter what mode dc(1) is in.
The other statuses will only be returned when dc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since dc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, dc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, dc(1) turns
on "TTY mode."
{{ A E N P EN EP NP ENP }}
TTY mode is required for history to be enabled (see the **COMMAND LINE HISTORY**
section). It is also required to enable special handling for **SIGINT** signals.
{{ end }}
{{ A E H N EH EN HN EHN }}
The prompt is enabled in TTY mode.
{{ end }}
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause dc(1) to stop execution of the current input. If
dc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If dc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If dc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to dc(1) as it is executing a file, it
can seem as though dc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause dc(1) to clean up and exit, and it uses the
{{ A E N P EN EP NP ENP }}
default handler for all other signals. The one exception is **SIGHUP**; in that
case, when dc(1) is in TTY mode, a **SIGHUP** will cause dc(1) to clean up and
exit.
{{ end }}
{{ H EH HN HP EHN EHP HNP EHNP }}
default handler for all other signals.
{{ end }}
{{ A E N P EN EP NP ENP }}
# COMMAND LINE HISTORY
dc(1) supports interactive command-line editing. If dc(1) is in TTY mode (see
the **TTY MODE** section), history is enabled. Previous lines can be recalled
and edited with the arrow keys.
**Note**: tabs are converted to 8 spaces.
{{ end }}
{{ A E H P EH EP HP EHP }}
# LOCALES
This dc(1) ships with support for adding error messages for different locales
and thus, supports **LC_MESSAGS**.
{{ end }}
# SEE ALSO
bc(1)
# STANDARDS
The dc(1) utility operators are compliant with the operators in the bc(1)
[IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1] specification.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHOR
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
diff --git a/contrib/bc/manuals/dc/A.1 b/contrib/bc/manuals/dc/A.1
index 0f1e877cc2e0..2fc16a5b8b73 100644
--- a/contrib/bc/manuals/dc/A.1
+++ b/contrib/bc/manuals/dc/A.1
@@ -1,1338 +1,1351 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "DC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "DC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH Name
.PP
dc - arbitrary-precision decimal reverse-Polish notation calculator
.SH SYNOPSIS
.PP
\f[B]dc\f[R] [\f[B]-hiPvVx\f[R]] [\f[B]\[en]version\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]no-prompt\f[R]] [\f[B]\[en]extended-register\f[R]]
[\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
dc(1) is an arbitrary-precision calculator.
It uses a stack (reverse Polish notation) to store numbers and results
of computations.
Arithmetic operations pop arguments off of the stack and push the
results.
.PP
If no files are given on the command-line as extra arguments (i.e., not
as \f[B]-f\f[R] or \f[B]\[en]file\f[R] arguments), then dc(1) reads from
\f[B]stdin\f[R].
Otherwise, those files are processed, and dc(1) will then exit.
.PP
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where \f[B]-e\f[R] (\f[B]\[en]expression\f[R]) and
\f[B]-f\f[R] (\f[B]\[en]file\f[R]) arguments cause dc(1) to execute them
and exit.
The reason for this is that this dc(1) allows users to set arguments in
the environment variable \f[B]DC_ENV_ARGS\f[R] (see the \f[B]ENVIRONMENT
VARIABLES\f[R] section).
Any expressions given on the command-line should be used to set up a
standard environment.
For example, if a user wants the \f[B]scale\f[R] always set to
\f[B]10\f[R], they can set \f[B]DC_ENV_ARGS\f[R] to \f[B]-e 10k\f[R],
and this dc(1) will always start with a \f[B]scale\f[R] of \f[B]10\f[R].
.PP
If users want to have dc(1) exit after processing all input from
\f[B]-e\f[R] and \f[B]-f\f[R] arguments (and their equivalents), then
they can just simply add \f[B]-e q\f[R] as the last command-line
argument or define the environment variable \f[B]DC_EXPR_EXIT\f[R].
.SH OPTIONS
.PP
The following are the options that dc(1) accepts.
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
Disables the prompt in TTY mode.
(The prompt is only enabled in TTY mode.
See the \f[B]TTY MODE\f[R] section) This is mostly for those users that
do not want a prompt or are not used to having them in dc(1).
Most of those users would want to put this option in
\f[B]DC_ENV_ARGS\f[R].
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-x\f[R] \f[B]\[en]extended-register\f[R]
Enables extended register mode.
See the \f[I]Extended Register Mode\f[R] subsection of the
\f[B]REGISTERS\f[R] section for more information.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]DC_ENV_ARGS\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]dc >&-\f[R], it will quit with an error.
This is done so that dc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]dc 2>&-\f[R], it will quit with an error.
This is done so that dc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
Each item in the input source code, either a number (see the
\f[B]NUMBERS\f[R] section) or a command (see the \f[B]COMMANDS\f[R]
section), is processed and executed, in order.
Input is processed immediately when entered.
.PP
\f[B]ibase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to interpret constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]ibase\f[R] is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in dc(1)
programs with the \f[B]T\f[R] command.
.PP
\f[B]obase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]DC_BASE_MAX\f[R] and
can be queried with the \f[B]U\f[R] command.
The min allowable value for \f[B]obase\f[R] is \f[B]0\f[R].
If \f[B]obase\f[R] is \f[B]0\f[R], values are output in scientific
notation, and if \f[B]obase\f[R] is \f[B]1\f[R], values are output in
engineering notation.
Otherwise, values are output in the specified base.
.PP
Outputting in scientific and engineering notations are \f[B]non-portable
extensions\f[R].
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a register (see the \f[B]REGISTERS\f[R] section) that sets the
precision of any operations (with exceptions).
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] can be queried in dc(1)
programs with the \f[B]V\f[R] command.
.PP
\f[B]seed\f[R] is a register containing the current seed for the
pseudo-random number generator.
If the current value of \f[B]seed\f[R] is queried and stored, then if it
is assigned to \f[B]seed\f[R] later, the pseudo-random number generator
is guaranteed to produce the same sequence of pseudo-random numbers that
were generated after the value of \f[B]seed\f[R] was first queried.
.PP
Multiple values assigned to \f[B]seed\f[R] can produce the same sequence
of pseudo-random numbers.
Likewise, when a value is assigned to \f[B]seed\f[R], it is not
guaranteed that querying \f[B]seed\f[R] immediately after will return
the same value.
In addition, the value of \f[B]seed\f[R] will change after any call to
the \f[B]\[cq]\f[R] command or the \f[B]\[dq]\f[R] command that does not
get receive a value of \f[B]0\f[R] or \f[B]1\f[R].
The maximum integer returned by the \f[B]\[cq]\f[R] command can be
queried with the \f[B]W\f[R] command.
.PP
\f[B]Note\f[R]: The values returned by the pseudo-random number
generator with the \f[B]\[cq]\f[R] and \f[B]\[dq]\f[R] commands are
guaranteed to \f[B]NOT\f[R] be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator.
However, they \f[I]are\f[R] guaranteed to be reproducible with identical
\f[B]seed\f[R] values.
-This means that the pseudo-random values from bc(1) should only be used
+This means that the pseudo-random values from dc(1) should only be used
where a reproducible stream of pseudo-random numbers is
\f[I]ESSENTIAL\f[R].
In any other case, use a non-seeded pseudo-random number generator.
.PP
The pseudo-random number generator, \f[B]seed\f[R], and all associated
operations are \f[B]non-portable extensions\f[R].
.SS Comments
.PP
Comments go from \f[B]#\f[R] until, and not including, the next newline.
This is a \f[B]non-portable extension\f[R].
.SH NUMBERS
.PP
Numbers are strings made up of digits, uppercase letters up to
\f[B]F\f[R], and at most \f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]DC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]F\f[R] alone always equals decimal \f[B]15\f[R].
.PP
In addition, dc(1) accepts numbers in scientific notation.
These have the form \f[B]<number>e<integer>\f[R].
The exponent (the portion after the \f[B]e\f[R]) must be an integer.
An example is \f[B]1.89237e9\f[R], which is equal to
\f[B]1892370000\f[R].
Negative exponents are also allowed, so \f[B]4.2890e_3\f[R] is equal to
\f[B]0.0042890\f[R].
.PP
\f[B]WARNING\f[R]: Both the number and the exponent in scientific
notation are interpreted according to the current \f[B]ibase\f[R], but
the number is still multiplied by \f[B]10\[ha]exponent\f[R] regardless
of the current \f[B]ibase\f[R].
For example, if \f[B]ibase\f[R] is \f[B]16\f[R] and dc(1) is given the
number string \f[B]FFeA\f[R], the resulting decimal number will be
\f[B]2550000000000\f[R], and if dc(1) is given the number string
\f[B]10e_4\f[R], the resulting decimal number will be \f[B]0.0016\f[R].
.PP
Accepting input as scientific notation is a \f[B]non-portable
extension\f[R].
.SH COMMANDS
.PP
The valid commands are listed below.
.SS Printing
.PP
These commands are used for printing.
.PP
Note that both scientific notation and engineering notation are
available for printing numbers.
Scientific notation is activated by assigning \f[B]0\f[R] to
\f[B]obase\f[R] using \f[B]0o\f[R], and engineering notation is
activated by assigning \f[B]1\f[R] to \f[B]obase\f[R] using
\f[B]1o\f[R].
To deactivate them, just assign a different value to \f[B]obase\f[R].
.PP
Printing numbers in scientific notation and/or engineering notation is a
\f[B]non-portable extension\f[R].
.TP
\f[B]p\f[R]
Prints the value on top of the stack, whether number or string, and
prints a newline after.
.RS
.PP
This does not alter the stack.
.RE
.TP
\f[B]n\f[R]
Prints the value on top of the stack, whether number or string, and pops
it off of the stack.
.TP
\f[B]P\f[R]
Pops a value off the stack.
.RS
.PP
If the value is a number, it is truncated and the absolute value of the
result is printed as though \f[B]obase\f[R] is \f[B]UCHAR_MAX+1\f[R] and
each digit is interpreted as an ASCII character, making it a byte
stream.
.PP
If the value is a string, it is printed without a trailing newline.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]f\f[R]
Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
.RS
.PP
Users should use this command when they get lost.
.RE
.SS Arithmetic
.PP
These are the commands used for arithmetic.
.TP
\f[B]+\f[R]
The top two values are popped off the stack, added, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]-\f[R]
The top two values are popped off the stack, subtracted, and the result
is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]*\f[R]
The top two values are popped off the stack, multiplied, and the result
is pushed onto the stack.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The top two values are popped off the stack, divided, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]%\f[R]
The top two values are popped off the stack, remaindered, and the result
is pushed onto the stack.
.RS
.PP
Remaindering is equivalent to 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R], and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]\[ti]\f[R]
The top two values are popped off the stack, divided and remaindered,
and the results (divided first, remainder second) are pushed onto the
stack.
This is equivalent to \f[B]x y / x y %\f[R] except that \f[B]x\f[R] and
\f[B]y\f[R] are only evaluated once.
.RS
.PP
The first value popped off of the stack must be non-zero.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
.RE
.TP
\f[B]v\f[R]
The top value is popped off the stack, its square root is computed, and
the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The value popped off of the stack must be non-negative.
.RE
.TP
\f[B]_\f[R]
If this command \f[I]immediately\f[R] precedes a number (i.e., no spaces
or other commands), then that number is input as a negative number.
.RS
.PP
Otherwise, the top value on the stack is popped and copied, and the copy
is negated and pushed onto the stack.
This behavior without a number is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]b\f[R]
The top value is popped off the stack, and if it is zero, it is pushed
back onto the stack.
Otherwise, its absolute value is pushed onto the stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]|\f[R]
The top three values are popped off the stack, a modular exponentiation
is computed, and the result is pushed onto the stack.
.RS
.PP
The first value popped is used as the reduction modulus and must be an
integer and non-zero.
The second value popped is used as the exponent and must be an integer
and non-negative.
The third value popped is the base and must be an integer.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]$\f[R]
The top value is popped off the stack and copied, and the copy is
truncated and pushed onto the stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[at]\f[R]
The top two values are popped off the stack, and the precision of the
second is set to the value of the first, whether by truncation or
extension.
.RS
.PP
The first value popped off of the stack must be an integer and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]H\f[R]
The top two values are popped off the stack, and the second is shifted
left (radix shifted right) to the value of the first.
.RS
.PP
The first value popped off of the stack must be an integer and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]h\f[R]
The top two values are popped off the stack, and the second is shifted
right (radix shifted left) to the value of the first.
.RS
.PP
The first value popped off of the stack must be an integer and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]G\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if they are equal, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]N\f[R]
The top value is popped off of the stack, and if it a \f[B]0\f[R], a
\f[B]1\f[R] is pushed; otherwise, a \f[B]0\f[R] is pushed.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B](\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]{\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than or equal to the second,
or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B])\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]}\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than or equal to the
second, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]M\f[R]
The top two values are popped off of the stack.
If they are both non-zero, a \f[B]1\f[R] is pushed onto the stack.
If either of them is zero, or both of them are, then a \f[B]0\f[R] is
pushed onto the stack.
.RS
.PP
This is like the \f[B]&&\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]m\f[R]
The top two values are popped off of the stack.
If at least one of them is non-zero, a \f[B]1\f[R] is pushed onto the
stack.
If both of them are zero, then a \f[B]0\f[R] is pushed onto the stack.
.RS
.PP
This is like the \f[B]||\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Pseudo-Random Number Generator
.PP
dc(1) has a built-in pseudo-random number generator.
These commands query the pseudo-random number generator.
(See Parameters for more information about the \f[B]seed\f[R] value that
controls the pseudo-random number generator.)
.PP
The pseudo-random number generator is guaranteed to \f[B]NOT\f[R] be
cryptographically secure.
.TP
\f[B]\[cq]\f[R]
Generates an integer between 0 and \f[B]DC_RAND_MAX\f[R], inclusive (see
the \f[B]LIMITS\f[R] section).
.RS
.PP
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[dq]\f[R]
Pops a value off of the stack, which is used as an \f[B]exclusive\f[R]
upper bound on the integer that will be generated.
If the bound is negative or is a non-integer, an error is raised, and
dc(1) resets (see the \f[B]RESET\f[R] section) while \f[B]seed\f[R]
remains unchanged.
If the bound is larger than \f[B]DC_RAND_MAX\f[R], the higher bound is
honored by generating several pseudo-random integers, multiplying them
by appropriate powers of \f[B]DC_RAND_MAX+1\f[R], and adding them
together.
Thus, the size of integer that can be generated with this command is
unbounded.
Using this command will change the value of \f[B]seed\f[R], unless the
operand is \f[B]0\f[R] or \f[B]1\f[R].
In that case, \f[B]0\f[R] is pushed onto the stack, and \f[B]seed\f[R]
is \f[I]not\f[R] changed.
.RS
.PP
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Stack Control
.PP
These commands control the stack.
.TP
\f[B]c\f[R]
Removes all items from (\[lq]clears\[rq]) the stack.
.TP
\f[B]d\f[R]
Copies the item on top of the stack (\[lq]duplicates\[rq]) and pushes
the copy onto the stack.
.TP
\f[B]r\f[R]
Swaps (\[lq]reverses\[rq]) the two top items on the stack.
.TP
\f[B]R\f[R]
Pops (\[lq]removes\[rq]) the top value from the stack.
.SS Register Control
.PP
These commands control registers (see the \f[B]REGISTERS\f[R] section).
.TP
\f[B]s\f[R]\f[I]r\f[R]
Pops the value off the top of the stack and stores it into register
\f[I]r\f[R].
.TP
\f[B]l\f[R]\f[I]r\f[R]
Copies the value in register \f[I]r\f[R] and pushes it onto the stack.
This does not alter the contents of \f[I]r\f[R].
.TP
\f[B]S\f[R]\f[I]r\f[R]
Pops the value off the top of the (main) stack and pushes it onto the
stack of register \f[I]r\f[R].
The previous value of the register becomes inaccessible.
.TP
\f[B]L\f[R]\f[I]r\f[R]
Pops the value off the top of the stack for register \f[I]r\f[R] and
push it onto the main stack.
The previous value in the stack for register \f[I]r\f[R], if any, is now
accessible via the \f[B]l\f[R]\f[I]r\f[R] command.
.SS Parameters
.PP
These commands control the values of \f[B]ibase\f[R], \f[B]obase\f[R],
\f[B]scale\f[R], and \f[B]seed\f[R].
Also see the \f[B]SYNTAX\f[R] section.
.TP
\f[B]i\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]ibase\f[R], which must be between \f[B]2\f[R] and \f[B]16\f[R],
inclusive.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]o\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]obase\f[R], which must be between \f[B]0\f[R] and
\f[B]DC_BASE_MAX\f[R], inclusive (see the \f[B]LIMITS\f[R] section and
the \f[B]NUMBERS\f[R] section).
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]k\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]scale\f[R], which must be non-negative.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]j\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]seed\f[R].
The meaning of \f[B]seed\f[R] is dependent on the current pseudo-random
number generator but is guaranteed to not change except for new major
versions.
.RS
.PP
The \f[I]scale\f[R] and sign of the value may be significant.
.PP
If a previously used \f[B]seed\f[R] value is used again, the
pseudo-random number generator is guaranteed to produce the same
sequence of pseudo-random numbers as it did when the \f[B]seed\f[R]
value was previously used.
.PP
The exact value assigned to \f[B]seed\f[R] is not guaranteed to be
returned if the \f[B]J\f[R] command is used.
However, if \f[B]seed\f[R] \f[I]does\f[R] return a different value, both
values, when assigned to \f[B]seed\f[R], are guaranteed to produce the
same sequence of pseudo-random numbers.
This means that certain values assigned to \f[B]seed\f[R] will not
produce unique sequences of pseudo-random numbers.
.PP
There is no limit to the length (number of significant decimal digits)
or \f[I]scale\f[R] of the value that can be assigned to \f[B]seed\f[R].
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]I\f[R]
Pushes the current value of \f[B]ibase\f[R] onto the main stack.
.TP
\f[B]O\f[R]
Pushes the current value of \f[B]obase\f[R] onto the main stack.
.TP
\f[B]K\f[R]
Pushes the current value of \f[B]scale\f[R] onto the main stack.
.TP
\f[B]J\f[R]
Pushes the current value of \f[B]seed\f[R] onto the main stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]T\f[R]
Pushes the maximum allowable value of \f[B]ibase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]U\f[R]
Pushes the maximum allowable value of \f[B]obase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]V\f[R]
Pushes the maximum allowable value of \f[B]scale\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]W\f[R]
Pushes the maximum (inclusive) integer that can be generated with the
\f[B]\[cq]\f[R] pseudo-random number generator command.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Strings
.PP
The following commands control strings.
.PP
dc(1) can work with both numbers and strings, and registers (see the
\f[B]REGISTERS\f[R] section) can hold both strings and numbers.
dc(1) always knows whether the contents of a register are a string or a
number.
.PP
While arithmetic operations have to have numbers, and will print an
error if given a string, other commands accept strings.
.PP
Strings can also be executed as macros.
For example, if the string \f[B][1pR]\f[R] is executed as a macro, then
the code \f[B]1pR\f[R] is executed, meaning that the \f[B]1\f[R] will be
printed with a newline after and then popped from the stack.
.TP
\f[B][\f[R]_characters_\f[B]]\f[R]
Makes a string containing \f[I]characters\f[R] and pushes it onto the
stack.
.RS
.PP
If there are brackets (\f[B][\f[R] and \f[B]]\f[R]) in the string, then
they must be balanced.
Unbalanced brackets can be escaped using a backslash (\f[B]\[rs]\f[R])
character.
.PP
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the
(first) backslash is not.
.RE
.TP
\f[B]a\f[R]
The value on top of the stack is popped.
.RS
.PP
If it is a number, it is truncated and its absolute value is taken.
The result mod \f[B]UCHAR_MAX+1\f[R] is calculated.
If that result is \f[B]0\f[R], push an empty string; otherwise, push a
one-character string where the character is the result of the mod
interpreted as an ASCII character.
.PP
If it is a string, then a new string is made.
If the original string is empty, the new string is empty.
If it is not, then the first character of the original string is used to
create the new string as a one-character string.
The new string is then pushed onto the stack.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]x\f[R]
Pops a value off of the top of the stack.
.RS
.PP
If it is a number, it is pushed back onto the stack.
.PP
If it is a string, it is executed as a macro.
.PP
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is greater than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
For example, \f[B]0 1>a\f[R] will execute the contents of register
\f[B]a\f[R], and \f[B]1 0>a\f[R] will not.
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not greater than the second (less than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is less than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not less than the second (greater than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is equal to the second, then the contents of register
\f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not equal to the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]?\f[R]
Reads a line from the \f[B]stdin\f[R] and executes it.
This is to allow macros to request input from users.
.TP
\f[B]q\f[R]
During execution of a macro, this exits the execution of that macro and
the execution of the macro that executed it.
If there are no macros, or only one macro executing, dc(1) exits.
.TP
\f[B]Q\f[R]
Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack.
If the number of levels to pop is greater than the number of executing
macros, dc(1) exits.
.SS Status
.PP
These commands query status of the stack or its top value.
.TP
\f[B]Z\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, calculates the number of significant decimal digits
it has and pushes the result.
.PP
If it is a string, pushes the number of characters the string has.
.RE
.TP
\f[B]X\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, pushes the \f[I]scale\f[R] of the value onto the
stack.
.PP
If it is a string, pushes \f[B]0\f[R].
.RE
.TP
\f[B]z\f[R]
Pushes the current stack depth (before execution of this command).
.SS Arrays
.PP
These commands manipulate arrays.
.TP
\f[B]:\f[R]\f[I]r\f[R]
Pops the top two values off of the stack.
The second value will be stored in the array \f[I]r\f[R] (see the
\f[B]REGISTERS\f[R] section), indexed by the first value.
.TP
\f[B];\f[R]\f[I]r\f[R]
Pops the value on top of the stack and uses it as an index into the
array \f[I]r\f[R].
The selected value is then pushed onto the stack.
.SH REGISTERS
.PP
Registers are names that can store strings, numbers, and arrays.
(Number/string registers do not interfere with array registers.)
.PP
Each register is also its own stack, so the current register value is
the top of the stack for the register.
All registers, when first referenced, have one value (\f[B]0\f[R]) in
their stack.
.PP
In non-extended register mode, a register name is just the single
character that follows any command that needs a register name.
The only exception is a newline (\f[B]`\[rs]n'\f[R]); it is a parse
error for a newline to be used as a register name.
.SS Extended Register Mode
.PP
Unlike most other dc(1) implentations, this dc(1) provides nearly
unlimited amounts of registers, if extended register mode is enabled.
.PP
If extended register mode is enabled (\f[B]-x\f[R] or
\f[B]\[en]extended-register\f[R] command-line arguments are given), then
normal single character registers are used \f[I]unless\f[R] the
character immediately following a command that needs a register name is
a space (according to \f[B]isspace()\f[R]) and not a newline
(\f[B]`\[rs]n'\f[R]).
.PP
In that case, the register name is found according to the regex
\f[B][a-z][a-z0-9_]*\f[R] (like bc(1) identifiers), and it is a parse
error if the next non-space characters do not match that regex.
.SH RESET
.PP
When dc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any macros that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all macros returned) is skipped.
.PP
Thus, when dc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.SH PERFORMANCE
.PP
Most dc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This dc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]DC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]DC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]DC_BASE_DIGS\f[R].
.PP
In addition, this dc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]DC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on dc(1):
.TP
\f[B]DC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
dc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]DC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]DC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]DC_BASE_DIGS\f[R].
.TP
\f[B]DC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]DC_BASE_POW\f[R].
.TP
\f[B]DC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]DC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_RAND_MAX\f[R]
The maximum integer (inclusive) returned by the \f[B]\[cq]\f[R] command,
if dc(1).
Set at \f[B]2\[ha]DC_LONG_BIT-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]DC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
dc(1) recognizes the following environment variables:
.TP
\f[B]DC_ENV_ARGS\f[R]
This is another way to give command-line arguments to dc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]DC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs.
Another use would be to use the \f[B]-e\f[R] option to set
\f[B]scale\f[R] to a value other than \f[B]0\f[R].
.RS
.PP
The code that parses \f[B]DC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some dc file.dc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]dc\[dq] file.dc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
-in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
+in \f[B]\[rq]some `dc' file.dc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]DC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]DC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), dc(1) will output lines to that length,
including the backslash newline combo.
The default line length is \f[B]70\f[R].
.TP
\f[B]DC_EXPR_EXIT\f[R]
If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the
\f[B]-e\f[R] and/or \f[B]-f\f[R] command-line options (and any
equivalents).
.SH EXIT STATUS
.PP
dc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, using a negative number as a bound for the
pseudo-random number generator, attempting to convert a negative number
to a hardware integer, overflow when converting a number to a hardware
integer, and attempting to use a non-integer where an integer is
required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]), places (\f[B]\[at]\f[R]), left shift
(\f[B]H\f[R]), and right shift (\f[B]h\f[R]) operators.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, and using a
token where it is invalid.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, and attempting an operation when the
stack has too few elements.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (dc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, dc(1)
always exits and returns \f[B]4\f[R], no matter what mode dc(1) is in.
.PP
The other statuses will only be returned when dc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
dc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, dc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, dc(1) turns on \[lq]TTY mode.\[rq]
.PP
TTY mode is required for history to be enabled (see the \f[B]COMMAND
LINE HISTORY\f[R] section).
It is also required to enable special handling for \f[B]SIGINT\f[R]
signals.
.PP
The prompt is enabled in TTY mode.
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause dc(1) to stop execution of the
current input.
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If dc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If dc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to dc(1) as it is
executing a file, it can seem as though dc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause dc(1) to clean up and
exit, and it uses the default handler for all other signals.
The one exception is \f[B]SIGHUP\f[R]; in that case, when dc(1) is in
TTY mode, a \f[B]SIGHUP\f[R] will cause dc(1) to clean up and exit.
.SH COMMAND LINE HISTORY
.PP
dc(1) supports interactive command-line editing.
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), history is
enabled.
Previous lines can be recalled and edited with the arrow keys.
.PP
\f[B]Note\f[R]: tabs are converted to 8 spaces.
.SH LOCALES
.PP
This dc(1) ships with support for adding error messages for different
locales and thus, supports \f[B]LC_MESSAGS\f[R].
.SH SEE ALSO
.PP
bc(1)
.SH STANDARDS
.PP
The dc(1) utility operators are compliant with the operators in the
bc(1) IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHOR
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/dc/A.1.md b/contrib/bc/manuals/dc/A.1.md
index 6b278ede8ad0..0c4fd2b9ef13 100644
--- a/contrib/bc/manuals/dc/A.1.md
+++ b/contrib/bc/manuals/dc/A.1.md
@@ -1,1198 +1,1207 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# Name
dc - arbitrary-precision decimal reverse-Polish notation calculator
# SYNOPSIS
**dc** [**-hiPvVx**] [**--version**] [**--help**] [**--interactive**] [**--no-prompt**] [**--extended-register**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...] [*file*...]
# DESCRIPTION
dc(1) is an arbitrary-precision calculator. It uses a stack (reverse Polish
notation) to store numbers and results of computations. Arithmetic operations
pop arguments off of the stack and push the results.
If no files are given on the command-line as extra arguments (i.e., not as
**-f** or **--file** arguments), then dc(1) reads from **stdin**. Otherwise,
those files are processed, and dc(1) will then exit.
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where **-e** (**--expression**) and **-f** (**--file**)
arguments cause dc(1) to execute them and exit. The reason for this is that this
dc(1) allows users to set arguments in the environment variable **DC_ENV_ARGS**
(see the **ENVIRONMENT VARIABLES** section). Any expressions given on the
command-line should be used to set up a standard environment. For example, if a
user wants the **scale** always set to **10**, they can set **DC_ENV_ARGS** to
**-e 10k**, and this dc(1) will always start with a **scale** of **10**.
If users want to have dc(1) exit after processing all input from **-e** and
**-f** arguments (and their equivalents), then they can just simply add **-e q**
as the last command-line argument or define the environment variable
**DC_EXPR_EXIT**.
# OPTIONS
The following are the options that dc(1) accepts.
**-h**, **--help**
: Prints a usage message and quits.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-P**, **--no-prompt**
: Disables the prompt in TTY mode. (The prompt is only enabled in TTY mode.
See the **TTY MODE** section) This is mostly for those users that do not
want a prompt or are not used to having them in dc(1). Most of those users
would want to put this option in **DC_ENV_ARGS**.
This is a **non-portable extension**.
**-x** **--extended-register**
: Enables extended register mode. See the *Extended Register Mode* subsection
of the **REGISTERS** section for more information.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **DC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **dc <file> >&-**, it will quit with an error. This
is done so that dc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **dc <file> 2>&-**, it will quit with an error. This
is done so that dc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
Each item in the input source code, either a number (see the **NUMBERS**
section) or a command (see the **COMMANDS** section), is processed and executed,
in order. Input is processed immediately when entered.
**ibase** is a register (see the **REGISTERS** section) that determines how to
interpret constant numbers. It is the "input" base, or the number base used for
interpreting input numbers. **ibase** is initially **10**. The max allowable
value for **ibase** is **16**. The min allowable value for **ibase** is **2**.
The max allowable value for **ibase** can be queried in dc(1) programs with the
**T** command.
**obase** is a register (see the **REGISTERS** section) that determines how to
output results. It is the "output" base, or the number base used for outputting
numbers. **obase** is initially **10**. The max allowable value for **obase** is
**DC_BASE_MAX** and can be queried with the **U** command. The min allowable
value for **obase** is **0**. If **obase** is **0**, values are output in
scientific notation, and if **obase** is **1**, values are output in engineering
notation. Otherwise, values are output in the specified base.
Outputting in scientific and engineering notations are **non-portable
extensions**.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a register (see the
**REGISTERS** section) that sets the precision of any operations (with
exceptions). **scale** is initially **0**. **scale** cannot be negative. The max
allowable value for **scale** can be queried in dc(1) programs with the **V**
command.
**seed** is a register containing the current seed for the pseudo-random number
generator. If the current value of **seed** is queried and stored, then if it is
assigned to **seed** later, the pseudo-random number generator is guaranteed to
produce the same sequence of pseudo-random numbers that were generated after the
value of **seed** was first queried.
Multiple values assigned to **seed** can produce the same sequence of
pseudo-random numbers. Likewise, when a value is assigned to **seed**, it is not
guaranteed that querying **seed** immediately after will return the same value.
In addition, the value of **seed** will change after any call to the **'**
command or the **"** command that does not get receive a value of **0** or
**1**. The maximum integer returned by the **'** command can be queried with the
**W** command.
**Note**: The values returned by the pseudo-random number generator with the
**'** and **"** commands are guaranteed to **NOT** be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator. However,
they *are* guaranteed to be reproducible with identical **seed** values. This
-means that the pseudo-random values from bc(1) should only be used where a
+means that the pseudo-random values from dc(1) should only be used where a
reproducible stream of pseudo-random numbers is *ESSENTIAL*. In any other case,
use a non-seeded pseudo-random number generator.
The pseudo-random number generator, **seed**, and all associated operations are
**non-portable extensions**.
## Comments
Comments go from **#** until, and not including, the next newline. This is a
**non-portable extension**.
# NUMBERS
Numbers are strings made up of digits, uppercase letters up to **F**, and at
most **1** period for a radix. Numbers can have up to **DC_NUM_MAX** digits.
Uppercase letters are equal to **9** + their position in the alphabet (i.e.,
**A** equals **10**, or **9+1**). If a digit or letter makes no sense with the
current value of **ibase**, they are set to the value of the highest valid digit
in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **F** alone always equals decimal
**15**.
In addition, dc(1) accepts numbers in scientific notation. These have the form
**\<number\>e\<integer\>**. The exponent (the portion after the **e**) must be
an integer. An example is **1.89237e9**, which is equal to **1892370000**.
Negative exponents are also allowed, so **4.2890e_3** is equal to **0.0042890**.
**WARNING**: Both the number and the exponent in scientific notation are
interpreted according to the current **ibase**, but the number is still
multiplied by **10\^exponent** regardless of the current **ibase**. For example,
if **ibase** is **16** and dc(1) is given the number string **FFeA**, the
resulting decimal number will be **2550000000000**, and if dc(1) is given the
number string **10e_4**, the resulting decimal number will be **0.0016**.
Accepting input as scientific notation is a **non-portable extension**.
# COMMANDS
The valid commands are listed below.
## Printing
These commands are used for printing.
Note that both scientific notation and engineering notation are available for
printing numbers. Scientific notation is activated by assigning **0** to
**obase** using **0o**, and engineering notation is activated by assigning **1**
to **obase** using **1o**. To deactivate them, just assign a different value to
**obase**.
Printing numbers in scientific notation and/or engineering notation is a
**non-portable extension**.
**p**
: Prints the value on top of the stack, whether number or string, and prints a
newline after.
This does not alter the stack.
**n**
: Prints the value on top of the stack, whether number or string, and pops it
off of the stack.
**P**
: Pops a value off the stack.
If the value is a number, it is truncated and the absolute value of the
result is printed as though **obase** is **UCHAR_MAX+1** and each digit is
interpreted as an ASCII character, making it a byte stream.
If the value is a string, it is printed without a trailing newline.
This is a **non-portable extension**.
**f**
: Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
Users should use this command when they get lost.
## Arithmetic
These are the commands used for arithmetic.
**+**
: The top two values are popped off the stack, added, and the result is pushed
onto the stack. The *scale* of the result is equal to the max *scale* of
both operands.
**-**
: The top two values are popped off the stack, subtracted, and the result is
pushed onto the stack. The *scale* of the result is equal to the max
*scale* of both operands.
**\***
: The top two values are popped off the stack, multiplied, and the result is
pushed onto the stack. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result
is equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The top two values are popped off the stack, divided, and the result is
pushed onto the stack. The *scale* of the result is equal to **scale**.
The first value popped off of the stack must be non-zero.
**%**
: The top two values are popped off the stack, remaindered, and the result is
pushed onto the stack.
Remaindering is equivalent to 1) Computing **a/b** to current **scale**, and
2) Using the result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The first value popped off of the stack must be non-zero.
**~**
: The top two values are popped off the stack, divided and remaindered, and
the results (divided first, remainder second) are pushed onto the stack.
This is equivalent to **x y / x y %** except that **x** and **y** are only
evaluated once.
The first value popped off of the stack must be non-zero.
This is a **non-portable extension**.
**\^**
: The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack. The *scale* of
the result is equal to **scale**.
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
**v**
: The top value is popped off the stack, its square root is computed, and the
result is pushed onto the stack. The *scale* of the result is equal to
**scale**.
The value popped off of the stack must be non-negative.
**\_**
: If this command *immediately* precedes a number (i.e., no spaces or other
commands), then that number is input as a negative number.
Otherwise, the top value on the stack is popped and copied, and the copy is
negated and pushed onto the stack. This behavior without a number is a
**non-portable extension**.
**b**
: The top value is popped off the stack, and if it is zero, it is pushed back
onto the stack. Otherwise, its absolute value is pushed onto the stack.
This is a **non-portable extension**.
**|**
: The top three values are popped off the stack, a modular exponentiation is
computed, and the result is pushed onto the stack.
The first value popped is used as the reduction modulus and must be an
integer and non-zero. The second value popped is used as the exponent and
must be an integer and non-negative. The third value popped is the base and
must be an integer.
This is a **non-portable extension**.
**\$**
: The top value is popped off the stack and copied, and the copy is truncated
and pushed onto the stack.
This is a **non-portable extension**.
**\@**
: The top two values are popped off the stack, and the precision of the second
is set to the value of the first, whether by truncation or extension.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**H**
: The top two values are popped off the stack, and the second is shifted left
(radix shifted right) to the value of the first.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**h**
: The top two values are popped off the stack, and the second is shifted right
(radix shifted left) to the value of the first.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**G**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if they are equal, or **0** otherwise.
This is a **non-portable extension**.
**N**
: The top value is popped off of the stack, and if it a **0**, a **1** is
pushed; otherwise, a **0** is pushed.
This is a **non-portable extension**.
**(**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than the second, or **0** otherwise.
This is a **non-portable extension**.
**{**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than or equal to the second, or **0**
otherwise.
This is a **non-portable extension**.
**)**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than the second, or **0** otherwise.
This is a **non-portable extension**.
**}**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than or equal to the second, or
**0** otherwise.
This is a **non-portable extension**.
**M**
: The top two values are popped off of the stack. If they are both non-zero, a
**1** is pushed onto the stack. If either of them is zero, or both of them
are, then a **0** is pushed onto the stack.
This is like the **&&** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
**m**
: The top two values are popped off of the stack. If at least one of them is
non-zero, a **1** is pushed onto the stack. If both of them are zero, then a
**0** is pushed onto the stack.
This is like the **||** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
## Pseudo-Random Number Generator
dc(1) has a built-in pseudo-random number generator. These commands query the
pseudo-random number generator. (See Parameters for more information about the
**seed** value that controls the pseudo-random number generator.)
The pseudo-random number generator is guaranteed to **NOT** be
cryptographically secure.
**'**
: Generates an integer between 0 and **DC_RAND_MAX**, inclusive (see the
**LIMITS** section).
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
This is a **non-portable extension**.
**"**
: Pops a value off of the stack, which is used as an **exclusive** upper bound
on the integer that will be generated. If the bound is negative or is a
non-integer, an error is raised, and dc(1) resets (see the **RESET**
section) while **seed** remains unchanged. If the bound is larger than
**DC_RAND_MAX**, the higher bound is honored by generating several
pseudo-random integers, multiplying them by appropriate powers of
**DC_RAND_MAX+1**, and adding them together. Thus, the size of integer that
can be generated with this command is unbounded. Using this command will
change the value of **seed**, unless the operand is **0** or **1**. In that
case, **0** is pushed onto the stack, and **seed** is *not* changed.
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
This is a **non-portable extension**.
## Stack Control
These commands control the stack.
**c**
: Removes all items from ("clears") the stack.
**d**
: Copies the item on top of the stack ("duplicates") and pushes the copy onto
the stack.
**r**
: Swaps ("reverses") the two top items on the stack.
**R**
: Pops ("removes") the top value from the stack.
## Register Control
These commands control registers (see the **REGISTERS** section).
**s***r*
: Pops the value off the top of the stack and stores it into register *r*.
**l***r*
: Copies the value in register *r* and pushes it onto the stack. This does not
alter the contents of *r*.
**S***r*
: Pops the value off the top of the (main) stack and pushes it onto the stack
of register *r*. The previous value of the register becomes inaccessible.
**L***r*
: Pops the value off the top of the stack for register *r* and push it onto
the main stack. The previous value in the stack for register *r*, if any, is
now accessible via the **l***r* command.
## Parameters
These commands control the values of **ibase**, **obase**, **scale**, and
**seed**. Also see the **SYNTAX** section.
**i**
: Pops the value off of the top of the stack and uses it to set **ibase**,
which must be between **2** and **16**, inclusive.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**o**
: Pops the value off of the top of the stack and uses it to set **obase**,
which must be between **0** and **DC_BASE_MAX**, inclusive (see the
**LIMITS** section and the **NUMBERS** section).
If the value on top of the stack has any *scale*, the *scale* is ignored.
**k**
: Pops the value off of the top of the stack and uses it to set **scale**,
which must be non-negative.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**j**
: Pops the value off of the top of the stack and uses it to set **seed**. The
meaning of **seed** is dependent on the current pseudo-random number
generator but is guaranteed to not change except for new major versions.
The *scale* and sign of the value may be significant.
If a previously used **seed** value is used again, the pseudo-random number
generator is guaranteed to produce the same sequence of pseudo-random
numbers as it did when the **seed** value was previously used.
The exact value assigned to **seed** is not guaranteed to be returned if the
**J** command is used. However, if **seed** *does* return a different value,
both values, when assigned to **seed**, are guaranteed to produce the same
sequence of pseudo-random numbers. This means that certain values assigned
to **seed** will not produce unique sequences of pseudo-random numbers.
There is no limit to the length (number of significant decimal digits) or
*scale* of the value that can be assigned to **seed**.
This is a **non-portable extension**.
**I**
: Pushes the current value of **ibase** onto the main stack.
**O**
: Pushes the current value of **obase** onto the main stack.
**K**
: Pushes the current value of **scale** onto the main stack.
**J**
: Pushes the current value of **seed** onto the main stack.
This is a **non-portable extension**.
**T**
: Pushes the maximum allowable value of **ibase** onto the main stack.
This is a **non-portable extension**.
**U**
: Pushes the maximum allowable value of **obase** onto the main stack.
This is a **non-portable extension**.
**V**
: Pushes the maximum allowable value of **scale** onto the main stack.
This is a **non-portable extension**.
**W**
: Pushes the maximum (inclusive) integer that can be generated with the **'**
pseudo-random number generator command.
This is a **non-portable extension**.
## Strings
The following commands control strings.
dc(1) can work with both numbers and strings, and registers (see the
**REGISTERS** section) can hold both strings and numbers. dc(1) always knows
whether the contents of a register are a string or a number.
While arithmetic operations have to have numbers, and will print an error if
given a string, other commands accept strings.
Strings can also be executed as macros. For example, if the string **[1pR]** is
executed as a macro, then the code **1pR** is executed, meaning that the **1**
will be printed with a newline after and then popped from the stack.
**\[**_characters_**\]**
: Makes a string containing *characters* and pushes it onto the stack.
If there are brackets (**\[** and **\]**) in the string, then they must be
balanced. Unbalanced brackets can be escaped using a backslash (**\\**)
character.
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the (first)
backslash is not.
**a**
: The value on top of the stack is popped.
If it is a number, it is truncated and its absolute value is taken. The
result mod **UCHAR_MAX+1** is calculated. If that result is **0**, push an
empty string; otherwise, push a one-character string where the character is
the result of the mod interpreted as an ASCII character.
If it is a string, then a new string is made. If the original string is
empty, the new string is empty. If it is not, then the first character of
the original string is used to create the new string as a one-character
string. The new string is then pushed onto the stack.
This is a **non-portable extension**.
**x**
: Pops a value off of the top of the stack.
If it is a number, it is pushed back onto the stack.
If it is a string, it is executed as a macro.
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
**\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is greater than the second, then the contents of register
*r* are executed.
For example, **0 1>a** will execute the contents of register **a**, and
**1 0>a** will not.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not greater than the second (less than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is less than the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not less than the second (greater than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is equal to the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not equal to the second, then the contents of register
*r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**?**
: Reads a line from the **stdin** and executes it. This is to allow macros to
request input from users.
**q**
: During execution of a macro, this exits the execution of that macro and the
execution of the macro that executed it. If there are no macros, or only one
macro executing, dc(1) exits.
**Q**
: Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack. If the number
of levels to pop is greater than the number of executing macros, dc(1)
exits.
## Status
These commands query status of the stack or its top value.
**Z**
: Pops a value off of the stack.
If it is a number, calculates the number of significant decimal digits it
has and pushes the result.
If it is a string, pushes the number of characters the string has.
**X**
: Pops a value off of the stack.
If it is a number, pushes the *scale* of the value onto the stack.
If it is a string, pushes **0**.
**z**
: Pushes the current stack depth (before execution of this command).
## Arrays
These commands manipulate arrays.
**:***r*
: Pops the top two values off of the stack. The second value will be stored in
the array *r* (see the **REGISTERS** section), indexed by the first value.
**;***r*
: Pops the value on top of the stack and uses it as an index into the array
*r*. The selected value is then pushed onto the stack.
# REGISTERS
Registers are names that can store strings, numbers, and arrays. (Number/string
registers do not interfere with array registers.)
Each register is also its own stack, so the current register value is the top of
the stack for the register. All registers, when first referenced, have one value
(**0**) in their stack.
In non-extended register mode, a register name is just the single character that
follows any command that needs a register name. The only exception is a newline
(**'\\n'**); it is a parse error for a newline to be used as a register name.
## Extended Register Mode
Unlike most other dc(1) implentations, this dc(1) provides nearly unlimited
amounts of registers, if extended register mode is enabled.
If extended register mode is enabled (**-x** or **--extended-register**
command-line arguments are given), then normal single character registers are
used *unless* the character immediately following a command that needs a
register name is a space (according to **isspace()**) and not a newline
(**'\\n'**).
In that case, the register name is found according to the regex
**\[a-z\]\[a-z0-9\_\]\*** (like bc(1) identifiers), and it is a parse error if
the next non-space characters do not match that regex.
# RESET
When dc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any macros that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
macros returned) is skipped.
Thus, when dc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
# PERFORMANCE
Most dc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This dc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **DC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **DC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**DC_BASE_DIGS**.
In addition, this dc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **DC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on dc(1):
**DC_LONG_BIT**
: The number of bits in the **long** type in the environment where dc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**DC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **DC_LONG_BIT**.
**DC_BASE_POW**
: The max decimal number that each large integer can store (see
**DC_BASE_DIGS**) plus **1**. Depends on **DC_BASE_DIGS**.
**DC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **DC_LONG_BIT**.
**DC_BASE_MAX**
: The maximum output base. Set at **DC_BASE_POW**.
**DC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**DC_SCALE_MAX**
: The maximum **scale**. Set at **DC_OVERFLOW_MAX-1**.
**DC_STRING_MAX**
: The maximum length of strings. Set at **DC_OVERFLOW_MAX-1**.
**DC_NAME_MAX**
: The maximum length of identifiers. Set at **DC_OVERFLOW_MAX-1**.
**DC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **DC_OVERFLOW_MAX-1**.
**DC_RAND_MAX**
: The maximum integer (inclusive) returned by the **'** command, if dc(1). Set
at **2\^DC_LONG_BIT-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**DC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
dc(1) recognizes the following environment variables:
**DC_ENV_ARGS**
: This is another way to give command-line arguments to dc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **DC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs. Another use would
be to use the **-e** option to set **scale** to a value other than **0**.
The code that parses **DC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some dc file.dc"** will be correctly parsed, but the string
**"/home/gavin/some \"dc\" file.dc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
- double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
+ double quotes as the outside quotes, as in **"some 'dc' file.dc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **DC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**DC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), dc(1) will output
lines to that length, including the backslash newline combo. The default
line length is **70**.
**DC_EXPR_EXIT**
: If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the **-e** and/or
**-f** command-line options (and any equivalents).
# EXIT STATUS
dc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, using a negative number as a bound for the pseudo-random number
generator, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**), places (**\@**), left shift (**H**), and right shift (**h**)
operators.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, and using a token where it is
invalid.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, and attempting an operation when
the stack has too few elements.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (dc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, dc(1) always exits
and returns **4**, no matter what mode dc(1) is in.
The other statuses will only be returned when dc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since dc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, dc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, dc(1) turns
on "TTY mode."
TTY mode is required for history to be enabled (see the **COMMAND LINE HISTORY**
section). It is also required to enable special handling for **SIGINT** signals.
The prompt is enabled in TTY mode.
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause dc(1) to stop execution of the current input. If
dc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If dc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If dc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to dc(1) as it is executing a file, it
can seem as though dc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause dc(1) to clean up and exit, and it uses the
default handler for all other signals. The one exception is **SIGHUP**; in that
case, when dc(1) is in TTY mode, a **SIGHUP** will cause dc(1) to clean up and
exit.
# COMMAND LINE HISTORY
dc(1) supports interactive command-line editing. If dc(1) is in TTY mode (see
the **TTY MODE** section), history is enabled. Previous lines can be recalled
and edited with the arrow keys.
**Note**: tabs are converted to 8 spaces.
# LOCALES
This dc(1) ships with support for adding error messages for different locales
and thus, supports **LC_MESSAGS**.
# SEE ALSO
bc(1)
# STANDARDS
The dc(1) utility operators are compliant with the operators in the bc(1)
[IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1] specification.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHOR
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
diff --git a/contrib/bc/manuals/dc/E.1 b/contrib/bc/manuals/dc/E.1
index 612187d62353..54b77232d76e 100644
--- a/contrib/bc/manuals/dc/E.1
+++ b/contrib/bc/manuals/dc/E.1
@@ -1,1130 +1,1143 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "DC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "DC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH Name
.PP
dc - arbitrary-precision decimal reverse-Polish notation calculator
.SH SYNOPSIS
.PP
\f[B]dc\f[R] [\f[B]-hiPvVx\f[R]] [\f[B]\[en]version\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]no-prompt\f[R]] [\f[B]\[en]extended-register\f[R]]
[\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
dc(1) is an arbitrary-precision calculator.
It uses a stack (reverse Polish notation) to store numbers and results
of computations.
Arithmetic operations pop arguments off of the stack and push the
results.
.PP
If no files are given on the command-line as extra arguments (i.e., not
as \f[B]-f\f[R] or \f[B]\[en]file\f[R] arguments), then dc(1) reads from
\f[B]stdin\f[R].
Otherwise, those files are processed, and dc(1) will then exit.
.PP
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where \f[B]-e\f[R] (\f[B]\[en]expression\f[R]) and
\f[B]-f\f[R] (\f[B]\[en]file\f[R]) arguments cause dc(1) to execute them
and exit.
The reason for this is that this dc(1) allows users to set arguments in
the environment variable \f[B]DC_ENV_ARGS\f[R] (see the \f[B]ENVIRONMENT
VARIABLES\f[R] section).
Any expressions given on the command-line should be used to set up a
standard environment.
For example, if a user wants the \f[B]scale\f[R] always set to
\f[B]10\f[R], they can set \f[B]DC_ENV_ARGS\f[R] to \f[B]-e 10k\f[R],
and this dc(1) will always start with a \f[B]scale\f[R] of \f[B]10\f[R].
.PP
If users want to have dc(1) exit after processing all input from
\f[B]-e\f[R] and \f[B]-f\f[R] arguments (and their equivalents), then
they can just simply add \f[B]-e q\f[R] as the last command-line
argument or define the environment variable \f[B]DC_EXPR_EXIT\f[R].
.SH OPTIONS
.PP
The following are the options that dc(1) accepts.
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
Disables the prompt in TTY mode.
(The prompt is only enabled in TTY mode.
See the \f[B]TTY MODE\f[R] section) This is mostly for those users that
do not want a prompt or are not used to having them in dc(1).
Most of those users would want to put this option in
\f[B]DC_ENV_ARGS\f[R].
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-x\f[R] \f[B]\[en]extended-register\f[R]
Enables extended register mode.
See the \f[I]Extended Register Mode\f[R] subsection of the
\f[B]REGISTERS\f[R] section for more information.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]DC_ENV_ARGS\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]dc >&-\f[R], it will quit with an error.
This is done so that dc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]dc 2>&-\f[R], it will quit with an error.
This is done so that dc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
Each item in the input source code, either a number (see the
\f[B]NUMBERS\f[R] section) or a command (see the \f[B]COMMANDS\f[R]
section), is processed and executed, in order.
Input is processed immediately when entered.
.PP
\f[B]ibase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to interpret constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]ibase\f[R] is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in dc(1)
programs with the \f[B]T\f[R] command.
.PP
\f[B]obase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]DC_BASE_MAX\f[R] and
can be queried with the \f[B]U\f[R] command.
The min allowable value for \f[B]obase\f[R] is \f[B]2\f[R].
Values are output in the specified base.
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a register (see the \f[B]REGISTERS\f[R] section) that sets the
precision of any operations (with exceptions).
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] can be queried in dc(1)
programs with the \f[B]V\f[R] command.
.SS Comments
.PP
Comments go from \f[B]#\f[R] until, and not including, the next newline.
This is a \f[B]non-portable extension\f[R].
.SH NUMBERS
.PP
Numbers are strings made up of digits, uppercase letters up to
\f[B]F\f[R], and at most \f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]DC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]F\f[R] alone always equals decimal \f[B]15\f[R].
.SH COMMANDS
.PP
The valid commands are listed below.
.SS Printing
.PP
These commands are used for printing.
.TP
\f[B]p\f[R]
Prints the value on top of the stack, whether number or string, and
prints a newline after.
.RS
.PP
This does not alter the stack.
.RE
.TP
\f[B]n\f[R]
Prints the value on top of the stack, whether number or string, and pops
it off of the stack.
.TP
\f[B]P\f[R]
Pops a value off the stack.
.RS
.PP
If the value is a number, it is truncated and the absolute value of the
result is printed as though \f[B]obase\f[R] is \f[B]UCHAR_MAX+1\f[R] and
each digit is interpreted as an ASCII character, making it a byte
stream.
.PP
If the value is a string, it is printed without a trailing newline.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]f\f[R]
Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
.RS
.PP
Users should use this command when they get lost.
.RE
.SS Arithmetic
.PP
These are the commands used for arithmetic.
.TP
\f[B]+\f[R]
The top two values are popped off the stack, added, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]-\f[R]
The top two values are popped off the stack, subtracted, and the result
is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]*\f[R]
The top two values are popped off the stack, multiplied, and the result
is pushed onto the stack.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The top two values are popped off the stack, divided, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]%\f[R]
The top two values are popped off the stack, remaindered, and the result
is pushed onto the stack.
.RS
.PP
Remaindering is equivalent to 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R], and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]\[ti]\f[R]
The top two values are popped off the stack, divided and remaindered,
and the results (divided first, remainder second) are pushed onto the
stack.
This is equivalent to \f[B]x y / x y %\f[R] except that \f[B]x\f[R] and
\f[B]y\f[R] are only evaluated once.
.RS
.PP
The first value popped off of the stack must be non-zero.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
.RE
.TP
\f[B]v\f[R]
The top value is popped off the stack, its square root is computed, and
the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The value popped off of the stack must be non-negative.
.RE
.TP
\f[B]_\f[R]
If this command \f[I]immediately\f[R] precedes a number (i.e., no spaces
or other commands), then that number is input as a negative number.
.RS
.PP
Otherwise, the top value on the stack is popped and copied, and the copy
is negated and pushed onto the stack.
This behavior without a number is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]b\f[R]
The top value is popped off the stack, and if it is zero, it is pushed
back onto the stack.
Otherwise, its absolute value is pushed onto the stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]|\f[R]
The top three values are popped off the stack, a modular exponentiation
is computed, and the result is pushed onto the stack.
.RS
.PP
The first value popped is used as the reduction modulus and must be an
integer and non-zero.
The second value popped is used as the exponent and must be an integer
and non-negative.
The third value popped is the base and must be an integer.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]G\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if they are equal, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]N\f[R]
The top value is popped off of the stack, and if it a \f[B]0\f[R], a
\f[B]1\f[R] is pushed; otherwise, a \f[B]0\f[R] is pushed.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B](\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]{\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than or equal to the second,
or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B])\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]}\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than or equal to the
second, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]M\f[R]
The top two values are popped off of the stack.
If they are both non-zero, a \f[B]1\f[R] is pushed onto the stack.
If either of them is zero, or both of them are, then a \f[B]0\f[R] is
pushed onto the stack.
.RS
.PP
This is like the \f[B]&&\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]m\f[R]
The top two values are popped off of the stack.
If at least one of them is non-zero, a \f[B]1\f[R] is pushed onto the
stack.
If both of them are zero, then a \f[B]0\f[R] is pushed onto the stack.
.RS
.PP
This is like the \f[B]||\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Stack Control
.PP
These commands control the stack.
.TP
\f[B]c\f[R]
Removes all items from (\[lq]clears\[rq]) the stack.
.TP
\f[B]d\f[R]
Copies the item on top of the stack (\[lq]duplicates\[rq]) and pushes
the copy onto the stack.
.TP
\f[B]r\f[R]
Swaps (\[lq]reverses\[rq]) the two top items on the stack.
.TP
\f[B]R\f[R]
Pops (\[lq]removes\[rq]) the top value from the stack.
.SS Register Control
.PP
These commands control registers (see the \f[B]REGISTERS\f[R] section).
.TP
\f[B]s\f[R]\f[I]r\f[R]
Pops the value off the top of the stack and stores it into register
\f[I]r\f[R].
.TP
\f[B]l\f[R]\f[I]r\f[R]
Copies the value in register \f[I]r\f[R] and pushes it onto the stack.
This does not alter the contents of \f[I]r\f[R].
.TP
\f[B]S\f[R]\f[I]r\f[R]
Pops the value off the top of the (main) stack and pushes it onto the
stack of register \f[I]r\f[R].
The previous value of the register becomes inaccessible.
.TP
\f[B]L\f[R]\f[I]r\f[R]
Pops the value off the top of the stack for register \f[I]r\f[R] and
push it onto the main stack.
The previous value in the stack for register \f[I]r\f[R], if any, is now
accessible via the \f[B]l\f[R]\f[I]r\f[R] command.
.SS Parameters
.PP
These commands control the values of \f[B]ibase\f[R], \f[B]obase\f[R],
and \f[B]scale\f[R].
Also see the \f[B]SYNTAX\f[R] section.
.TP
\f[B]i\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]ibase\f[R], which must be between \f[B]2\f[R] and \f[B]16\f[R],
inclusive.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]o\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]obase\f[R], which must be between \f[B]2\f[R] and
\f[B]DC_BASE_MAX\f[R], inclusive (see the \f[B]LIMITS\f[R] section).
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]k\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]scale\f[R], which must be non-negative.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]I\f[R]
Pushes the current value of \f[B]ibase\f[R] onto the main stack.
.TP
\f[B]O\f[R]
Pushes the current value of \f[B]obase\f[R] onto the main stack.
.TP
\f[B]K\f[R]
Pushes the current value of \f[B]scale\f[R] onto the main stack.
.TP
\f[B]T\f[R]
Pushes the maximum allowable value of \f[B]ibase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]U\f[R]
Pushes the maximum allowable value of \f[B]obase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]V\f[R]
Pushes the maximum allowable value of \f[B]scale\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Strings
.PP
The following commands control strings.
.PP
dc(1) can work with both numbers and strings, and registers (see the
\f[B]REGISTERS\f[R] section) can hold both strings and numbers.
dc(1) always knows whether the contents of a register are a string or a
number.
.PP
While arithmetic operations have to have numbers, and will print an
error if given a string, other commands accept strings.
.PP
Strings can also be executed as macros.
For example, if the string \f[B][1pR]\f[R] is executed as a macro, then
the code \f[B]1pR\f[R] is executed, meaning that the \f[B]1\f[R] will be
printed with a newline after and then popped from the stack.
.TP
\f[B][\f[R]_characters_\f[B]]\f[R]
Makes a string containing \f[I]characters\f[R] and pushes it onto the
stack.
.RS
.PP
If there are brackets (\f[B][\f[R] and \f[B]]\f[R]) in the string, then
they must be balanced.
Unbalanced brackets can be escaped using a backslash (\f[B]\[rs]\f[R])
character.
.PP
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the
(first) backslash is not.
.RE
.TP
\f[B]a\f[R]
The value on top of the stack is popped.
.RS
.PP
If it is a number, it is truncated and its absolute value is taken.
The result mod \f[B]UCHAR_MAX+1\f[R] is calculated.
If that result is \f[B]0\f[R], push an empty string; otherwise, push a
one-character string where the character is the result of the mod
interpreted as an ASCII character.
.PP
If it is a string, then a new string is made.
If the original string is empty, the new string is empty.
If it is not, then the first character of the original string is used to
create the new string as a one-character string.
The new string is then pushed onto the stack.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]x\f[R]
Pops a value off of the top of the stack.
.RS
.PP
If it is a number, it is pushed back onto the stack.
.PP
If it is a string, it is executed as a macro.
.PP
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is greater than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
For example, \f[B]0 1>a\f[R] will execute the contents of register
\f[B]a\f[R], and \f[B]1 0>a\f[R] will not.
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not greater than the second (less than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is less than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not less than the second (greater than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is equal to the second, then the contents of register
\f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not equal to the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]?\f[R]
Reads a line from the \f[B]stdin\f[R] and executes it.
This is to allow macros to request input from users.
.TP
\f[B]q\f[R]
During execution of a macro, this exits the execution of that macro and
the execution of the macro that executed it.
If there are no macros, or only one macro executing, dc(1) exits.
.TP
\f[B]Q\f[R]
Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack.
If the number of levels to pop is greater than the number of executing
macros, dc(1) exits.
.SS Status
.PP
These commands query status of the stack or its top value.
.TP
\f[B]Z\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, calculates the number of significant decimal digits
it has and pushes the result.
.PP
If it is a string, pushes the number of characters the string has.
.RE
.TP
\f[B]X\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, pushes the \f[I]scale\f[R] of the value onto the
stack.
.PP
If it is a string, pushes \f[B]0\f[R].
.RE
.TP
\f[B]z\f[R]
Pushes the current stack depth (before execution of this command).
.SS Arrays
.PP
These commands manipulate arrays.
.TP
\f[B]:\f[R]\f[I]r\f[R]
Pops the top two values off of the stack.
The second value will be stored in the array \f[I]r\f[R] (see the
\f[B]REGISTERS\f[R] section), indexed by the first value.
.TP
\f[B];\f[R]\f[I]r\f[R]
Pops the value on top of the stack and uses it as an index into the
array \f[I]r\f[R].
The selected value is then pushed onto the stack.
.SH REGISTERS
.PP
Registers are names that can store strings, numbers, and arrays.
(Number/string registers do not interfere with array registers.)
.PP
Each register is also its own stack, so the current register value is
the top of the stack for the register.
All registers, when first referenced, have one value (\f[B]0\f[R]) in
their stack.
.PP
In non-extended register mode, a register name is just the single
character that follows any command that needs a register name.
The only exception is a newline (\f[B]`\[rs]n'\f[R]); it is a parse
error for a newline to be used as a register name.
.SS Extended Register Mode
.PP
Unlike most other dc(1) implentations, this dc(1) provides nearly
unlimited amounts of registers, if extended register mode is enabled.
.PP
If extended register mode is enabled (\f[B]-x\f[R] or
\f[B]\[en]extended-register\f[R] command-line arguments are given), then
normal single character registers are used \f[I]unless\f[R] the
character immediately following a command that needs a register name is
a space (according to \f[B]isspace()\f[R]) and not a newline
(\f[B]`\[rs]n'\f[R]).
.PP
In that case, the register name is found according to the regex
\f[B][a-z][a-z0-9_]*\f[R] (like bc(1) identifiers), and it is a parse
error if the next non-space characters do not match that regex.
.SH RESET
.PP
When dc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any macros that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all macros returned) is skipped.
.PP
Thus, when dc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.SH PERFORMANCE
.PP
Most dc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This dc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]DC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]DC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]DC_BASE_DIGS\f[R].
.PP
In addition, this dc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]DC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on dc(1):
.TP
\f[B]DC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
dc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]DC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]DC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]DC_BASE_DIGS\f[R].
.TP
\f[B]DC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]DC_BASE_POW\f[R].
.TP
\f[B]DC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]DC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]DC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
dc(1) recognizes the following environment variables:
.TP
\f[B]DC_ENV_ARGS\f[R]
This is another way to give command-line arguments to dc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]DC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs.
Another use would be to use the \f[B]-e\f[R] option to set
\f[B]scale\f[R] to a value other than \f[B]0\f[R].
.RS
.PP
The code that parses \f[B]DC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some dc file.dc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]dc\[dq] file.dc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
-in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
+in \f[B]\[rq]some `dc' file.dc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]DC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]DC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), dc(1) will output lines to that length,
including the backslash newline combo.
The default line length is \f[B]70\f[R].
.TP
\f[B]DC_EXPR_EXIT\f[R]
If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the
\f[B]-e\f[R] and/or \f[B]-f\f[R] command-line options (and any
equivalents).
.SH EXIT STATUS
.PP
dc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, attempting to convert a negative number to a hardware
integer, overflow when converting a number to a hardware integer, and
attempting to use a non-integer where an integer is required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]) operator.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, and using a
token where it is invalid.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, and attempting an operation when the
stack has too few elements.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (dc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, dc(1)
always exits and returns \f[B]4\f[R], no matter what mode dc(1) is in.
.PP
The other statuses will only be returned when dc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
dc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, dc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, dc(1) turns on \[lq]TTY mode.\[rq]
.PP
TTY mode is required for history to be enabled (see the \f[B]COMMAND
LINE HISTORY\f[R] section).
It is also required to enable special handling for \f[B]SIGINT\f[R]
signals.
.PP
The prompt is enabled in TTY mode.
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause dc(1) to stop execution of the
current input.
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If dc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If dc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to dc(1) as it is
executing a file, it can seem as though dc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause dc(1) to clean up and
exit, and it uses the default handler for all other signals.
The one exception is \f[B]SIGHUP\f[R]; in that case, when dc(1) is in
TTY mode, a \f[B]SIGHUP\f[R] will cause dc(1) to clean up and exit.
.SH COMMAND LINE HISTORY
.PP
dc(1) supports interactive command-line editing.
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), history is
enabled.
Previous lines can be recalled and edited with the arrow keys.
.PP
\f[B]Note\f[R]: tabs are converted to 8 spaces.
.SH LOCALES
.PP
This dc(1) ships with support for adding error messages for different
locales and thus, supports \f[B]LC_MESSAGS\f[R].
.SH SEE ALSO
.PP
bc(1)
.SH STANDARDS
.PP
The dc(1) utility operators are compliant with the operators in the
bc(1) IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHOR
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/dc/E.1.md b/contrib/bc/manuals/dc/E.1.md
index 74011dfd332f..b7cc625df362 100644
--- a/contrib/bc/manuals/dc/E.1.md
+++ b/contrib/bc/manuals/dc/E.1.md
@@ -1,1031 +1,1040 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# Name
dc - arbitrary-precision decimal reverse-Polish notation calculator
# SYNOPSIS
**dc** [**-hiPvVx**] [**--version**] [**--help**] [**--interactive**] [**--no-prompt**] [**--extended-register**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...] [*file*...]
# DESCRIPTION
dc(1) is an arbitrary-precision calculator. It uses a stack (reverse Polish
notation) to store numbers and results of computations. Arithmetic operations
pop arguments off of the stack and push the results.
If no files are given on the command-line as extra arguments (i.e., not as
**-f** or **--file** arguments), then dc(1) reads from **stdin**. Otherwise,
those files are processed, and dc(1) will then exit.
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where **-e** (**--expression**) and **-f** (**--file**)
arguments cause dc(1) to execute them and exit. The reason for this is that this
dc(1) allows users to set arguments in the environment variable **DC_ENV_ARGS**
(see the **ENVIRONMENT VARIABLES** section). Any expressions given on the
command-line should be used to set up a standard environment. For example, if a
user wants the **scale** always set to **10**, they can set **DC_ENV_ARGS** to
**-e 10k**, and this dc(1) will always start with a **scale** of **10**.
If users want to have dc(1) exit after processing all input from **-e** and
**-f** arguments (and their equivalents), then they can just simply add **-e q**
as the last command-line argument or define the environment variable
**DC_EXPR_EXIT**.
# OPTIONS
The following are the options that dc(1) accepts.
**-h**, **--help**
: Prints a usage message and quits.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-P**, **--no-prompt**
: Disables the prompt in TTY mode. (The prompt is only enabled in TTY mode.
See the **TTY MODE** section) This is mostly for those users that do not
want a prompt or are not used to having them in dc(1). Most of those users
would want to put this option in **DC_ENV_ARGS**.
This is a **non-portable extension**.
**-x** **--extended-register**
: Enables extended register mode. See the *Extended Register Mode* subsection
of the **REGISTERS** section for more information.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **DC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **dc <file> >&-**, it will quit with an error. This
is done so that dc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **dc <file> 2>&-**, it will quit with an error. This
is done so that dc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
Each item in the input source code, either a number (see the **NUMBERS**
section) or a command (see the **COMMANDS** section), is processed and executed,
in order. Input is processed immediately when entered.
**ibase** is a register (see the **REGISTERS** section) that determines how to
interpret constant numbers. It is the "input" base, or the number base used for
interpreting input numbers. **ibase** is initially **10**. The max allowable
value for **ibase** is **16**. The min allowable value for **ibase** is **2**.
The max allowable value for **ibase** can be queried in dc(1) programs with the
**T** command.
**obase** is a register (see the **REGISTERS** section) that determines how to
output results. It is the "output" base, or the number base used for outputting
numbers. **obase** is initially **10**. The max allowable value for **obase** is
**DC_BASE_MAX** and can be queried with the **U** command. The min allowable
value for **obase** is **2**. Values are output in the specified base.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a register (see the
**REGISTERS** section) that sets the precision of any operations (with
exceptions). **scale** is initially **0**. **scale** cannot be negative. The max
allowable value for **scale** can be queried in dc(1) programs with the **V**
command.
## Comments
Comments go from **#** until, and not including, the next newline. This is a
**non-portable extension**.
# NUMBERS
Numbers are strings made up of digits, uppercase letters up to **F**, and at
most **1** period for a radix. Numbers can have up to **DC_NUM_MAX** digits.
Uppercase letters are equal to **9** + their position in the alphabet (i.e.,
**A** equals **10**, or **9+1**). If a digit or letter makes no sense with the
current value of **ibase**, they are set to the value of the highest valid digit
in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **F** alone always equals decimal
**15**.
# COMMANDS
The valid commands are listed below.
## Printing
These commands are used for printing.
**p**
: Prints the value on top of the stack, whether number or string, and prints a
newline after.
This does not alter the stack.
**n**
: Prints the value on top of the stack, whether number or string, and pops it
off of the stack.
**P**
: Pops a value off the stack.
If the value is a number, it is truncated and the absolute value of the
result is printed as though **obase** is **UCHAR_MAX+1** and each digit is
interpreted as an ASCII character, making it a byte stream.
If the value is a string, it is printed without a trailing newline.
This is a **non-portable extension**.
**f**
: Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
Users should use this command when they get lost.
## Arithmetic
These are the commands used for arithmetic.
**+**
: The top two values are popped off the stack, added, and the result is pushed
onto the stack. The *scale* of the result is equal to the max *scale* of
both operands.
**-**
: The top two values are popped off the stack, subtracted, and the result is
pushed onto the stack. The *scale* of the result is equal to the max
*scale* of both operands.
**\***
: The top two values are popped off the stack, multiplied, and the result is
pushed onto the stack. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result
is equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The top two values are popped off the stack, divided, and the result is
pushed onto the stack. The *scale* of the result is equal to **scale**.
The first value popped off of the stack must be non-zero.
**%**
: The top two values are popped off the stack, remaindered, and the result is
pushed onto the stack.
Remaindering is equivalent to 1) Computing **a/b** to current **scale**, and
2) Using the result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The first value popped off of the stack must be non-zero.
**~**
: The top two values are popped off the stack, divided and remaindered, and
the results (divided first, remainder second) are pushed onto the stack.
This is equivalent to **x y / x y %** except that **x** and **y** are only
evaluated once.
The first value popped off of the stack must be non-zero.
This is a **non-portable extension**.
**\^**
: The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack. The *scale* of
the result is equal to **scale**.
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
**v**
: The top value is popped off the stack, its square root is computed, and the
result is pushed onto the stack. The *scale* of the result is equal to
**scale**.
The value popped off of the stack must be non-negative.
**\_**
: If this command *immediately* precedes a number (i.e., no spaces or other
commands), then that number is input as a negative number.
Otherwise, the top value on the stack is popped and copied, and the copy is
negated and pushed onto the stack. This behavior without a number is a
**non-portable extension**.
**b**
: The top value is popped off the stack, and if it is zero, it is pushed back
onto the stack. Otherwise, its absolute value is pushed onto the stack.
This is a **non-portable extension**.
**|**
: The top three values are popped off the stack, a modular exponentiation is
computed, and the result is pushed onto the stack.
The first value popped is used as the reduction modulus and must be an
integer and non-zero. The second value popped is used as the exponent and
must be an integer and non-negative. The third value popped is the base and
must be an integer.
This is a **non-portable extension**.
**G**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if they are equal, or **0** otherwise.
This is a **non-portable extension**.
**N**
: The top value is popped off of the stack, and if it a **0**, a **1** is
pushed; otherwise, a **0** is pushed.
This is a **non-portable extension**.
**(**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than the second, or **0** otherwise.
This is a **non-portable extension**.
**{**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than or equal to the second, or **0**
otherwise.
This is a **non-portable extension**.
**)**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than the second, or **0** otherwise.
This is a **non-portable extension**.
**}**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than or equal to the second, or
**0** otherwise.
This is a **non-portable extension**.
**M**
: The top two values are popped off of the stack. If they are both non-zero, a
**1** is pushed onto the stack. If either of them is zero, or both of them
are, then a **0** is pushed onto the stack.
This is like the **&&** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
**m**
: The top two values are popped off of the stack. If at least one of them is
non-zero, a **1** is pushed onto the stack. If both of them are zero, then a
**0** is pushed onto the stack.
This is like the **||** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
## Stack Control
These commands control the stack.
**c**
: Removes all items from ("clears") the stack.
**d**
: Copies the item on top of the stack ("duplicates") and pushes the copy onto
the stack.
**r**
: Swaps ("reverses") the two top items on the stack.
**R**
: Pops ("removes") the top value from the stack.
## Register Control
These commands control registers (see the **REGISTERS** section).
**s***r*
: Pops the value off the top of the stack and stores it into register *r*.
**l***r*
: Copies the value in register *r* and pushes it onto the stack. This does not
alter the contents of *r*.
**S***r*
: Pops the value off the top of the (main) stack and pushes it onto the stack
of register *r*. The previous value of the register becomes inaccessible.
**L***r*
: Pops the value off the top of the stack for register *r* and push it onto
the main stack. The previous value in the stack for register *r*, if any, is
now accessible via the **l***r* command.
## Parameters
These commands control the values of **ibase**, **obase**, and **scale**. Also
see the **SYNTAX** section.
**i**
: Pops the value off of the top of the stack and uses it to set **ibase**,
which must be between **2** and **16**, inclusive.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**o**
: Pops the value off of the top of the stack and uses it to set **obase**,
which must be between **2** and **DC_BASE_MAX**, inclusive (see the
**LIMITS** section).
If the value on top of the stack has any *scale*, the *scale* is ignored.
**k**
: Pops the value off of the top of the stack and uses it to set **scale**,
which must be non-negative.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**I**
: Pushes the current value of **ibase** onto the main stack.
**O**
: Pushes the current value of **obase** onto the main stack.
**K**
: Pushes the current value of **scale** onto the main stack.
**T**
: Pushes the maximum allowable value of **ibase** onto the main stack.
This is a **non-portable extension**.
**U**
: Pushes the maximum allowable value of **obase** onto the main stack.
This is a **non-portable extension**.
**V**
: Pushes the maximum allowable value of **scale** onto the main stack.
This is a **non-portable extension**.
## Strings
The following commands control strings.
dc(1) can work with both numbers and strings, and registers (see the
**REGISTERS** section) can hold both strings and numbers. dc(1) always knows
whether the contents of a register are a string or a number.
While arithmetic operations have to have numbers, and will print an error if
given a string, other commands accept strings.
Strings can also be executed as macros. For example, if the string **[1pR]** is
executed as a macro, then the code **1pR** is executed, meaning that the **1**
will be printed with a newline after and then popped from the stack.
**\[**_characters_**\]**
: Makes a string containing *characters* and pushes it onto the stack.
If there are brackets (**\[** and **\]**) in the string, then they must be
balanced. Unbalanced brackets can be escaped using a backslash (**\\**)
character.
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the (first)
backslash is not.
**a**
: The value on top of the stack is popped.
If it is a number, it is truncated and its absolute value is taken. The
result mod **UCHAR_MAX+1** is calculated. If that result is **0**, push an
empty string; otherwise, push a one-character string where the character is
the result of the mod interpreted as an ASCII character.
If it is a string, then a new string is made. If the original string is
empty, the new string is empty. If it is not, then the first character of
the original string is used to create the new string as a one-character
string. The new string is then pushed onto the stack.
This is a **non-portable extension**.
**x**
: Pops a value off of the top of the stack.
If it is a number, it is pushed back onto the stack.
If it is a string, it is executed as a macro.
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
**\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is greater than the second, then the contents of register
*r* are executed.
For example, **0 1>a** will execute the contents of register **a**, and
**1 0>a** will not.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not greater than the second (less than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is less than the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not less than the second (greater than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is equal to the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not equal to the second, then the contents of register
*r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**?**
: Reads a line from the **stdin** and executes it. This is to allow macros to
request input from users.
**q**
: During execution of a macro, this exits the execution of that macro and the
execution of the macro that executed it. If there are no macros, or only one
macro executing, dc(1) exits.
**Q**
: Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack. If the number
of levels to pop is greater than the number of executing macros, dc(1)
exits.
## Status
These commands query status of the stack or its top value.
**Z**
: Pops a value off of the stack.
If it is a number, calculates the number of significant decimal digits it
has and pushes the result.
If it is a string, pushes the number of characters the string has.
**X**
: Pops a value off of the stack.
If it is a number, pushes the *scale* of the value onto the stack.
If it is a string, pushes **0**.
**z**
: Pushes the current stack depth (before execution of this command).
## Arrays
These commands manipulate arrays.
**:***r*
: Pops the top two values off of the stack. The second value will be stored in
the array *r* (see the **REGISTERS** section), indexed by the first value.
**;***r*
: Pops the value on top of the stack and uses it as an index into the array
*r*. The selected value is then pushed onto the stack.
# REGISTERS
Registers are names that can store strings, numbers, and arrays. (Number/string
registers do not interfere with array registers.)
Each register is also its own stack, so the current register value is the top of
the stack for the register. All registers, when first referenced, have one value
(**0**) in their stack.
In non-extended register mode, a register name is just the single character that
follows any command that needs a register name. The only exception is a newline
(**'\\n'**); it is a parse error for a newline to be used as a register name.
## Extended Register Mode
Unlike most other dc(1) implentations, this dc(1) provides nearly unlimited
amounts of registers, if extended register mode is enabled.
If extended register mode is enabled (**-x** or **--extended-register**
command-line arguments are given), then normal single character registers are
used *unless* the character immediately following a command that needs a
register name is a space (according to **isspace()**) and not a newline
(**'\\n'**).
In that case, the register name is found according to the regex
**\[a-z\]\[a-z0-9\_\]\*** (like bc(1) identifiers), and it is a parse error if
the next non-space characters do not match that regex.
# RESET
When dc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any macros that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
macros returned) is skipped.
Thus, when dc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
# PERFORMANCE
Most dc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This dc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **DC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **DC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**DC_BASE_DIGS**.
In addition, this dc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **DC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on dc(1):
**DC_LONG_BIT**
: The number of bits in the **long** type in the environment where dc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**DC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **DC_LONG_BIT**.
**DC_BASE_POW**
: The max decimal number that each large integer can store (see
**DC_BASE_DIGS**) plus **1**. Depends on **DC_BASE_DIGS**.
**DC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **DC_LONG_BIT**.
**DC_BASE_MAX**
: The maximum output base. Set at **DC_BASE_POW**.
**DC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**DC_SCALE_MAX**
: The maximum **scale**. Set at **DC_OVERFLOW_MAX-1**.
**DC_STRING_MAX**
: The maximum length of strings. Set at **DC_OVERFLOW_MAX-1**.
**DC_NAME_MAX**
: The maximum length of identifiers. Set at **DC_OVERFLOW_MAX-1**.
**DC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **DC_OVERFLOW_MAX-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**DC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
dc(1) recognizes the following environment variables:
**DC_ENV_ARGS**
: This is another way to give command-line arguments to dc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **DC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs. Another use would
be to use the **-e** option to set **scale** to a value other than **0**.
The code that parses **DC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some dc file.dc"** will be correctly parsed, but the string
**"/home/gavin/some \"dc\" file.dc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
- double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
+ double quotes as the outside quotes, as in **"some 'dc' file.dc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **DC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**DC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), dc(1) will output
lines to that length, including the backslash newline combo. The default
line length is **70**.
**DC_EXPR_EXIT**
: If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the **-e** and/or
**-f** command-line options (and any equivalents).
# EXIT STATUS
dc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**) operator.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, and using a token where it is
invalid.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, and attempting an operation when
the stack has too few elements.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (dc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, dc(1) always exits
and returns **4**, no matter what mode dc(1) is in.
The other statuses will only be returned when dc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since dc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, dc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, dc(1) turns
on "TTY mode."
TTY mode is required for history to be enabled (see the **COMMAND LINE HISTORY**
section). It is also required to enable special handling for **SIGINT** signals.
The prompt is enabled in TTY mode.
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause dc(1) to stop execution of the current input. If
dc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If dc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If dc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to dc(1) as it is executing a file, it
can seem as though dc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause dc(1) to clean up and exit, and it uses the
default handler for all other signals. The one exception is **SIGHUP**; in that
case, when dc(1) is in TTY mode, a **SIGHUP** will cause dc(1) to clean up and
exit.
# COMMAND LINE HISTORY
dc(1) supports interactive command-line editing. If dc(1) is in TTY mode (see
the **TTY MODE** section), history is enabled. Previous lines can be recalled
and edited with the arrow keys.
**Note**: tabs are converted to 8 spaces.
# LOCALES
This dc(1) ships with support for adding error messages for different locales
and thus, supports **LC_MESSAGS**.
# SEE ALSO
bc(1)
# STANDARDS
The dc(1) utility operators are compliant with the operators in the bc(1)
[IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1] specification.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHOR
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
diff --git a/contrib/bc/manuals/dc/EH.1 b/contrib/bc/manuals/dc/EH.1
index 04006d873958..986e686239e4 100644
--- a/contrib/bc/manuals/dc/EH.1
+++ b/contrib/bc/manuals/dc/EH.1
@@ -1,1115 +1,1128 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "DC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "DC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH Name
.PP
dc - arbitrary-precision decimal reverse-Polish notation calculator
.SH SYNOPSIS
.PP
\f[B]dc\f[R] [\f[B]-hiPvVx\f[R]] [\f[B]\[en]version\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]no-prompt\f[R]] [\f[B]\[en]extended-register\f[R]]
[\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
dc(1) is an arbitrary-precision calculator.
It uses a stack (reverse Polish notation) to store numbers and results
of computations.
Arithmetic operations pop arguments off of the stack and push the
results.
.PP
If no files are given on the command-line as extra arguments (i.e., not
as \f[B]-f\f[R] or \f[B]\[en]file\f[R] arguments), then dc(1) reads from
\f[B]stdin\f[R].
Otherwise, those files are processed, and dc(1) will then exit.
.PP
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where \f[B]-e\f[R] (\f[B]\[en]expression\f[R]) and
\f[B]-f\f[R] (\f[B]\[en]file\f[R]) arguments cause dc(1) to execute them
and exit.
The reason for this is that this dc(1) allows users to set arguments in
the environment variable \f[B]DC_ENV_ARGS\f[R] (see the \f[B]ENVIRONMENT
VARIABLES\f[R] section).
Any expressions given on the command-line should be used to set up a
standard environment.
For example, if a user wants the \f[B]scale\f[R] always set to
\f[B]10\f[R], they can set \f[B]DC_ENV_ARGS\f[R] to \f[B]-e 10k\f[R],
and this dc(1) will always start with a \f[B]scale\f[R] of \f[B]10\f[R].
.PP
If users want to have dc(1) exit after processing all input from
\f[B]-e\f[R] and \f[B]-f\f[R] arguments (and their equivalents), then
they can just simply add \f[B]-e q\f[R] as the last command-line
argument or define the environment variable \f[B]DC_EXPR_EXIT\f[R].
.SH OPTIONS
.PP
The following are the options that dc(1) accepts.
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
Disables the prompt in TTY mode.
(The prompt is only enabled in TTY mode.
See the \f[B]TTY MODE\f[R] section) This is mostly for those users that
do not want a prompt or are not used to having them in dc(1).
Most of those users would want to put this option in
\f[B]DC_ENV_ARGS\f[R].
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-x\f[R] \f[B]\[en]extended-register\f[R]
Enables extended register mode.
See the \f[I]Extended Register Mode\f[R] subsection of the
\f[B]REGISTERS\f[R] section for more information.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]DC_ENV_ARGS\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]dc >&-\f[R], it will quit with an error.
This is done so that dc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]dc 2>&-\f[R], it will quit with an error.
This is done so that dc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
Each item in the input source code, either a number (see the
\f[B]NUMBERS\f[R] section) or a command (see the \f[B]COMMANDS\f[R]
section), is processed and executed, in order.
Input is processed immediately when entered.
.PP
\f[B]ibase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to interpret constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]ibase\f[R] is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in dc(1)
programs with the \f[B]T\f[R] command.
.PP
\f[B]obase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]DC_BASE_MAX\f[R] and
can be queried with the \f[B]U\f[R] command.
The min allowable value for \f[B]obase\f[R] is \f[B]2\f[R].
Values are output in the specified base.
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a register (see the \f[B]REGISTERS\f[R] section) that sets the
precision of any operations (with exceptions).
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] can be queried in dc(1)
programs with the \f[B]V\f[R] command.
.SS Comments
.PP
Comments go from \f[B]#\f[R] until, and not including, the next newline.
This is a \f[B]non-portable extension\f[R].
.SH NUMBERS
.PP
Numbers are strings made up of digits, uppercase letters up to
\f[B]F\f[R], and at most \f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]DC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]F\f[R] alone always equals decimal \f[B]15\f[R].
.SH COMMANDS
.PP
The valid commands are listed below.
.SS Printing
.PP
These commands are used for printing.
.TP
\f[B]p\f[R]
Prints the value on top of the stack, whether number or string, and
prints a newline after.
.RS
.PP
This does not alter the stack.
.RE
.TP
\f[B]n\f[R]
Prints the value on top of the stack, whether number or string, and pops
it off of the stack.
.TP
\f[B]P\f[R]
Pops a value off the stack.
.RS
.PP
If the value is a number, it is truncated and the absolute value of the
result is printed as though \f[B]obase\f[R] is \f[B]UCHAR_MAX+1\f[R] and
each digit is interpreted as an ASCII character, making it a byte
stream.
.PP
If the value is a string, it is printed without a trailing newline.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]f\f[R]
Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
.RS
.PP
Users should use this command when they get lost.
.RE
.SS Arithmetic
.PP
These are the commands used for arithmetic.
.TP
\f[B]+\f[R]
The top two values are popped off the stack, added, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]-\f[R]
The top two values are popped off the stack, subtracted, and the result
is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]*\f[R]
The top two values are popped off the stack, multiplied, and the result
is pushed onto the stack.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The top two values are popped off the stack, divided, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]%\f[R]
The top two values are popped off the stack, remaindered, and the result
is pushed onto the stack.
.RS
.PP
Remaindering is equivalent to 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R], and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]\[ti]\f[R]
The top two values are popped off the stack, divided and remaindered,
and the results (divided first, remainder second) are pushed onto the
stack.
This is equivalent to \f[B]x y / x y %\f[R] except that \f[B]x\f[R] and
\f[B]y\f[R] are only evaluated once.
.RS
.PP
The first value popped off of the stack must be non-zero.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
.RE
.TP
\f[B]v\f[R]
The top value is popped off the stack, its square root is computed, and
the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The value popped off of the stack must be non-negative.
.RE
.TP
\f[B]_\f[R]
If this command \f[I]immediately\f[R] precedes a number (i.e., no spaces
or other commands), then that number is input as a negative number.
.RS
.PP
Otherwise, the top value on the stack is popped and copied, and the copy
is negated and pushed onto the stack.
This behavior without a number is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]b\f[R]
The top value is popped off the stack, and if it is zero, it is pushed
back onto the stack.
Otherwise, its absolute value is pushed onto the stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]|\f[R]
The top three values are popped off the stack, a modular exponentiation
is computed, and the result is pushed onto the stack.
.RS
.PP
The first value popped is used as the reduction modulus and must be an
integer and non-zero.
The second value popped is used as the exponent and must be an integer
and non-negative.
The third value popped is the base and must be an integer.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]G\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if they are equal, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]N\f[R]
The top value is popped off of the stack, and if it a \f[B]0\f[R], a
\f[B]1\f[R] is pushed; otherwise, a \f[B]0\f[R] is pushed.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B](\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]{\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than or equal to the second,
or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B])\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]}\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than or equal to the
second, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]M\f[R]
The top two values are popped off of the stack.
If they are both non-zero, a \f[B]1\f[R] is pushed onto the stack.
If either of them is zero, or both of them are, then a \f[B]0\f[R] is
pushed onto the stack.
.RS
.PP
This is like the \f[B]&&\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]m\f[R]
The top two values are popped off of the stack.
If at least one of them is non-zero, a \f[B]1\f[R] is pushed onto the
stack.
If both of them are zero, then a \f[B]0\f[R] is pushed onto the stack.
.RS
.PP
This is like the \f[B]||\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Stack Control
.PP
These commands control the stack.
.TP
\f[B]c\f[R]
Removes all items from (\[lq]clears\[rq]) the stack.
.TP
\f[B]d\f[R]
Copies the item on top of the stack (\[lq]duplicates\[rq]) and pushes
the copy onto the stack.
.TP
\f[B]r\f[R]
Swaps (\[lq]reverses\[rq]) the two top items on the stack.
.TP
\f[B]R\f[R]
Pops (\[lq]removes\[rq]) the top value from the stack.
.SS Register Control
.PP
These commands control registers (see the \f[B]REGISTERS\f[R] section).
.TP
\f[B]s\f[R]\f[I]r\f[R]
Pops the value off the top of the stack and stores it into register
\f[I]r\f[R].
.TP
\f[B]l\f[R]\f[I]r\f[R]
Copies the value in register \f[I]r\f[R] and pushes it onto the stack.
This does not alter the contents of \f[I]r\f[R].
.TP
\f[B]S\f[R]\f[I]r\f[R]
Pops the value off the top of the (main) stack and pushes it onto the
stack of register \f[I]r\f[R].
The previous value of the register becomes inaccessible.
.TP
\f[B]L\f[R]\f[I]r\f[R]
Pops the value off the top of the stack for register \f[I]r\f[R] and
push it onto the main stack.
The previous value in the stack for register \f[I]r\f[R], if any, is now
accessible via the \f[B]l\f[R]\f[I]r\f[R] command.
.SS Parameters
.PP
These commands control the values of \f[B]ibase\f[R], \f[B]obase\f[R],
and \f[B]scale\f[R].
Also see the \f[B]SYNTAX\f[R] section.
.TP
\f[B]i\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]ibase\f[R], which must be between \f[B]2\f[R] and \f[B]16\f[R],
inclusive.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]o\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]obase\f[R], which must be between \f[B]2\f[R] and
\f[B]DC_BASE_MAX\f[R], inclusive (see the \f[B]LIMITS\f[R] section).
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]k\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]scale\f[R], which must be non-negative.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]I\f[R]
Pushes the current value of \f[B]ibase\f[R] onto the main stack.
.TP
\f[B]O\f[R]
Pushes the current value of \f[B]obase\f[R] onto the main stack.
.TP
\f[B]K\f[R]
Pushes the current value of \f[B]scale\f[R] onto the main stack.
.TP
\f[B]T\f[R]
Pushes the maximum allowable value of \f[B]ibase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]U\f[R]
Pushes the maximum allowable value of \f[B]obase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]V\f[R]
Pushes the maximum allowable value of \f[B]scale\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Strings
.PP
The following commands control strings.
.PP
dc(1) can work with both numbers and strings, and registers (see the
\f[B]REGISTERS\f[R] section) can hold both strings and numbers.
dc(1) always knows whether the contents of a register are a string or a
number.
.PP
While arithmetic operations have to have numbers, and will print an
error if given a string, other commands accept strings.
.PP
Strings can also be executed as macros.
For example, if the string \f[B][1pR]\f[R] is executed as a macro, then
the code \f[B]1pR\f[R] is executed, meaning that the \f[B]1\f[R] will be
printed with a newline after and then popped from the stack.
.TP
\f[B][\f[R]_characters_\f[B]]\f[R]
Makes a string containing \f[I]characters\f[R] and pushes it onto the
stack.
.RS
.PP
If there are brackets (\f[B][\f[R] and \f[B]]\f[R]) in the string, then
they must be balanced.
Unbalanced brackets can be escaped using a backslash (\f[B]\[rs]\f[R])
character.
.PP
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the
(first) backslash is not.
.RE
.TP
\f[B]a\f[R]
The value on top of the stack is popped.
.RS
.PP
If it is a number, it is truncated and its absolute value is taken.
The result mod \f[B]UCHAR_MAX+1\f[R] is calculated.
If that result is \f[B]0\f[R], push an empty string; otherwise, push a
one-character string where the character is the result of the mod
interpreted as an ASCII character.
.PP
If it is a string, then a new string is made.
If the original string is empty, the new string is empty.
If it is not, then the first character of the original string is used to
create the new string as a one-character string.
The new string is then pushed onto the stack.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]x\f[R]
Pops a value off of the top of the stack.
.RS
.PP
If it is a number, it is pushed back onto the stack.
.PP
If it is a string, it is executed as a macro.
.PP
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is greater than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
For example, \f[B]0 1>a\f[R] will execute the contents of register
\f[B]a\f[R], and \f[B]1 0>a\f[R] will not.
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not greater than the second (less than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is less than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not less than the second (greater than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is equal to the second, then the contents of register
\f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not equal to the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]?\f[R]
Reads a line from the \f[B]stdin\f[R] and executes it.
This is to allow macros to request input from users.
.TP
\f[B]q\f[R]
During execution of a macro, this exits the execution of that macro and
the execution of the macro that executed it.
If there are no macros, or only one macro executing, dc(1) exits.
.TP
\f[B]Q\f[R]
Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack.
If the number of levels to pop is greater than the number of executing
macros, dc(1) exits.
.SS Status
.PP
These commands query status of the stack or its top value.
.TP
\f[B]Z\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, calculates the number of significant decimal digits
it has and pushes the result.
.PP
If it is a string, pushes the number of characters the string has.
.RE
.TP
\f[B]X\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, pushes the \f[I]scale\f[R] of the value onto the
stack.
.PP
If it is a string, pushes \f[B]0\f[R].
.RE
.TP
\f[B]z\f[R]
Pushes the current stack depth (before execution of this command).
.SS Arrays
.PP
These commands manipulate arrays.
.TP
\f[B]:\f[R]\f[I]r\f[R]
Pops the top two values off of the stack.
The second value will be stored in the array \f[I]r\f[R] (see the
\f[B]REGISTERS\f[R] section), indexed by the first value.
.TP
\f[B];\f[R]\f[I]r\f[R]
Pops the value on top of the stack and uses it as an index into the
array \f[I]r\f[R].
The selected value is then pushed onto the stack.
.SH REGISTERS
.PP
Registers are names that can store strings, numbers, and arrays.
(Number/string registers do not interfere with array registers.)
.PP
Each register is also its own stack, so the current register value is
the top of the stack for the register.
All registers, when first referenced, have one value (\f[B]0\f[R]) in
their stack.
.PP
In non-extended register mode, a register name is just the single
character that follows any command that needs a register name.
The only exception is a newline (\f[B]`\[rs]n'\f[R]); it is a parse
error for a newline to be used as a register name.
.SS Extended Register Mode
.PP
Unlike most other dc(1) implentations, this dc(1) provides nearly
unlimited amounts of registers, if extended register mode is enabled.
.PP
If extended register mode is enabled (\f[B]-x\f[R] or
\f[B]\[en]extended-register\f[R] command-line arguments are given), then
normal single character registers are used \f[I]unless\f[R] the
character immediately following a command that needs a register name is
a space (according to \f[B]isspace()\f[R]) and not a newline
(\f[B]`\[rs]n'\f[R]).
.PP
In that case, the register name is found according to the regex
\f[B][a-z][a-z0-9_]*\f[R] (like bc(1) identifiers), and it is a parse
error if the next non-space characters do not match that regex.
.SH RESET
.PP
When dc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any macros that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all macros returned) is skipped.
.PP
Thus, when dc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.SH PERFORMANCE
.PP
Most dc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This dc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]DC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]DC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]DC_BASE_DIGS\f[R].
.PP
In addition, this dc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]DC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on dc(1):
.TP
\f[B]DC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
dc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]DC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]DC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]DC_BASE_DIGS\f[R].
.TP
\f[B]DC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]DC_BASE_POW\f[R].
.TP
\f[B]DC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]DC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]DC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
dc(1) recognizes the following environment variables:
.TP
\f[B]DC_ENV_ARGS\f[R]
This is another way to give command-line arguments to dc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]DC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs.
Another use would be to use the \f[B]-e\f[R] option to set
\f[B]scale\f[R] to a value other than \f[B]0\f[R].
.RS
.PP
The code that parses \f[B]DC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some dc file.dc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]dc\[dq] file.dc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
-in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
+in \f[B]\[rq]some `dc' file.dc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]DC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]DC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), dc(1) will output lines to that length,
including the backslash newline combo.
The default line length is \f[B]70\f[R].
.TP
\f[B]DC_EXPR_EXIT\f[R]
If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the
\f[B]-e\f[R] and/or \f[B]-f\f[R] command-line options (and any
equivalents).
.SH EXIT STATUS
.PP
dc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, attempting to convert a negative number to a hardware
integer, overflow when converting a number to a hardware integer, and
attempting to use a non-integer where an integer is required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]) operator.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, and using a
token where it is invalid.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, and attempting an operation when the
stack has too few elements.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (dc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, dc(1)
always exits and returns \f[B]4\f[R], no matter what mode dc(1) is in.
.PP
The other statuses will only be returned when dc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
dc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, dc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, dc(1) turns on \[lq]TTY mode.\[rq]
.PP
The prompt is enabled in TTY mode.
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause dc(1) to stop execution of the
current input.
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If dc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If dc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to dc(1) as it is
executing a file, it can seem as though dc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause dc(1) to clean up and
exit, and it uses the default handler for all other signals.
.SH LOCALES
.PP
This dc(1) ships with support for adding error messages for different
locales and thus, supports \f[B]LC_MESSAGS\f[R].
.SH SEE ALSO
.PP
bc(1)
.SH STANDARDS
.PP
The dc(1) utility operators are compliant with the operators in the
bc(1) IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHOR
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/dc/EH.1.md b/contrib/bc/manuals/dc/EH.1.md
index 0fe5bd455ecf..0f6df3e6f474 100644
--- a/contrib/bc/manuals/dc/EH.1.md
+++ b/contrib/bc/manuals/dc/EH.1.md
@@ -1,1018 +1,1027 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# Name
dc - arbitrary-precision decimal reverse-Polish notation calculator
# SYNOPSIS
**dc** [**-hiPvVx**] [**--version**] [**--help**] [**--interactive**] [**--no-prompt**] [**--extended-register**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...] [*file*...]
# DESCRIPTION
dc(1) is an arbitrary-precision calculator. It uses a stack (reverse Polish
notation) to store numbers and results of computations. Arithmetic operations
pop arguments off of the stack and push the results.
If no files are given on the command-line as extra arguments (i.e., not as
**-f** or **--file** arguments), then dc(1) reads from **stdin**. Otherwise,
those files are processed, and dc(1) will then exit.
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where **-e** (**--expression**) and **-f** (**--file**)
arguments cause dc(1) to execute them and exit. The reason for this is that this
dc(1) allows users to set arguments in the environment variable **DC_ENV_ARGS**
(see the **ENVIRONMENT VARIABLES** section). Any expressions given on the
command-line should be used to set up a standard environment. For example, if a
user wants the **scale** always set to **10**, they can set **DC_ENV_ARGS** to
**-e 10k**, and this dc(1) will always start with a **scale** of **10**.
If users want to have dc(1) exit after processing all input from **-e** and
**-f** arguments (and their equivalents), then they can just simply add **-e q**
as the last command-line argument or define the environment variable
**DC_EXPR_EXIT**.
# OPTIONS
The following are the options that dc(1) accepts.
**-h**, **--help**
: Prints a usage message and quits.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-P**, **--no-prompt**
: Disables the prompt in TTY mode. (The prompt is only enabled in TTY mode.
See the **TTY MODE** section) This is mostly for those users that do not
want a prompt or are not used to having them in dc(1). Most of those users
would want to put this option in **DC_ENV_ARGS**.
This is a **non-portable extension**.
**-x** **--extended-register**
: Enables extended register mode. See the *Extended Register Mode* subsection
of the **REGISTERS** section for more information.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **DC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **dc <file> >&-**, it will quit with an error. This
is done so that dc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **dc <file> 2>&-**, it will quit with an error. This
is done so that dc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
Each item in the input source code, either a number (see the **NUMBERS**
section) or a command (see the **COMMANDS** section), is processed and executed,
in order. Input is processed immediately when entered.
**ibase** is a register (see the **REGISTERS** section) that determines how to
interpret constant numbers. It is the "input" base, or the number base used for
interpreting input numbers. **ibase** is initially **10**. The max allowable
value for **ibase** is **16**. The min allowable value for **ibase** is **2**.
The max allowable value for **ibase** can be queried in dc(1) programs with the
**T** command.
**obase** is a register (see the **REGISTERS** section) that determines how to
output results. It is the "output" base, or the number base used for outputting
numbers. **obase** is initially **10**. The max allowable value for **obase** is
**DC_BASE_MAX** and can be queried with the **U** command. The min allowable
value for **obase** is **2**. Values are output in the specified base.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a register (see the
**REGISTERS** section) that sets the precision of any operations (with
exceptions). **scale** is initially **0**. **scale** cannot be negative. The max
allowable value for **scale** can be queried in dc(1) programs with the **V**
command.
## Comments
Comments go from **#** until, and not including, the next newline. This is a
**non-portable extension**.
# NUMBERS
Numbers are strings made up of digits, uppercase letters up to **F**, and at
most **1** period for a radix. Numbers can have up to **DC_NUM_MAX** digits.
Uppercase letters are equal to **9** + their position in the alphabet (i.e.,
**A** equals **10**, or **9+1**). If a digit or letter makes no sense with the
current value of **ibase**, they are set to the value of the highest valid digit
in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **F** alone always equals decimal
**15**.
# COMMANDS
The valid commands are listed below.
## Printing
These commands are used for printing.
**p**
: Prints the value on top of the stack, whether number or string, and prints a
newline after.
This does not alter the stack.
**n**
: Prints the value on top of the stack, whether number or string, and pops it
off of the stack.
**P**
: Pops a value off the stack.
If the value is a number, it is truncated and the absolute value of the
result is printed as though **obase** is **UCHAR_MAX+1** and each digit is
interpreted as an ASCII character, making it a byte stream.
If the value is a string, it is printed without a trailing newline.
This is a **non-portable extension**.
**f**
: Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
Users should use this command when they get lost.
## Arithmetic
These are the commands used for arithmetic.
**+**
: The top two values are popped off the stack, added, and the result is pushed
onto the stack. The *scale* of the result is equal to the max *scale* of
both operands.
**-**
: The top two values are popped off the stack, subtracted, and the result is
pushed onto the stack. The *scale* of the result is equal to the max
*scale* of both operands.
**\***
: The top two values are popped off the stack, multiplied, and the result is
pushed onto the stack. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result
is equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The top two values are popped off the stack, divided, and the result is
pushed onto the stack. The *scale* of the result is equal to **scale**.
The first value popped off of the stack must be non-zero.
**%**
: The top two values are popped off the stack, remaindered, and the result is
pushed onto the stack.
Remaindering is equivalent to 1) Computing **a/b** to current **scale**, and
2) Using the result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The first value popped off of the stack must be non-zero.
**~**
: The top two values are popped off the stack, divided and remaindered, and
the results (divided first, remainder second) are pushed onto the stack.
This is equivalent to **x y / x y %** except that **x** and **y** are only
evaluated once.
The first value popped off of the stack must be non-zero.
This is a **non-portable extension**.
**\^**
: The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack. The *scale* of
the result is equal to **scale**.
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
**v**
: The top value is popped off the stack, its square root is computed, and the
result is pushed onto the stack. The *scale* of the result is equal to
**scale**.
The value popped off of the stack must be non-negative.
**\_**
: If this command *immediately* precedes a number (i.e., no spaces or other
commands), then that number is input as a negative number.
Otherwise, the top value on the stack is popped and copied, and the copy is
negated and pushed onto the stack. This behavior without a number is a
**non-portable extension**.
**b**
: The top value is popped off the stack, and if it is zero, it is pushed back
onto the stack. Otherwise, its absolute value is pushed onto the stack.
This is a **non-portable extension**.
**|**
: The top three values are popped off the stack, a modular exponentiation is
computed, and the result is pushed onto the stack.
The first value popped is used as the reduction modulus and must be an
integer and non-zero. The second value popped is used as the exponent and
must be an integer and non-negative. The third value popped is the base and
must be an integer.
This is a **non-portable extension**.
**G**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if they are equal, or **0** otherwise.
This is a **non-portable extension**.
**N**
: The top value is popped off of the stack, and if it a **0**, a **1** is
pushed; otherwise, a **0** is pushed.
This is a **non-portable extension**.
**(**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than the second, or **0** otherwise.
This is a **non-portable extension**.
**{**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than or equal to the second, or **0**
otherwise.
This is a **non-portable extension**.
**)**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than the second, or **0** otherwise.
This is a **non-portable extension**.
**}**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than or equal to the second, or
**0** otherwise.
This is a **non-portable extension**.
**M**
: The top two values are popped off of the stack. If they are both non-zero, a
**1** is pushed onto the stack. If either of them is zero, or both of them
are, then a **0** is pushed onto the stack.
This is like the **&&** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
**m**
: The top two values are popped off of the stack. If at least one of them is
non-zero, a **1** is pushed onto the stack. If both of them are zero, then a
**0** is pushed onto the stack.
This is like the **||** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
## Stack Control
These commands control the stack.
**c**
: Removes all items from ("clears") the stack.
**d**
: Copies the item on top of the stack ("duplicates") and pushes the copy onto
the stack.
**r**
: Swaps ("reverses") the two top items on the stack.
**R**
: Pops ("removes") the top value from the stack.
## Register Control
These commands control registers (see the **REGISTERS** section).
**s***r*
: Pops the value off the top of the stack and stores it into register *r*.
**l***r*
: Copies the value in register *r* and pushes it onto the stack. This does not
alter the contents of *r*.
**S***r*
: Pops the value off the top of the (main) stack and pushes it onto the stack
of register *r*. The previous value of the register becomes inaccessible.
**L***r*
: Pops the value off the top of the stack for register *r* and push it onto
the main stack. The previous value in the stack for register *r*, if any, is
now accessible via the **l***r* command.
## Parameters
These commands control the values of **ibase**, **obase**, and **scale**. Also
see the **SYNTAX** section.
**i**
: Pops the value off of the top of the stack and uses it to set **ibase**,
which must be between **2** and **16**, inclusive.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**o**
: Pops the value off of the top of the stack and uses it to set **obase**,
which must be between **2** and **DC_BASE_MAX**, inclusive (see the
**LIMITS** section).
If the value on top of the stack has any *scale*, the *scale* is ignored.
**k**
: Pops the value off of the top of the stack and uses it to set **scale**,
which must be non-negative.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**I**
: Pushes the current value of **ibase** onto the main stack.
**O**
: Pushes the current value of **obase** onto the main stack.
**K**
: Pushes the current value of **scale** onto the main stack.
**T**
: Pushes the maximum allowable value of **ibase** onto the main stack.
This is a **non-portable extension**.
**U**
: Pushes the maximum allowable value of **obase** onto the main stack.
This is a **non-portable extension**.
**V**
: Pushes the maximum allowable value of **scale** onto the main stack.
This is a **non-portable extension**.
## Strings
The following commands control strings.
dc(1) can work with both numbers and strings, and registers (see the
**REGISTERS** section) can hold both strings and numbers. dc(1) always knows
whether the contents of a register are a string or a number.
While arithmetic operations have to have numbers, and will print an error if
given a string, other commands accept strings.
Strings can also be executed as macros. For example, if the string **[1pR]** is
executed as a macro, then the code **1pR** is executed, meaning that the **1**
will be printed with a newline after and then popped from the stack.
**\[**_characters_**\]**
: Makes a string containing *characters* and pushes it onto the stack.
If there are brackets (**\[** and **\]**) in the string, then they must be
balanced. Unbalanced brackets can be escaped using a backslash (**\\**)
character.
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the (first)
backslash is not.
**a**
: The value on top of the stack is popped.
If it is a number, it is truncated and its absolute value is taken. The
result mod **UCHAR_MAX+1** is calculated. If that result is **0**, push an
empty string; otherwise, push a one-character string where the character is
the result of the mod interpreted as an ASCII character.
If it is a string, then a new string is made. If the original string is
empty, the new string is empty. If it is not, then the first character of
the original string is used to create the new string as a one-character
string. The new string is then pushed onto the stack.
This is a **non-portable extension**.
**x**
: Pops a value off of the top of the stack.
If it is a number, it is pushed back onto the stack.
If it is a string, it is executed as a macro.
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
**\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is greater than the second, then the contents of register
*r* are executed.
For example, **0 1>a** will execute the contents of register **a**, and
**1 0>a** will not.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not greater than the second (less than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is less than the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not less than the second (greater than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is equal to the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not equal to the second, then the contents of register
*r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**?**
: Reads a line from the **stdin** and executes it. This is to allow macros to
request input from users.
**q**
: During execution of a macro, this exits the execution of that macro and the
execution of the macro that executed it. If there are no macros, or only one
macro executing, dc(1) exits.
**Q**
: Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack. If the number
of levels to pop is greater than the number of executing macros, dc(1)
exits.
## Status
These commands query status of the stack or its top value.
**Z**
: Pops a value off of the stack.
If it is a number, calculates the number of significant decimal digits it
has and pushes the result.
If it is a string, pushes the number of characters the string has.
**X**
: Pops a value off of the stack.
If it is a number, pushes the *scale* of the value onto the stack.
If it is a string, pushes **0**.
**z**
: Pushes the current stack depth (before execution of this command).
## Arrays
These commands manipulate arrays.
**:***r*
: Pops the top two values off of the stack. The second value will be stored in
the array *r* (see the **REGISTERS** section), indexed by the first value.
**;***r*
: Pops the value on top of the stack and uses it as an index into the array
*r*. The selected value is then pushed onto the stack.
# REGISTERS
Registers are names that can store strings, numbers, and arrays. (Number/string
registers do not interfere with array registers.)
Each register is also its own stack, so the current register value is the top of
the stack for the register. All registers, when first referenced, have one value
(**0**) in their stack.
In non-extended register mode, a register name is just the single character that
follows any command that needs a register name. The only exception is a newline
(**'\\n'**); it is a parse error for a newline to be used as a register name.
## Extended Register Mode
Unlike most other dc(1) implentations, this dc(1) provides nearly unlimited
amounts of registers, if extended register mode is enabled.
If extended register mode is enabled (**-x** or **--extended-register**
command-line arguments are given), then normal single character registers are
used *unless* the character immediately following a command that needs a
register name is a space (according to **isspace()**) and not a newline
(**'\\n'**).
In that case, the register name is found according to the regex
**\[a-z\]\[a-z0-9\_\]\*** (like bc(1) identifiers), and it is a parse error if
the next non-space characters do not match that regex.
# RESET
When dc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any macros that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
macros returned) is skipped.
Thus, when dc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
# PERFORMANCE
Most dc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This dc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **DC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **DC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**DC_BASE_DIGS**.
In addition, this dc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **DC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on dc(1):
**DC_LONG_BIT**
: The number of bits in the **long** type in the environment where dc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**DC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **DC_LONG_BIT**.
**DC_BASE_POW**
: The max decimal number that each large integer can store (see
**DC_BASE_DIGS**) plus **1**. Depends on **DC_BASE_DIGS**.
**DC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **DC_LONG_BIT**.
**DC_BASE_MAX**
: The maximum output base. Set at **DC_BASE_POW**.
**DC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**DC_SCALE_MAX**
: The maximum **scale**. Set at **DC_OVERFLOW_MAX-1**.
**DC_STRING_MAX**
: The maximum length of strings. Set at **DC_OVERFLOW_MAX-1**.
**DC_NAME_MAX**
: The maximum length of identifiers. Set at **DC_OVERFLOW_MAX-1**.
**DC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **DC_OVERFLOW_MAX-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**DC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
dc(1) recognizes the following environment variables:
**DC_ENV_ARGS**
: This is another way to give command-line arguments to dc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **DC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs. Another use would
be to use the **-e** option to set **scale** to a value other than **0**.
The code that parses **DC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some dc file.dc"** will be correctly parsed, but the string
**"/home/gavin/some \"dc\" file.dc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
- double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
+ double quotes as the outside quotes, as in **"some 'dc' file.dc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **DC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**DC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), dc(1) will output
lines to that length, including the backslash newline combo. The default
line length is **70**.
**DC_EXPR_EXIT**
: If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the **-e** and/or
**-f** command-line options (and any equivalents).
# EXIT STATUS
dc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**) operator.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, and using a token where it is
invalid.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, and attempting an operation when
the stack has too few elements.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (dc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, dc(1) always exits
and returns **4**, no matter what mode dc(1) is in.
The other statuses will only be returned when dc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since dc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, dc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, dc(1) turns
on "TTY mode."
The prompt is enabled in TTY mode.
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause dc(1) to stop execution of the current input. If
dc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If dc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If dc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to dc(1) as it is executing a file, it
can seem as though dc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause dc(1) to clean up and exit, and it uses the
default handler for all other signals.
# LOCALES
This dc(1) ships with support for adding error messages for different locales
and thus, supports **LC_MESSAGS**.
# SEE ALSO
bc(1)
# STANDARDS
The dc(1) utility operators are compliant with the operators in the bc(1)
[IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1] specification.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHOR
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
diff --git a/contrib/bc/manuals/dc/EHN.1 b/contrib/bc/manuals/dc/EHN.1
index d6d821627ed5..0b8d34cfa25f 100644
--- a/contrib/bc/manuals/dc/EHN.1
+++ b/contrib/bc/manuals/dc/EHN.1
@@ -1,1111 +1,1124 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "DC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "DC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH Name
.PP
dc - arbitrary-precision decimal reverse-Polish notation calculator
.SH SYNOPSIS
.PP
\f[B]dc\f[R] [\f[B]-hiPvVx\f[R]] [\f[B]\[en]version\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]no-prompt\f[R]] [\f[B]\[en]extended-register\f[R]]
[\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
dc(1) is an arbitrary-precision calculator.
It uses a stack (reverse Polish notation) to store numbers and results
of computations.
Arithmetic operations pop arguments off of the stack and push the
results.
.PP
If no files are given on the command-line as extra arguments (i.e., not
as \f[B]-f\f[R] or \f[B]\[en]file\f[R] arguments), then dc(1) reads from
\f[B]stdin\f[R].
Otherwise, those files are processed, and dc(1) will then exit.
.PP
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where \f[B]-e\f[R] (\f[B]\[en]expression\f[R]) and
\f[B]-f\f[R] (\f[B]\[en]file\f[R]) arguments cause dc(1) to execute them
and exit.
The reason for this is that this dc(1) allows users to set arguments in
the environment variable \f[B]DC_ENV_ARGS\f[R] (see the \f[B]ENVIRONMENT
VARIABLES\f[R] section).
Any expressions given on the command-line should be used to set up a
standard environment.
For example, if a user wants the \f[B]scale\f[R] always set to
\f[B]10\f[R], they can set \f[B]DC_ENV_ARGS\f[R] to \f[B]-e 10k\f[R],
and this dc(1) will always start with a \f[B]scale\f[R] of \f[B]10\f[R].
.PP
If users want to have dc(1) exit after processing all input from
\f[B]-e\f[R] and \f[B]-f\f[R] arguments (and their equivalents), then
they can just simply add \f[B]-e q\f[R] as the last command-line
argument or define the environment variable \f[B]DC_EXPR_EXIT\f[R].
.SH OPTIONS
.PP
The following are the options that dc(1) accepts.
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
Disables the prompt in TTY mode.
(The prompt is only enabled in TTY mode.
See the \f[B]TTY MODE\f[R] section) This is mostly for those users that
do not want a prompt or are not used to having them in dc(1).
Most of those users would want to put this option in
\f[B]DC_ENV_ARGS\f[R].
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-x\f[R] \f[B]\[en]extended-register\f[R]
Enables extended register mode.
See the \f[I]Extended Register Mode\f[R] subsection of the
\f[B]REGISTERS\f[R] section for more information.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]DC_ENV_ARGS\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]dc >&-\f[R], it will quit with an error.
This is done so that dc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]dc 2>&-\f[R], it will quit with an error.
This is done so that dc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
Each item in the input source code, either a number (see the
\f[B]NUMBERS\f[R] section) or a command (see the \f[B]COMMANDS\f[R]
section), is processed and executed, in order.
Input is processed immediately when entered.
.PP
\f[B]ibase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to interpret constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]ibase\f[R] is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in dc(1)
programs with the \f[B]T\f[R] command.
.PP
\f[B]obase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]DC_BASE_MAX\f[R] and
can be queried with the \f[B]U\f[R] command.
The min allowable value for \f[B]obase\f[R] is \f[B]2\f[R].
Values are output in the specified base.
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a register (see the \f[B]REGISTERS\f[R] section) that sets the
precision of any operations (with exceptions).
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] can be queried in dc(1)
programs with the \f[B]V\f[R] command.
.SS Comments
.PP
Comments go from \f[B]#\f[R] until, and not including, the next newline.
This is a \f[B]non-portable extension\f[R].
.SH NUMBERS
.PP
Numbers are strings made up of digits, uppercase letters up to
\f[B]F\f[R], and at most \f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]DC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]F\f[R] alone always equals decimal \f[B]15\f[R].
.SH COMMANDS
.PP
The valid commands are listed below.
.SS Printing
.PP
These commands are used for printing.
.TP
\f[B]p\f[R]
Prints the value on top of the stack, whether number or string, and
prints a newline after.
.RS
.PP
This does not alter the stack.
.RE
.TP
\f[B]n\f[R]
Prints the value on top of the stack, whether number or string, and pops
it off of the stack.
.TP
\f[B]P\f[R]
Pops a value off the stack.
.RS
.PP
If the value is a number, it is truncated and the absolute value of the
result is printed as though \f[B]obase\f[R] is \f[B]UCHAR_MAX+1\f[R] and
each digit is interpreted as an ASCII character, making it a byte
stream.
.PP
If the value is a string, it is printed without a trailing newline.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]f\f[R]
Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
.RS
.PP
Users should use this command when they get lost.
.RE
.SS Arithmetic
.PP
These are the commands used for arithmetic.
.TP
\f[B]+\f[R]
The top two values are popped off the stack, added, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]-\f[R]
The top two values are popped off the stack, subtracted, and the result
is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]*\f[R]
The top two values are popped off the stack, multiplied, and the result
is pushed onto the stack.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The top two values are popped off the stack, divided, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]%\f[R]
The top two values are popped off the stack, remaindered, and the result
is pushed onto the stack.
.RS
.PP
Remaindering is equivalent to 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R], and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]\[ti]\f[R]
The top two values are popped off the stack, divided and remaindered,
and the results (divided first, remainder second) are pushed onto the
stack.
This is equivalent to \f[B]x y / x y %\f[R] except that \f[B]x\f[R] and
\f[B]y\f[R] are only evaluated once.
.RS
.PP
The first value popped off of the stack must be non-zero.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
.RE
.TP
\f[B]v\f[R]
The top value is popped off the stack, its square root is computed, and
the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The value popped off of the stack must be non-negative.
.RE
.TP
\f[B]_\f[R]
If this command \f[I]immediately\f[R] precedes a number (i.e., no spaces
or other commands), then that number is input as a negative number.
.RS
.PP
Otherwise, the top value on the stack is popped and copied, and the copy
is negated and pushed onto the stack.
This behavior without a number is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]b\f[R]
The top value is popped off the stack, and if it is zero, it is pushed
back onto the stack.
Otherwise, its absolute value is pushed onto the stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]|\f[R]
The top three values are popped off the stack, a modular exponentiation
is computed, and the result is pushed onto the stack.
.RS
.PP
The first value popped is used as the reduction modulus and must be an
integer and non-zero.
The second value popped is used as the exponent and must be an integer
and non-negative.
The third value popped is the base and must be an integer.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]G\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if they are equal, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]N\f[R]
The top value is popped off of the stack, and if it a \f[B]0\f[R], a
\f[B]1\f[R] is pushed; otherwise, a \f[B]0\f[R] is pushed.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B](\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]{\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than or equal to the second,
or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B])\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]}\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than or equal to the
second, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]M\f[R]
The top two values are popped off of the stack.
If they are both non-zero, a \f[B]1\f[R] is pushed onto the stack.
If either of them is zero, or both of them are, then a \f[B]0\f[R] is
pushed onto the stack.
.RS
.PP
This is like the \f[B]&&\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]m\f[R]
The top two values are popped off of the stack.
If at least one of them is non-zero, a \f[B]1\f[R] is pushed onto the
stack.
If both of them are zero, then a \f[B]0\f[R] is pushed onto the stack.
.RS
.PP
This is like the \f[B]||\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Stack Control
.PP
These commands control the stack.
.TP
\f[B]c\f[R]
Removes all items from (\[lq]clears\[rq]) the stack.
.TP
\f[B]d\f[R]
Copies the item on top of the stack (\[lq]duplicates\[rq]) and pushes
the copy onto the stack.
.TP
\f[B]r\f[R]
Swaps (\[lq]reverses\[rq]) the two top items on the stack.
.TP
\f[B]R\f[R]
Pops (\[lq]removes\[rq]) the top value from the stack.
.SS Register Control
.PP
These commands control registers (see the \f[B]REGISTERS\f[R] section).
.TP
\f[B]s\f[R]\f[I]r\f[R]
Pops the value off the top of the stack and stores it into register
\f[I]r\f[R].
.TP
\f[B]l\f[R]\f[I]r\f[R]
Copies the value in register \f[I]r\f[R] and pushes it onto the stack.
This does not alter the contents of \f[I]r\f[R].
.TP
\f[B]S\f[R]\f[I]r\f[R]
Pops the value off the top of the (main) stack and pushes it onto the
stack of register \f[I]r\f[R].
The previous value of the register becomes inaccessible.
.TP
\f[B]L\f[R]\f[I]r\f[R]
Pops the value off the top of the stack for register \f[I]r\f[R] and
push it onto the main stack.
The previous value in the stack for register \f[I]r\f[R], if any, is now
accessible via the \f[B]l\f[R]\f[I]r\f[R] command.
.SS Parameters
.PP
These commands control the values of \f[B]ibase\f[R], \f[B]obase\f[R],
and \f[B]scale\f[R].
Also see the \f[B]SYNTAX\f[R] section.
.TP
\f[B]i\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]ibase\f[R], which must be between \f[B]2\f[R] and \f[B]16\f[R],
inclusive.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]o\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]obase\f[R], which must be between \f[B]2\f[R] and
\f[B]DC_BASE_MAX\f[R], inclusive (see the \f[B]LIMITS\f[R] section).
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]k\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]scale\f[R], which must be non-negative.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]I\f[R]
Pushes the current value of \f[B]ibase\f[R] onto the main stack.
.TP
\f[B]O\f[R]
Pushes the current value of \f[B]obase\f[R] onto the main stack.
.TP
\f[B]K\f[R]
Pushes the current value of \f[B]scale\f[R] onto the main stack.
.TP
\f[B]T\f[R]
Pushes the maximum allowable value of \f[B]ibase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]U\f[R]
Pushes the maximum allowable value of \f[B]obase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]V\f[R]
Pushes the maximum allowable value of \f[B]scale\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Strings
.PP
The following commands control strings.
.PP
dc(1) can work with both numbers and strings, and registers (see the
\f[B]REGISTERS\f[R] section) can hold both strings and numbers.
dc(1) always knows whether the contents of a register are a string or a
number.
.PP
While arithmetic operations have to have numbers, and will print an
error if given a string, other commands accept strings.
.PP
Strings can also be executed as macros.
For example, if the string \f[B][1pR]\f[R] is executed as a macro, then
the code \f[B]1pR\f[R] is executed, meaning that the \f[B]1\f[R] will be
printed with a newline after and then popped from the stack.
.TP
\f[B][\f[R]_characters_\f[B]]\f[R]
Makes a string containing \f[I]characters\f[R] and pushes it onto the
stack.
.RS
.PP
If there are brackets (\f[B][\f[R] and \f[B]]\f[R]) in the string, then
they must be balanced.
Unbalanced brackets can be escaped using a backslash (\f[B]\[rs]\f[R])
character.
.PP
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the
(first) backslash is not.
.RE
.TP
\f[B]a\f[R]
The value on top of the stack is popped.
.RS
.PP
If it is a number, it is truncated and its absolute value is taken.
The result mod \f[B]UCHAR_MAX+1\f[R] is calculated.
If that result is \f[B]0\f[R], push an empty string; otherwise, push a
one-character string where the character is the result of the mod
interpreted as an ASCII character.
.PP
If it is a string, then a new string is made.
If the original string is empty, the new string is empty.
If it is not, then the first character of the original string is used to
create the new string as a one-character string.
The new string is then pushed onto the stack.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]x\f[R]
Pops a value off of the top of the stack.
.RS
.PP
If it is a number, it is pushed back onto the stack.
.PP
If it is a string, it is executed as a macro.
.PP
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is greater than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
For example, \f[B]0 1>a\f[R] will execute the contents of register
\f[B]a\f[R], and \f[B]1 0>a\f[R] will not.
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not greater than the second (less than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is less than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not less than the second (greater than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is equal to the second, then the contents of register
\f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not equal to the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]?\f[R]
Reads a line from the \f[B]stdin\f[R] and executes it.
This is to allow macros to request input from users.
.TP
\f[B]q\f[R]
During execution of a macro, this exits the execution of that macro and
the execution of the macro that executed it.
If there are no macros, or only one macro executing, dc(1) exits.
.TP
\f[B]Q\f[R]
Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack.
If the number of levels to pop is greater than the number of executing
macros, dc(1) exits.
.SS Status
.PP
These commands query status of the stack or its top value.
.TP
\f[B]Z\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, calculates the number of significant decimal digits
it has and pushes the result.
.PP
If it is a string, pushes the number of characters the string has.
.RE
.TP
\f[B]X\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, pushes the \f[I]scale\f[R] of the value onto the
stack.
.PP
If it is a string, pushes \f[B]0\f[R].
.RE
.TP
\f[B]z\f[R]
Pushes the current stack depth (before execution of this command).
.SS Arrays
.PP
These commands manipulate arrays.
.TP
\f[B]:\f[R]\f[I]r\f[R]
Pops the top two values off of the stack.
The second value will be stored in the array \f[I]r\f[R] (see the
\f[B]REGISTERS\f[R] section), indexed by the first value.
.TP
\f[B];\f[R]\f[I]r\f[R]
Pops the value on top of the stack and uses it as an index into the
array \f[I]r\f[R].
The selected value is then pushed onto the stack.
.SH REGISTERS
.PP
Registers are names that can store strings, numbers, and arrays.
(Number/string registers do not interfere with array registers.)
.PP
Each register is also its own stack, so the current register value is
the top of the stack for the register.
All registers, when first referenced, have one value (\f[B]0\f[R]) in
their stack.
.PP
In non-extended register mode, a register name is just the single
character that follows any command that needs a register name.
The only exception is a newline (\f[B]`\[rs]n'\f[R]); it is a parse
error for a newline to be used as a register name.
.SS Extended Register Mode
.PP
Unlike most other dc(1) implentations, this dc(1) provides nearly
unlimited amounts of registers, if extended register mode is enabled.
.PP
If extended register mode is enabled (\f[B]-x\f[R] or
\f[B]\[en]extended-register\f[R] command-line arguments are given), then
normal single character registers are used \f[I]unless\f[R] the
character immediately following a command that needs a register name is
a space (according to \f[B]isspace()\f[R]) and not a newline
(\f[B]`\[rs]n'\f[R]).
.PP
In that case, the register name is found according to the regex
\f[B][a-z][a-z0-9_]*\f[R] (like bc(1) identifiers), and it is a parse
error if the next non-space characters do not match that regex.
.SH RESET
.PP
When dc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any macros that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all macros returned) is skipped.
.PP
Thus, when dc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.SH PERFORMANCE
.PP
Most dc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This dc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]DC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]DC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]DC_BASE_DIGS\f[R].
.PP
In addition, this dc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]DC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on dc(1):
.TP
\f[B]DC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
dc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]DC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]DC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]DC_BASE_DIGS\f[R].
.TP
\f[B]DC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]DC_BASE_POW\f[R].
.TP
\f[B]DC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]DC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]DC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
dc(1) recognizes the following environment variables:
.TP
\f[B]DC_ENV_ARGS\f[R]
This is another way to give command-line arguments to dc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]DC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs.
Another use would be to use the \f[B]-e\f[R] option to set
\f[B]scale\f[R] to a value other than \f[B]0\f[R].
.RS
.PP
The code that parses \f[B]DC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some dc file.dc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]dc\[dq] file.dc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
-in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
+in \f[B]\[rq]some `dc' file.dc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]DC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]DC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), dc(1) will output lines to that length,
including the backslash newline combo.
The default line length is \f[B]70\f[R].
.TP
\f[B]DC_EXPR_EXIT\f[R]
If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the
\f[B]-e\f[R] and/or \f[B]-f\f[R] command-line options (and any
equivalents).
.SH EXIT STATUS
.PP
dc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, attempting to convert a negative number to a hardware
integer, overflow when converting a number to a hardware integer, and
attempting to use a non-integer where an integer is required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]) operator.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, and using a
token where it is invalid.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, and attempting an operation when the
stack has too few elements.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (dc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, dc(1)
always exits and returns \f[B]4\f[R], no matter what mode dc(1) is in.
.PP
The other statuses will only be returned when dc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
dc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, dc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, dc(1) turns on \[lq]TTY mode.\[rq]
.PP
The prompt is enabled in TTY mode.
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause dc(1) to stop execution of the
current input.
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If dc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If dc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to dc(1) as it is
executing a file, it can seem as though dc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause dc(1) to clean up and
exit, and it uses the default handler for all other signals.
.SH SEE ALSO
.PP
bc(1)
.SH STANDARDS
.PP
The dc(1) utility operators are compliant with the operators in the
bc(1) IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHOR
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/dc/EHN.1.md b/contrib/bc/manuals/dc/EHN.1.md
index a510e6e64de3..361d641b50b2 100644
--- a/contrib/bc/manuals/dc/EHN.1.md
+++ b/contrib/bc/manuals/dc/EHN.1.md
@@ -1,1013 +1,1022 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# Name
dc - arbitrary-precision decimal reverse-Polish notation calculator
# SYNOPSIS
**dc** [**-hiPvVx**] [**--version**] [**--help**] [**--interactive**] [**--no-prompt**] [**--extended-register**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...] [*file*...]
# DESCRIPTION
dc(1) is an arbitrary-precision calculator. It uses a stack (reverse Polish
notation) to store numbers and results of computations. Arithmetic operations
pop arguments off of the stack and push the results.
If no files are given on the command-line as extra arguments (i.e., not as
**-f** or **--file** arguments), then dc(1) reads from **stdin**. Otherwise,
those files are processed, and dc(1) will then exit.
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where **-e** (**--expression**) and **-f** (**--file**)
arguments cause dc(1) to execute them and exit. The reason for this is that this
dc(1) allows users to set arguments in the environment variable **DC_ENV_ARGS**
(see the **ENVIRONMENT VARIABLES** section). Any expressions given on the
command-line should be used to set up a standard environment. For example, if a
user wants the **scale** always set to **10**, they can set **DC_ENV_ARGS** to
**-e 10k**, and this dc(1) will always start with a **scale** of **10**.
If users want to have dc(1) exit after processing all input from **-e** and
**-f** arguments (and their equivalents), then they can just simply add **-e q**
as the last command-line argument or define the environment variable
**DC_EXPR_EXIT**.
# OPTIONS
The following are the options that dc(1) accepts.
**-h**, **--help**
: Prints a usage message and quits.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-P**, **--no-prompt**
: Disables the prompt in TTY mode. (The prompt is only enabled in TTY mode.
See the **TTY MODE** section) This is mostly for those users that do not
want a prompt or are not used to having them in dc(1). Most of those users
would want to put this option in **DC_ENV_ARGS**.
This is a **non-portable extension**.
**-x** **--extended-register**
: Enables extended register mode. See the *Extended Register Mode* subsection
of the **REGISTERS** section for more information.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **DC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **dc <file> >&-**, it will quit with an error. This
is done so that dc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **dc <file> 2>&-**, it will quit with an error. This
is done so that dc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
Each item in the input source code, either a number (see the **NUMBERS**
section) or a command (see the **COMMANDS** section), is processed and executed,
in order. Input is processed immediately when entered.
**ibase** is a register (see the **REGISTERS** section) that determines how to
interpret constant numbers. It is the "input" base, or the number base used for
interpreting input numbers. **ibase** is initially **10**. The max allowable
value for **ibase** is **16**. The min allowable value for **ibase** is **2**.
The max allowable value for **ibase** can be queried in dc(1) programs with the
**T** command.
**obase** is a register (see the **REGISTERS** section) that determines how to
output results. It is the "output" base, or the number base used for outputting
numbers. **obase** is initially **10**. The max allowable value for **obase** is
**DC_BASE_MAX** and can be queried with the **U** command. The min allowable
value for **obase** is **2**. Values are output in the specified base.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a register (see the
**REGISTERS** section) that sets the precision of any operations (with
exceptions). **scale** is initially **0**. **scale** cannot be negative. The max
allowable value for **scale** can be queried in dc(1) programs with the **V**
command.
## Comments
Comments go from **#** until, and not including, the next newline. This is a
**non-portable extension**.
# NUMBERS
Numbers are strings made up of digits, uppercase letters up to **F**, and at
most **1** period for a radix. Numbers can have up to **DC_NUM_MAX** digits.
Uppercase letters are equal to **9** + their position in the alphabet (i.e.,
**A** equals **10**, or **9+1**). If a digit or letter makes no sense with the
current value of **ibase**, they are set to the value of the highest valid digit
in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **F** alone always equals decimal
**15**.
# COMMANDS
The valid commands are listed below.
## Printing
These commands are used for printing.
**p**
: Prints the value on top of the stack, whether number or string, and prints a
newline after.
This does not alter the stack.
**n**
: Prints the value on top of the stack, whether number or string, and pops it
off of the stack.
**P**
: Pops a value off the stack.
If the value is a number, it is truncated and the absolute value of the
result is printed as though **obase** is **UCHAR_MAX+1** and each digit is
interpreted as an ASCII character, making it a byte stream.
If the value is a string, it is printed without a trailing newline.
This is a **non-portable extension**.
**f**
: Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
Users should use this command when they get lost.
## Arithmetic
These are the commands used for arithmetic.
**+**
: The top two values are popped off the stack, added, and the result is pushed
onto the stack. The *scale* of the result is equal to the max *scale* of
both operands.
**-**
: The top two values are popped off the stack, subtracted, and the result is
pushed onto the stack. The *scale* of the result is equal to the max
*scale* of both operands.
**\***
: The top two values are popped off the stack, multiplied, and the result is
pushed onto the stack. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result
is equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The top two values are popped off the stack, divided, and the result is
pushed onto the stack. The *scale* of the result is equal to **scale**.
The first value popped off of the stack must be non-zero.
**%**
: The top two values are popped off the stack, remaindered, and the result is
pushed onto the stack.
Remaindering is equivalent to 1) Computing **a/b** to current **scale**, and
2) Using the result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The first value popped off of the stack must be non-zero.
**~**
: The top two values are popped off the stack, divided and remaindered, and
the results (divided first, remainder second) are pushed onto the stack.
This is equivalent to **x y / x y %** except that **x** and **y** are only
evaluated once.
The first value popped off of the stack must be non-zero.
This is a **non-portable extension**.
**\^**
: The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack. The *scale* of
the result is equal to **scale**.
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
**v**
: The top value is popped off the stack, its square root is computed, and the
result is pushed onto the stack. The *scale* of the result is equal to
**scale**.
The value popped off of the stack must be non-negative.
**\_**
: If this command *immediately* precedes a number (i.e., no spaces or other
commands), then that number is input as a negative number.
Otherwise, the top value on the stack is popped and copied, and the copy is
negated and pushed onto the stack. This behavior without a number is a
**non-portable extension**.
**b**
: The top value is popped off the stack, and if it is zero, it is pushed back
onto the stack. Otherwise, its absolute value is pushed onto the stack.
This is a **non-portable extension**.
**|**
: The top three values are popped off the stack, a modular exponentiation is
computed, and the result is pushed onto the stack.
The first value popped is used as the reduction modulus and must be an
integer and non-zero. The second value popped is used as the exponent and
must be an integer and non-negative. The third value popped is the base and
must be an integer.
This is a **non-portable extension**.
**G**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if they are equal, or **0** otherwise.
This is a **non-portable extension**.
**N**
: The top value is popped off of the stack, and if it a **0**, a **1** is
pushed; otherwise, a **0** is pushed.
This is a **non-portable extension**.
**(**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than the second, or **0** otherwise.
This is a **non-portable extension**.
**{**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than or equal to the second, or **0**
otherwise.
This is a **non-portable extension**.
**)**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than the second, or **0** otherwise.
This is a **non-portable extension**.
**}**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than or equal to the second, or
**0** otherwise.
This is a **non-portable extension**.
**M**
: The top two values are popped off of the stack. If they are both non-zero, a
**1** is pushed onto the stack. If either of them is zero, or both of them
are, then a **0** is pushed onto the stack.
This is like the **&&** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
**m**
: The top two values are popped off of the stack. If at least one of them is
non-zero, a **1** is pushed onto the stack. If both of them are zero, then a
**0** is pushed onto the stack.
This is like the **||** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
## Stack Control
These commands control the stack.
**c**
: Removes all items from ("clears") the stack.
**d**
: Copies the item on top of the stack ("duplicates") and pushes the copy onto
the stack.
**r**
: Swaps ("reverses") the two top items on the stack.
**R**
: Pops ("removes") the top value from the stack.
## Register Control
These commands control registers (see the **REGISTERS** section).
**s***r*
: Pops the value off the top of the stack and stores it into register *r*.
**l***r*
: Copies the value in register *r* and pushes it onto the stack. This does not
alter the contents of *r*.
**S***r*
: Pops the value off the top of the (main) stack and pushes it onto the stack
of register *r*. The previous value of the register becomes inaccessible.
**L***r*
: Pops the value off the top of the stack for register *r* and push it onto
the main stack. The previous value in the stack for register *r*, if any, is
now accessible via the **l***r* command.
## Parameters
These commands control the values of **ibase**, **obase**, and **scale**. Also
see the **SYNTAX** section.
**i**
: Pops the value off of the top of the stack and uses it to set **ibase**,
which must be between **2** and **16**, inclusive.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**o**
: Pops the value off of the top of the stack and uses it to set **obase**,
which must be between **2** and **DC_BASE_MAX**, inclusive (see the
**LIMITS** section).
If the value on top of the stack has any *scale*, the *scale* is ignored.
**k**
: Pops the value off of the top of the stack and uses it to set **scale**,
which must be non-negative.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**I**
: Pushes the current value of **ibase** onto the main stack.
**O**
: Pushes the current value of **obase** onto the main stack.
**K**
: Pushes the current value of **scale** onto the main stack.
**T**
: Pushes the maximum allowable value of **ibase** onto the main stack.
This is a **non-portable extension**.
**U**
: Pushes the maximum allowable value of **obase** onto the main stack.
This is a **non-portable extension**.
**V**
: Pushes the maximum allowable value of **scale** onto the main stack.
This is a **non-portable extension**.
## Strings
The following commands control strings.
dc(1) can work with both numbers and strings, and registers (see the
**REGISTERS** section) can hold both strings and numbers. dc(1) always knows
whether the contents of a register are a string or a number.
While arithmetic operations have to have numbers, and will print an error if
given a string, other commands accept strings.
Strings can also be executed as macros. For example, if the string **[1pR]** is
executed as a macro, then the code **1pR** is executed, meaning that the **1**
will be printed with a newline after and then popped from the stack.
**\[**_characters_**\]**
: Makes a string containing *characters* and pushes it onto the stack.
If there are brackets (**\[** and **\]**) in the string, then they must be
balanced. Unbalanced brackets can be escaped using a backslash (**\\**)
character.
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the (first)
backslash is not.
**a**
: The value on top of the stack is popped.
If it is a number, it is truncated and its absolute value is taken. The
result mod **UCHAR_MAX+1** is calculated. If that result is **0**, push an
empty string; otherwise, push a one-character string where the character is
the result of the mod interpreted as an ASCII character.
If it is a string, then a new string is made. If the original string is
empty, the new string is empty. If it is not, then the first character of
the original string is used to create the new string as a one-character
string. The new string is then pushed onto the stack.
This is a **non-portable extension**.
**x**
: Pops a value off of the top of the stack.
If it is a number, it is pushed back onto the stack.
If it is a string, it is executed as a macro.
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
**\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is greater than the second, then the contents of register
*r* are executed.
For example, **0 1>a** will execute the contents of register **a**, and
**1 0>a** will not.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not greater than the second (less than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is less than the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not less than the second (greater than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is equal to the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not equal to the second, then the contents of register
*r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**?**
: Reads a line from the **stdin** and executes it. This is to allow macros to
request input from users.
**q**
: During execution of a macro, this exits the execution of that macro and the
execution of the macro that executed it. If there are no macros, or only one
macro executing, dc(1) exits.
**Q**
: Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack. If the number
of levels to pop is greater than the number of executing macros, dc(1)
exits.
## Status
These commands query status of the stack or its top value.
**Z**
: Pops a value off of the stack.
If it is a number, calculates the number of significant decimal digits it
has and pushes the result.
If it is a string, pushes the number of characters the string has.
**X**
: Pops a value off of the stack.
If it is a number, pushes the *scale* of the value onto the stack.
If it is a string, pushes **0**.
**z**
: Pushes the current stack depth (before execution of this command).
## Arrays
These commands manipulate arrays.
**:***r*
: Pops the top two values off of the stack. The second value will be stored in
the array *r* (see the **REGISTERS** section), indexed by the first value.
**;***r*
: Pops the value on top of the stack and uses it as an index into the array
*r*. The selected value is then pushed onto the stack.
# REGISTERS
Registers are names that can store strings, numbers, and arrays. (Number/string
registers do not interfere with array registers.)
Each register is also its own stack, so the current register value is the top of
the stack for the register. All registers, when first referenced, have one value
(**0**) in their stack.
In non-extended register mode, a register name is just the single character that
follows any command that needs a register name. The only exception is a newline
(**'\\n'**); it is a parse error for a newline to be used as a register name.
## Extended Register Mode
Unlike most other dc(1) implentations, this dc(1) provides nearly unlimited
amounts of registers, if extended register mode is enabled.
If extended register mode is enabled (**-x** or **--extended-register**
command-line arguments are given), then normal single character registers are
used *unless* the character immediately following a command that needs a
register name is a space (according to **isspace()**) and not a newline
(**'\\n'**).
In that case, the register name is found according to the regex
**\[a-z\]\[a-z0-9\_\]\*** (like bc(1) identifiers), and it is a parse error if
the next non-space characters do not match that regex.
# RESET
When dc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any macros that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
macros returned) is skipped.
Thus, when dc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
# PERFORMANCE
Most dc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This dc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **DC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **DC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**DC_BASE_DIGS**.
In addition, this dc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **DC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on dc(1):
**DC_LONG_BIT**
: The number of bits in the **long** type in the environment where dc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**DC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **DC_LONG_BIT**.
**DC_BASE_POW**
: The max decimal number that each large integer can store (see
**DC_BASE_DIGS**) plus **1**. Depends on **DC_BASE_DIGS**.
**DC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **DC_LONG_BIT**.
**DC_BASE_MAX**
: The maximum output base. Set at **DC_BASE_POW**.
**DC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**DC_SCALE_MAX**
: The maximum **scale**. Set at **DC_OVERFLOW_MAX-1**.
**DC_STRING_MAX**
: The maximum length of strings. Set at **DC_OVERFLOW_MAX-1**.
**DC_NAME_MAX**
: The maximum length of identifiers. Set at **DC_OVERFLOW_MAX-1**.
**DC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **DC_OVERFLOW_MAX-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**DC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
dc(1) recognizes the following environment variables:
**DC_ENV_ARGS**
: This is another way to give command-line arguments to dc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **DC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs. Another use would
be to use the **-e** option to set **scale** to a value other than **0**.
The code that parses **DC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some dc file.dc"** will be correctly parsed, but the string
**"/home/gavin/some \"dc\" file.dc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
- double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
+ double quotes as the outside quotes, as in **"some 'dc' file.dc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **DC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**DC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), dc(1) will output
lines to that length, including the backslash newline combo. The default
line length is **70**.
**DC_EXPR_EXIT**
: If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the **-e** and/or
**-f** command-line options (and any equivalents).
# EXIT STATUS
dc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**) operator.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, and using a token where it is
invalid.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, and attempting an operation when
the stack has too few elements.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (dc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, dc(1) always exits
and returns **4**, no matter what mode dc(1) is in.
The other statuses will only be returned when dc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since dc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, dc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, dc(1) turns
on "TTY mode."
The prompt is enabled in TTY mode.
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause dc(1) to stop execution of the current input. If
dc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If dc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If dc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to dc(1) as it is executing a file, it
can seem as though dc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause dc(1) to clean up and exit, and it uses the
default handler for all other signals.
# SEE ALSO
bc(1)
# STANDARDS
The dc(1) utility operators are compliant with the operators in the bc(1)
[IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1] specification.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHOR
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
diff --git a/contrib/bc/manuals/dc/EHNP.1 b/contrib/bc/manuals/dc/EHNP.1
index 9f331a30e310..c4e2acf5544e 100644
--- a/contrib/bc/manuals/dc/EHNP.1
+++ b/contrib/bc/manuals/dc/EHNP.1
@@ -1,1104 +1,1117 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "DC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "DC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH Name
.PP
dc - arbitrary-precision decimal reverse-Polish notation calculator
.SH SYNOPSIS
.PP
\f[B]dc\f[R] [\f[B]-hiPvVx\f[R]] [\f[B]\[en]version\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]no-prompt\f[R]] [\f[B]\[en]extended-register\f[R]]
[\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
dc(1) is an arbitrary-precision calculator.
It uses a stack (reverse Polish notation) to store numbers and results
of computations.
Arithmetic operations pop arguments off of the stack and push the
results.
.PP
If no files are given on the command-line as extra arguments (i.e., not
as \f[B]-f\f[R] or \f[B]\[en]file\f[R] arguments), then dc(1) reads from
\f[B]stdin\f[R].
Otherwise, those files are processed, and dc(1) will then exit.
.PP
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where \f[B]-e\f[R] (\f[B]\[en]expression\f[R]) and
\f[B]-f\f[R] (\f[B]\[en]file\f[R]) arguments cause dc(1) to execute them
and exit.
The reason for this is that this dc(1) allows users to set arguments in
the environment variable \f[B]DC_ENV_ARGS\f[R] (see the \f[B]ENVIRONMENT
VARIABLES\f[R] section).
Any expressions given on the command-line should be used to set up a
standard environment.
For example, if a user wants the \f[B]scale\f[R] always set to
\f[B]10\f[R], they can set \f[B]DC_ENV_ARGS\f[R] to \f[B]-e 10k\f[R],
and this dc(1) will always start with a \f[B]scale\f[R] of \f[B]10\f[R].
.PP
If users want to have dc(1) exit after processing all input from
\f[B]-e\f[R] and \f[B]-f\f[R] arguments (and their equivalents), then
they can just simply add \f[B]-e q\f[R] as the last command-line
argument or define the environment variable \f[B]DC_EXPR_EXIT\f[R].
.SH OPTIONS
.PP
The following are the options that dc(1) accepts.
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
This option is a no-op.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-x\f[R] \f[B]\[en]extended-register\f[R]
Enables extended register mode.
See the \f[I]Extended Register Mode\f[R] subsection of the
\f[B]REGISTERS\f[R] section for more information.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]DC_ENV_ARGS\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]dc >&-\f[R], it will quit with an error.
This is done so that dc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]dc 2>&-\f[R], it will quit with an error.
This is done so that dc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
Each item in the input source code, either a number (see the
\f[B]NUMBERS\f[R] section) or a command (see the \f[B]COMMANDS\f[R]
section), is processed and executed, in order.
Input is processed immediately when entered.
.PP
\f[B]ibase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to interpret constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]ibase\f[R] is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in dc(1)
programs with the \f[B]T\f[R] command.
.PP
\f[B]obase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]DC_BASE_MAX\f[R] and
can be queried with the \f[B]U\f[R] command.
The min allowable value for \f[B]obase\f[R] is \f[B]2\f[R].
Values are output in the specified base.
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a register (see the \f[B]REGISTERS\f[R] section) that sets the
precision of any operations (with exceptions).
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] can be queried in dc(1)
programs with the \f[B]V\f[R] command.
.SS Comments
.PP
Comments go from \f[B]#\f[R] until, and not including, the next newline.
This is a \f[B]non-portable extension\f[R].
.SH NUMBERS
.PP
Numbers are strings made up of digits, uppercase letters up to
\f[B]F\f[R], and at most \f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]DC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]F\f[R] alone always equals decimal \f[B]15\f[R].
.SH COMMANDS
.PP
The valid commands are listed below.
.SS Printing
.PP
These commands are used for printing.
.TP
\f[B]p\f[R]
Prints the value on top of the stack, whether number or string, and
prints a newline after.
.RS
.PP
This does not alter the stack.
.RE
.TP
\f[B]n\f[R]
Prints the value on top of the stack, whether number or string, and pops
it off of the stack.
.TP
\f[B]P\f[R]
Pops a value off the stack.
.RS
.PP
If the value is a number, it is truncated and the absolute value of the
result is printed as though \f[B]obase\f[R] is \f[B]UCHAR_MAX+1\f[R] and
each digit is interpreted as an ASCII character, making it a byte
stream.
.PP
If the value is a string, it is printed without a trailing newline.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]f\f[R]
Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
.RS
.PP
Users should use this command when they get lost.
.RE
.SS Arithmetic
.PP
These are the commands used for arithmetic.
.TP
\f[B]+\f[R]
The top two values are popped off the stack, added, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]-\f[R]
The top two values are popped off the stack, subtracted, and the result
is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]*\f[R]
The top two values are popped off the stack, multiplied, and the result
is pushed onto the stack.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The top two values are popped off the stack, divided, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]%\f[R]
The top two values are popped off the stack, remaindered, and the result
is pushed onto the stack.
.RS
.PP
Remaindering is equivalent to 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R], and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]\[ti]\f[R]
The top two values are popped off the stack, divided and remaindered,
and the results (divided first, remainder second) are pushed onto the
stack.
This is equivalent to \f[B]x y / x y %\f[R] except that \f[B]x\f[R] and
\f[B]y\f[R] are only evaluated once.
.RS
.PP
The first value popped off of the stack must be non-zero.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
.RE
.TP
\f[B]v\f[R]
The top value is popped off the stack, its square root is computed, and
the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The value popped off of the stack must be non-negative.
.RE
.TP
\f[B]_\f[R]
If this command \f[I]immediately\f[R] precedes a number (i.e., no spaces
or other commands), then that number is input as a negative number.
.RS
.PP
Otherwise, the top value on the stack is popped and copied, and the copy
is negated and pushed onto the stack.
This behavior without a number is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]b\f[R]
The top value is popped off the stack, and if it is zero, it is pushed
back onto the stack.
Otherwise, its absolute value is pushed onto the stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]|\f[R]
The top three values are popped off the stack, a modular exponentiation
is computed, and the result is pushed onto the stack.
.RS
.PP
The first value popped is used as the reduction modulus and must be an
integer and non-zero.
The second value popped is used as the exponent and must be an integer
and non-negative.
The third value popped is the base and must be an integer.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]G\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if they are equal, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]N\f[R]
The top value is popped off of the stack, and if it a \f[B]0\f[R], a
\f[B]1\f[R] is pushed; otherwise, a \f[B]0\f[R] is pushed.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B](\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]{\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than or equal to the second,
or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B])\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]}\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than or equal to the
second, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]M\f[R]
The top two values are popped off of the stack.
If they are both non-zero, a \f[B]1\f[R] is pushed onto the stack.
If either of them is zero, or both of them are, then a \f[B]0\f[R] is
pushed onto the stack.
.RS
.PP
This is like the \f[B]&&\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]m\f[R]
The top two values are popped off of the stack.
If at least one of them is non-zero, a \f[B]1\f[R] is pushed onto the
stack.
If both of them are zero, then a \f[B]0\f[R] is pushed onto the stack.
.RS
.PP
This is like the \f[B]||\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Stack Control
.PP
These commands control the stack.
.TP
\f[B]c\f[R]
Removes all items from (\[lq]clears\[rq]) the stack.
.TP
\f[B]d\f[R]
Copies the item on top of the stack (\[lq]duplicates\[rq]) and pushes
the copy onto the stack.
.TP
\f[B]r\f[R]
Swaps (\[lq]reverses\[rq]) the two top items on the stack.
.TP
\f[B]R\f[R]
Pops (\[lq]removes\[rq]) the top value from the stack.
.SS Register Control
.PP
These commands control registers (see the \f[B]REGISTERS\f[R] section).
.TP
\f[B]s\f[R]\f[I]r\f[R]
Pops the value off the top of the stack and stores it into register
\f[I]r\f[R].
.TP
\f[B]l\f[R]\f[I]r\f[R]
Copies the value in register \f[I]r\f[R] and pushes it onto the stack.
This does not alter the contents of \f[I]r\f[R].
.TP
\f[B]S\f[R]\f[I]r\f[R]
Pops the value off the top of the (main) stack and pushes it onto the
stack of register \f[I]r\f[R].
The previous value of the register becomes inaccessible.
.TP
\f[B]L\f[R]\f[I]r\f[R]
Pops the value off the top of the stack for register \f[I]r\f[R] and
push it onto the main stack.
The previous value in the stack for register \f[I]r\f[R], if any, is now
accessible via the \f[B]l\f[R]\f[I]r\f[R] command.
.SS Parameters
.PP
These commands control the values of \f[B]ibase\f[R], \f[B]obase\f[R],
and \f[B]scale\f[R].
Also see the \f[B]SYNTAX\f[R] section.
.TP
\f[B]i\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]ibase\f[R], which must be between \f[B]2\f[R] and \f[B]16\f[R],
inclusive.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]o\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]obase\f[R], which must be between \f[B]2\f[R] and
\f[B]DC_BASE_MAX\f[R], inclusive (see the \f[B]LIMITS\f[R] section).
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]k\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]scale\f[R], which must be non-negative.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]I\f[R]
Pushes the current value of \f[B]ibase\f[R] onto the main stack.
.TP
\f[B]O\f[R]
Pushes the current value of \f[B]obase\f[R] onto the main stack.
.TP
\f[B]K\f[R]
Pushes the current value of \f[B]scale\f[R] onto the main stack.
.TP
\f[B]T\f[R]
Pushes the maximum allowable value of \f[B]ibase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]U\f[R]
Pushes the maximum allowable value of \f[B]obase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]V\f[R]
Pushes the maximum allowable value of \f[B]scale\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Strings
.PP
The following commands control strings.
.PP
dc(1) can work with both numbers and strings, and registers (see the
\f[B]REGISTERS\f[R] section) can hold both strings and numbers.
dc(1) always knows whether the contents of a register are a string or a
number.
.PP
While arithmetic operations have to have numbers, and will print an
error if given a string, other commands accept strings.
.PP
Strings can also be executed as macros.
For example, if the string \f[B][1pR]\f[R] is executed as a macro, then
the code \f[B]1pR\f[R] is executed, meaning that the \f[B]1\f[R] will be
printed with a newline after and then popped from the stack.
.TP
\f[B][\f[R]_characters_\f[B]]\f[R]
Makes a string containing \f[I]characters\f[R] and pushes it onto the
stack.
.RS
.PP
If there are brackets (\f[B][\f[R] and \f[B]]\f[R]) in the string, then
they must be balanced.
Unbalanced brackets can be escaped using a backslash (\f[B]\[rs]\f[R])
character.
.PP
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the
(first) backslash is not.
.RE
.TP
\f[B]a\f[R]
The value on top of the stack is popped.
.RS
.PP
If it is a number, it is truncated and its absolute value is taken.
The result mod \f[B]UCHAR_MAX+1\f[R] is calculated.
If that result is \f[B]0\f[R], push an empty string; otherwise, push a
one-character string where the character is the result of the mod
interpreted as an ASCII character.
.PP
If it is a string, then a new string is made.
If the original string is empty, the new string is empty.
If it is not, then the first character of the original string is used to
create the new string as a one-character string.
The new string is then pushed onto the stack.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]x\f[R]
Pops a value off of the top of the stack.
.RS
.PP
If it is a number, it is pushed back onto the stack.
.PP
If it is a string, it is executed as a macro.
.PP
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is greater than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
For example, \f[B]0 1>a\f[R] will execute the contents of register
\f[B]a\f[R], and \f[B]1 0>a\f[R] will not.
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not greater than the second (less than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is less than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not less than the second (greater than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is equal to the second, then the contents of register
\f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not equal to the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]?\f[R]
Reads a line from the \f[B]stdin\f[R] and executes it.
This is to allow macros to request input from users.
.TP
\f[B]q\f[R]
During execution of a macro, this exits the execution of that macro and
the execution of the macro that executed it.
If there are no macros, or only one macro executing, dc(1) exits.
.TP
\f[B]Q\f[R]
Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack.
If the number of levels to pop is greater than the number of executing
macros, dc(1) exits.
.SS Status
.PP
These commands query status of the stack or its top value.
.TP
\f[B]Z\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, calculates the number of significant decimal digits
it has and pushes the result.
.PP
If it is a string, pushes the number of characters the string has.
.RE
.TP
\f[B]X\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, pushes the \f[I]scale\f[R] of the value onto the
stack.
.PP
If it is a string, pushes \f[B]0\f[R].
.RE
.TP
\f[B]z\f[R]
Pushes the current stack depth (before execution of this command).
.SS Arrays
.PP
These commands manipulate arrays.
.TP
\f[B]:\f[R]\f[I]r\f[R]
Pops the top two values off of the stack.
The second value will be stored in the array \f[I]r\f[R] (see the
\f[B]REGISTERS\f[R] section), indexed by the first value.
.TP
\f[B];\f[R]\f[I]r\f[R]
Pops the value on top of the stack and uses it as an index into the
array \f[I]r\f[R].
The selected value is then pushed onto the stack.
.SH REGISTERS
.PP
Registers are names that can store strings, numbers, and arrays.
(Number/string registers do not interfere with array registers.)
.PP
Each register is also its own stack, so the current register value is
the top of the stack for the register.
All registers, when first referenced, have one value (\f[B]0\f[R]) in
their stack.
.PP
In non-extended register mode, a register name is just the single
character that follows any command that needs a register name.
The only exception is a newline (\f[B]`\[rs]n'\f[R]); it is a parse
error for a newline to be used as a register name.
.SS Extended Register Mode
.PP
Unlike most other dc(1) implentations, this dc(1) provides nearly
unlimited amounts of registers, if extended register mode is enabled.
.PP
If extended register mode is enabled (\f[B]-x\f[R] or
\f[B]\[en]extended-register\f[R] command-line arguments are given), then
normal single character registers are used \f[I]unless\f[R] the
character immediately following a command that needs a register name is
a space (according to \f[B]isspace()\f[R]) and not a newline
(\f[B]`\[rs]n'\f[R]).
.PP
In that case, the register name is found according to the regex
\f[B][a-z][a-z0-9_]*\f[R] (like bc(1) identifiers), and it is a parse
error if the next non-space characters do not match that regex.
.SH RESET
.PP
When dc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any macros that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all macros returned) is skipped.
.PP
Thus, when dc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.SH PERFORMANCE
.PP
Most dc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This dc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]DC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]DC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]DC_BASE_DIGS\f[R].
.PP
In addition, this dc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]DC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on dc(1):
.TP
\f[B]DC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
dc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]DC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]DC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]DC_BASE_DIGS\f[R].
.TP
\f[B]DC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]DC_BASE_POW\f[R].
.TP
\f[B]DC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]DC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]DC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
dc(1) recognizes the following environment variables:
.TP
\f[B]DC_ENV_ARGS\f[R]
This is another way to give command-line arguments to dc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]DC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs.
Another use would be to use the \f[B]-e\f[R] option to set
\f[B]scale\f[R] to a value other than \f[B]0\f[R].
.RS
.PP
The code that parses \f[B]DC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some dc file.dc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]dc\[dq] file.dc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
-in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
+in \f[B]\[rq]some `dc' file.dc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]DC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]DC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), dc(1) will output lines to that length,
including the backslash newline combo.
The default line length is \f[B]70\f[R].
.TP
\f[B]DC_EXPR_EXIT\f[R]
If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the
\f[B]-e\f[R] and/or \f[B]-f\f[R] command-line options (and any
equivalents).
.SH EXIT STATUS
.PP
dc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, attempting to convert a negative number to a hardware
integer, overflow when converting a number to a hardware integer, and
attempting to use a non-integer where an integer is required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]) operator.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, and using a
token where it is invalid.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, and attempting an operation when the
stack has too few elements.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (dc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, dc(1)
always exits and returns \f[B]4\f[R], no matter what mode dc(1) is in.
.PP
The other statuses will only be returned when dc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
dc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, dc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, dc(1) turns on \[lq]TTY mode.\[rq]
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause dc(1) to stop execution of the
current input.
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If dc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If dc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to dc(1) as it is
executing a file, it can seem as though dc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause dc(1) to clean up and
exit, and it uses the default handler for all other signals.
.SH SEE ALSO
.PP
bc(1)
.SH STANDARDS
.PP
The dc(1) utility operators are compliant with the operators in the
bc(1) IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHOR
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/dc/EHNP.1.md b/contrib/bc/manuals/dc/EHNP.1.md
index d21343137a5f..acbd58e543dc 100644
--- a/contrib/bc/manuals/dc/EHNP.1.md
+++ b/contrib/bc/manuals/dc/EHNP.1.md
@@ -1,1008 +1,1017 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# Name
dc - arbitrary-precision decimal reverse-Polish notation calculator
# SYNOPSIS
**dc** [**-hiPvVx**] [**--version**] [**--help**] [**--interactive**] [**--no-prompt**] [**--extended-register**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...] [*file*...]
# DESCRIPTION
dc(1) is an arbitrary-precision calculator. It uses a stack (reverse Polish
notation) to store numbers and results of computations. Arithmetic operations
pop arguments off of the stack and push the results.
If no files are given on the command-line as extra arguments (i.e., not as
**-f** or **--file** arguments), then dc(1) reads from **stdin**. Otherwise,
those files are processed, and dc(1) will then exit.
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where **-e** (**--expression**) and **-f** (**--file**)
arguments cause dc(1) to execute them and exit. The reason for this is that this
dc(1) allows users to set arguments in the environment variable **DC_ENV_ARGS**
(see the **ENVIRONMENT VARIABLES** section). Any expressions given on the
command-line should be used to set up a standard environment. For example, if a
user wants the **scale** always set to **10**, they can set **DC_ENV_ARGS** to
**-e 10k**, and this dc(1) will always start with a **scale** of **10**.
If users want to have dc(1) exit after processing all input from **-e** and
**-f** arguments (and their equivalents), then they can just simply add **-e q**
as the last command-line argument or define the environment variable
**DC_EXPR_EXIT**.
# OPTIONS
The following are the options that dc(1) accepts.
**-h**, **--help**
: Prints a usage message and quits.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-P**, **--no-prompt**
: This option is a no-op.
This is a **non-portable extension**.
**-x** **--extended-register**
: Enables extended register mode. See the *Extended Register Mode* subsection
of the **REGISTERS** section for more information.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **DC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **dc <file> >&-**, it will quit with an error. This
is done so that dc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **dc <file> 2>&-**, it will quit with an error. This
is done so that dc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
Each item in the input source code, either a number (see the **NUMBERS**
section) or a command (see the **COMMANDS** section), is processed and executed,
in order. Input is processed immediately when entered.
**ibase** is a register (see the **REGISTERS** section) that determines how to
interpret constant numbers. It is the "input" base, or the number base used for
interpreting input numbers. **ibase** is initially **10**. The max allowable
value for **ibase** is **16**. The min allowable value for **ibase** is **2**.
The max allowable value for **ibase** can be queried in dc(1) programs with the
**T** command.
**obase** is a register (see the **REGISTERS** section) that determines how to
output results. It is the "output" base, or the number base used for outputting
numbers. **obase** is initially **10**. The max allowable value for **obase** is
**DC_BASE_MAX** and can be queried with the **U** command. The min allowable
value for **obase** is **2**. Values are output in the specified base.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a register (see the
**REGISTERS** section) that sets the precision of any operations (with
exceptions). **scale** is initially **0**. **scale** cannot be negative. The max
allowable value for **scale** can be queried in dc(1) programs with the **V**
command.
## Comments
Comments go from **#** until, and not including, the next newline. This is a
**non-portable extension**.
# NUMBERS
Numbers are strings made up of digits, uppercase letters up to **F**, and at
most **1** period for a radix. Numbers can have up to **DC_NUM_MAX** digits.
Uppercase letters are equal to **9** + their position in the alphabet (i.e.,
**A** equals **10**, or **9+1**). If a digit or letter makes no sense with the
current value of **ibase**, they are set to the value of the highest valid digit
in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **F** alone always equals decimal
**15**.
# COMMANDS
The valid commands are listed below.
## Printing
These commands are used for printing.
**p**
: Prints the value on top of the stack, whether number or string, and prints a
newline after.
This does not alter the stack.
**n**
: Prints the value on top of the stack, whether number or string, and pops it
off of the stack.
**P**
: Pops a value off the stack.
If the value is a number, it is truncated and the absolute value of the
result is printed as though **obase** is **UCHAR_MAX+1** and each digit is
interpreted as an ASCII character, making it a byte stream.
If the value is a string, it is printed without a trailing newline.
This is a **non-portable extension**.
**f**
: Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
Users should use this command when they get lost.
## Arithmetic
These are the commands used for arithmetic.
**+**
: The top two values are popped off the stack, added, and the result is pushed
onto the stack. The *scale* of the result is equal to the max *scale* of
both operands.
**-**
: The top two values are popped off the stack, subtracted, and the result is
pushed onto the stack. The *scale* of the result is equal to the max
*scale* of both operands.
**\***
: The top two values are popped off the stack, multiplied, and the result is
pushed onto the stack. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result
is equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The top two values are popped off the stack, divided, and the result is
pushed onto the stack. The *scale* of the result is equal to **scale**.
The first value popped off of the stack must be non-zero.
**%**
: The top two values are popped off the stack, remaindered, and the result is
pushed onto the stack.
Remaindering is equivalent to 1) Computing **a/b** to current **scale**, and
2) Using the result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The first value popped off of the stack must be non-zero.
**~**
: The top two values are popped off the stack, divided and remaindered, and
the results (divided first, remainder second) are pushed onto the stack.
This is equivalent to **x y / x y %** except that **x** and **y** are only
evaluated once.
The first value popped off of the stack must be non-zero.
This is a **non-portable extension**.
**\^**
: The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack. The *scale* of
the result is equal to **scale**.
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
**v**
: The top value is popped off the stack, its square root is computed, and the
result is pushed onto the stack. The *scale* of the result is equal to
**scale**.
The value popped off of the stack must be non-negative.
**\_**
: If this command *immediately* precedes a number (i.e., no spaces or other
commands), then that number is input as a negative number.
Otherwise, the top value on the stack is popped and copied, and the copy is
negated and pushed onto the stack. This behavior without a number is a
**non-portable extension**.
**b**
: The top value is popped off the stack, and if it is zero, it is pushed back
onto the stack. Otherwise, its absolute value is pushed onto the stack.
This is a **non-portable extension**.
**|**
: The top three values are popped off the stack, a modular exponentiation is
computed, and the result is pushed onto the stack.
The first value popped is used as the reduction modulus and must be an
integer and non-zero. The second value popped is used as the exponent and
must be an integer and non-negative. The third value popped is the base and
must be an integer.
This is a **non-portable extension**.
**G**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if they are equal, or **0** otherwise.
This is a **non-portable extension**.
**N**
: The top value is popped off of the stack, and if it a **0**, a **1** is
pushed; otherwise, a **0** is pushed.
This is a **non-portable extension**.
**(**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than the second, or **0** otherwise.
This is a **non-portable extension**.
**{**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than or equal to the second, or **0**
otherwise.
This is a **non-portable extension**.
**)**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than the second, or **0** otherwise.
This is a **non-portable extension**.
**}**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than or equal to the second, or
**0** otherwise.
This is a **non-portable extension**.
**M**
: The top two values are popped off of the stack. If they are both non-zero, a
**1** is pushed onto the stack. If either of them is zero, or both of them
are, then a **0** is pushed onto the stack.
This is like the **&&** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
**m**
: The top two values are popped off of the stack. If at least one of them is
non-zero, a **1** is pushed onto the stack. If both of them are zero, then a
**0** is pushed onto the stack.
This is like the **||** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
## Stack Control
These commands control the stack.
**c**
: Removes all items from ("clears") the stack.
**d**
: Copies the item on top of the stack ("duplicates") and pushes the copy onto
the stack.
**r**
: Swaps ("reverses") the two top items on the stack.
**R**
: Pops ("removes") the top value from the stack.
## Register Control
These commands control registers (see the **REGISTERS** section).
**s***r*
: Pops the value off the top of the stack and stores it into register *r*.
**l***r*
: Copies the value in register *r* and pushes it onto the stack. This does not
alter the contents of *r*.
**S***r*
: Pops the value off the top of the (main) stack and pushes it onto the stack
of register *r*. The previous value of the register becomes inaccessible.
**L***r*
: Pops the value off the top of the stack for register *r* and push it onto
the main stack. The previous value in the stack for register *r*, if any, is
now accessible via the **l***r* command.
## Parameters
These commands control the values of **ibase**, **obase**, and **scale**. Also
see the **SYNTAX** section.
**i**
: Pops the value off of the top of the stack and uses it to set **ibase**,
which must be between **2** and **16**, inclusive.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**o**
: Pops the value off of the top of the stack and uses it to set **obase**,
which must be between **2** and **DC_BASE_MAX**, inclusive (see the
**LIMITS** section).
If the value on top of the stack has any *scale*, the *scale* is ignored.
**k**
: Pops the value off of the top of the stack and uses it to set **scale**,
which must be non-negative.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**I**
: Pushes the current value of **ibase** onto the main stack.
**O**
: Pushes the current value of **obase** onto the main stack.
**K**
: Pushes the current value of **scale** onto the main stack.
**T**
: Pushes the maximum allowable value of **ibase** onto the main stack.
This is a **non-portable extension**.
**U**
: Pushes the maximum allowable value of **obase** onto the main stack.
This is a **non-portable extension**.
**V**
: Pushes the maximum allowable value of **scale** onto the main stack.
This is a **non-portable extension**.
## Strings
The following commands control strings.
dc(1) can work with both numbers and strings, and registers (see the
**REGISTERS** section) can hold both strings and numbers. dc(1) always knows
whether the contents of a register are a string or a number.
While arithmetic operations have to have numbers, and will print an error if
given a string, other commands accept strings.
Strings can also be executed as macros. For example, if the string **[1pR]** is
executed as a macro, then the code **1pR** is executed, meaning that the **1**
will be printed with a newline after and then popped from the stack.
**\[**_characters_**\]**
: Makes a string containing *characters* and pushes it onto the stack.
If there are brackets (**\[** and **\]**) in the string, then they must be
balanced. Unbalanced brackets can be escaped using a backslash (**\\**)
character.
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the (first)
backslash is not.
**a**
: The value on top of the stack is popped.
If it is a number, it is truncated and its absolute value is taken. The
result mod **UCHAR_MAX+1** is calculated. If that result is **0**, push an
empty string; otherwise, push a one-character string where the character is
the result of the mod interpreted as an ASCII character.
If it is a string, then a new string is made. If the original string is
empty, the new string is empty. If it is not, then the first character of
the original string is used to create the new string as a one-character
string. The new string is then pushed onto the stack.
This is a **non-portable extension**.
**x**
: Pops a value off of the top of the stack.
If it is a number, it is pushed back onto the stack.
If it is a string, it is executed as a macro.
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
**\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is greater than the second, then the contents of register
*r* are executed.
For example, **0 1>a** will execute the contents of register **a**, and
**1 0>a** will not.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not greater than the second (less than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is less than the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not less than the second (greater than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is equal to the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not equal to the second, then the contents of register
*r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**?**
: Reads a line from the **stdin** and executes it. This is to allow macros to
request input from users.
**q**
: During execution of a macro, this exits the execution of that macro and the
execution of the macro that executed it. If there are no macros, or only one
macro executing, dc(1) exits.
**Q**
: Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack. If the number
of levels to pop is greater than the number of executing macros, dc(1)
exits.
## Status
These commands query status of the stack or its top value.
**Z**
: Pops a value off of the stack.
If it is a number, calculates the number of significant decimal digits it
has and pushes the result.
If it is a string, pushes the number of characters the string has.
**X**
: Pops a value off of the stack.
If it is a number, pushes the *scale* of the value onto the stack.
If it is a string, pushes **0**.
**z**
: Pushes the current stack depth (before execution of this command).
## Arrays
These commands manipulate arrays.
**:***r*
: Pops the top two values off of the stack. The second value will be stored in
the array *r* (see the **REGISTERS** section), indexed by the first value.
**;***r*
: Pops the value on top of the stack and uses it as an index into the array
*r*. The selected value is then pushed onto the stack.
# REGISTERS
Registers are names that can store strings, numbers, and arrays. (Number/string
registers do not interfere with array registers.)
Each register is also its own stack, so the current register value is the top of
the stack for the register. All registers, when first referenced, have one value
(**0**) in their stack.
In non-extended register mode, a register name is just the single character that
follows any command that needs a register name. The only exception is a newline
(**'\\n'**); it is a parse error for a newline to be used as a register name.
## Extended Register Mode
Unlike most other dc(1) implentations, this dc(1) provides nearly unlimited
amounts of registers, if extended register mode is enabled.
If extended register mode is enabled (**-x** or **--extended-register**
command-line arguments are given), then normal single character registers are
used *unless* the character immediately following a command that needs a
register name is a space (according to **isspace()**) and not a newline
(**'\\n'**).
In that case, the register name is found according to the regex
**\[a-z\]\[a-z0-9\_\]\*** (like bc(1) identifiers), and it is a parse error if
the next non-space characters do not match that regex.
# RESET
When dc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any macros that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
macros returned) is skipped.
Thus, when dc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
# PERFORMANCE
Most dc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This dc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **DC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **DC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**DC_BASE_DIGS**.
In addition, this dc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **DC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on dc(1):
**DC_LONG_BIT**
: The number of bits in the **long** type in the environment where dc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**DC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **DC_LONG_BIT**.
**DC_BASE_POW**
: The max decimal number that each large integer can store (see
**DC_BASE_DIGS**) plus **1**. Depends on **DC_BASE_DIGS**.
**DC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **DC_LONG_BIT**.
**DC_BASE_MAX**
: The maximum output base. Set at **DC_BASE_POW**.
**DC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**DC_SCALE_MAX**
: The maximum **scale**. Set at **DC_OVERFLOW_MAX-1**.
**DC_STRING_MAX**
: The maximum length of strings. Set at **DC_OVERFLOW_MAX-1**.
**DC_NAME_MAX**
: The maximum length of identifiers. Set at **DC_OVERFLOW_MAX-1**.
**DC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **DC_OVERFLOW_MAX-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**DC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
dc(1) recognizes the following environment variables:
**DC_ENV_ARGS**
: This is another way to give command-line arguments to dc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **DC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs. Another use would
be to use the **-e** option to set **scale** to a value other than **0**.
The code that parses **DC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some dc file.dc"** will be correctly parsed, but the string
**"/home/gavin/some \"dc\" file.dc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
- double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
+ double quotes as the outside quotes, as in **"some 'dc' file.dc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **DC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**DC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), dc(1) will output
lines to that length, including the backslash newline combo. The default
line length is **70**.
**DC_EXPR_EXIT**
: If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the **-e** and/or
**-f** command-line options (and any equivalents).
# EXIT STATUS
dc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**) operator.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, and using a token where it is
invalid.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, and attempting an operation when
the stack has too few elements.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (dc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, dc(1) always exits
and returns **4**, no matter what mode dc(1) is in.
The other statuses will only be returned when dc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since dc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, dc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, dc(1) turns
on "TTY mode."
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause dc(1) to stop execution of the current input. If
dc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If dc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If dc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to dc(1) as it is executing a file, it
can seem as though dc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause dc(1) to clean up and exit, and it uses the
default handler for all other signals.
# SEE ALSO
bc(1)
# STANDARDS
The dc(1) utility operators are compliant with the operators in the bc(1)
[IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1] specification.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHOR
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
diff --git a/contrib/bc/manuals/dc/EHP.1 b/contrib/bc/manuals/dc/EHP.1
index 8a635ed5780f..2ac14f02bf45 100644
--- a/contrib/bc/manuals/dc/EHP.1
+++ b/contrib/bc/manuals/dc/EHP.1
@@ -1,1108 +1,1121 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "DC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "DC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH Name
.PP
dc - arbitrary-precision decimal reverse-Polish notation calculator
.SH SYNOPSIS
.PP
\f[B]dc\f[R] [\f[B]-hiPvVx\f[R]] [\f[B]\[en]version\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]no-prompt\f[R]] [\f[B]\[en]extended-register\f[R]]
[\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
dc(1) is an arbitrary-precision calculator.
It uses a stack (reverse Polish notation) to store numbers and results
of computations.
Arithmetic operations pop arguments off of the stack and push the
results.
.PP
If no files are given on the command-line as extra arguments (i.e., not
as \f[B]-f\f[R] or \f[B]\[en]file\f[R] arguments), then dc(1) reads from
\f[B]stdin\f[R].
Otherwise, those files are processed, and dc(1) will then exit.
.PP
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where \f[B]-e\f[R] (\f[B]\[en]expression\f[R]) and
\f[B]-f\f[R] (\f[B]\[en]file\f[R]) arguments cause dc(1) to execute them
and exit.
The reason for this is that this dc(1) allows users to set arguments in
the environment variable \f[B]DC_ENV_ARGS\f[R] (see the \f[B]ENVIRONMENT
VARIABLES\f[R] section).
Any expressions given on the command-line should be used to set up a
standard environment.
For example, if a user wants the \f[B]scale\f[R] always set to
\f[B]10\f[R], they can set \f[B]DC_ENV_ARGS\f[R] to \f[B]-e 10k\f[R],
and this dc(1) will always start with a \f[B]scale\f[R] of \f[B]10\f[R].
.PP
If users want to have dc(1) exit after processing all input from
\f[B]-e\f[R] and \f[B]-f\f[R] arguments (and their equivalents), then
they can just simply add \f[B]-e q\f[R] as the last command-line
argument or define the environment variable \f[B]DC_EXPR_EXIT\f[R].
.SH OPTIONS
.PP
The following are the options that dc(1) accepts.
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
This option is a no-op.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-x\f[R] \f[B]\[en]extended-register\f[R]
Enables extended register mode.
See the \f[I]Extended Register Mode\f[R] subsection of the
\f[B]REGISTERS\f[R] section for more information.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]DC_ENV_ARGS\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]dc >&-\f[R], it will quit with an error.
This is done so that dc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]dc 2>&-\f[R], it will quit with an error.
This is done so that dc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
Each item in the input source code, either a number (see the
\f[B]NUMBERS\f[R] section) or a command (see the \f[B]COMMANDS\f[R]
section), is processed and executed, in order.
Input is processed immediately when entered.
.PP
\f[B]ibase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to interpret constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]ibase\f[R] is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in dc(1)
programs with the \f[B]T\f[R] command.
.PP
\f[B]obase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]DC_BASE_MAX\f[R] and
can be queried with the \f[B]U\f[R] command.
The min allowable value for \f[B]obase\f[R] is \f[B]2\f[R].
Values are output in the specified base.
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a register (see the \f[B]REGISTERS\f[R] section) that sets the
precision of any operations (with exceptions).
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] can be queried in dc(1)
programs with the \f[B]V\f[R] command.
.SS Comments
.PP
Comments go from \f[B]#\f[R] until, and not including, the next newline.
This is a \f[B]non-portable extension\f[R].
.SH NUMBERS
.PP
Numbers are strings made up of digits, uppercase letters up to
\f[B]F\f[R], and at most \f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]DC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]F\f[R] alone always equals decimal \f[B]15\f[R].
.SH COMMANDS
.PP
The valid commands are listed below.
.SS Printing
.PP
These commands are used for printing.
.TP
\f[B]p\f[R]
Prints the value on top of the stack, whether number or string, and
prints a newline after.
.RS
.PP
This does not alter the stack.
.RE
.TP
\f[B]n\f[R]
Prints the value on top of the stack, whether number or string, and pops
it off of the stack.
.TP
\f[B]P\f[R]
Pops a value off the stack.
.RS
.PP
If the value is a number, it is truncated and the absolute value of the
result is printed as though \f[B]obase\f[R] is \f[B]UCHAR_MAX+1\f[R] and
each digit is interpreted as an ASCII character, making it a byte
stream.
.PP
If the value is a string, it is printed without a trailing newline.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]f\f[R]
Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
.RS
.PP
Users should use this command when they get lost.
.RE
.SS Arithmetic
.PP
These are the commands used for arithmetic.
.TP
\f[B]+\f[R]
The top two values are popped off the stack, added, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]-\f[R]
The top two values are popped off the stack, subtracted, and the result
is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]*\f[R]
The top two values are popped off the stack, multiplied, and the result
is pushed onto the stack.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The top two values are popped off the stack, divided, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]%\f[R]
The top two values are popped off the stack, remaindered, and the result
is pushed onto the stack.
.RS
.PP
Remaindering is equivalent to 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R], and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]\[ti]\f[R]
The top two values are popped off the stack, divided and remaindered,
and the results (divided first, remainder second) are pushed onto the
stack.
This is equivalent to \f[B]x y / x y %\f[R] except that \f[B]x\f[R] and
\f[B]y\f[R] are only evaluated once.
.RS
.PP
The first value popped off of the stack must be non-zero.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
.RE
.TP
\f[B]v\f[R]
The top value is popped off the stack, its square root is computed, and
the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The value popped off of the stack must be non-negative.
.RE
.TP
\f[B]_\f[R]
If this command \f[I]immediately\f[R] precedes a number (i.e., no spaces
or other commands), then that number is input as a negative number.
.RS
.PP
Otherwise, the top value on the stack is popped and copied, and the copy
is negated and pushed onto the stack.
This behavior without a number is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]b\f[R]
The top value is popped off the stack, and if it is zero, it is pushed
back onto the stack.
Otherwise, its absolute value is pushed onto the stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]|\f[R]
The top three values are popped off the stack, a modular exponentiation
is computed, and the result is pushed onto the stack.
.RS
.PP
The first value popped is used as the reduction modulus and must be an
integer and non-zero.
The second value popped is used as the exponent and must be an integer
and non-negative.
The third value popped is the base and must be an integer.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]G\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if they are equal, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]N\f[R]
The top value is popped off of the stack, and if it a \f[B]0\f[R], a
\f[B]1\f[R] is pushed; otherwise, a \f[B]0\f[R] is pushed.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B](\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]{\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than or equal to the second,
or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B])\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]}\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than or equal to the
second, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]M\f[R]
The top two values are popped off of the stack.
If they are both non-zero, a \f[B]1\f[R] is pushed onto the stack.
If either of them is zero, or both of them are, then a \f[B]0\f[R] is
pushed onto the stack.
.RS
.PP
This is like the \f[B]&&\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]m\f[R]
The top two values are popped off of the stack.
If at least one of them is non-zero, a \f[B]1\f[R] is pushed onto the
stack.
If both of them are zero, then a \f[B]0\f[R] is pushed onto the stack.
.RS
.PP
This is like the \f[B]||\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Stack Control
.PP
These commands control the stack.
.TP
\f[B]c\f[R]
Removes all items from (\[lq]clears\[rq]) the stack.
.TP
\f[B]d\f[R]
Copies the item on top of the stack (\[lq]duplicates\[rq]) and pushes
the copy onto the stack.
.TP
\f[B]r\f[R]
Swaps (\[lq]reverses\[rq]) the two top items on the stack.
.TP
\f[B]R\f[R]
Pops (\[lq]removes\[rq]) the top value from the stack.
.SS Register Control
.PP
These commands control registers (see the \f[B]REGISTERS\f[R] section).
.TP
\f[B]s\f[R]\f[I]r\f[R]
Pops the value off the top of the stack and stores it into register
\f[I]r\f[R].
.TP
\f[B]l\f[R]\f[I]r\f[R]
Copies the value in register \f[I]r\f[R] and pushes it onto the stack.
This does not alter the contents of \f[I]r\f[R].
.TP
\f[B]S\f[R]\f[I]r\f[R]
Pops the value off the top of the (main) stack and pushes it onto the
stack of register \f[I]r\f[R].
The previous value of the register becomes inaccessible.
.TP
\f[B]L\f[R]\f[I]r\f[R]
Pops the value off the top of the stack for register \f[I]r\f[R] and
push it onto the main stack.
The previous value in the stack for register \f[I]r\f[R], if any, is now
accessible via the \f[B]l\f[R]\f[I]r\f[R] command.
.SS Parameters
.PP
These commands control the values of \f[B]ibase\f[R], \f[B]obase\f[R],
and \f[B]scale\f[R].
Also see the \f[B]SYNTAX\f[R] section.
.TP
\f[B]i\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]ibase\f[R], which must be between \f[B]2\f[R] and \f[B]16\f[R],
inclusive.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]o\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]obase\f[R], which must be between \f[B]2\f[R] and
\f[B]DC_BASE_MAX\f[R], inclusive (see the \f[B]LIMITS\f[R] section).
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]k\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]scale\f[R], which must be non-negative.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]I\f[R]
Pushes the current value of \f[B]ibase\f[R] onto the main stack.
.TP
\f[B]O\f[R]
Pushes the current value of \f[B]obase\f[R] onto the main stack.
.TP
\f[B]K\f[R]
Pushes the current value of \f[B]scale\f[R] onto the main stack.
.TP
\f[B]T\f[R]
Pushes the maximum allowable value of \f[B]ibase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]U\f[R]
Pushes the maximum allowable value of \f[B]obase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]V\f[R]
Pushes the maximum allowable value of \f[B]scale\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Strings
.PP
The following commands control strings.
.PP
dc(1) can work with both numbers and strings, and registers (see the
\f[B]REGISTERS\f[R] section) can hold both strings and numbers.
dc(1) always knows whether the contents of a register are a string or a
number.
.PP
While arithmetic operations have to have numbers, and will print an
error if given a string, other commands accept strings.
.PP
Strings can also be executed as macros.
For example, if the string \f[B][1pR]\f[R] is executed as a macro, then
the code \f[B]1pR\f[R] is executed, meaning that the \f[B]1\f[R] will be
printed with a newline after and then popped from the stack.
.TP
\f[B][\f[R]_characters_\f[B]]\f[R]
Makes a string containing \f[I]characters\f[R] and pushes it onto the
stack.
.RS
.PP
If there are brackets (\f[B][\f[R] and \f[B]]\f[R]) in the string, then
they must be balanced.
Unbalanced brackets can be escaped using a backslash (\f[B]\[rs]\f[R])
character.
.PP
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the
(first) backslash is not.
.RE
.TP
\f[B]a\f[R]
The value on top of the stack is popped.
.RS
.PP
If it is a number, it is truncated and its absolute value is taken.
The result mod \f[B]UCHAR_MAX+1\f[R] is calculated.
If that result is \f[B]0\f[R], push an empty string; otherwise, push a
one-character string where the character is the result of the mod
interpreted as an ASCII character.
.PP
If it is a string, then a new string is made.
If the original string is empty, the new string is empty.
If it is not, then the first character of the original string is used to
create the new string as a one-character string.
The new string is then pushed onto the stack.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]x\f[R]
Pops a value off of the top of the stack.
.RS
.PP
If it is a number, it is pushed back onto the stack.
.PP
If it is a string, it is executed as a macro.
.PP
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is greater than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
For example, \f[B]0 1>a\f[R] will execute the contents of register
\f[B]a\f[R], and \f[B]1 0>a\f[R] will not.
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not greater than the second (less than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is less than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not less than the second (greater than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is equal to the second, then the contents of register
\f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not equal to the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]?\f[R]
Reads a line from the \f[B]stdin\f[R] and executes it.
This is to allow macros to request input from users.
.TP
\f[B]q\f[R]
During execution of a macro, this exits the execution of that macro and
the execution of the macro that executed it.
If there are no macros, or only one macro executing, dc(1) exits.
.TP
\f[B]Q\f[R]
Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack.
If the number of levels to pop is greater than the number of executing
macros, dc(1) exits.
.SS Status
.PP
These commands query status of the stack or its top value.
.TP
\f[B]Z\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, calculates the number of significant decimal digits
it has and pushes the result.
.PP
If it is a string, pushes the number of characters the string has.
.RE
.TP
\f[B]X\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, pushes the \f[I]scale\f[R] of the value onto the
stack.
.PP
If it is a string, pushes \f[B]0\f[R].
.RE
.TP
\f[B]z\f[R]
Pushes the current stack depth (before execution of this command).
.SS Arrays
.PP
These commands manipulate arrays.
.TP
\f[B]:\f[R]\f[I]r\f[R]
Pops the top two values off of the stack.
The second value will be stored in the array \f[I]r\f[R] (see the
\f[B]REGISTERS\f[R] section), indexed by the first value.
.TP
\f[B];\f[R]\f[I]r\f[R]
Pops the value on top of the stack and uses it as an index into the
array \f[I]r\f[R].
The selected value is then pushed onto the stack.
.SH REGISTERS
.PP
Registers are names that can store strings, numbers, and arrays.
(Number/string registers do not interfere with array registers.)
.PP
Each register is also its own stack, so the current register value is
the top of the stack for the register.
All registers, when first referenced, have one value (\f[B]0\f[R]) in
their stack.
.PP
In non-extended register mode, a register name is just the single
character that follows any command that needs a register name.
The only exception is a newline (\f[B]`\[rs]n'\f[R]); it is a parse
error for a newline to be used as a register name.
.SS Extended Register Mode
.PP
Unlike most other dc(1) implentations, this dc(1) provides nearly
unlimited amounts of registers, if extended register mode is enabled.
.PP
If extended register mode is enabled (\f[B]-x\f[R] or
\f[B]\[en]extended-register\f[R] command-line arguments are given), then
normal single character registers are used \f[I]unless\f[R] the
character immediately following a command that needs a register name is
a space (according to \f[B]isspace()\f[R]) and not a newline
(\f[B]`\[rs]n'\f[R]).
.PP
In that case, the register name is found according to the regex
\f[B][a-z][a-z0-9_]*\f[R] (like bc(1) identifiers), and it is a parse
error if the next non-space characters do not match that regex.
.SH RESET
.PP
When dc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any macros that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all macros returned) is skipped.
.PP
Thus, when dc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.SH PERFORMANCE
.PP
Most dc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This dc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]DC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]DC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]DC_BASE_DIGS\f[R].
.PP
In addition, this dc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]DC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on dc(1):
.TP
\f[B]DC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
dc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]DC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]DC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]DC_BASE_DIGS\f[R].
.TP
\f[B]DC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]DC_BASE_POW\f[R].
.TP
\f[B]DC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]DC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]DC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
dc(1) recognizes the following environment variables:
.TP
\f[B]DC_ENV_ARGS\f[R]
This is another way to give command-line arguments to dc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]DC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs.
Another use would be to use the \f[B]-e\f[R] option to set
\f[B]scale\f[R] to a value other than \f[B]0\f[R].
.RS
.PP
The code that parses \f[B]DC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some dc file.dc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]dc\[dq] file.dc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
-in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
+in \f[B]\[rq]some `dc' file.dc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]DC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]DC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), dc(1) will output lines to that length,
including the backslash newline combo.
The default line length is \f[B]70\f[R].
.TP
\f[B]DC_EXPR_EXIT\f[R]
If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the
\f[B]-e\f[R] and/or \f[B]-f\f[R] command-line options (and any
equivalents).
.SH EXIT STATUS
.PP
dc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, attempting to convert a negative number to a hardware
integer, overflow when converting a number to a hardware integer, and
attempting to use a non-integer where an integer is required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]) operator.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, and using a
token where it is invalid.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, and attempting an operation when the
stack has too few elements.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (dc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, dc(1)
always exits and returns \f[B]4\f[R], no matter what mode dc(1) is in.
.PP
The other statuses will only be returned when dc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
dc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, dc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, dc(1) turns on \[lq]TTY mode.\[rq]
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause dc(1) to stop execution of the
current input.
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If dc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If dc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to dc(1) as it is
executing a file, it can seem as though dc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause dc(1) to clean up and
exit, and it uses the default handler for all other signals.
.SH LOCALES
.PP
This dc(1) ships with support for adding error messages for different
locales and thus, supports \f[B]LC_MESSAGS\f[R].
.SH SEE ALSO
.PP
bc(1)
.SH STANDARDS
.PP
The dc(1) utility operators are compliant with the operators in the
bc(1) IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHOR
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/dc/EHP.1.md b/contrib/bc/manuals/dc/EHP.1.md
index e4ec08ad0ba4..982570c9c999 100644
--- a/contrib/bc/manuals/dc/EHP.1.md
+++ b/contrib/bc/manuals/dc/EHP.1.md
@@ -1,1013 +1,1022 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# Name
dc - arbitrary-precision decimal reverse-Polish notation calculator
# SYNOPSIS
**dc** [**-hiPvVx**] [**--version**] [**--help**] [**--interactive**] [**--no-prompt**] [**--extended-register**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...] [*file*...]
# DESCRIPTION
dc(1) is an arbitrary-precision calculator. It uses a stack (reverse Polish
notation) to store numbers and results of computations. Arithmetic operations
pop arguments off of the stack and push the results.
If no files are given on the command-line as extra arguments (i.e., not as
**-f** or **--file** arguments), then dc(1) reads from **stdin**. Otherwise,
those files are processed, and dc(1) will then exit.
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where **-e** (**--expression**) and **-f** (**--file**)
arguments cause dc(1) to execute them and exit. The reason for this is that this
dc(1) allows users to set arguments in the environment variable **DC_ENV_ARGS**
(see the **ENVIRONMENT VARIABLES** section). Any expressions given on the
command-line should be used to set up a standard environment. For example, if a
user wants the **scale** always set to **10**, they can set **DC_ENV_ARGS** to
**-e 10k**, and this dc(1) will always start with a **scale** of **10**.
If users want to have dc(1) exit after processing all input from **-e** and
**-f** arguments (and their equivalents), then they can just simply add **-e q**
as the last command-line argument or define the environment variable
**DC_EXPR_EXIT**.
# OPTIONS
The following are the options that dc(1) accepts.
**-h**, **--help**
: Prints a usage message and quits.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-P**, **--no-prompt**
: This option is a no-op.
This is a **non-portable extension**.
**-x** **--extended-register**
: Enables extended register mode. See the *Extended Register Mode* subsection
of the **REGISTERS** section for more information.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **DC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **dc <file> >&-**, it will quit with an error. This
is done so that dc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **dc <file> 2>&-**, it will quit with an error. This
is done so that dc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
Each item in the input source code, either a number (see the **NUMBERS**
section) or a command (see the **COMMANDS** section), is processed and executed,
in order. Input is processed immediately when entered.
**ibase** is a register (see the **REGISTERS** section) that determines how to
interpret constant numbers. It is the "input" base, or the number base used for
interpreting input numbers. **ibase** is initially **10**. The max allowable
value for **ibase** is **16**. The min allowable value for **ibase** is **2**.
The max allowable value for **ibase** can be queried in dc(1) programs with the
**T** command.
**obase** is a register (see the **REGISTERS** section) that determines how to
output results. It is the "output" base, or the number base used for outputting
numbers. **obase** is initially **10**. The max allowable value for **obase** is
**DC_BASE_MAX** and can be queried with the **U** command. The min allowable
value for **obase** is **2**. Values are output in the specified base.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a register (see the
**REGISTERS** section) that sets the precision of any operations (with
exceptions). **scale** is initially **0**. **scale** cannot be negative. The max
allowable value for **scale** can be queried in dc(1) programs with the **V**
command.
## Comments
Comments go from **#** until, and not including, the next newline. This is a
**non-portable extension**.
# NUMBERS
Numbers are strings made up of digits, uppercase letters up to **F**, and at
most **1** period for a radix. Numbers can have up to **DC_NUM_MAX** digits.
Uppercase letters are equal to **9** + their position in the alphabet (i.e.,
**A** equals **10**, or **9+1**). If a digit or letter makes no sense with the
current value of **ibase**, they are set to the value of the highest valid digit
in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **F** alone always equals decimal
**15**.
# COMMANDS
The valid commands are listed below.
## Printing
These commands are used for printing.
**p**
: Prints the value on top of the stack, whether number or string, and prints a
newline after.
This does not alter the stack.
**n**
: Prints the value on top of the stack, whether number or string, and pops it
off of the stack.
**P**
: Pops a value off the stack.
If the value is a number, it is truncated and the absolute value of the
result is printed as though **obase** is **UCHAR_MAX+1** and each digit is
interpreted as an ASCII character, making it a byte stream.
If the value is a string, it is printed without a trailing newline.
This is a **non-portable extension**.
**f**
: Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
Users should use this command when they get lost.
## Arithmetic
These are the commands used for arithmetic.
**+**
: The top two values are popped off the stack, added, and the result is pushed
onto the stack. The *scale* of the result is equal to the max *scale* of
both operands.
**-**
: The top two values are popped off the stack, subtracted, and the result is
pushed onto the stack. The *scale* of the result is equal to the max
*scale* of both operands.
**\***
: The top two values are popped off the stack, multiplied, and the result is
pushed onto the stack. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result
is equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The top two values are popped off the stack, divided, and the result is
pushed onto the stack. The *scale* of the result is equal to **scale**.
The first value popped off of the stack must be non-zero.
**%**
: The top two values are popped off the stack, remaindered, and the result is
pushed onto the stack.
Remaindering is equivalent to 1) Computing **a/b** to current **scale**, and
2) Using the result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The first value popped off of the stack must be non-zero.
**~**
: The top two values are popped off the stack, divided and remaindered, and
the results (divided first, remainder second) are pushed onto the stack.
This is equivalent to **x y / x y %** except that **x** and **y** are only
evaluated once.
The first value popped off of the stack must be non-zero.
This is a **non-portable extension**.
**\^**
: The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack. The *scale* of
the result is equal to **scale**.
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
**v**
: The top value is popped off the stack, its square root is computed, and the
result is pushed onto the stack. The *scale* of the result is equal to
**scale**.
The value popped off of the stack must be non-negative.
**\_**
: If this command *immediately* precedes a number (i.e., no spaces or other
commands), then that number is input as a negative number.
Otherwise, the top value on the stack is popped and copied, and the copy is
negated and pushed onto the stack. This behavior without a number is a
**non-portable extension**.
**b**
: The top value is popped off the stack, and if it is zero, it is pushed back
onto the stack. Otherwise, its absolute value is pushed onto the stack.
This is a **non-portable extension**.
**|**
: The top three values are popped off the stack, a modular exponentiation is
computed, and the result is pushed onto the stack.
The first value popped is used as the reduction modulus and must be an
integer and non-zero. The second value popped is used as the exponent and
must be an integer and non-negative. The third value popped is the base and
must be an integer.
This is a **non-portable extension**.
**G**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if they are equal, or **0** otherwise.
This is a **non-portable extension**.
**N**
: The top value is popped off of the stack, and if it a **0**, a **1** is
pushed; otherwise, a **0** is pushed.
This is a **non-portable extension**.
**(**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than the second, or **0** otherwise.
This is a **non-portable extension**.
**{**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than or equal to the second, or **0**
otherwise.
This is a **non-portable extension**.
**)**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than the second, or **0** otherwise.
This is a **non-portable extension**.
**}**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than or equal to the second, or
**0** otherwise.
This is a **non-portable extension**.
**M**
: The top two values are popped off of the stack. If they are both non-zero, a
**1** is pushed onto the stack. If either of them is zero, or both of them
are, then a **0** is pushed onto the stack.
This is like the **&&** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
**m**
: The top two values are popped off of the stack. If at least one of them is
non-zero, a **1** is pushed onto the stack. If both of them are zero, then a
**0** is pushed onto the stack.
This is like the **||** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
## Stack Control
These commands control the stack.
**c**
: Removes all items from ("clears") the stack.
**d**
: Copies the item on top of the stack ("duplicates") and pushes the copy onto
the stack.
**r**
: Swaps ("reverses") the two top items on the stack.
**R**
: Pops ("removes") the top value from the stack.
## Register Control
These commands control registers (see the **REGISTERS** section).
**s***r*
: Pops the value off the top of the stack and stores it into register *r*.
**l***r*
: Copies the value in register *r* and pushes it onto the stack. This does not
alter the contents of *r*.
**S***r*
: Pops the value off the top of the (main) stack and pushes it onto the stack
of register *r*. The previous value of the register becomes inaccessible.
**L***r*
: Pops the value off the top of the stack for register *r* and push it onto
the main stack. The previous value in the stack for register *r*, if any, is
now accessible via the **l***r* command.
## Parameters
These commands control the values of **ibase**, **obase**, and **scale**. Also
see the **SYNTAX** section.
**i**
: Pops the value off of the top of the stack and uses it to set **ibase**,
which must be between **2** and **16**, inclusive.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**o**
: Pops the value off of the top of the stack and uses it to set **obase**,
which must be between **2** and **DC_BASE_MAX**, inclusive (see the
**LIMITS** section).
If the value on top of the stack has any *scale*, the *scale* is ignored.
**k**
: Pops the value off of the top of the stack and uses it to set **scale**,
which must be non-negative.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**I**
: Pushes the current value of **ibase** onto the main stack.
**O**
: Pushes the current value of **obase** onto the main stack.
**K**
: Pushes the current value of **scale** onto the main stack.
**T**
: Pushes the maximum allowable value of **ibase** onto the main stack.
This is a **non-portable extension**.
**U**
: Pushes the maximum allowable value of **obase** onto the main stack.
This is a **non-portable extension**.
**V**
: Pushes the maximum allowable value of **scale** onto the main stack.
This is a **non-portable extension**.
## Strings
The following commands control strings.
dc(1) can work with both numbers and strings, and registers (see the
**REGISTERS** section) can hold both strings and numbers. dc(1) always knows
whether the contents of a register are a string or a number.
While arithmetic operations have to have numbers, and will print an error if
given a string, other commands accept strings.
Strings can also be executed as macros. For example, if the string **[1pR]** is
executed as a macro, then the code **1pR** is executed, meaning that the **1**
will be printed with a newline after and then popped from the stack.
**\[**_characters_**\]**
: Makes a string containing *characters* and pushes it onto the stack.
If there are brackets (**\[** and **\]**) in the string, then they must be
balanced. Unbalanced brackets can be escaped using a backslash (**\\**)
character.
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the (first)
backslash is not.
**a**
: The value on top of the stack is popped.
If it is a number, it is truncated and its absolute value is taken. The
result mod **UCHAR_MAX+1** is calculated. If that result is **0**, push an
empty string; otherwise, push a one-character string where the character is
the result of the mod interpreted as an ASCII character.
If it is a string, then a new string is made. If the original string is
empty, the new string is empty. If it is not, then the first character of
the original string is used to create the new string as a one-character
string. The new string is then pushed onto the stack.
This is a **non-portable extension**.
**x**
: Pops a value off of the top of the stack.
If it is a number, it is pushed back onto the stack.
If it is a string, it is executed as a macro.
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
**\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is greater than the second, then the contents of register
*r* are executed.
For example, **0 1>a** will execute the contents of register **a**, and
**1 0>a** will not.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not greater than the second (less than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is less than the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not less than the second (greater than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is equal to the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not equal to the second, then the contents of register
*r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**?**
: Reads a line from the **stdin** and executes it. This is to allow macros to
request input from users.
**q**
: During execution of a macro, this exits the execution of that macro and the
execution of the macro that executed it. If there are no macros, or only one
macro executing, dc(1) exits.
**Q**
: Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack. If the number
of levels to pop is greater than the number of executing macros, dc(1)
exits.
## Status
These commands query status of the stack or its top value.
**Z**
: Pops a value off of the stack.
If it is a number, calculates the number of significant decimal digits it
has and pushes the result.
If it is a string, pushes the number of characters the string has.
**X**
: Pops a value off of the stack.
If it is a number, pushes the *scale* of the value onto the stack.
If it is a string, pushes **0**.
**z**
: Pushes the current stack depth (before execution of this command).
## Arrays
These commands manipulate arrays.
**:***r*
: Pops the top two values off of the stack. The second value will be stored in
the array *r* (see the **REGISTERS** section), indexed by the first value.
**;***r*
: Pops the value on top of the stack and uses it as an index into the array
*r*. The selected value is then pushed onto the stack.
# REGISTERS
Registers are names that can store strings, numbers, and arrays. (Number/string
registers do not interfere with array registers.)
Each register is also its own stack, so the current register value is the top of
the stack for the register. All registers, when first referenced, have one value
(**0**) in their stack.
In non-extended register mode, a register name is just the single character that
follows any command that needs a register name. The only exception is a newline
(**'\\n'**); it is a parse error for a newline to be used as a register name.
## Extended Register Mode
Unlike most other dc(1) implentations, this dc(1) provides nearly unlimited
amounts of registers, if extended register mode is enabled.
If extended register mode is enabled (**-x** or **--extended-register**
command-line arguments are given), then normal single character registers are
used *unless* the character immediately following a command that needs a
register name is a space (according to **isspace()**) and not a newline
(**'\\n'**).
In that case, the register name is found according to the regex
**\[a-z\]\[a-z0-9\_\]\*** (like bc(1) identifiers), and it is a parse error if
the next non-space characters do not match that regex.
# RESET
When dc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any macros that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
macros returned) is skipped.
Thus, when dc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
# PERFORMANCE
Most dc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This dc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **DC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **DC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**DC_BASE_DIGS**.
In addition, this dc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **DC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on dc(1):
**DC_LONG_BIT**
: The number of bits in the **long** type in the environment where dc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**DC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **DC_LONG_BIT**.
**DC_BASE_POW**
: The max decimal number that each large integer can store (see
**DC_BASE_DIGS**) plus **1**. Depends on **DC_BASE_DIGS**.
**DC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **DC_LONG_BIT**.
**DC_BASE_MAX**
: The maximum output base. Set at **DC_BASE_POW**.
**DC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**DC_SCALE_MAX**
: The maximum **scale**. Set at **DC_OVERFLOW_MAX-1**.
**DC_STRING_MAX**
: The maximum length of strings. Set at **DC_OVERFLOW_MAX-1**.
**DC_NAME_MAX**
: The maximum length of identifiers. Set at **DC_OVERFLOW_MAX-1**.
**DC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **DC_OVERFLOW_MAX-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**DC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
dc(1) recognizes the following environment variables:
**DC_ENV_ARGS**
: This is another way to give command-line arguments to dc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **DC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs. Another use would
be to use the **-e** option to set **scale** to a value other than **0**.
The code that parses **DC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some dc file.dc"** will be correctly parsed, but the string
**"/home/gavin/some \"dc\" file.dc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
- double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
+ double quotes as the outside quotes, as in **"some 'dc' file.dc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **DC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**DC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), dc(1) will output
lines to that length, including the backslash newline combo. The default
line length is **70**.
**DC_EXPR_EXIT**
: If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the **-e** and/or
**-f** command-line options (and any equivalents).
# EXIT STATUS
dc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**) operator.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, and using a token where it is
invalid.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, and attempting an operation when
the stack has too few elements.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (dc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, dc(1) always exits
and returns **4**, no matter what mode dc(1) is in.
The other statuses will only be returned when dc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since dc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, dc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, dc(1) turns
on "TTY mode."
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause dc(1) to stop execution of the current input. If
dc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If dc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If dc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to dc(1) as it is executing a file, it
can seem as though dc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause dc(1) to clean up and exit, and it uses the
default handler for all other signals.
# LOCALES
This dc(1) ships with support for adding error messages for different locales
and thus, supports **LC_MESSAGS**.
# SEE ALSO
bc(1)
# STANDARDS
The dc(1) utility operators are compliant with the operators in the bc(1)
[IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1] specification.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHOR
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
diff --git a/contrib/bc/manuals/dc/EN.1 b/contrib/bc/manuals/dc/EN.1
index cc2dd3fcea0e..c38435ea86d8 100644
--- a/contrib/bc/manuals/dc/EN.1
+++ b/contrib/bc/manuals/dc/EN.1
@@ -1,1126 +1,1139 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "DC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "DC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH Name
.PP
dc - arbitrary-precision decimal reverse-Polish notation calculator
.SH SYNOPSIS
.PP
\f[B]dc\f[R] [\f[B]-hiPvVx\f[R]] [\f[B]\[en]version\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]no-prompt\f[R]] [\f[B]\[en]extended-register\f[R]]
[\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
dc(1) is an arbitrary-precision calculator.
It uses a stack (reverse Polish notation) to store numbers and results
of computations.
Arithmetic operations pop arguments off of the stack and push the
results.
.PP
If no files are given on the command-line as extra arguments (i.e., not
as \f[B]-f\f[R] or \f[B]\[en]file\f[R] arguments), then dc(1) reads from
\f[B]stdin\f[R].
Otherwise, those files are processed, and dc(1) will then exit.
.PP
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where \f[B]-e\f[R] (\f[B]\[en]expression\f[R]) and
\f[B]-f\f[R] (\f[B]\[en]file\f[R]) arguments cause dc(1) to execute them
and exit.
The reason for this is that this dc(1) allows users to set arguments in
the environment variable \f[B]DC_ENV_ARGS\f[R] (see the \f[B]ENVIRONMENT
VARIABLES\f[R] section).
Any expressions given on the command-line should be used to set up a
standard environment.
For example, if a user wants the \f[B]scale\f[R] always set to
\f[B]10\f[R], they can set \f[B]DC_ENV_ARGS\f[R] to \f[B]-e 10k\f[R],
and this dc(1) will always start with a \f[B]scale\f[R] of \f[B]10\f[R].
.PP
If users want to have dc(1) exit after processing all input from
\f[B]-e\f[R] and \f[B]-f\f[R] arguments (and their equivalents), then
they can just simply add \f[B]-e q\f[R] as the last command-line
argument or define the environment variable \f[B]DC_EXPR_EXIT\f[R].
.SH OPTIONS
.PP
The following are the options that dc(1) accepts.
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
Disables the prompt in TTY mode.
(The prompt is only enabled in TTY mode.
See the \f[B]TTY MODE\f[R] section) This is mostly for those users that
do not want a prompt or are not used to having them in dc(1).
Most of those users would want to put this option in
\f[B]DC_ENV_ARGS\f[R].
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-x\f[R] \f[B]\[en]extended-register\f[R]
Enables extended register mode.
See the \f[I]Extended Register Mode\f[R] subsection of the
\f[B]REGISTERS\f[R] section for more information.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]DC_ENV_ARGS\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]dc >&-\f[R], it will quit with an error.
This is done so that dc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]dc 2>&-\f[R], it will quit with an error.
This is done so that dc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
Each item in the input source code, either a number (see the
\f[B]NUMBERS\f[R] section) or a command (see the \f[B]COMMANDS\f[R]
section), is processed and executed, in order.
Input is processed immediately when entered.
.PP
\f[B]ibase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to interpret constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]ibase\f[R] is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in dc(1)
programs with the \f[B]T\f[R] command.
.PP
\f[B]obase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]DC_BASE_MAX\f[R] and
can be queried with the \f[B]U\f[R] command.
The min allowable value for \f[B]obase\f[R] is \f[B]2\f[R].
Values are output in the specified base.
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a register (see the \f[B]REGISTERS\f[R] section) that sets the
precision of any operations (with exceptions).
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] can be queried in dc(1)
programs with the \f[B]V\f[R] command.
.SS Comments
.PP
Comments go from \f[B]#\f[R] until, and not including, the next newline.
This is a \f[B]non-portable extension\f[R].
.SH NUMBERS
.PP
Numbers are strings made up of digits, uppercase letters up to
\f[B]F\f[R], and at most \f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]DC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]F\f[R] alone always equals decimal \f[B]15\f[R].
.SH COMMANDS
.PP
The valid commands are listed below.
.SS Printing
.PP
These commands are used for printing.
.TP
\f[B]p\f[R]
Prints the value on top of the stack, whether number or string, and
prints a newline after.
.RS
.PP
This does not alter the stack.
.RE
.TP
\f[B]n\f[R]
Prints the value on top of the stack, whether number or string, and pops
it off of the stack.
.TP
\f[B]P\f[R]
Pops a value off the stack.
.RS
.PP
If the value is a number, it is truncated and the absolute value of the
result is printed as though \f[B]obase\f[R] is \f[B]UCHAR_MAX+1\f[R] and
each digit is interpreted as an ASCII character, making it a byte
stream.
.PP
If the value is a string, it is printed without a trailing newline.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]f\f[R]
Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
.RS
.PP
Users should use this command when they get lost.
.RE
.SS Arithmetic
.PP
These are the commands used for arithmetic.
.TP
\f[B]+\f[R]
The top two values are popped off the stack, added, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]-\f[R]
The top two values are popped off the stack, subtracted, and the result
is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]*\f[R]
The top two values are popped off the stack, multiplied, and the result
is pushed onto the stack.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The top two values are popped off the stack, divided, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]%\f[R]
The top two values are popped off the stack, remaindered, and the result
is pushed onto the stack.
.RS
.PP
Remaindering is equivalent to 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R], and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]\[ti]\f[R]
The top two values are popped off the stack, divided and remaindered,
and the results (divided first, remainder second) are pushed onto the
stack.
This is equivalent to \f[B]x y / x y %\f[R] except that \f[B]x\f[R] and
\f[B]y\f[R] are only evaluated once.
.RS
.PP
The first value popped off of the stack must be non-zero.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
.RE
.TP
\f[B]v\f[R]
The top value is popped off the stack, its square root is computed, and
the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The value popped off of the stack must be non-negative.
.RE
.TP
\f[B]_\f[R]
If this command \f[I]immediately\f[R] precedes a number (i.e., no spaces
or other commands), then that number is input as a negative number.
.RS
.PP
Otherwise, the top value on the stack is popped and copied, and the copy
is negated and pushed onto the stack.
This behavior without a number is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]b\f[R]
The top value is popped off the stack, and if it is zero, it is pushed
back onto the stack.
Otherwise, its absolute value is pushed onto the stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]|\f[R]
The top three values are popped off the stack, a modular exponentiation
is computed, and the result is pushed onto the stack.
.RS
.PP
The first value popped is used as the reduction modulus and must be an
integer and non-zero.
The second value popped is used as the exponent and must be an integer
and non-negative.
The third value popped is the base and must be an integer.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]G\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if they are equal, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]N\f[R]
The top value is popped off of the stack, and if it a \f[B]0\f[R], a
\f[B]1\f[R] is pushed; otherwise, a \f[B]0\f[R] is pushed.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B](\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]{\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than or equal to the second,
or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B])\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]}\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than or equal to the
second, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]M\f[R]
The top two values are popped off of the stack.
If they are both non-zero, a \f[B]1\f[R] is pushed onto the stack.
If either of them is zero, or both of them are, then a \f[B]0\f[R] is
pushed onto the stack.
.RS
.PP
This is like the \f[B]&&\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]m\f[R]
The top two values are popped off of the stack.
If at least one of them is non-zero, a \f[B]1\f[R] is pushed onto the
stack.
If both of them are zero, then a \f[B]0\f[R] is pushed onto the stack.
.RS
.PP
This is like the \f[B]||\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Stack Control
.PP
These commands control the stack.
.TP
\f[B]c\f[R]
Removes all items from (\[lq]clears\[rq]) the stack.
.TP
\f[B]d\f[R]
Copies the item on top of the stack (\[lq]duplicates\[rq]) and pushes
the copy onto the stack.
.TP
\f[B]r\f[R]
Swaps (\[lq]reverses\[rq]) the two top items on the stack.
.TP
\f[B]R\f[R]
Pops (\[lq]removes\[rq]) the top value from the stack.
.SS Register Control
.PP
These commands control registers (see the \f[B]REGISTERS\f[R] section).
.TP
\f[B]s\f[R]\f[I]r\f[R]
Pops the value off the top of the stack and stores it into register
\f[I]r\f[R].
.TP
\f[B]l\f[R]\f[I]r\f[R]
Copies the value in register \f[I]r\f[R] and pushes it onto the stack.
This does not alter the contents of \f[I]r\f[R].
.TP
\f[B]S\f[R]\f[I]r\f[R]
Pops the value off the top of the (main) stack and pushes it onto the
stack of register \f[I]r\f[R].
The previous value of the register becomes inaccessible.
.TP
\f[B]L\f[R]\f[I]r\f[R]
Pops the value off the top of the stack for register \f[I]r\f[R] and
push it onto the main stack.
The previous value in the stack for register \f[I]r\f[R], if any, is now
accessible via the \f[B]l\f[R]\f[I]r\f[R] command.
.SS Parameters
.PP
These commands control the values of \f[B]ibase\f[R], \f[B]obase\f[R],
and \f[B]scale\f[R].
Also see the \f[B]SYNTAX\f[R] section.
.TP
\f[B]i\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]ibase\f[R], which must be between \f[B]2\f[R] and \f[B]16\f[R],
inclusive.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]o\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]obase\f[R], which must be between \f[B]2\f[R] and
\f[B]DC_BASE_MAX\f[R], inclusive (see the \f[B]LIMITS\f[R] section).
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]k\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]scale\f[R], which must be non-negative.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]I\f[R]
Pushes the current value of \f[B]ibase\f[R] onto the main stack.
.TP
\f[B]O\f[R]
Pushes the current value of \f[B]obase\f[R] onto the main stack.
.TP
\f[B]K\f[R]
Pushes the current value of \f[B]scale\f[R] onto the main stack.
.TP
\f[B]T\f[R]
Pushes the maximum allowable value of \f[B]ibase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]U\f[R]
Pushes the maximum allowable value of \f[B]obase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]V\f[R]
Pushes the maximum allowable value of \f[B]scale\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Strings
.PP
The following commands control strings.
.PP
dc(1) can work with both numbers and strings, and registers (see the
\f[B]REGISTERS\f[R] section) can hold both strings and numbers.
dc(1) always knows whether the contents of a register are a string or a
number.
.PP
While arithmetic operations have to have numbers, and will print an
error if given a string, other commands accept strings.
.PP
Strings can also be executed as macros.
For example, if the string \f[B][1pR]\f[R] is executed as a macro, then
the code \f[B]1pR\f[R] is executed, meaning that the \f[B]1\f[R] will be
printed with a newline after and then popped from the stack.
.TP
\f[B][\f[R]_characters_\f[B]]\f[R]
Makes a string containing \f[I]characters\f[R] and pushes it onto the
stack.
.RS
.PP
If there are brackets (\f[B][\f[R] and \f[B]]\f[R]) in the string, then
they must be balanced.
Unbalanced brackets can be escaped using a backslash (\f[B]\[rs]\f[R])
character.
.PP
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the
(first) backslash is not.
.RE
.TP
\f[B]a\f[R]
The value on top of the stack is popped.
.RS
.PP
If it is a number, it is truncated and its absolute value is taken.
The result mod \f[B]UCHAR_MAX+1\f[R] is calculated.
If that result is \f[B]0\f[R], push an empty string; otherwise, push a
one-character string where the character is the result of the mod
interpreted as an ASCII character.
.PP
If it is a string, then a new string is made.
If the original string is empty, the new string is empty.
If it is not, then the first character of the original string is used to
create the new string as a one-character string.
The new string is then pushed onto the stack.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]x\f[R]
Pops a value off of the top of the stack.
.RS
.PP
If it is a number, it is pushed back onto the stack.
.PP
If it is a string, it is executed as a macro.
.PP
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is greater than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
For example, \f[B]0 1>a\f[R] will execute the contents of register
\f[B]a\f[R], and \f[B]1 0>a\f[R] will not.
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not greater than the second (less than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is less than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not less than the second (greater than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is equal to the second, then the contents of register
\f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not equal to the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]?\f[R]
Reads a line from the \f[B]stdin\f[R] and executes it.
This is to allow macros to request input from users.
.TP
\f[B]q\f[R]
During execution of a macro, this exits the execution of that macro and
the execution of the macro that executed it.
If there are no macros, or only one macro executing, dc(1) exits.
.TP
\f[B]Q\f[R]
Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack.
If the number of levels to pop is greater than the number of executing
macros, dc(1) exits.
.SS Status
.PP
These commands query status of the stack or its top value.
.TP
\f[B]Z\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, calculates the number of significant decimal digits
it has and pushes the result.
.PP
If it is a string, pushes the number of characters the string has.
.RE
.TP
\f[B]X\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, pushes the \f[I]scale\f[R] of the value onto the
stack.
.PP
If it is a string, pushes \f[B]0\f[R].
.RE
.TP
\f[B]z\f[R]
Pushes the current stack depth (before execution of this command).
.SS Arrays
.PP
These commands manipulate arrays.
.TP
\f[B]:\f[R]\f[I]r\f[R]
Pops the top two values off of the stack.
The second value will be stored in the array \f[I]r\f[R] (see the
\f[B]REGISTERS\f[R] section), indexed by the first value.
.TP
\f[B];\f[R]\f[I]r\f[R]
Pops the value on top of the stack and uses it as an index into the
array \f[I]r\f[R].
The selected value is then pushed onto the stack.
.SH REGISTERS
.PP
Registers are names that can store strings, numbers, and arrays.
(Number/string registers do not interfere with array registers.)
.PP
Each register is also its own stack, so the current register value is
the top of the stack for the register.
All registers, when first referenced, have one value (\f[B]0\f[R]) in
their stack.
.PP
In non-extended register mode, a register name is just the single
character that follows any command that needs a register name.
The only exception is a newline (\f[B]`\[rs]n'\f[R]); it is a parse
error for a newline to be used as a register name.
.SS Extended Register Mode
.PP
Unlike most other dc(1) implentations, this dc(1) provides nearly
unlimited amounts of registers, if extended register mode is enabled.
.PP
If extended register mode is enabled (\f[B]-x\f[R] or
\f[B]\[en]extended-register\f[R] command-line arguments are given), then
normal single character registers are used \f[I]unless\f[R] the
character immediately following a command that needs a register name is
a space (according to \f[B]isspace()\f[R]) and not a newline
(\f[B]`\[rs]n'\f[R]).
.PP
In that case, the register name is found according to the regex
\f[B][a-z][a-z0-9_]*\f[R] (like bc(1) identifiers), and it is a parse
error if the next non-space characters do not match that regex.
.SH RESET
.PP
When dc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any macros that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all macros returned) is skipped.
.PP
Thus, when dc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.SH PERFORMANCE
.PP
Most dc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This dc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]DC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]DC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]DC_BASE_DIGS\f[R].
.PP
In addition, this dc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]DC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on dc(1):
.TP
\f[B]DC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
dc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]DC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]DC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]DC_BASE_DIGS\f[R].
.TP
\f[B]DC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]DC_BASE_POW\f[R].
.TP
\f[B]DC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]DC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]DC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
dc(1) recognizes the following environment variables:
.TP
\f[B]DC_ENV_ARGS\f[R]
This is another way to give command-line arguments to dc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]DC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs.
Another use would be to use the \f[B]-e\f[R] option to set
\f[B]scale\f[R] to a value other than \f[B]0\f[R].
.RS
.PP
The code that parses \f[B]DC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some dc file.dc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]dc\[dq] file.dc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
-in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
+in \f[B]\[rq]some `dc' file.dc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]DC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]DC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), dc(1) will output lines to that length,
including the backslash newline combo.
The default line length is \f[B]70\f[R].
.TP
\f[B]DC_EXPR_EXIT\f[R]
If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the
\f[B]-e\f[R] and/or \f[B]-f\f[R] command-line options (and any
equivalents).
.SH EXIT STATUS
.PP
dc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, attempting to convert a negative number to a hardware
integer, overflow when converting a number to a hardware integer, and
attempting to use a non-integer where an integer is required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]) operator.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, and using a
token where it is invalid.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, and attempting an operation when the
stack has too few elements.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (dc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, dc(1)
always exits and returns \f[B]4\f[R], no matter what mode dc(1) is in.
.PP
The other statuses will only be returned when dc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
dc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, dc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, dc(1) turns on \[lq]TTY mode.\[rq]
.PP
TTY mode is required for history to be enabled (see the \f[B]COMMAND
LINE HISTORY\f[R] section).
It is also required to enable special handling for \f[B]SIGINT\f[R]
signals.
.PP
The prompt is enabled in TTY mode.
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause dc(1) to stop execution of the
current input.
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If dc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If dc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to dc(1) as it is
executing a file, it can seem as though dc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause dc(1) to clean up and
exit, and it uses the default handler for all other signals.
The one exception is \f[B]SIGHUP\f[R]; in that case, when dc(1) is in
TTY mode, a \f[B]SIGHUP\f[R] will cause dc(1) to clean up and exit.
.SH COMMAND LINE HISTORY
.PP
dc(1) supports interactive command-line editing.
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), history is
enabled.
Previous lines can be recalled and edited with the arrow keys.
.PP
\f[B]Note\f[R]: tabs are converted to 8 spaces.
.SH SEE ALSO
.PP
bc(1)
.SH STANDARDS
.PP
The dc(1) utility operators are compliant with the operators in the
bc(1) IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHOR
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/dc/EN.1.md b/contrib/bc/manuals/dc/EN.1.md
index 0fa12db39760..4df214965ac5 100644
--- a/contrib/bc/manuals/dc/EN.1.md
+++ b/contrib/bc/manuals/dc/EN.1.md
@@ -1,1026 +1,1035 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# Name
dc - arbitrary-precision decimal reverse-Polish notation calculator
# SYNOPSIS
**dc** [**-hiPvVx**] [**--version**] [**--help**] [**--interactive**] [**--no-prompt**] [**--extended-register**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...] [*file*...]
# DESCRIPTION
dc(1) is an arbitrary-precision calculator. It uses a stack (reverse Polish
notation) to store numbers and results of computations. Arithmetic operations
pop arguments off of the stack and push the results.
If no files are given on the command-line as extra arguments (i.e., not as
**-f** or **--file** arguments), then dc(1) reads from **stdin**. Otherwise,
those files are processed, and dc(1) will then exit.
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where **-e** (**--expression**) and **-f** (**--file**)
arguments cause dc(1) to execute them and exit. The reason for this is that this
dc(1) allows users to set arguments in the environment variable **DC_ENV_ARGS**
(see the **ENVIRONMENT VARIABLES** section). Any expressions given on the
command-line should be used to set up a standard environment. For example, if a
user wants the **scale** always set to **10**, they can set **DC_ENV_ARGS** to
**-e 10k**, and this dc(1) will always start with a **scale** of **10**.
If users want to have dc(1) exit after processing all input from **-e** and
**-f** arguments (and their equivalents), then they can just simply add **-e q**
as the last command-line argument or define the environment variable
**DC_EXPR_EXIT**.
# OPTIONS
The following are the options that dc(1) accepts.
**-h**, **--help**
: Prints a usage message and quits.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-P**, **--no-prompt**
: Disables the prompt in TTY mode. (The prompt is only enabled in TTY mode.
See the **TTY MODE** section) This is mostly for those users that do not
want a prompt or are not used to having them in dc(1). Most of those users
would want to put this option in **DC_ENV_ARGS**.
This is a **non-portable extension**.
**-x** **--extended-register**
: Enables extended register mode. See the *Extended Register Mode* subsection
of the **REGISTERS** section for more information.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **DC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **dc <file> >&-**, it will quit with an error. This
is done so that dc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **dc <file> 2>&-**, it will quit with an error. This
is done so that dc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
Each item in the input source code, either a number (see the **NUMBERS**
section) or a command (see the **COMMANDS** section), is processed and executed,
in order. Input is processed immediately when entered.
**ibase** is a register (see the **REGISTERS** section) that determines how to
interpret constant numbers. It is the "input" base, or the number base used for
interpreting input numbers. **ibase** is initially **10**. The max allowable
value for **ibase** is **16**. The min allowable value for **ibase** is **2**.
The max allowable value for **ibase** can be queried in dc(1) programs with the
**T** command.
**obase** is a register (see the **REGISTERS** section) that determines how to
output results. It is the "output" base, or the number base used for outputting
numbers. **obase** is initially **10**. The max allowable value for **obase** is
**DC_BASE_MAX** and can be queried with the **U** command. The min allowable
value for **obase** is **2**. Values are output in the specified base.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a register (see the
**REGISTERS** section) that sets the precision of any operations (with
exceptions). **scale** is initially **0**. **scale** cannot be negative. The max
allowable value for **scale** can be queried in dc(1) programs with the **V**
command.
## Comments
Comments go from **#** until, and not including, the next newline. This is a
**non-portable extension**.
# NUMBERS
Numbers are strings made up of digits, uppercase letters up to **F**, and at
most **1** period for a radix. Numbers can have up to **DC_NUM_MAX** digits.
Uppercase letters are equal to **9** + their position in the alphabet (i.e.,
**A** equals **10**, or **9+1**). If a digit or letter makes no sense with the
current value of **ibase**, they are set to the value of the highest valid digit
in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **F** alone always equals decimal
**15**.
# COMMANDS
The valid commands are listed below.
## Printing
These commands are used for printing.
**p**
: Prints the value on top of the stack, whether number or string, and prints a
newline after.
This does not alter the stack.
**n**
: Prints the value on top of the stack, whether number or string, and pops it
off of the stack.
**P**
: Pops a value off the stack.
If the value is a number, it is truncated and the absolute value of the
result is printed as though **obase** is **UCHAR_MAX+1** and each digit is
interpreted as an ASCII character, making it a byte stream.
If the value is a string, it is printed without a trailing newline.
This is a **non-portable extension**.
**f**
: Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
Users should use this command when they get lost.
## Arithmetic
These are the commands used for arithmetic.
**+**
: The top two values are popped off the stack, added, and the result is pushed
onto the stack. The *scale* of the result is equal to the max *scale* of
both operands.
**-**
: The top two values are popped off the stack, subtracted, and the result is
pushed onto the stack. The *scale* of the result is equal to the max
*scale* of both operands.
**\***
: The top two values are popped off the stack, multiplied, and the result is
pushed onto the stack. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result
is equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The top two values are popped off the stack, divided, and the result is
pushed onto the stack. The *scale* of the result is equal to **scale**.
The first value popped off of the stack must be non-zero.
**%**
: The top two values are popped off the stack, remaindered, and the result is
pushed onto the stack.
Remaindering is equivalent to 1) Computing **a/b** to current **scale**, and
2) Using the result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The first value popped off of the stack must be non-zero.
**~**
: The top two values are popped off the stack, divided and remaindered, and
the results (divided first, remainder second) are pushed onto the stack.
This is equivalent to **x y / x y %** except that **x** and **y** are only
evaluated once.
The first value popped off of the stack must be non-zero.
This is a **non-portable extension**.
**\^**
: The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack. The *scale* of
the result is equal to **scale**.
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
**v**
: The top value is popped off the stack, its square root is computed, and the
result is pushed onto the stack. The *scale* of the result is equal to
**scale**.
The value popped off of the stack must be non-negative.
**\_**
: If this command *immediately* precedes a number (i.e., no spaces or other
commands), then that number is input as a negative number.
Otherwise, the top value on the stack is popped and copied, and the copy is
negated and pushed onto the stack. This behavior without a number is a
**non-portable extension**.
**b**
: The top value is popped off the stack, and if it is zero, it is pushed back
onto the stack. Otherwise, its absolute value is pushed onto the stack.
This is a **non-portable extension**.
**|**
: The top three values are popped off the stack, a modular exponentiation is
computed, and the result is pushed onto the stack.
The first value popped is used as the reduction modulus and must be an
integer and non-zero. The second value popped is used as the exponent and
must be an integer and non-negative. The third value popped is the base and
must be an integer.
This is a **non-portable extension**.
**G**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if they are equal, or **0** otherwise.
This is a **non-portable extension**.
**N**
: The top value is popped off of the stack, and if it a **0**, a **1** is
pushed; otherwise, a **0** is pushed.
This is a **non-portable extension**.
**(**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than the second, or **0** otherwise.
This is a **non-portable extension**.
**{**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than or equal to the second, or **0**
otherwise.
This is a **non-portable extension**.
**)**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than the second, or **0** otherwise.
This is a **non-portable extension**.
**}**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than or equal to the second, or
**0** otherwise.
This is a **non-portable extension**.
**M**
: The top two values are popped off of the stack. If they are both non-zero, a
**1** is pushed onto the stack. If either of them is zero, or both of them
are, then a **0** is pushed onto the stack.
This is like the **&&** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
**m**
: The top two values are popped off of the stack. If at least one of them is
non-zero, a **1** is pushed onto the stack. If both of them are zero, then a
**0** is pushed onto the stack.
This is like the **||** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
## Stack Control
These commands control the stack.
**c**
: Removes all items from ("clears") the stack.
**d**
: Copies the item on top of the stack ("duplicates") and pushes the copy onto
the stack.
**r**
: Swaps ("reverses") the two top items on the stack.
**R**
: Pops ("removes") the top value from the stack.
## Register Control
These commands control registers (see the **REGISTERS** section).
**s***r*
: Pops the value off the top of the stack and stores it into register *r*.
**l***r*
: Copies the value in register *r* and pushes it onto the stack. This does not
alter the contents of *r*.
**S***r*
: Pops the value off the top of the (main) stack and pushes it onto the stack
of register *r*. The previous value of the register becomes inaccessible.
**L***r*
: Pops the value off the top of the stack for register *r* and push it onto
the main stack. The previous value in the stack for register *r*, if any, is
now accessible via the **l***r* command.
## Parameters
These commands control the values of **ibase**, **obase**, and **scale**. Also
see the **SYNTAX** section.
**i**
: Pops the value off of the top of the stack and uses it to set **ibase**,
which must be between **2** and **16**, inclusive.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**o**
: Pops the value off of the top of the stack and uses it to set **obase**,
which must be between **2** and **DC_BASE_MAX**, inclusive (see the
**LIMITS** section).
If the value on top of the stack has any *scale*, the *scale* is ignored.
**k**
: Pops the value off of the top of the stack and uses it to set **scale**,
which must be non-negative.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**I**
: Pushes the current value of **ibase** onto the main stack.
**O**
: Pushes the current value of **obase** onto the main stack.
**K**
: Pushes the current value of **scale** onto the main stack.
**T**
: Pushes the maximum allowable value of **ibase** onto the main stack.
This is a **non-portable extension**.
**U**
: Pushes the maximum allowable value of **obase** onto the main stack.
This is a **non-portable extension**.
**V**
: Pushes the maximum allowable value of **scale** onto the main stack.
This is a **non-portable extension**.
## Strings
The following commands control strings.
dc(1) can work with both numbers and strings, and registers (see the
**REGISTERS** section) can hold both strings and numbers. dc(1) always knows
whether the contents of a register are a string or a number.
While arithmetic operations have to have numbers, and will print an error if
given a string, other commands accept strings.
Strings can also be executed as macros. For example, if the string **[1pR]** is
executed as a macro, then the code **1pR** is executed, meaning that the **1**
will be printed with a newline after and then popped from the stack.
**\[**_characters_**\]**
: Makes a string containing *characters* and pushes it onto the stack.
If there are brackets (**\[** and **\]**) in the string, then they must be
balanced. Unbalanced brackets can be escaped using a backslash (**\\**)
character.
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the (first)
backslash is not.
**a**
: The value on top of the stack is popped.
If it is a number, it is truncated and its absolute value is taken. The
result mod **UCHAR_MAX+1** is calculated. If that result is **0**, push an
empty string; otherwise, push a one-character string where the character is
the result of the mod interpreted as an ASCII character.
If it is a string, then a new string is made. If the original string is
empty, the new string is empty. If it is not, then the first character of
the original string is used to create the new string as a one-character
string. The new string is then pushed onto the stack.
This is a **non-portable extension**.
**x**
: Pops a value off of the top of the stack.
If it is a number, it is pushed back onto the stack.
If it is a string, it is executed as a macro.
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
**\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is greater than the second, then the contents of register
*r* are executed.
For example, **0 1>a** will execute the contents of register **a**, and
**1 0>a** will not.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not greater than the second (less than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is less than the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not less than the second (greater than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is equal to the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not equal to the second, then the contents of register
*r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**?**
: Reads a line from the **stdin** and executes it. This is to allow macros to
request input from users.
**q**
: During execution of a macro, this exits the execution of that macro and the
execution of the macro that executed it. If there are no macros, or only one
macro executing, dc(1) exits.
**Q**
: Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack. If the number
of levels to pop is greater than the number of executing macros, dc(1)
exits.
## Status
These commands query status of the stack or its top value.
**Z**
: Pops a value off of the stack.
If it is a number, calculates the number of significant decimal digits it
has and pushes the result.
If it is a string, pushes the number of characters the string has.
**X**
: Pops a value off of the stack.
If it is a number, pushes the *scale* of the value onto the stack.
If it is a string, pushes **0**.
**z**
: Pushes the current stack depth (before execution of this command).
## Arrays
These commands manipulate arrays.
**:***r*
: Pops the top two values off of the stack. The second value will be stored in
the array *r* (see the **REGISTERS** section), indexed by the first value.
**;***r*
: Pops the value on top of the stack and uses it as an index into the array
*r*. The selected value is then pushed onto the stack.
# REGISTERS
Registers are names that can store strings, numbers, and arrays. (Number/string
registers do not interfere with array registers.)
Each register is also its own stack, so the current register value is the top of
the stack for the register. All registers, when first referenced, have one value
(**0**) in their stack.
In non-extended register mode, a register name is just the single character that
follows any command that needs a register name. The only exception is a newline
(**'\\n'**); it is a parse error for a newline to be used as a register name.
## Extended Register Mode
Unlike most other dc(1) implentations, this dc(1) provides nearly unlimited
amounts of registers, if extended register mode is enabled.
If extended register mode is enabled (**-x** or **--extended-register**
command-line arguments are given), then normal single character registers are
used *unless* the character immediately following a command that needs a
register name is a space (according to **isspace()**) and not a newline
(**'\\n'**).
In that case, the register name is found according to the regex
**\[a-z\]\[a-z0-9\_\]\*** (like bc(1) identifiers), and it is a parse error if
the next non-space characters do not match that regex.
# RESET
When dc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any macros that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
macros returned) is skipped.
Thus, when dc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
# PERFORMANCE
Most dc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This dc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **DC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **DC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**DC_BASE_DIGS**.
In addition, this dc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **DC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on dc(1):
**DC_LONG_BIT**
: The number of bits in the **long** type in the environment where dc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**DC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **DC_LONG_BIT**.
**DC_BASE_POW**
: The max decimal number that each large integer can store (see
**DC_BASE_DIGS**) plus **1**. Depends on **DC_BASE_DIGS**.
**DC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **DC_LONG_BIT**.
**DC_BASE_MAX**
: The maximum output base. Set at **DC_BASE_POW**.
**DC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**DC_SCALE_MAX**
: The maximum **scale**. Set at **DC_OVERFLOW_MAX-1**.
**DC_STRING_MAX**
: The maximum length of strings. Set at **DC_OVERFLOW_MAX-1**.
**DC_NAME_MAX**
: The maximum length of identifiers. Set at **DC_OVERFLOW_MAX-1**.
**DC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **DC_OVERFLOW_MAX-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**DC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
dc(1) recognizes the following environment variables:
**DC_ENV_ARGS**
: This is another way to give command-line arguments to dc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **DC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs. Another use would
be to use the **-e** option to set **scale** to a value other than **0**.
The code that parses **DC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some dc file.dc"** will be correctly parsed, but the string
**"/home/gavin/some \"dc\" file.dc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
- double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
+ double quotes as the outside quotes, as in **"some 'dc' file.dc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **DC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**DC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), dc(1) will output
lines to that length, including the backslash newline combo. The default
line length is **70**.
**DC_EXPR_EXIT**
: If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the **-e** and/or
**-f** command-line options (and any equivalents).
# EXIT STATUS
dc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**) operator.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, and using a token where it is
invalid.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, and attempting an operation when
the stack has too few elements.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (dc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, dc(1) always exits
and returns **4**, no matter what mode dc(1) is in.
The other statuses will only be returned when dc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since dc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, dc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, dc(1) turns
on "TTY mode."
TTY mode is required for history to be enabled (see the **COMMAND LINE HISTORY**
section). It is also required to enable special handling for **SIGINT** signals.
The prompt is enabled in TTY mode.
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause dc(1) to stop execution of the current input. If
dc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If dc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If dc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to dc(1) as it is executing a file, it
can seem as though dc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause dc(1) to clean up and exit, and it uses the
default handler for all other signals. The one exception is **SIGHUP**; in that
case, when dc(1) is in TTY mode, a **SIGHUP** will cause dc(1) to clean up and
exit.
# COMMAND LINE HISTORY
dc(1) supports interactive command-line editing. If dc(1) is in TTY mode (see
the **TTY MODE** section), history is enabled. Previous lines can be recalled
and edited with the arrow keys.
**Note**: tabs are converted to 8 spaces.
# SEE ALSO
bc(1)
# STANDARDS
The dc(1) utility operators are compliant with the operators in the bc(1)
[IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1] specification.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHOR
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
diff --git a/contrib/bc/manuals/dc/ENP.1 b/contrib/bc/manuals/dc/ENP.1
index 4bdafbb469a2..aea2ec6a6c39 100644
--- a/contrib/bc/manuals/dc/ENP.1
+++ b/contrib/bc/manuals/dc/ENP.1
@@ -1,1119 +1,1132 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "DC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "DC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH Name
.PP
dc - arbitrary-precision decimal reverse-Polish notation calculator
.SH SYNOPSIS
.PP
\f[B]dc\f[R] [\f[B]-hiPvVx\f[R]] [\f[B]\[en]version\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]no-prompt\f[R]] [\f[B]\[en]extended-register\f[R]]
[\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
dc(1) is an arbitrary-precision calculator.
It uses a stack (reverse Polish notation) to store numbers and results
of computations.
Arithmetic operations pop arguments off of the stack and push the
results.
.PP
If no files are given on the command-line as extra arguments (i.e., not
as \f[B]-f\f[R] or \f[B]\[en]file\f[R] arguments), then dc(1) reads from
\f[B]stdin\f[R].
Otherwise, those files are processed, and dc(1) will then exit.
.PP
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where \f[B]-e\f[R] (\f[B]\[en]expression\f[R]) and
\f[B]-f\f[R] (\f[B]\[en]file\f[R]) arguments cause dc(1) to execute them
and exit.
The reason for this is that this dc(1) allows users to set arguments in
the environment variable \f[B]DC_ENV_ARGS\f[R] (see the \f[B]ENVIRONMENT
VARIABLES\f[R] section).
Any expressions given on the command-line should be used to set up a
standard environment.
For example, if a user wants the \f[B]scale\f[R] always set to
\f[B]10\f[R], they can set \f[B]DC_ENV_ARGS\f[R] to \f[B]-e 10k\f[R],
and this dc(1) will always start with a \f[B]scale\f[R] of \f[B]10\f[R].
.PP
If users want to have dc(1) exit after processing all input from
\f[B]-e\f[R] and \f[B]-f\f[R] arguments (and their equivalents), then
they can just simply add \f[B]-e q\f[R] as the last command-line
argument or define the environment variable \f[B]DC_EXPR_EXIT\f[R].
.SH OPTIONS
.PP
The following are the options that dc(1) accepts.
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
This option is a no-op.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-x\f[R] \f[B]\[en]extended-register\f[R]
Enables extended register mode.
See the \f[I]Extended Register Mode\f[R] subsection of the
\f[B]REGISTERS\f[R] section for more information.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]DC_ENV_ARGS\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]dc >&-\f[R], it will quit with an error.
This is done so that dc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]dc 2>&-\f[R], it will quit with an error.
This is done so that dc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
Each item in the input source code, either a number (see the
\f[B]NUMBERS\f[R] section) or a command (see the \f[B]COMMANDS\f[R]
section), is processed and executed, in order.
Input is processed immediately when entered.
.PP
\f[B]ibase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to interpret constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]ibase\f[R] is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in dc(1)
programs with the \f[B]T\f[R] command.
.PP
\f[B]obase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]DC_BASE_MAX\f[R] and
can be queried with the \f[B]U\f[R] command.
The min allowable value for \f[B]obase\f[R] is \f[B]2\f[R].
Values are output in the specified base.
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a register (see the \f[B]REGISTERS\f[R] section) that sets the
precision of any operations (with exceptions).
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] can be queried in dc(1)
programs with the \f[B]V\f[R] command.
.SS Comments
.PP
Comments go from \f[B]#\f[R] until, and not including, the next newline.
This is a \f[B]non-portable extension\f[R].
.SH NUMBERS
.PP
Numbers are strings made up of digits, uppercase letters up to
\f[B]F\f[R], and at most \f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]DC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]F\f[R] alone always equals decimal \f[B]15\f[R].
.SH COMMANDS
.PP
The valid commands are listed below.
.SS Printing
.PP
These commands are used for printing.
.TP
\f[B]p\f[R]
Prints the value on top of the stack, whether number or string, and
prints a newline after.
.RS
.PP
This does not alter the stack.
.RE
.TP
\f[B]n\f[R]
Prints the value on top of the stack, whether number or string, and pops
it off of the stack.
.TP
\f[B]P\f[R]
Pops a value off the stack.
.RS
.PP
If the value is a number, it is truncated and the absolute value of the
result is printed as though \f[B]obase\f[R] is \f[B]UCHAR_MAX+1\f[R] and
each digit is interpreted as an ASCII character, making it a byte
stream.
.PP
If the value is a string, it is printed without a trailing newline.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]f\f[R]
Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
.RS
.PP
Users should use this command when they get lost.
.RE
.SS Arithmetic
.PP
These are the commands used for arithmetic.
.TP
\f[B]+\f[R]
The top two values are popped off the stack, added, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]-\f[R]
The top two values are popped off the stack, subtracted, and the result
is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]*\f[R]
The top two values are popped off the stack, multiplied, and the result
is pushed onto the stack.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The top two values are popped off the stack, divided, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]%\f[R]
The top two values are popped off the stack, remaindered, and the result
is pushed onto the stack.
.RS
.PP
Remaindering is equivalent to 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R], and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]\[ti]\f[R]
The top two values are popped off the stack, divided and remaindered,
and the results (divided first, remainder second) are pushed onto the
stack.
This is equivalent to \f[B]x y / x y %\f[R] except that \f[B]x\f[R] and
\f[B]y\f[R] are only evaluated once.
.RS
.PP
The first value popped off of the stack must be non-zero.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
.RE
.TP
\f[B]v\f[R]
The top value is popped off the stack, its square root is computed, and
the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The value popped off of the stack must be non-negative.
.RE
.TP
\f[B]_\f[R]
If this command \f[I]immediately\f[R] precedes a number (i.e., no spaces
or other commands), then that number is input as a negative number.
.RS
.PP
Otherwise, the top value on the stack is popped and copied, and the copy
is negated and pushed onto the stack.
This behavior without a number is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]b\f[R]
The top value is popped off the stack, and if it is zero, it is pushed
back onto the stack.
Otherwise, its absolute value is pushed onto the stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]|\f[R]
The top three values are popped off the stack, a modular exponentiation
is computed, and the result is pushed onto the stack.
.RS
.PP
The first value popped is used as the reduction modulus and must be an
integer and non-zero.
The second value popped is used as the exponent and must be an integer
and non-negative.
The third value popped is the base and must be an integer.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]G\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if they are equal, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]N\f[R]
The top value is popped off of the stack, and if it a \f[B]0\f[R], a
\f[B]1\f[R] is pushed; otherwise, a \f[B]0\f[R] is pushed.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B](\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]{\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than or equal to the second,
or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B])\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]}\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than or equal to the
second, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]M\f[R]
The top two values are popped off of the stack.
If they are both non-zero, a \f[B]1\f[R] is pushed onto the stack.
If either of them is zero, or both of them are, then a \f[B]0\f[R] is
pushed onto the stack.
.RS
.PP
This is like the \f[B]&&\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]m\f[R]
The top two values are popped off of the stack.
If at least one of them is non-zero, a \f[B]1\f[R] is pushed onto the
stack.
If both of them are zero, then a \f[B]0\f[R] is pushed onto the stack.
.RS
.PP
This is like the \f[B]||\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Stack Control
.PP
These commands control the stack.
.TP
\f[B]c\f[R]
Removes all items from (\[lq]clears\[rq]) the stack.
.TP
\f[B]d\f[R]
Copies the item on top of the stack (\[lq]duplicates\[rq]) and pushes
the copy onto the stack.
.TP
\f[B]r\f[R]
Swaps (\[lq]reverses\[rq]) the two top items on the stack.
.TP
\f[B]R\f[R]
Pops (\[lq]removes\[rq]) the top value from the stack.
.SS Register Control
.PP
These commands control registers (see the \f[B]REGISTERS\f[R] section).
.TP
\f[B]s\f[R]\f[I]r\f[R]
Pops the value off the top of the stack and stores it into register
\f[I]r\f[R].
.TP
\f[B]l\f[R]\f[I]r\f[R]
Copies the value in register \f[I]r\f[R] and pushes it onto the stack.
This does not alter the contents of \f[I]r\f[R].
.TP
\f[B]S\f[R]\f[I]r\f[R]
Pops the value off the top of the (main) stack and pushes it onto the
stack of register \f[I]r\f[R].
The previous value of the register becomes inaccessible.
.TP
\f[B]L\f[R]\f[I]r\f[R]
Pops the value off the top of the stack for register \f[I]r\f[R] and
push it onto the main stack.
The previous value in the stack for register \f[I]r\f[R], if any, is now
accessible via the \f[B]l\f[R]\f[I]r\f[R] command.
.SS Parameters
.PP
These commands control the values of \f[B]ibase\f[R], \f[B]obase\f[R],
and \f[B]scale\f[R].
Also see the \f[B]SYNTAX\f[R] section.
.TP
\f[B]i\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]ibase\f[R], which must be between \f[B]2\f[R] and \f[B]16\f[R],
inclusive.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]o\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]obase\f[R], which must be between \f[B]2\f[R] and
\f[B]DC_BASE_MAX\f[R], inclusive (see the \f[B]LIMITS\f[R] section).
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]k\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]scale\f[R], which must be non-negative.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]I\f[R]
Pushes the current value of \f[B]ibase\f[R] onto the main stack.
.TP
\f[B]O\f[R]
Pushes the current value of \f[B]obase\f[R] onto the main stack.
.TP
\f[B]K\f[R]
Pushes the current value of \f[B]scale\f[R] onto the main stack.
.TP
\f[B]T\f[R]
Pushes the maximum allowable value of \f[B]ibase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]U\f[R]
Pushes the maximum allowable value of \f[B]obase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]V\f[R]
Pushes the maximum allowable value of \f[B]scale\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Strings
.PP
The following commands control strings.
.PP
dc(1) can work with both numbers and strings, and registers (see the
\f[B]REGISTERS\f[R] section) can hold both strings and numbers.
dc(1) always knows whether the contents of a register are a string or a
number.
.PP
While arithmetic operations have to have numbers, and will print an
error if given a string, other commands accept strings.
.PP
Strings can also be executed as macros.
For example, if the string \f[B][1pR]\f[R] is executed as a macro, then
the code \f[B]1pR\f[R] is executed, meaning that the \f[B]1\f[R] will be
printed with a newline after and then popped from the stack.
.TP
\f[B][\f[R]_characters_\f[B]]\f[R]
Makes a string containing \f[I]characters\f[R] and pushes it onto the
stack.
.RS
.PP
If there are brackets (\f[B][\f[R] and \f[B]]\f[R]) in the string, then
they must be balanced.
Unbalanced brackets can be escaped using a backslash (\f[B]\[rs]\f[R])
character.
.PP
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the
(first) backslash is not.
.RE
.TP
\f[B]a\f[R]
The value on top of the stack is popped.
.RS
.PP
If it is a number, it is truncated and its absolute value is taken.
The result mod \f[B]UCHAR_MAX+1\f[R] is calculated.
If that result is \f[B]0\f[R], push an empty string; otherwise, push a
one-character string where the character is the result of the mod
interpreted as an ASCII character.
.PP
If it is a string, then a new string is made.
If the original string is empty, the new string is empty.
If it is not, then the first character of the original string is used to
create the new string as a one-character string.
The new string is then pushed onto the stack.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]x\f[R]
Pops a value off of the top of the stack.
.RS
.PP
If it is a number, it is pushed back onto the stack.
.PP
If it is a string, it is executed as a macro.
.PP
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is greater than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
For example, \f[B]0 1>a\f[R] will execute the contents of register
\f[B]a\f[R], and \f[B]1 0>a\f[R] will not.
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not greater than the second (less than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is less than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not less than the second (greater than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is equal to the second, then the contents of register
\f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not equal to the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]?\f[R]
Reads a line from the \f[B]stdin\f[R] and executes it.
This is to allow macros to request input from users.
.TP
\f[B]q\f[R]
During execution of a macro, this exits the execution of that macro and
the execution of the macro that executed it.
If there are no macros, or only one macro executing, dc(1) exits.
.TP
\f[B]Q\f[R]
Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack.
If the number of levels to pop is greater than the number of executing
macros, dc(1) exits.
.SS Status
.PP
These commands query status of the stack or its top value.
.TP
\f[B]Z\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, calculates the number of significant decimal digits
it has and pushes the result.
.PP
If it is a string, pushes the number of characters the string has.
.RE
.TP
\f[B]X\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, pushes the \f[I]scale\f[R] of the value onto the
stack.
.PP
If it is a string, pushes \f[B]0\f[R].
.RE
.TP
\f[B]z\f[R]
Pushes the current stack depth (before execution of this command).
.SS Arrays
.PP
These commands manipulate arrays.
.TP
\f[B]:\f[R]\f[I]r\f[R]
Pops the top two values off of the stack.
The second value will be stored in the array \f[I]r\f[R] (see the
\f[B]REGISTERS\f[R] section), indexed by the first value.
.TP
\f[B];\f[R]\f[I]r\f[R]
Pops the value on top of the stack and uses it as an index into the
array \f[I]r\f[R].
The selected value is then pushed onto the stack.
.SH REGISTERS
.PP
Registers are names that can store strings, numbers, and arrays.
(Number/string registers do not interfere with array registers.)
.PP
Each register is also its own stack, so the current register value is
the top of the stack for the register.
All registers, when first referenced, have one value (\f[B]0\f[R]) in
their stack.
.PP
In non-extended register mode, a register name is just the single
character that follows any command that needs a register name.
The only exception is a newline (\f[B]`\[rs]n'\f[R]); it is a parse
error for a newline to be used as a register name.
.SS Extended Register Mode
.PP
Unlike most other dc(1) implentations, this dc(1) provides nearly
unlimited amounts of registers, if extended register mode is enabled.
.PP
If extended register mode is enabled (\f[B]-x\f[R] or
\f[B]\[en]extended-register\f[R] command-line arguments are given), then
normal single character registers are used \f[I]unless\f[R] the
character immediately following a command that needs a register name is
a space (according to \f[B]isspace()\f[R]) and not a newline
(\f[B]`\[rs]n'\f[R]).
.PP
In that case, the register name is found according to the regex
\f[B][a-z][a-z0-9_]*\f[R] (like bc(1) identifiers), and it is a parse
error if the next non-space characters do not match that regex.
.SH RESET
.PP
When dc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any macros that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all macros returned) is skipped.
.PP
Thus, when dc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.SH PERFORMANCE
.PP
Most dc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This dc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]DC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]DC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]DC_BASE_DIGS\f[R].
.PP
In addition, this dc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]DC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on dc(1):
.TP
\f[B]DC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
dc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]DC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]DC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]DC_BASE_DIGS\f[R].
.TP
\f[B]DC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]DC_BASE_POW\f[R].
.TP
\f[B]DC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]DC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]DC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
dc(1) recognizes the following environment variables:
.TP
\f[B]DC_ENV_ARGS\f[R]
This is another way to give command-line arguments to dc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]DC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs.
Another use would be to use the \f[B]-e\f[R] option to set
\f[B]scale\f[R] to a value other than \f[B]0\f[R].
.RS
.PP
The code that parses \f[B]DC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some dc file.dc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]dc\[dq] file.dc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
-in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
+in \f[B]\[rq]some `dc' file.dc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]DC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]DC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), dc(1) will output lines to that length,
including the backslash newline combo.
The default line length is \f[B]70\f[R].
.TP
\f[B]DC_EXPR_EXIT\f[R]
If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the
\f[B]-e\f[R] and/or \f[B]-f\f[R] command-line options (and any
equivalents).
.SH EXIT STATUS
.PP
dc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, attempting to convert a negative number to a hardware
integer, overflow when converting a number to a hardware integer, and
attempting to use a non-integer where an integer is required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]) operator.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, and using a
token where it is invalid.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, and attempting an operation when the
stack has too few elements.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (dc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, dc(1)
always exits and returns \f[B]4\f[R], no matter what mode dc(1) is in.
.PP
The other statuses will only be returned when dc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
dc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, dc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, dc(1) turns on \[lq]TTY mode.\[rq]
.PP
TTY mode is required for history to be enabled (see the \f[B]COMMAND
LINE HISTORY\f[R] section).
It is also required to enable special handling for \f[B]SIGINT\f[R]
signals.
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause dc(1) to stop execution of the
current input.
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If dc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If dc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to dc(1) as it is
executing a file, it can seem as though dc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause dc(1) to clean up and
exit, and it uses the default handler for all other signals.
The one exception is \f[B]SIGHUP\f[R]; in that case, when dc(1) is in
TTY mode, a \f[B]SIGHUP\f[R] will cause dc(1) to clean up and exit.
.SH COMMAND LINE HISTORY
.PP
dc(1) supports interactive command-line editing.
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), history is
enabled.
Previous lines can be recalled and edited with the arrow keys.
.PP
\f[B]Note\f[R]: tabs are converted to 8 spaces.
.SH SEE ALSO
.PP
bc(1)
.SH STANDARDS
.PP
The dc(1) utility operators are compliant with the operators in the
bc(1) IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHOR
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/dc/ENP.1.md b/contrib/bc/manuals/dc/ENP.1.md
index 708ddf4e957e..f88b418e3bfe 100644
--- a/contrib/bc/manuals/dc/ENP.1.md
+++ b/contrib/bc/manuals/dc/ENP.1.md
@@ -1,1021 +1,1030 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# Name
dc - arbitrary-precision decimal reverse-Polish notation calculator
# SYNOPSIS
**dc** [**-hiPvVx**] [**--version**] [**--help**] [**--interactive**] [**--no-prompt**] [**--extended-register**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...] [*file*...]
# DESCRIPTION
dc(1) is an arbitrary-precision calculator. It uses a stack (reverse Polish
notation) to store numbers and results of computations. Arithmetic operations
pop arguments off of the stack and push the results.
If no files are given on the command-line as extra arguments (i.e., not as
**-f** or **--file** arguments), then dc(1) reads from **stdin**. Otherwise,
those files are processed, and dc(1) will then exit.
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where **-e** (**--expression**) and **-f** (**--file**)
arguments cause dc(1) to execute them and exit. The reason for this is that this
dc(1) allows users to set arguments in the environment variable **DC_ENV_ARGS**
(see the **ENVIRONMENT VARIABLES** section). Any expressions given on the
command-line should be used to set up a standard environment. For example, if a
user wants the **scale** always set to **10**, they can set **DC_ENV_ARGS** to
**-e 10k**, and this dc(1) will always start with a **scale** of **10**.
If users want to have dc(1) exit after processing all input from **-e** and
**-f** arguments (and their equivalents), then they can just simply add **-e q**
as the last command-line argument or define the environment variable
**DC_EXPR_EXIT**.
# OPTIONS
The following are the options that dc(1) accepts.
**-h**, **--help**
: Prints a usage message and quits.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-P**, **--no-prompt**
: This option is a no-op.
This is a **non-portable extension**.
**-x** **--extended-register**
: Enables extended register mode. See the *Extended Register Mode* subsection
of the **REGISTERS** section for more information.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **DC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **dc <file> >&-**, it will quit with an error. This
is done so that dc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **dc <file> 2>&-**, it will quit with an error. This
is done so that dc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
Each item in the input source code, either a number (see the **NUMBERS**
section) or a command (see the **COMMANDS** section), is processed and executed,
in order. Input is processed immediately when entered.
**ibase** is a register (see the **REGISTERS** section) that determines how to
interpret constant numbers. It is the "input" base, or the number base used for
interpreting input numbers. **ibase** is initially **10**. The max allowable
value for **ibase** is **16**. The min allowable value for **ibase** is **2**.
The max allowable value for **ibase** can be queried in dc(1) programs with the
**T** command.
**obase** is a register (see the **REGISTERS** section) that determines how to
output results. It is the "output" base, or the number base used for outputting
numbers. **obase** is initially **10**. The max allowable value for **obase** is
**DC_BASE_MAX** and can be queried with the **U** command. The min allowable
value for **obase** is **2**. Values are output in the specified base.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a register (see the
**REGISTERS** section) that sets the precision of any operations (with
exceptions). **scale** is initially **0**. **scale** cannot be negative. The max
allowable value for **scale** can be queried in dc(1) programs with the **V**
command.
## Comments
Comments go from **#** until, and not including, the next newline. This is a
**non-portable extension**.
# NUMBERS
Numbers are strings made up of digits, uppercase letters up to **F**, and at
most **1** period for a radix. Numbers can have up to **DC_NUM_MAX** digits.
Uppercase letters are equal to **9** + their position in the alphabet (i.e.,
**A** equals **10**, or **9+1**). If a digit or letter makes no sense with the
current value of **ibase**, they are set to the value of the highest valid digit
in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **F** alone always equals decimal
**15**.
# COMMANDS
The valid commands are listed below.
## Printing
These commands are used for printing.
**p**
: Prints the value on top of the stack, whether number or string, and prints a
newline after.
This does not alter the stack.
**n**
: Prints the value on top of the stack, whether number or string, and pops it
off of the stack.
**P**
: Pops a value off the stack.
If the value is a number, it is truncated and the absolute value of the
result is printed as though **obase** is **UCHAR_MAX+1** and each digit is
interpreted as an ASCII character, making it a byte stream.
If the value is a string, it is printed without a trailing newline.
This is a **non-portable extension**.
**f**
: Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
Users should use this command when they get lost.
## Arithmetic
These are the commands used for arithmetic.
**+**
: The top two values are popped off the stack, added, and the result is pushed
onto the stack. The *scale* of the result is equal to the max *scale* of
both operands.
**-**
: The top two values are popped off the stack, subtracted, and the result is
pushed onto the stack. The *scale* of the result is equal to the max
*scale* of both operands.
**\***
: The top two values are popped off the stack, multiplied, and the result is
pushed onto the stack. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result
is equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The top two values are popped off the stack, divided, and the result is
pushed onto the stack. The *scale* of the result is equal to **scale**.
The first value popped off of the stack must be non-zero.
**%**
: The top two values are popped off the stack, remaindered, and the result is
pushed onto the stack.
Remaindering is equivalent to 1) Computing **a/b** to current **scale**, and
2) Using the result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The first value popped off of the stack must be non-zero.
**~**
: The top two values are popped off the stack, divided and remaindered, and
the results (divided first, remainder second) are pushed onto the stack.
This is equivalent to **x y / x y %** except that **x** and **y** are only
evaluated once.
The first value popped off of the stack must be non-zero.
This is a **non-portable extension**.
**\^**
: The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack. The *scale* of
the result is equal to **scale**.
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
**v**
: The top value is popped off the stack, its square root is computed, and the
result is pushed onto the stack. The *scale* of the result is equal to
**scale**.
The value popped off of the stack must be non-negative.
**\_**
: If this command *immediately* precedes a number (i.e., no spaces or other
commands), then that number is input as a negative number.
Otherwise, the top value on the stack is popped and copied, and the copy is
negated and pushed onto the stack. This behavior without a number is a
**non-portable extension**.
**b**
: The top value is popped off the stack, and if it is zero, it is pushed back
onto the stack. Otherwise, its absolute value is pushed onto the stack.
This is a **non-portable extension**.
**|**
: The top three values are popped off the stack, a modular exponentiation is
computed, and the result is pushed onto the stack.
The first value popped is used as the reduction modulus and must be an
integer and non-zero. The second value popped is used as the exponent and
must be an integer and non-negative. The third value popped is the base and
must be an integer.
This is a **non-portable extension**.
**G**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if they are equal, or **0** otherwise.
This is a **non-portable extension**.
**N**
: The top value is popped off of the stack, and if it a **0**, a **1** is
pushed; otherwise, a **0** is pushed.
This is a **non-portable extension**.
**(**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than the second, or **0** otherwise.
This is a **non-portable extension**.
**{**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than or equal to the second, or **0**
otherwise.
This is a **non-portable extension**.
**)**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than the second, or **0** otherwise.
This is a **non-portable extension**.
**}**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than or equal to the second, or
**0** otherwise.
This is a **non-portable extension**.
**M**
: The top two values are popped off of the stack. If they are both non-zero, a
**1** is pushed onto the stack. If either of them is zero, or both of them
are, then a **0** is pushed onto the stack.
This is like the **&&** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
**m**
: The top two values are popped off of the stack. If at least one of them is
non-zero, a **1** is pushed onto the stack. If both of them are zero, then a
**0** is pushed onto the stack.
This is like the **||** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
## Stack Control
These commands control the stack.
**c**
: Removes all items from ("clears") the stack.
**d**
: Copies the item on top of the stack ("duplicates") and pushes the copy onto
the stack.
**r**
: Swaps ("reverses") the two top items on the stack.
**R**
: Pops ("removes") the top value from the stack.
## Register Control
These commands control registers (see the **REGISTERS** section).
**s***r*
: Pops the value off the top of the stack and stores it into register *r*.
**l***r*
: Copies the value in register *r* and pushes it onto the stack. This does not
alter the contents of *r*.
**S***r*
: Pops the value off the top of the (main) stack and pushes it onto the stack
of register *r*. The previous value of the register becomes inaccessible.
**L***r*
: Pops the value off the top of the stack for register *r* and push it onto
the main stack. The previous value in the stack for register *r*, if any, is
now accessible via the **l***r* command.
## Parameters
These commands control the values of **ibase**, **obase**, and **scale**. Also
see the **SYNTAX** section.
**i**
: Pops the value off of the top of the stack and uses it to set **ibase**,
which must be between **2** and **16**, inclusive.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**o**
: Pops the value off of the top of the stack and uses it to set **obase**,
which must be between **2** and **DC_BASE_MAX**, inclusive (see the
**LIMITS** section).
If the value on top of the stack has any *scale*, the *scale* is ignored.
**k**
: Pops the value off of the top of the stack and uses it to set **scale**,
which must be non-negative.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**I**
: Pushes the current value of **ibase** onto the main stack.
**O**
: Pushes the current value of **obase** onto the main stack.
**K**
: Pushes the current value of **scale** onto the main stack.
**T**
: Pushes the maximum allowable value of **ibase** onto the main stack.
This is a **non-portable extension**.
**U**
: Pushes the maximum allowable value of **obase** onto the main stack.
This is a **non-portable extension**.
**V**
: Pushes the maximum allowable value of **scale** onto the main stack.
This is a **non-portable extension**.
## Strings
The following commands control strings.
dc(1) can work with both numbers and strings, and registers (see the
**REGISTERS** section) can hold both strings and numbers. dc(1) always knows
whether the contents of a register are a string or a number.
While arithmetic operations have to have numbers, and will print an error if
given a string, other commands accept strings.
Strings can also be executed as macros. For example, if the string **[1pR]** is
executed as a macro, then the code **1pR** is executed, meaning that the **1**
will be printed with a newline after and then popped from the stack.
**\[**_characters_**\]**
: Makes a string containing *characters* and pushes it onto the stack.
If there are brackets (**\[** and **\]**) in the string, then they must be
balanced. Unbalanced brackets can be escaped using a backslash (**\\**)
character.
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the (first)
backslash is not.
**a**
: The value on top of the stack is popped.
If it is a number, it is truncated and its absolute value is taken. The
result mod **UCHAR_MAX+1** is calculated. If that result is **0**, push an
empty string; otherwise, push a one-character string where the character is
the result of the mod interpreted as an ASCII character.
If it is a string, then a new string is made. If the original string is
empty, the new string is empty. If it is not, then the first character of
the original string is used to create the new string as a one-character
string. The new string is then pushed onto the stack.
This is a **non-portable extension**.
**x**
: Pops a value off of the top of the stack.
If it is a number, it is pushed back onto the stack.
If it is a string, it is executed as a macro.
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
**\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is greater than the second, then the contents of register
*r* are executed.
For example, **0 1>a** will execute the contents of register **a**, and
**1 0>a** will not.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not greater than the second (less than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is less than the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not less than the second (greater than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is equal to the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not equal to the second, then the contents of register
*r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**?**
: Reads a line from the **stdin** and executes it. This is to allow macros to
request input from users.
**q**
: During execution of a macro, this exits the execution of that macro and the
execution of the macro that executed it. If there are no macros, or only one
macro executing, dc(1) exits.
**Q**
: Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack. If the number
of levels to pop is greater than the number of executing macros, dc(1)
exits.
## Status
These commands query status of the stack or its top value.
**Z**
: Pops a value off of the stack.
If it is a number, calculates the number of significant decimal digits it
has and pushes the result.
If it is a string, pushes the number of characters the string has.
**X**
: Pops a value off of the stack.
If it is a number, pushes the *scale* of the value onto the stack.
If it is a string, pushes **0**.
**z**
: Pushes the current stack depth (before execution of this command).
## Arrays
These commands manipulate arrays.
**:***r*
: Pops the top two values off of the stack. The second value will be stored in
the array *r* (see the **REGISTERS** section), indexed by the first value.
**;***r*
: Pops the value on top of the stack and uses it as an index into the array
*r*. The selected value is then pushed onto the stack.
# REGISTERS
Registers are names that can store strings, numbers, and arrays. (Number/string
registers do not interfere with array registers.)
Each register is also its own stack, so the current register value is the top of
the stack for the register. All registers, when first referenced, have one value
(**0**) in their stack.
In non-extended register mode, a register name is just the single character that
follows any command that needs a register name. The only exception is a newline
(**'\\n'**); it is a parse error for a newline to be used as a register name.
## Extended Register Mode
Unlike most other dc(1) implentations, this dc(1) provides nearly unlimited
amounts of registers, if extended register mode is enabled.
If extended register mode is enabled (**-x** or **--extended-register**
command-line arguments are given), then normal single character registers are
used *unless* the character immediately following a command that needs a
register name is a space (according to **isspace()**) and not a newline
(**'\\n'**).
In that case, the register name is found according to the regex
**\[a-z\]\[a-z0-9\_\]\*** (like bc(1) identifiers), and it is a parse error if
the next non-space characters do not match that regex.
# RESET
When dc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any macros that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
macros returned) is skipped.
Thus, when dc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
# PERFORMANCE
Most dc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This dc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **DC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **DC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**DC_BASE_DIGS**.
In addition, this dc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **DC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on dc(1):
**DC_LONG_BIT**
: The number of bits in the **long** type in the environment where dc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**DC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **DC_LONG_BIT**.
**DC_BASE_POW**
: The max decimal number that each large integer can store (see
**DC_BASE_DIGS**) plus **1**. Depends on **DC_BASE_DIGS**.
**DC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **DC_LONG_BIT**.
**DC_BASE_MAX**
: The maximum output base. Set at **DC_BASE_POW**.
**DC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**DC_SCALE_MAX**
: The maximum **scale**. Set at **DC_OVERFLOW_MAX-1**.
**DC_STRING_MAX**
: The maximum length of strings. Set at **DC_OVERFLOW_MAX-1**.
**DC_NAME_MAX**
: The maximum length of identifiers. Set at **DC_OVERFLOW_MAX-1**.
**DC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **DC_OVERFLOW_MAX-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**DC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
dc(1) recognizes the following environment variables:
**DC_ENV_ARGS**
: This is another way to give command-line arguments to dc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **DC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs. Another use would
be to use the **-e** option to set **scale** to a value other than **0**.
The code that parses **DC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some dc file.dc"** will be correctly parsed, but the string
**"/home/gavin/some \"dc\" file.dc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
- double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
+ double quotes as the outside quotes, as in **"some 'dc' file.dc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **DC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**DC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), dc(1) will output
lines to that length, including the backslash newline combo. The default
line length is **70**.
**DC_EXPR_EXIT**
: If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the **-e** and/or
**-f** command-line options (and any equivalents).
# EXIT STATUS
dc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**) operator.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, and using a token where it is
invalid.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, and attempting an operation when
the stack has too few elements.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (dc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, dc(1) always exits
and returns **4**, no matter what mode dc(1) is in.
The other statuses will only be returned when dc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since dc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, dc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, dc(1) turns
on "TTY mode."
TTY mode is required for history to be enabled (see the **COMMAND LINE HISTORY**
section). It is also required to enable special handling for **SIGINT** signals.
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause dc(1) to stop execution of the current input. If
dc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If dc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If dc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to dc(1) as it is executing a file, it
can seem as though dc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause dc(1) to clean up and exit, and it uses the
default handler for all other signals. The one exception is **SIGHUP**; in that
case, when dc(1) is in TTY mode, a **SIGHUP** will cause dc(1) to clean up and
exit.
# COMMAND LINE HISTORY
dc(1) supports interactive command-line editing. If dc(1) is in TTY mode (see
the **TTY MODE** section), history is enabled. Previous lines can be recalled
and edited with the arrow keys.
**Note**: tabs are converted to 8 spaces.
# SEE ALSO
bc(1)
# STANDARDS
The dc(1) utility operators are compliant with the operators in the bc(1)
[IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1] specification.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHOR
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
diff --git a/contrib/bc/manuals/dc/EP.1 b/contrib/bc/manuals/dc/EP.1
index 7419872596f8..1e16db4a3d47 100644
--- a/contrib/bc/manuals/dc/EP.1
+++ b/contrib/bc/manuals/dc/EP.1
@@ -1,1123 +1,1136 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "DC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "DC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH Name
.PP
dc - arbitrary-precision decimal reverse-Polish notation calculator
.SH SYNOPSIS
.PP
\f[B]dc\f[R] [\f[B]-hiPvVx\f[R]] [\f[B]\[en]version\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]no-prompt\f[R]] [\f[B]\[en]extended-register\f[R]]
[\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
dc(1) is an arbitrary-precision calculator.
It uses a stack (reverse Polish notation) to store numbers and results
of computations.
Arithmetic operations pop arguments off of the stack and push the
results.
.PP
If no files are given on the command-line as extra arguments (i.e., not
as \f[B]-f\f[R] or \f[B]\[en]file\f[R] arguments), then dc(1) reads from
\f[B]stdin\f[R].
Otherwise, those files are processed, and dc(1) will then exit.
.PP
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where \f[B]-e\f[R] (\f[B]\[en]expression\f[R]) and
\f[B]-f\f[R] (\f[B]\[en]file\f[R]) arguments cause dc(1) to execute them
and exit.
The reason for this is that this dc(1) allows users to set arguments in
the environment variable \f[B]DC_ENV_ARGS\f[R] (see the \f[B]ENVIRONMENT
VARIABLES\f[R] section).
Any expressions given on the command-line should be used to set up a
standard environment.
For example, if a user wants the \f[B]scale\f[R] always set to
\f[B]10\f[R], they can set \f[B]DC_ENV_ARGS\f[R] to \f[B]-e 10k\f[R],
and this dc(1) will always start with a \f[B]scale\f[R] of \f[B]10\f[R].
.PP
If users want to have dc(1) exit after processing all input from
\f[B]-e\f[R] and \f[B]-f\f[R] arguments (and their equivalents), then
they can just simply add \f[B]-e q\f[R] as the last command-line
argument or define the environment variable \f[B]DC_EXPR_EXIT\f[R].
.SH OPTIONS
.PP
The following are the options that dc(1) accepts.
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
This option is a no-op.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-x\f[R] \f[B]\[en]extended-register\f[R]
Enables extended register mode.
See the \f[I]Extended Register Mode\f[R] subsection of the
\f[B]REGISTERS\f[R] section for more information.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]DC_ENV_ARGS\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]dc >&-\f[R], it will quit with an error.
This is done so that dc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]dc 2>&-\f[R], it will quit with an error.
This is done so that dc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
Each item in the input source code, either a number (see the
\f[B]NUMBERS\f[R] section) or a command (see the \f[B]COMMANDS\f[R]
section), is processed and executed, in order.
Input is processed immediately when entered.
.PP
\f[B]ibase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to interpret constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]ibase\f[R] is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in dc(1)
programs with the \f[B]T\f[R] command.
.PP
\f[B]obase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]DC_BASE_MAX\f[R] and
can be queried with the \f[B]U\f[R] command.
The min allowable value for \f[B]obase\f[R] is \f[B]2\f[R].
Values are output in the specified base.
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a register (see the \f[B]REGISTERS\f[R] section) that sets the
precision of any operations (with exceptions).
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] can be queried in dc(1)
programs with the \f[B]V\f[R] command.
.SS Comments
.PP
Comments go from \f[B]#\f[R] until, and not including, the next newline.
This is a \f[B]non-portable extension\f[R].
.SH NUMBERS
.PP
Numbers are strings made up of digits, uppercase letters up to
\f[B]F\f[R], and at most \f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]DC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]F\f[R] alone always equals decimal \f[B]15\f[R].
.SH COMMANDS
.PP
The valid commands are listed below.
.SS Printing
.PP
These commands are used for printing.
.TP
\f[B]p\f[R]
Prints the value on top of the stack, whether number or string, and
prints a newline after.
.RS
.PP
This does not alter the stack.
.RE
.TP
\f[B]n\f[R]
Prints the value on top of the stack, whether number or string, and pops
it off of the stack.
.TP
\f[B]P\f[R]
Pops a value off the stack.
.RS
.PP
If the value is a number, it is truncated and the absolute value of the
result is printed as though \f[B]obase\f[R] is \f[B]UCHAR_MAX+1\f[R] and
each digit is interpreted as an ASCII character, making it a byte
stream.
.PP
If the value is a string, it is printed without a trailing newline.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]f\f[R]
Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
.RS
.PP
Users should use this command when they get lost.
.RE
.SS Arithmetic
.PP
These are the commands used for arithmetic.
.TP
\f[B]+\f[R]
The top two values are popped off the stack, added, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]-\f[R]
The top two values are popped off the stack, subtracted, and the result
is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]*\f[R]
The top two values are popped off the stack, multiplied, and the result
is pushed onto the stack.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The top two values are popped off the stack, divided, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]%\f[R]
The top two values are popped off the stack, remaindered, and the result
is pushed onto the stack.
.RS
.PP
Remaindering is equivalent to 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R], and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]\[ti]\f[R]
The top two values are popped off the stack, divided and remaindered,
and the results (divided first, remainder second) are pushed onto the
stack.
This is equivalent to \f[B]x y / x y %\f[R] except that \f[B]x\f[R] and
\f[B]y\f[R] are only evaluated once.
.RS
.PP
The first value popped off of the stack must be non-zero.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
.RE
.TP
\f[B]v\f[R]
The top value is popped off the stack, its square root is computed, and
the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The value popped off of the stack must be non-negative.
.RE
.TP
\f[B]_\f[R]
If this command \f[I]immediately\f[R] precedes a number (i.e., no spaces
or other commands), then that number is input as a negative number.
.RS
.PP
Otherwise, the top value on the stack is popped and copied, and the copy
is negated and pushed onto the stack.
This behavior without a number is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]b\f[R]
The top value is popped off the stack, and if it is zero, it is pushed
back onto the stack.
Otherwise, its absolute value is pushed onto the stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]|\f[R]
The top three values are popped off the stack, a modular exponentiation
is computed, and the result is pushed onto the stack.
.RS
.PP
The first value popped is used as the reduction modulus and must be an
integer and non-zero.
The second value popped is used as the exponent and must be an integer
and non-negative.
The third value popped is the base and must be an integer.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]G\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if they are equal, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]N\f[R]
The top value is popped off of the stack, and if it a \f[B]0\f[R], a
\f[B]1\f[R] is pushed; otherwise, a \f[B]0\f[R] is pushed.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B](\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]{\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than or equal to the second,
or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B])\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]}\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than or equal to the
second, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]M\f[R]
The top two values are popped off of the stack.
If they are both non-zero, a \f[B]1\f[R] is pushed onto the stack.
If either of them is zero, or both of them are, then a \f[B]0\f[R] is
pushed onto the stack.
.RS
.PP
This is like the \f[B]&&\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]m\f[R]
The top two values are popped off of the stack.
If at least one of them is non-zero, a \f[B]1\f[R] is pushed onto the
stack.
If both of them are zero, then a \f[B]0\f[R] is pushed onto the stack.
.RS
.PP
This is like the \f[B]||\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Stack Control
.PP
These commands control the stack.
.TP
\f[B]c\f[R]
Removes all items from (\[lq]clears\[rq]) the stack.
.TP
\f[B]d\f[R]
Copies the item on top of the stack (\[lq]duplicates\[rq]) and pushes
the copy onto the stack.
.TP
\f[B]r\f[R]
Swaps (\[lq]reverses\[rq]) the two top items on the stack.
.TP
\f[B]R\f[R]
Pops (\[lq]removes\[rq]) the top value from the stack.
.SS Register Control
.PP
These commands control registers (see the \f[B]REGISTERS\f[R] section).
.TP
\f[B]s\f[R]\f[I]r\f[R]
Pops the value off the top of the stack and stores it into register
\f[I]r\f[R].
.TP
\f[B]l\f[R]\f[I]r\f[R]
Copies the value in register \f[I]r\f[R] and pushes it onto the stack.
This does not alter the contents of \f[I]r\f[R].
.TP
\f[B]S\f[R]\f[I]r\f[R]
Pops the value off the top of the (main) stack and pushes it onto the
stack of register \f[I]r\f[R].
The previous value of the register becomes inaccessible.
.TP
\f[B]L\f[R]\f[I]r\f[R]
Pops the value off the top of the stack for register \f[I]r\f[R] and
push it onto the main stack.
The previous value in the stack for register \f[I]r\f[R], if any, is now
accessible via the \f[B]l\f[R]\f[I]r\f[R] command.
.SS Parameters
.PP
These commands control the values of \f[B]ibase\f[R], \f[B]obase\f[R],
and \f[B]scale\f[R].
Also see the \f[B]SYNTAX\f[R] section.
.TP
\f[B]i\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]ibase\f[R], which must be between \f[B]2\f[R] and \f[B]16\f[R],
inclusive.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]o\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]obase\f[R], which must be between \f[B]2\f[R] and
\f[B]DC_BASE_MAX\f[R], inclusive (see the \f[B]LIMITS\f[R] section).
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]k\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]scale\f[R], which must be non-negative.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]I\f[R]
Pushes the current value of \f[B]ibase\f[R] onto the main stack.
.TP
\f[B]O\f[R]
Pushes the current value of \f[B]obase\f[R] onto the main stack.
.TP
\f[B]K\f[R]
Pushes the current value of \f[B]scale\f[R] onto the main stack.
.TP
\f[B]T\f[R]
Pushes the maximum allowable value of \f[B]ibase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]U\f[R]
Pushes the maximum allowable value of \f[B]obase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]V\f[R]
Pushes the maximum allowable value of \f[B]scale\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Strings
.PP
The following commands control strings.
.PP
dc(1) can work with both numbers and strings, and registers (see the
\f[B]REGISTERS\f[R] section) can hold both strings and numbers.
dc(1) always knows whether the contents of a register are a string or a
number.
.PP
While arithmetic operations have to have numbers, and will print an
error if given a string, other commands accept strings.
.PP
Strings can also be executed as macros.
For example, if the string \f[B][1pR]\f[R] is executed as a macro, then
the code \f[B]1pR\f[R] is executed, meaning that the \f[B]1\f[R] will be
printed with a newline after and then popped from the stack.
.TP
\f[B][\f[R]_characters_\f[B]]\f[R]
Makes a string containing \f[I]characters\f[R] and pushes it onto the
stack.
.RS
.PP
If there are brackets (\f[B][\f[R] and \f[B]]\f[R]) in the string, then
they must be balanced.
Unbalanced brackets can be escaped using a backslash (\f[B]\[rs]\f[R])
character.
.PP
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the
(first) backslash is not.
.RE
.TP
\f[B]a\f[R]
The value on top of the stack is popped.
.RS
.PP
If it is a number, it is truncated and its absolute value is taken.
The result mod \f[B]UCHAR_MAX+1\f[R] is calculated.
If that result is \f[B]0\f[R], push an empty string; otherwise, push a
one-character string where the character is the result of the mod
interpreted as an ASCII character.
.PP
If it is a string, then a new string is made.
If the original string is empty, the new string is empty.
If it is not, then the first character of the original string is used to
create the new string as a one-character string.
The new string is then pushed onto the stack.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]x\f[R]
Pops a value off of the top of the stack.
.RS
.PP
If it is a number, it is pushed back onto the stack.
.PP
If it is a string, it is executed as a macro.
.PP
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is greater than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
For example, \f[B]0 1>a\f[R] will execute the contents of register
\f[B]a\f[R], and \f[B]1 0>a\f[R] will not.
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not greater than the second (less than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is less than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not less than the second (greater than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is equal to the second, then the contents of register
\f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not equal to the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]?\f[R]
Reads a line from the \f[B]stdin\f[R] and executes it.
This is to allow macros to request input from users.
.TP
\f[B]q\f[R]
During execution of a macro, this exits the execution of that macro and
the execution of the macro that executed it.
If there are no macros, or only one macro executing, dc(1) exits.
.TP
\f[B]Q\f[R]
Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack.
If the number of levels to pop is greater than the number of executing
macros, dc(1) exits.
.SS Status
.PP
These commands query status of the stack or its top value.
.TP
\f[B]Z\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, calculates the number of significant decimal digits
it has and pushes the result.
.PP
If it is a string, pushes the number of characters the string has.
.RE
.TP
\f[B]X\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, pushes the \f[I]scale\f[R] of the value onto the
stack.
.PP
If it is a string, pushes \f[B]0\f[R].
.RE
.TP
\f[B]z\f[R]
Pushes the current stack depth (before execution of this command).
.SS Arrays
.PP
These commands manipulate arrays.
.TP
\f[B]:\f[R]\f[I]r\f[R]
Pops the top two values off of the stack.
The second value will be stored in the array \f[I]r\f[R] (see the
\f[B]REGISTERS\f[R] section), indexed by the first value.
.TP
\f[B];\f[R]\f[I]r\f[R]
Pops the value on top of the stack and uses it as an index into the
array \f[I]r\f[R].
The selected value is then pushed onto the stack.
.SH REGISTERS
.PP
Registers are names that can store strings, numbers, and arrays.
(Number/string registers do not interfere with array registers.)
.PP
Each register is also its own stack, so the current register value is
the top of the stack for the register.
All registers, when first referenced, have one value (\f[B]0\f[R]) in
their stack.
.PP
In non-extended register mode, a register name is just the single
character that follows any command that needs a register name.
The only exception is a newline (\f[B]`\[rs]n'\f[R]); it is a parse
error for a newline to be used as a register name.
.SS Extended Register Mode
.PP
Unlike most other dc(1) implentations, this dc(1) provides nearly
unlimited amounts of registers, if extended register mode is enabled.
.PP
If extended register mode is enabled (\f[B]-x\f[R] or
\f[B]\[en]extended-register\f[R] command-line arguments are given), then
normal single character registers are used \f[I]unless\f[R] the
character immediately following a command that needs a register name is
a space (according to \f[B]isspace()\f[R]) and not a newline
(\f[B]`\[rs]n'\f[R]).
.PP
In that case, the register name is found according to the regex
\f[B][a-z][a-z0-9_]*\f[R] (like bc(1) identifiers), and it is a parse
error if the next non-space characters do not match that regex.
.SH RESET
.PP
When dc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any macros that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all macros returned) is skipped.
.PP
Thus, when dc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.SH PERFORMANCE
.PP
Most dc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This dc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]DC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]DC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]DC_BASE_DIGS\f[R].
.PP
In addition, this dc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]DC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on dc(1):
.TP
\f[B]DC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
dc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]DC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]DC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]DC_BASE_DIGS\f[R].
.TP
\f[B]DC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]DC_BASE_POW\f[R].
.TP
\f[B]DC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]DC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]DC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
dc(1) recognizes the following environment variables:
.TP
\f[B]DC_ENV_ARGS\f[R]
This is another way to give command-line arguments to dc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]DC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs.
Another use would be to use the \f[B]-e\f[R] option to set
\f[B]scale\f[R] to a value other than \f[B]0\f[R].
.RS
.PP
The code that parses \f[B]DC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some dc file.dc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]dc\[dq] file.dc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
-in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
+in \f[B]\[rq]some `dc' file.dc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]DC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]DC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), dc(1) will output lines to that length,
including the backslash newline combo.
The default line length is \f[B]70\f[R].
.TP
\f[B]DC_EXPR_EXIT\f[R]
If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the
\f[B]-e\f[R] and/or \f[B]-f\f[R] command-line options (and any
equivalents).
.SH EXIT STATUS
.PP
dc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, attempting to convert a negative number to a hardware
integer, overflow when converting a number to a hardware integer, and
attempting to use a non-integer where an integer is required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]) operator.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, and using a
token where it is invalid.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, and attempting an operation when the
stack has too few elements.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (dc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, dc(1)
always exits and returns \f[B]4\f[R], no matter what mode dc(1) is in.
.PP
The other statuses will only be returned when dc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
dc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, dc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, dc(1) turns on \[lq]TTY mode.\[rq]
.PP
TTY mode is required for history to be enabled (see the \f[B]COMMAND
LINE HISTORY\f[R] section).
It is also required to enable special handling for \f[B]SIGINT\f[R]
signals.
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause dc(1) to stop execution of the
current input.
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If dc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If dc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to dc(1) as it is
executing a file, it can seem as though dc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause dc(1) to clean up and
exit, and it uses the default handler for all other signals.
The one exception is \f[B]SIGHUP\f[R]; in that case, when dc(1) is in
TTY mode, a \f[B]SIGHUP\f[R] will cause dc(1) to clean up and exit.
.SH COMMAND LINE HISTORY
.PP
dc(1) supports interactive command-line editing.
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), history is
enabled.
Previous lines can be recalled and edited with the arrow keys.
.PP
\f[B]Note\f[R]: tabs are converted to 8 spaces.
.SH LOCALES
.PP
This dc(1) ships with support for adding error messages for different
locales and thus, supports \f[B]LC_MESSAGS\f[R].
.SH SEE ALSO
.PP
bc(1)
.SH STANDARDS
.PP
The dc(1) utility operators are compliant with the operators in the
bc(1) IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHOR
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/dc/EP.1.md b/contrib/bc/manuals/dc/EP.1.md
index 30a55b4074bf..a64d49b13433 100644
--- a/contrib/bc/manuals/dc/EP.1.md
+++ b/contrib/bc/manuals/dc/EP.1.md
@@ -1,1026 +1,1035 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# Name
dc - arbitrary-precision decimal reverse-Polish notation calculator
# SYNOPSIS
**dc** [**-hiPvVx**] [**--version**] [**--help**] [**--interactive**] [**--no-prompt**] [**--extended-register**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...] [*file*...]
# DESCRIPTION
dc(1) is an arbitrary-precision calculator. It uses a stack (reverse Polish
notation) to store numbers and results of computations. Arithmetic operations
pop arguments off of the stack and push the results.
If no files are given on the command-line as extra arguments (i.e., not as
**-f** or **--file** arguments), then dc(1) reads from **stdin**. Otherwise,
those files are processed, and dc(1) will then exit.
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where **-e** (**--expression**) and **-f** (**--file**)
arguments cause dc(1) to execute them and exit. The reason for this is that this
dc(1) allows users to set arguments in the environment variable **DC_ENV_ARGS**
(see the **ENVIRONMENT VARIABLES** section). Any expressions given on the
command-line should be used to set up a standard environment. For example, if a
user wants the **scale** always set to **10**, they can set **DC_ENV_ARGS** to
**-e 10k**, and this dc(1) will always start with a **scale** of **10**.
If users want to have dc(1) exit after processing all input from **-e** and
**-f** arguments (and their equivalents), then they can just simply add **-e q**
as the last command-line argument or define the environment variable
**DC_EXPR_EXIT**.
# OPTIONS
The following are the options that dc(1) accepts.
**-h**, **--help**
: Prints a usage message and quits.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-P**, **--no-prompt**
: This option is a no-op.
This is a **non-portable extension**.
**-x** **--extended-register**
: Enables extended register mode. See the *Extended Register Mode* subsection
of the **REGISTERS** section for more information.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **DC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **dc <file> >&-**, it will quit with an error. This
is done so that dc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **dc <file> 2>&-**, it will quit with an error. This
is done so that dc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
Each item in the input source code, either a number (see the **NUMBERS**
section) or a command (see the **COMMANDS** section), is processed and executed,
in order. Input is processed immediately when entered.
**ibase** is a register (see the **REGISTERS** section) that determines how to
interpret constant numbers. It is the "input" base, or the number base used for
interpreting input numbers. **ibase** is initially **10**. The max allowable
value for **ibase** is **16**. The min allowable value for **ibase** is **2**.
The max allowable value for **ibase** can be queried in dc(1) programs with the
**T** command.
**obase** is a register (see the **REGISTERS** section) that determines how to
output results. It is the "output" base, or the number base used for outputting
numbers. **obase** is initially **10**. The max allowable value for **obase** is
**DC_BASE_MAX** and can be queried with the **U** command. The min allowable
value for **obase** is **2**. Values are output in the specified base.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a register (see the
**REGISTERS** section) that sets the precision of any operations (with
exceptions). **scale** is initially **0**. **scale** cannot be negative. The max
allowable value for **scale** can be queried in dc(1) programs with the **V**
command.
## Comments
Comments go from **#** until, and not including, the next newline. This is a
**non-portable extension**.
# NUMBERS
Numbers are strings made up of digits, uppercase letters up to **F**, and at
most **1** period for a radix. Numbers can have up to **DC_NUM_MAX** digits.
Uppercase letters are equal to **9** + their position in the alphabet (i.e.,
**A** equals **10**, or **9+1**). If a digit or letter makes no sense with the
current value of **ibase**, they are set to the value of the highest valid digit
in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **F** alone always equals decimal
**15**.
# COMMANDS
The valid commands are listed below.
## Printing
These commands are used for printing.
**p**
: Prints the value on top of the stack, whether number or string, and prints a
newline after.
This does not alter the stack.
**n**
: Prints the value on top of the stack, whether number or string, and pops it
off of the stack.
**P**
: Pops a value off the stack.
If the value is a number, it is truncated and the absolute value of the
result is printed as though **obase** is **UCHAR_MAX+1** and each digit is
interpreted as an ASCII character, making it a byte stream.
If the value is a string, it is printed without a trailing newline.
This is a **non-portable extension**.
**f**
: Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
Users should use this command when they get lost.
## Arithmetic
These are the commands used for arithmetic.
**+**
: The top two values are popped off the stack, added, and the result is pushed
onto the stack. The *scale* of the result is equal to the max *scale* of
both operands.
**-**
: The top two values are popped off the stack, subtracted, and the result is
pushed onto the stack. The *scale* of the result is equal to the max
*scale* of both operands.
**\***
: The top two values are popped off the stack, multiplied, and the result is
pushed onto the stack. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result
is equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The top two values are popped off the stack, divided, and the result is
pushed onto the stack. The *scale* of the result is equal to **scale**.
The first value popped off of the stack must be non-zero.
**%**
: The top two values are popped off the stack, remaindered, and the result is
pushed onto the stack.
Remaindering is equivalent to 1) Computing **a/b** to current **scale**, and
2) Using the result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The first value popped off of the stack must be non-zero.
**~**
: The top two values are popped off the stack, divided and remaindered, and
the results (divided first, remainder second) are pushed onto the stack.
This is equivalent to **x y / x y %** except that **x** and **y** are only
evaluated once.
The first value popped off of the stack must be non-zero.
This is a **non-portable extension**.
**\^**
: The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack. The *scale* of
the result is equal to **scale**.
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
**v**
: The top value is popped off the stack, its square root is computed, and the
result is pushed onto the stack. The *scale* of the result is equal to
**scale**.
The value popped off of the stack must be non-negative.
**\_**
: If this command *immediately* precedes a number (i.e., no spaces or other
commands), then that number is input as a negative number.
Otherwise, the top value on the stack is popped and copied, and the copy is
negated and pushed onto the stack. This behavior without a number is a
**non-portable extension**.
**b**
: The top value is popped off the stack, and if it is zero, it is pushed back
onto the stack. Otherwise, its absolute value is pushed onto the stack.
This is a **non-portable extension**.
**|**
: The top three values are popped off the stack, a modular exponentiation is
computed, and the result is pushed onto the stack.
The first value popped is used as the reduction modulus and must be an
integer and non-zero. The second value popped is used as the exponent and
must be an integer and non-negative. The third value popped is the base and
must be an integer.
This is a **non-portable extension**.
**G**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if they are equal, or **0** otherwise.
This is a **non-portable extension**.
**N**
: The top value is popped off of the stack, and if it a **0**, a **1** is
pushed; otherwise, a **0** is pushed.
This is a **non-portable extension**.
**(**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than the second, or **0** otherwise.
This is a **non-portable extension**.
**{**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than or equal to the second, or **0**
otherwise.
This is a **non-portable extension**.
**)**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than the second, or **0** otherwise.
This is a **non-portable extension**.
**}**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than or equal to the second, or
**0** otherwise.
This is a **non-portable extension**.
**M**
: The top two values are popped off of the stack. If they are both non-zero, a
**1** is pushed onto the stack. If either of them is zero, or both of them
are, then a **0** is pushed onto the stack.
This is like the **&&** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
**m**
: The top two values are popped off of the stack. If at least one of them is
non-zero, a **1** is pushed onto the stack. If both of them are zero, then a
**0** is pushed onto the stack.
This is like the **||** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
## Stack Control
These commands control the stack.
**c**
: Removes all items from ("clears") the stack.
**d**
: Copies the item on top of the stack ("duplicates") and pushes the copy onto
the stack.
**r**
: Swaps ("reverses") the two top items on the stack.
**R**
: Pops ("removes") the top value from the stack.
## Register Control
These commands control registers (see the **REGISTERS** section).
**s***r*
: Pops the value off the top of the stack and stores it into register *r*.
**l***r*
: Copies the value in register *r* and pushes it onto the stack. This does not
alter the contents of *r*.
**S***r*
: Pops the value off the top of the (main) stack and pushes it onto the stack
of register *r*. The previous value of the register becomes inaccessible.
**L***r*
: Pops the value off the top of the stack for register *r* and push it onto
the main stack. The previous value in the stack for register *r*, if any, is
now accessible via the **l***r* command.
## Parameters
These commands control the values of **ibase**, **obase**, and **scale**. Also
see the **SYNTAX** section.
**i**
: Pops the value off of the top of the stack and uses it to set **ibase**,
which must be between **2** and **16**, inclusive.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**o**
: Pops the value off of the top of the stack and uses it to set **obase**,
which must be between **2** and **DC_BASE_MAX**, inclusive (see the
**LIMITS** section).
If the value on top of the stack has any *scale*, the *scale* is ignored.
**k**
: Pops the value off of the top of the stack and uses it to set **scale**,
which must be non-negative.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**I**
: Pushes the current value of **ibase** onto the main stack.
**O**
: Pushes the current value of **obase** onto the main stack.
**K**
: Pushes the current value of **scale** onto the main stack.
**T**
: Pushes the maximum allowable value of **ibase** onto the main stack.
This is a **non-portable extension**.
**U**
: Pushes the maximum allowable value of **obase** onto the main stack.
This is a **non-portable extension**.
**V**
: Pushes the maximum allowable value of **scale** onto the main stack.
This is a **non-portable extension**.
## Strings
The following commands control strings.
dc(1) can work with both numbers and strings, and registers (see the
**REGISTERS** section) can hold both strings and numbers. dc(1) always knows
whether the contents of a register are a string or a number.
While arithmetic operations have to have numbers, and will print an error if
given a string, other commands accept strings.
Strings can also be executed as macros. For example, if the string **[1pR]** is
executed as a macro, then the code **1pR** is executed, meaning that the **1**
will be printed with a newline after and then popped from the stack.
**\[**_characters_**\]**
: Makes a string containing *characters* and pushes it onto the stack.
If there are brackets (**\[** and **\]**) in the string, then they must be
balanced. Unbalanced brackets can be escaped using a backslash (**\\**)
character.
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the (first)
backslash is not.
**a**
: The value on top of the stack is popped.
If it is a number, it is truncated and its absolute value is taken. The
result mod **UCHAR_MAX+1** is calculated. If that result is **0**, push an
empty string; otherwise, push a one-character string where the character is
the result of the mod interpreted as an ASCII character.
If it is a string, then a new string is made. If the original string is
empty, the new string is empty. If it is not, then the first character of
the original string is used to create the new string as a one-character
string. The new string is then pushed onto the stack.
This is a **non-portable extension**.
**x**
: Pops a value off of the top of the stack.
If it is a number, it is pushed back onto the stack.
If it is a string, it is executed as a macro.
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
**\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is greater than the second, then the contents of register
*r* are executed.
For example, **0 1>a** will execute the contents of register **a**, and
**1 0>a** will not.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not greater than the second (less than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is less than the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not less than the second (greater than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is equal to the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not equal to the second, then the contents of register
*r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**?**
: Reads a line from the **stdin** and executes it. This is to allow macros to
request input from users.
**q**
: During execution of a macro, this exits the execution of that macro and the
execution of the macro that executed it. If there are no macros, or only one
macro executing, dc(1) exits.
**Q**
: Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack. If the number
of levels to pop is greater than the number of executing macros, dc(1)
exits.
## Status
These commands query status of the stack or its top value.
**Z**
: Pops a value off of the stack.
If it is a number, calculates the number of significant decimal digits it
has and pushes the result.
If it is a string, pushes the number of characters the string has.
**X**
: Pops a value off of the stack.
If it is a number, pushes the *scale* of the value onto the stack.
If it is a string, pushes **0**.
**z**
: Pushes the current stack depth (before execution of this command).
## Arrays
These commands manipulate arrays.
**:***r*
: Pops the top two values off of the stack. The second value will be stored in
the array *r* (see the **REGISTERS** section), indexed by the first value.
**;***r*
: Pops the value on top of the stack and uses it as an index into the array
*r*. The selected value is then pushed onto the stack.
# REGISTERS
Registers are names that can store strings, numbers, and arrays. (Number/string
registers do not interfere with array registers.)
Each register is also its own stack, so the current register value is the top of
the stack for the register. All registers, when first referenced, have one value
(**0**) in their stack.
In non-extended register mode, a register name is just the single character that
follows any command that needs a register name. The only exception is a newline
(**'\\n'**); it is a parse error for a newline to be used as a register name.
## Extended Register Mode
Unlike most other dc(1) implentations, this dc(1) provides nearly unlimited
amounts of registers, if extended register mode is enabled.
If extended register mode is enabled (**-x** or **--extended-register**
command-line arguments are given), then normal single character registers are
used *unless* the character immediately following a command that needs a
register name is a space (according to **isspace()**) and not a newline
(**'\\n'**).
In that case, the register name is found according to the regex
**\[a-z\]\[a-z0-9\_\]\*** (like bc(1) identifiers), and it is a parse error if
the next non-space characters do not match that regex.
# RESET
When dc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any macros that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
macros returned) is skipped.
Thus, when dc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
# PERFORMANCE
Most dc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This dc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **DC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **DC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**DC_BASE_DIGS**.
In addition, this dc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **DC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on dc(1):
**DC_LONG_BIT**
: The number of bits in the **long** type in the environment where dc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**DC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **DC_LONG_BIT**.
**DC_BASE_POW**
: The max decimal number that each large integer can store (see
**DC_BASE_DIGS**) plus **1**. Depends on **DC_BASE_DIGS**.
**DC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **DC_LONG_BIT**.
**DC_BASE_MAX**
: The maximum output base. Set at **DC_BASE_POW**.
**DC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**DC_SCALE_MAX**
: The maximum **scale**. Set at **DC_OVERFLOW_MAX-1**.
**DC_STRING_MAX**
: The maximum length of strings. Set at **DC_OVERFLOW_MAX-1**.
**DC_NAME_MAX**
: The maximum length of identifiers. Set at **DC_OVERFLOW_MAX-1**.
**DC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **DC_OVERFLOW_MAX-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**DC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
dc(1) recognizes the following environment variables:
**DC_ENV_ARGS**
: This is another way to give command-line arguments to dc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **DC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs. Another use would
be to use the **-e** option to set **scale** to a value other than **0**.
The code that parses **DC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some dc file.dc"** will be correctly parsed, but the string
**"/home/gavin/some \"dc\" file.dc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
- double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
+ double quotes as the outside quotes, as in **"some 'dc' file.dc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **DC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**DC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), dc(1) will output
lines to that length, including the backslash newline combo. The default
line length is **70**.
**DC_EXPR_EXIT**
: If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the **-e** and/or
**-f** command-line options (and any equivalents).
# EXIT STATUS
dc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**) operator.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, and using a token where it is
invalid.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, and attempting an operation when
the stack has too few elements.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (dc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, dc(1) always exits
and returns **4**, no matter what mode dc(1) is in.
The other statuses will only be returned when dc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since dc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, dc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, dc(1) turns
on "TTY mode."
TTY mode is required for history to be enabled (see the **COMMAND LINE HISTORY**
section). It is also required to enable special handling for **SIGINT** signals.
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause dc(1) to stop execution of the current input. If
dc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If dc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If dc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to dc(1) as it is executing a file, it
can seem as though dc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause dc(1) to clean up and exit, and it uses the
default handler for all other signals. The one exception is **SIGHUP**; in that
case, when dc(1) is in TTY mode, a **SIGHUP** will cause dc(1) to clean up and
exit.
# COMMAND LINE HISTORY
dc(1) supports interactive command-line editing. If dc(1) is in TTY mode (see
the **TTY MODE** section), history is enabled. Previous lines can be recalled
and edited with the arrow keys.
**Note**: tabs are converted to 8 spaces.
# LOCALES
This dc(1) ships with support for adding error messages for different locales
and thus, supports **LC_MESSAGS**.
# SEE ALSO
bc(1)
# STANDARDS
The dc(1) utility operators are compliant with the operators in the bc(1)
[IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1] specification.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHOR
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
diff --git a/contrib/bc/manuals/dc/H.1 b/contrib/bc/manuals/dc/H.1
index 9eabf89b6f07..5c09b430db8e 100644
--- a/contrib/bc/manuals/dc/H.1
+++ b/contrib/bc/manuals/dc/H.1
@@ -1,1323 +1,1336 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "DC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "DC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH Name
.PP
dc - arbitrary-precision decimal reverse-Polish notation calculator
.SH SYNOPSIS
.PP
\f[B]dc\f[R] [\f[B]-hiPvVx\f[R]] [\f[B]\[en]version\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]no-prompt\f[R]] [\f[B]\[en]extended-register\f[R]]
[\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
dc(1) is an arbitrary-precision calculator.
It uses a stack (reverse Polish notation) to store numbers and results
of computations.
Arithmetic operations pop arguments off of the stack and push the
results.
.PP
If no files are given on the command-line as extra arguments (i.e., not
as \f[B]-f\f[R] or \f[B]\[en]file\f[R] arguments), then dc(1) reads from
\f[B]stdin\f[R].
Otherwise, those files are processed, and dc(1) will then exit.
.PP
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where \f[B]-e\f[R] (\f[B]\[en]expression\f[R]) and
\f[B]-f\f[R] (\f[B]\[en]file\f[R]) arguments cause dc(1) to execute them
and exit.
The reason for this is that this dc(1) allows users to set arguments in
the environment variable \f[B]DC_ENV_ARGS\f[R] (see the \f[B]ENVIRONMENT
VARIABLES\f[R] section).
Any expressions given on the command-line should be used to set up a
standard environment.
For example, if a user wants the \f[B]scale\f[R] always set to
\f[B]10\f[R], they can set \f[B]DC_ENV_ARGS\f[R] to \f[B]-e 10k\f[R],
and this dc(1) will always start with a \f[B]scale\f[R] of \f[B]10\f[R].
.PP
If users want to have dc(1) exit after processing all input from
\f[B]-e\f[R] and \f[B]-f\f[R] arguments (and their equivalents), then
they can just simply add \f[B]-e q\f[R] as the last command-line
argument or define the environment variable \f[B]DC_EXPR_EXIT\f[R].
.SH OPTIONS
.PP
The following are the options that dc(1) accepts.
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
Disables the prompt in TTY mode.
(The prompt is only enabled in TTY mode.
See the \f[B]TTY MODE\f[R] section) This is mostly for those users that
do not want a prompt or are not used to having them in dc(1).
Most of those users would want to put this option in
\f[B]DC_ENV_ARGS\f[R].
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-x\f[R] \f[B]\[en]extended-register\f[R]
Enables extended register mode.
See the \f[I]Extended Register Mode\f[R] subsection of the
\f[B]REGISTERS\f[R] section for more information.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]DC_ENV_ARGS\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]dc >&-\f[R], it will quit with an error.
This is done so that dc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]dc 2>&-\f[R], it will quit with an error.
This is done so that dc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
Each item in the input source code, either a number (see the
\f[B]NUMBERS\f[R] section) or a command (see the \f[B]COMMANDS\f[R]
section), is processed and executed, in order.
Input is processed immediately when entered.
.PP
\f[B]ibase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to interpret constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]ibase\f[R] is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in dc(1)
programs with the \f[B]T\f[R] command.
.PP
\f[B]obase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]DC_BASE_MAX\f[R] and
can be queried with the \f[B]U\f[R] command.
The min allowable value for \f[B]obase\f[R] is \f[B]0\f[R].
If \f[B]obase\f[R] is \f[B]0\f[R], values are output in scientific
notation, and if \f[B]obase\f[R] is \f[B]1\f[R], values are output in
engineering notation.
Otherwise, values are output in the specified base.
.PP
Outputting in scientific and engineering notations are \f[B]non-portable
extensions\f[R].
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a register (see the \f[B]REGISTERS\f[R] section) that sets the
precision of any operations (with exceptions).
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] can be queried in dc(1)
programs with the \f[B]V\f[R] command.
.PP
\f[B]seed\f[R] is a register containing the current seed for the
pseudo-random number generator.
If the current value of \f[B]seed\f[R] is queried and stored, then if it
is assigned to \f[B]seed\f[R] later, the pseudo-random number generator
is guaranteed to produce the same sequence of pseudo-random numbers that
were generated after the value of \f[B]seed\f[R] was first queried.
.PP
Multiple values assigned to \f[B]seed\f[R] can produce the same sequence
of pseudo-random numbers.
Likewise, when a value is assigned to \f[B]seed\f[R], it is not
guaranteed that querying \f[B]seed\f[R] immediately after will return
the same value.
In addition, the value of \f[B]seed\f[R] will change after any call to
the \f[B]\[cq]\f[R] command or the \f[B]\[dq]\f[R] command that does not
get receive a value of \f[B]0\f[R] or \f[B]1\f[R].
The maximum integer returned by the \f[B]\[cq]\f[R] command can be
queried with the \f[B]W\f[R] command.
.PP
\f[B]Note\f[R]: The values returned by the pseudo-random number
generator with the \f[B]\[cq]\f[R] and \f[B]\[dq]\f[R] commands are
guaranteed to \f[B]NOT\f[R] be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator.
However, they \f[I]are\f[R] guaranteed to be reproducible with identical
\f[B]seed\f[R] values.
-This means that the pseudo-random values from bc(1) should only be used
+This means that the pseudo-random values from dc(1) should only be used
where a reproducible stream of pseudo-random numbers is
\f[I]ESSENTIAL\f[R].
In any other case, use a non-seeded pseudo-random number generator.
.PP
The pseudo-random number generator, \f[B]seed\f[R], and all associated
operations are \f[B]non-portable extensions\f[R].
.SS Comments
.PP
Comments go from \f[B]#\f[R] until, and not including, the next newline.
This is a \f[B]non-portable extension\f[R].
.SH NUMBERS
.PP
Numbers are strings made up of digits, uppercase letters up to
\f[B]F\f[R], and at most \f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]DC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]F\f[R] alone always equals decimal \f[B]15\f[R].
.PP
In addition, dc(1) accepts numbers in scientific notation.
These have the form \f[B]<number>e<integer>\f[R].
The exponent (the portion after the \f[B]e\f[R]) must be an integer.
An example is \f[B]1.89237e9\f[R], which is equal to
\f[B]1892370000\f[R].
Negative exponents are also allowed, so \f[B]4.2890e_3\f[R] is equal to
\f[B]0.0042890\f[R].
.PP
\f[B]WARNING\f[R]: Both the number and the exponent in scientific
notation are interpreted according to the current \f[B]ibase\f[R], but
the number is still multiplied by \f[B]10\[ha]exponent\f[R] regardless
of the current \f[B]ibase\f[R].
For example, if \f[B]ibase\f[R] is \f[B]16\f[R] and dc(1) is given the
number string \f[B]FFeA\f[R], the resulting decimal number will be
\f[B]2550000000000\f[R], and if dc(1) is given the number string
\f[B]10e_4\f[R], the resulting decimal number will be \f[B]0.0016\f[R].
.PP
Accepting input as scientific notation is a \f[B]non-portable
extension\f[R].
.SH COMMANDS
.PP
The valid commands are listed below.
.SS Printing
.PP
These commands are used for printing.
.PP
Note that both scientific notation and engineering notation are
available for printing numbers.
Scientific notation is activated by assigning \f[B]0\f[R] to
\f[B]obase\f[R] using \f[B]0o\f[R], and engineering notation is
activated by assigning \f[B]1\f[R] to \f[B]obase\f[R] using
\f[B]1o\f[R].
To deactivate them, just assign a different value to \f[B]obase\f[R].
.PP
Printing numbers in scientific notation and/or engineering notation is a
\f[B]non-portable extension\f[R].
.TP
\f[B]p\f[R]
Prints the value on top of the stack, whether number or string, and
prints a newline after.
.RS
.PP
This does not alter the stack.
.RE
.TP
\f[B]n\f[R]
Prints the value on top of the stack, whether number or string, and pops
it off of the stack.
.TP
\f[B]P\f[R]
Pops a value off the stack.
.RS
.PP
If the value is a number, it is truncated and the absolute value of the
result is printed as though \f[B]obase\f[R] is \f[B]UCHAR_MAX+1\f[R] and
each digit is interpreted as an ASCII character, making it a byte
stream.
.PP
If the value is a string, it is printed without a trailing newline.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]f\f[R]
Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
.RS
.PP
Users should use this command when they get lost.
.RE
.SS Arithmetic
.PP
These are the commands used for arithmetic.
.TP
\f[B]+\f[R]
The top two values are popped off the stack, added, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]-\f[R]
The top two values are popped off the stack, subtracted, and the result
is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]*\f[R]
The top two values are popped off the stack, multiplied, and the result
is pushed onto the stack.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The top two values are popped off the stack, divided, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]%\f[R]
The top two values are popped off the stack, remaindered, and the result
is pushed onto the stack.
.RS
.PP
Remaindering is equivalent to 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R], and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]\[ti]\f[R]
The top two values are popped off the stack, divided and remaindered,
and the results (divided first, remainder second) are pushed onto the
stack.
This is equivalent to \f[B]x y / x y %\f[R] except that \f[B]x\f[R] and
\f[B]y\f[R] are only evaluated once.
.RS
.PP
The first value popped off of the stack must be non-zero.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
.RE
.TP
\f[B]v\f[R]
The top value is popped off the stack, its square root is computed, and
the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The value popped off of the stack must be non-negative.
.RE
.TP
\f[B]_\f[R]
If this command \f[I]immediately\f[R] precedes a number (i.e., no spaces
or other commands), then that number is input as a negative number.
.RS
.PP
Otherwise, the top value on the stack is popped and copied, and the copy
is negated and pushed onto the stack.
This behavior without a number is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]b\f[R]
The top value is popped off the stack, and if it is zero, it is pushed
back onto the stack.
Otherwise, its absolute value is pushed onto the stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]|\f[R]
The top three values are popped off the stack, a modular exponentiation
is computed, and the result is pushed onto the stack.
.RS
.PP
The first value popped is used as the reduction modulus and must be an
integer and non-zero.
The second value popped is used as the exponent and must be an integer
and non-negative.
The third value popped is the base and must be an integer.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]$\f[R]
The top value is popped off the stack and copied, and the copy is
truncated and pushed onto the stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[at]\f[R]
The top two values are popped off the stack, and the precision of the
second is set to the value of the first, whether by truncation or
extension.
.RS
.PP
The first value popped off of the stack must be an integer and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]H\f[R]
The top two values are popped off the stack, and the second is shifted
left (radix shifted right) to the value of the first.
.RS
.PP
The first value popped off of the stack must be an integer and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]h\f[R]
The top two values are popped off the stack, and the second is shifted
right (radix shifted left) to the value of the first.
.RS
.PP
The first value popped off of the stack must be an integer and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]G\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if they are equal, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]N\f[R]
The top value is popped off of the stack, and if it a \f[B]0\f[R], a
\f[B]1\f[R] is pushed; otherwise, a \f[B]0\f[R] is pushed.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B](\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]{\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than or equal to the second,
or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B])\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]}\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than or equal to the
second, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]M\f[R]
The top two values are popped off of the stack.
If they are both non-zero, a \f[B]1\f[R] is pushed onto the stack.
If either of them is zero, or both of them are, then a \f[B]0\f[R] is
pushed onto the stack.
.RS
.PP
This is like the \f[B]&&\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]m\f[R]
The top two values are popped off of the stack.
If at least one of them is non-zero, a \f[B]1\f[R] is pushed onto the
stack.
If both of them are zero, then a \f[B]0\f[R] is pushed onto the stack.
.RS
.PP
This is like the \f[B]||\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Pseudo-Random Number Generator
.PP
dc(1) has a built-in pseudo-random number generator.
These commands query the pseudo-random number generator.
(See Parameters for more information about the \f[B]seed\f[R] value that
controls the pseudo-random number generator.)
.PP
The pseudo-random number generator is guaranteed to \f[B]NOT\f[R] be
cryptographically secure.
.TP
\f[B]\[cq]\f[R]
Generates an integer between 0 and \f[B]DC_RAND_MAX\f[R], inclusive (see
the \f[B]LIMITS\f[R] section).
.RS
.PP
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[dq]\f[R]
Pops a value off of the stack, which is used as an \f[B]exclusive\f[R]
upper bound on the integer that will be generated.
If the bound is negative or is a non-integer, an error is raised, and
dc(1) resets (see the \f[B]RESET\f[R] section) while \f[B]seed\f[R]
remains unchanged.
If the bound is larger than \f[B]DC_RAND_MAX\f[R], the higher bound is
honored by generating several pseudo-random integers, multiplying them
by appropriate powers of \f[B]DC_RAND_MAX+1\f[R], and adding them
together.
Thus, the size of integer that can be generated with this command is
unbounded.
Using this command will change the value of \f[B]seed\f[R], unless the
operand is \f[B]0\f[R] or \f[B]1\f[R].
In that case, \f[B]0\f[R] is pushed onto the stack, and \f[B]seed\f[R]
is \f[I]not\f[R] changed.
.RS
.PP
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Stack Control
.PP
These commands control the stack.
.TP
\f[B]c\f[R]
Removes all items from (\[lq]clears\[rq]) the stack.
.TP
\f[B]d\f[R]
Copies the item on top of the stack (\[lq]duplicates\[rq]) and pushes
the copy onto the stack.
.TP
\f[B]r\f[R]
Swaps (\[lq]reverses\[rq]) the two top items on the stack.
.TP
\f[B]R\f[R]
Pops (\[lq]removes\[rq]) the top value from the stack.
.SS Register Control
.PP
These commands control registers (see the \f[B]REGISTERS\f[R] section).
.TP
\f[B]s\f[R]\f[I]r\f[R]
Pops the value off the top of the stack and stores it into register
\f[I]r\f[R].
.TP
\f[B]l\f[R]\f[I]r\f[R]
Copies the value in register \f[I]r\f[R] and pushes it onto the stack.
This does not alter the contents of \f[I]r\f[R].
.TP
\f[B]S\f[R]\f[I]r\f[R]
Pops the value off the top of the (main) stack and pushes it onto the
stack of register \f[I]r\f[R].
The previous value of the register becomes inaccessible.
.TP
\f[B]L\f[R]\f[I]r\f[R]
Pops the value off the top of the stack for register \f[I]r\f[R] and
push it onto the main stack.
The previous value in the stack for register \f[I]r\f[R], if any, is now
accessible via the \f[B]l\f[R]\f[I]r\f[R] command.
.SS Parameters
.PP
These commands control the values of \f[B]ibase\f[R], \f[B]obase\f[R],
\f[B]scale\f[R], and \f[B]seed\f[R].
Also see the \f[B]SYNTAX\f[R] section.
.TP
\f[B]i\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]ibase\f[R], which must be between \f[B]2\f[R] and \f[B]16\f[R],
inclusive.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]o\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]obase\f[R], which must be between \f[B]0\f[R] and
\f[B]DC_BASE_MAX\f[R], inclusive (see the \f[B]LIMITS\f[R] section and
the \f[B]NUMBERS\f[R] section).
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]k\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]scale\f[R], which must be non-negative.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]j\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]seed\f[R].
The meaning of \f[B]seed\f[R] is dependent on the current pseudo-random
number generator but is guaranteed to not change except for new major
versions.
.RS
.PP
The \f[I]scale\f[R] and sign of the value may be significant.
.PP
If a previously used \f[B]seed\f[R] value is used again, the
pseudo-random number generator is guaranteed to produce the same
sequence of pseudo-random numbers as it did when the \f[B]seed\f[R]
value was previously used.
.PP
The exact value assigned to \f[B]seed\f[R] is not guaranteed to be
returned if the \f[B]J\f[R] command is used.
However, if \f[B]seed\f[R] \f[I]does\f[R] return a different value, both
values, when assigned to \f[B]seed\f[R], are guaranteed to produce the
same sequence of pseudo-random numbers.
This means that certain values assigned to \f[B]seed\f[R] will not
produce unique sequences of pseudo-random numbers.
.PP
There is no limit to the length (number of significant decimal digits)
or \f[I]scale\f[R] of the value that can be assigned to \f[B]seed\f[R].
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]I\f[R]
Pushes the current value of \f[B]ibase\f[R] onto the main stack.
.TP
\f[B]O\f[R]
Pushes the current value of \f[B]obase\f[R] onto the main stack.
.TP
\f[B]K\f[R]
Pushes the current value of \f[B]scale\f[R] onto the main stack.
.TP
\f[B]J\f[R]
Pushes the current value of \f[B]seed\f[R] onto the main stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]T\f[R]
Pushes the maximum allowable value of \f[B]ibase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]U\f[R]
Pushes the maximum allowable value of \f[B]obase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]V\f[R]
Pushes the maximum allowable value of \f[B]scale\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]W\f[R]
Pushes the maximum (inclusive) integer that can be generated with the
\f[B]\[cq]\f[R] pseudo-random number generator command.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Strings
.PP
The following commands control strings.
.PP
dc(1) can work with both numbers and strings, and registers (see the
\f[B]REGISTERS\f[R] section) can hold both strings and numbers.
dc(1) always knows whether the contents of a register are a string or a
number.
.PP
While arithmetic operations have to have numbers, and will print an
error if given a string, other commands accept strings.
.PP
Strings can also be executed as macros.
For example, if the string \f[B][1pR]\f[R] is executed as a macro, then
the code \f[B]1pR\f[R] is executed, meaning that the \f[B]1\f[R] will be
printed with a newline after and then popped from the stack.
.TP
\f[B][\f[R]_characters_\f[B]]\f[R]
Makes a string containing \f[I]characters\f[R] and pushes it onto the
stack.
.RS
.PP
If there are brackets (\f[B][\f[R] and \f[B]]\f[R]) in the string, then
they must be balanced.
Unbalanced brackets can be escaped using a backslash (\f[B]\[rs]\f[R])
character.
.PP
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the
(first) backslash is not.
.RE
.TP
\f[B]a\f[R]
The value on top of the stack is popped.
.RS
.PP
If it is a number, it is truncated and its absolute value is taken.
The result mod \f[B]UCHAR_MAX+1\f[R] is calculated.
If that result is \f[B]0\f[R], push an empty string; otherwise, push a
one-character string where the character is the result of the mod
interpreted as an ASCII character.
.PP
If it is a string, then a new string is made.
If the original string is empty, the new string is empty.
If it is not, then the first character of the original string is used to
create the new string as a one-character string.
The new string is then pushed onto the stack.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]x\f[R]
Pops a value off of the top of the stack.
.RS
.PP
If it is a number, it is pushed back onto the stack.
.PP
If it is a string, it is executed as a macro.
.PP
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is greater than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
For example, \f[B]0 1>a\f[R] will execute the contents of register
\f[B]a\f[R], and \f[B]1 0>a\f[R] will not.
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not greater than the second (less than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is less than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not less than the second (greater than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is equal to the second, then the contents of register
\f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not equal to the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]?\f[R]
Reads a line from the \f[B]stdin\f[R] and executes it.
This is to allow macros to request input from users.
.TP
\f[B]q\f[R]
During execution of a macro, this exits the execution of that macro and
the execution of the macro that executed it.
If there are no macros, or only one macro executing, dc(1) exits.
.TP
\f[B]Q\f[R]
Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack.
If the number of levels to pop is greater than the number of executing
macros, dc(1) exits.
.SS Status
.PP
These commands query status of the stack or its top value.
.TP
\f[B]Z\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, calculates the number of significant decimal digits
it has and pushes the result.
.PP
If it is a string, pushes the number of characters the string has.
.RE
.TP
\f[B]X\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, pushes the \f[I]scale\f[R] of the value onto the
stack.
.PP
If it is a string, pushes \f[B]0\f[R].
.RE
.TP
\f[B]z\f[R]
Pushes the current stack depth (before execution of this command).
.SS Arrays
.PP
These commands manipulate arrays.
.TP
\f[B]:\f[R]\f[I]r\f[R]
Pops the top two values off of the stack.
The second value will be stored in the array \f[I]r\f[R] (see the
\f[B]REGISTERS\f[R] section), indexed by the first value.
.TP
\f[B];\f[R]\f[I]r\f[R]
Pops the value on top of the stack and uses it as an index into the
array \f[I]r\f[R].
The selected value is then pushed onto the stack.
.SH REGISTERS
.PP
Registers are names that can store strings, numbers, and arrays.
(Number/string registers do not interfere with array registers.)
.PP
Each register is also its own stack, so the current register value is
the top of the stack for the register.
All registers, when first referenced, have one value (\f[B]0\f[R]) in
their stack.
.PP
In non-extended register mode, a register name is just the single
character that follows any command that needs a register name.
The only exception is a newline (\f[B]`\[rs]n'\f[R]); it is a parse
error for a newline to be used as a register name.
.SS Extended Register Mode
.PP
Unlike most other dc(1) implentations, this dc(1) provides nearly
unlimited amounts of registers, if extended register mode is enabled.
.PP
If extended register mode is enabled (\f[B]-x\f[R] or
\f[B]\[en]extended-register\f[R] command-line arguments are given), then
normal single character registers are used \f[I]unless\f[R] the
character immediately following a command that needs a register name is
a space (according to \f[B]isspace()\f[R]) and not a newline
(\f[B]`\[rs]n'\f[R]).
.PP
In that case, the register name is found according to the regex
\f[B][a-z][a-z0-9_]*\f[R] (like bc(1) identifiers), and it is a parse
error if the next non-space characters do not match that regex.
.SH RESET
.PP
When dc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any macros that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all macros returned) is skipped.
.PP
Thus, when dc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.SH PERFORMANCE
.PP
Most dc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This dc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]DC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]DC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]DC_BASE_DIGS\f[R].
.PP
In addition, this dc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]DC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on dc(1):
.TP
\f[B]DC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
dc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]DC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]DC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]DC_BASE_DIGS\f[R].
.TP
\f[B]DC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]DC_BASE_POW\f[R].
.TP
\f[B]DC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]DC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_RAND_MAX\f[R]
The maximum integer (inclusive) returned by the \f[B]\[cq]\f[R] command,
if dc(1).
Set at \f[B]2\[ha]DC_LONG_BIT-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]DC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
dc(1) recognizes the following environment variables:
.TP
\f[B]DC_ENV_ARGS\f[R]
This is another way to give command-line arguments to dc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]DC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs.
Another use would be to use the \f[B]-e\f[R] option to set
\f[B]scale\f[R] to a value other than \f[B]0\f[R].
.RS
.PP
The code that parses \f[B]DC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some dc file.dc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]dc\[dq] file.dc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
-in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
+in \f[B]\[rq]some `dc' file.dc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]DC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]DC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), dc(1) will output lines to that length,
including the backslash newline combo.
The default line length is \f[B]70\f[R].
.TP
\f[B]DC_EXPR_EXIT\f[R]
If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the
\f[B]-e\f[R] and/or \f[B]-f\f[R] command-line options (and any
equivalents).
.SH EXIT STATUS
.PP
dc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, using a negative number as a bound for the
pseudo-random number generator, attempting to convert a negative number
to a hardware integer, overflow when converting a number to a hardware
integer, and attempting to use a non-integer where an integer is
required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]), places (\f[B]\[at]\f[R]), left shift
(\f[B]H\f[R]), and right shift (\f[B]h\f[R]) operators.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, and using a
token where it is invalid.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, and attempting an operation when the
stack has too few elements.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (dc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, dc(1)
always exits and returns \f[B]4\f[R], no matter what mode dc(1) is in.
.PP
The other statuses will only be returned when dc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
dc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, dc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, dc(1) turns on \[lq]TTY mode.\[rq]
.PP
The prompt is enabled in TTY mode.
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause dc(1) to stop execution of the
current input.
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If dc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If dc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to dc(1) as it is
executing a file, it can seem as though dc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause dc(1) to clean up and
exit, and it uses the default handler for all other signals.
.SH LOCALES
.PP
This dc(1) ships with support for adding error messages for different
locales and thus, supports \f[B]LC_MESSAGS\f[R].
.SH SEE ALSO
.PP
bc(1)
.SH STANDARDS
.PP
The dc(1) utility operators are compliant with the operators in the
bc(1) IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHOR
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/dc/H.1.md b/contrib/bc/manuals/dc/H.1.md
index 102ef2e74e6d..aff75f379e10 100644
--- a/contrib/bc/manuals/dc/H.1.md
+++ b/contrib/bc/manuals/dc/H.1.md
@@ -1,1185 +1,1194 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# Name
dc - arbitrary-precision decimal reverse-Polish notation calculator
# SYNOPSIS
**dc** [**-hiPvVx**] [**--version**] [**--help**] [**--interactive**] [**--no-prompt**] [**--extended-register**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...] [*file*...]
# DESCRIPTION
dc(1) is an arbitrary-precision calculator. It uses a stack (reverse Polish
notation) to store numbers and results of computations. Arithmetic operations
pop arguments off of the stack and push the results.
If no files are given on the command-line as extra arguments (i.e., not as
**-f** or **--file** arguments), then dc(1) reads from **stdin**. Otherwise,
those files are processed, and dc(1) will then exit.
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where **-e** (**--expression**) and **-f** (**--file**)
arguments cause dc(1) to execute them and exit. The reason for this is that this
dc(1) allows users to set arguments in the environment variable **DC_ENV_ARGS**
(see the **ENVIRONMENT VARIABLES** section). Any expressions given on the
command-line should be used to set up a standard environment. For example, if a
user wants the **scale** always set to **10**, they can set **DC_ENV_ARGS** to
**-e 10k**, and this dc(1) will always start with a **scale** of **10**.
If users want to have dc(1) exit after processing all input from **-e** and
**-f** arguments (and their equivalents), then they can just simply add **-e q**
as the last command-line argument or define the environment variable
**DC_EXPR_EXIT**.
# OPTIONS
The following are the options that dc(1) accepts.
**-h**, **--help**
: Prints a usage message and quits.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-P**, **--no-prompt**
: Disables the prompt in TTY mode. (The prompt is only enabled in TTY mode.
See the **TTY MODE** section) This is mostly for those users that do not
want a prompt or are not used to having them in dc(1). Most of those users
would want to put this option in **DC_ENV_ARGS**.
This is a **non-portable extension**.
**-x** **--extended-register**
: Enables extended register mode. See the *Extended Register Mode* subsection
of the **REGISTERS** section for more information.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **DC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **dc <file> >&-**, it will quit with an error. This
is done so that dc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **dc <file> 2>&-**, it will quit with an error. This
is done so that dc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
Each item in the input source code, either a number (see the **NUMBERS**
section) or a command (see the **COMMANDS** section), is processed and executed,
in order. Input is processed immediately when entered.
**ibase** is a register (see the **REGISTERS** section) that determines how to
interpret constant numbers. It is the "input" base, or the number base used for
interpreting input numbers. **ibase** is initially **10**. The max allowable
value for **ibase** is **16**. The min allowable value for **ibase** is **2**.
The max allowable value for **ibase** can be queried in dc(1) programs with the
**T** command.
**obase** is a register (see the **REGISTERS** section) that determines how to
output results. It is the "output" base, or the number base used for outputting
numbers. **obase** is initially **10**. The max allowable value for **obase** is
**DC_BASE_MAX** and can be queried with the **U** command. The min allowable
value for **obase** is **0**. If **obase** is **0**, values are output in
scientific notation, and if **obase** is **1**, values are output in engineering
notation. Otherwise, values are output in the specified base.
Outputting in scientific and engineering notations are **non-portable
extensions**.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a register (see the
**REGISTERS** section) that sets the precision of any operations (with
exceptions). **scale** is initially **0**. **scale** cannot be negative. The max
allowable value for **scale** can be queried in dc(1) programs with the **V**
command.
**seed** is a register containing the current seed for the pseudo-random number
generator. If the current value of **seed** is queried and stored, then if it is
assigned to **seed** later, the pseudo-random number generator is guaranteed to
produce the same sequence of pseudo-random numbers that were generated after the
value of **seed** was first queried.
Multiple values assigned to **seed** can produce the same sequence of
pseudo-random numbers. Likewise, when a value is assigned to **seed**, it is not
guaranteed that querying **seed** immediately after will return the same value.
In addition, the value of **seed** will change after any call to the **'**
command or the **"** command that does not get receive a value of **0** or
**1**. The maximum integer returned by the **'** command can be queried with the
**W** command.
**Note**: The values returned by the pseudo-random number generator with the
**'** and **"** commands are guaranteed to **NOT** be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator. However,
they *are* guaranteed to be reproducible with identical **seed** values. This
-means that the pseudo-random values from bc(1) should only be used where a
+means that the pseudo-random values from dc(1) should only be used where a
reproducible stream of pseudo-random numbers is *ESSENTIAL*. In any other case,
use a non-seeded pseudo-random number generator.
The pseudo-random number generator, **seed**, and all associated operations are
**non-portable extensions**.
## Comments
Comments go from **#** until, and not including, the next newline. This is a
**non-portable extension**.
# NUMBERS
Numbers are strings made up of digits, uppercase letters up to **F**, and at
most **1** period for a radix. Numbers can have up to **DC_NUM_MAX** digits.
Uppercase letters are equal to **9** + their position in the alphabet (i.e.,
**A** equals **10**, or **9+1**). If a digit or letter makes no sense with the
current value of **ibase**, they are set to the value of the highest valid digit
in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **F** alone always equals decimal
**15**.
In addition, dc(1) accepts numbers in scientific notation. These have the form
**\<number\>e\<integer\>**. The exponent (the portion after the **e**) must be
an integer. An example is **1.89237e9**, which is equal to **1892370000**.
Negative exponents are also allowed, so **4.2890e_3** is equal to **0.0042890**.
**WARNING**: Both the number and the exponent in scientific notation are
interpreted according to the current **ibase**, but the number is still
multiplied by **10\^exponent** regardless of the current **ibase**. For example,
if **ibase** is **16** and dc(1) is given the number string **FFeA**, the
resulting decimal number will be **2550000000000**, and if dc(1) is given the
number string **10e_4**, the resulting decimal number will be **0.0016**.
Accepting input as scientific notation is a **non-portable extension**.
# COMMANDS
The valid commands are listed below.
## Printing
These commands are used for printing.
Note that both scientific notation and engineering notation are available for
printing numbers. Scientific notation is activated by assigning **0** to
**obase** using **0o**, and engineering notation is activated by assigning **1**
to **obase** using **1o**. To deactivate them, just assign a different value to
**obase**.
Printing numbers in scientific notation and/or engineering notation is a
**non-portable extension**.
**p**
: Prints the value on top of the stack, whether number or string, and prints a
newline after.
This does not alter the stack.
**n**
: Prints the value on top of the stack, whether number or string, and pops it
off of the stack.
**P**
: Pops a value off the stack.
If the value is a number, it is truncated and the absolute value of the
result is printed as though **obase** is **UCHAR_MAX+1** and each digit is
interpreted as an ASCII character, making it a byte stream.
If the value is a string, it is printed without a trailing newline.
This is a **non-portable extension**.
**f**
: Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
Users should use this command when they get lost.
## Arithmetic
These are the commands used for arithmetic.
**+**
: The top two values are popped off the stack, added, and the result is pushed
onto the stack. The *scale* of the result is equal to the max *scale* of
both operands.
**-**
: The top two values are popped off the stack, subtracted, and the result is
pushed onto the stack. The *scale* of the result is equal to the max
*scale* of both operands.
**\***
: The top two values are popped off the stack, multiplied, and the result is
pushed onto the stack. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result
is equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The top two values are popped off the stack, divided, and the result is
pushed onto the stack. The *scale* of the result is equal to **scale**.
The first value popped off of the stack must be non-zero.
**%**
: The top two values are popped off the stack, remaindered, and the result is
pushed onto the stack.
Remaindering is equivalent to 1) Computing **a/b** to current **scale**, and
2) Using the result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The first value popped off of the stack must be non-zero.
**~**
: The top two values are popped off the stack, divided and remaindered, and
the results (divided first, remainder second) are pushed onto the stack.
This is equivalent to **x y / x y %** except that **x** and **y** are only
evaluated once.
The first value popped off of the stack must be non-zero.
This is a **non-portable extension**.
**\^**
: The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack. The *scale* of
the result is equal to **scale**.
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
**v**
: The top value is popped off the stack, its square root is computed, and the
result is pushed onto the stack. The *scale* of the result is equal to
**scale**.
The value popped off of the stack must be non-negative.
**\_**
: If this command *immediately* precedes a number (i.e., no spaces or other
commands), then that number is input as a negative number.
Otherwise, the top value on the stack is popped and copied, and the copy is
negated and pushed onto the stack. This behavior without a number is a
**non-portable extension**.
**b**
: The top value is popped off the stack, and if it is zero, it is pushed back
onto the stack. Otherwise, its absolute value is pushed onto the stack.
This is a **non-portable extension**.
**|**
: The top three values are popped off the stack, a modular exponentiation is
computed, and the result is pushed onto the stack.
The first value popped is used as the reduction modulus and must be an
integer and non-zero. The second value popped is used as the exponent and
must be an integer and non-negative. The third value popped is the base and
must be an integer.
This is a **non-portable extension**.
**\$**
: The top value is popped off the stack and copied, and the copy is truncated
and pushed onto the stack.
This is a **non-portable extension**.
**\@**
: The top two values are popped off the stack, and the precision of the second
is set to the value of the first, whether by truncation or extension.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**H**
: The top two values are popped off the stack, and the second is shifted left
(radix shifted right) to the value of the first.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**h**
: The top two values are popped off the stack, and the second is shifted right
(radix shifted left) to the value of the first.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**G**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if they are equal, or **0** otherwise.
This is a **non-portable extension**.
**N**
: The top value is popped off of the stack, and if it a **0**, a **1** is
pushed; otherwise, a **0** is pushed.
This is a **non-portable extension**.
**(**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than the second, or **0** otherwise.
This is a **non-portable extension**.
**{**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than or equal to the second, or **0**
otherwise.
This is a **non-portable extension**.
**)**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than the second, or **0** otherwise.
This is a **non-portable extension**.
**}**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than or equal to the second, or
**0** otherwise.
This is a **non-portable extension**.
**M**
: The top two values are popped off of the stack. If they are both non-zero, a
**1** is pushed onto the stack. If either of them is zero, or both of them
are, then a **0** is pushed onto the stack.
This is like the **&&** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
**m**
: The top two values are popped off of the stack. If at least one of them is
non-zero, a **1** is pushed onto the stack. If both of them are zero, then a
**0** is pushed onto the stack.
This is like the **||** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
## Pseudo-Random Number Generator
dc(1) has a built-in pseudo-random number generator. These commands query the
pseudo-random number generator. (See Parameters for more information about the
**seed** value that controls the pseudo-random number generator.)
The pseudo-random number generator is guaranteed to **NOT** be
cryptographically secure.
**'**
: Generates an integer between 0 and **DC_RAND_MAX**, inclusive (see the
**LIMITS** section).
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
This is a **non-portable extension**.
**"**
: Pops a value off of the stack, which is used as an **exclusive** upper bound
on the integer that will be generated. If the bound is negative or is a
non-integer, an error is raised, and dc(1) resets (see the **RESET**
section) while **seed** remains unchanged. If the bound is larger than
**DC_RAND_MAX**, the higher bound is honored by generating several
pseudo-random integers, multiplying them by appropriate powers of
**DC_RAND_MAX+1**, and adding them together. Thus, the size of integer that
can be generated with this command is unbounded. Using this command will
change the value of **seed**, unless the operand is **0** or **1**. In that
case, **0** is pushed onto the stack, and **seed** is *not* changed.
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
This is a **non-portable extension**.
## Stack Control
These commands control the stack.
**c**
: Removes all items from ("clears") the stack.
**d**
: Copies the item on top of the stack ("duplicates") and pushes the copy onto
the stack.
**r**
: Swaps ("reverses") the two top items on the stack.
**R**
: Pops ("removes") the top value from the stack.
## Register Control
These commands control registers (see the **REGISTERS** section).
**s***r*
: Pops the value off the top of the stack and stores it into register *r*.
**l***r*
: Copies the value in register *r* and pushes it onto the stack. This does not
alter the contents of *r*.
**S***r*
: Pops the value off the top of the (main) stack and pushes it onto the stack
of register *r*. The previous value of the register becomes inaccessible.
**L***r*
: Pops the value off the top of the stack for register *r* and push it onto
the main stack. The previous value in the stack for register *r*, if any, is
now accessible via the **l***r* command.
## Parameters
These commands control the values of **ibase**, **obase**, **scale**, and
**seed**. Also see the **SYNTAX** section.
**i**
: Pops the value off of the top of the stack and uses it to set **ibase**,
which must be between **2** and **16**, inclusive.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**o**
: Pops the value off of the top of the stack and uses it to set **obase**,
which must be between **0** and **DC_BASE_MAX**, inclusive (see the
**LIMITS** section and the **NUMBERS** section).
If the value on top of the stack has any *scale*, the *scale* is ignored.
**k**
: Pops the value off of the top of the stack and uses it to set **scale**,
which must be non-negative.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**j**
: Pops the value off of the top of the stack and uses it to set **seed**. The
meaning of **seed** is dependent on the current pseudo-random number
generator but is guaranteed to not change except for new major versions.
The *scale* and sign of the value may be significant.
If a previously used **seed** value is used again, the pseudo-random number
generator is guaranteed to produce the same sequence of pseudo-random
numbers as it did when the **seed** value was previously used.
The exact value assigned to **seed** is not guaranteed to be returned if the
**J** command is used. However, if **seed** *does* return a different value,
both values, when assigned to **seed**, are guaranteed to produce the same
sequence of pseudo-random numbers. This means that certain values assigned
to **seed** will not produce unique sequences of pseudo-random numbers.
There is no limit to the length (number of significant decimal digits) or
*scale* of the value that can be assigned to **seed**.
This is a **non-portable extension**.
**I**
: Pushes the current value of **ibase** onto the main stack.
**O**
: Pushes the current value of **obase** onto the main stack.
**K**
: Pushes the current value of **scale** onto the main stack.
**J**
: Pushes the current value of **seed** onto the main stack.
This is a **non-portable extension**.
**T**
: Pushes the maximum allowable value of **ibase** onto the main stack.
This is a **non-portable extension**.
**U**
: Pushes the maximum allowable value of **obase** onto the main stack.
This is a **non-portable extension**.
**V**
: Pushes the maximum allowable value of **scale** onto the main stack.
This is a **non-portable extension**.
**W**
: Pushes the maximum (inclusive) integer that can be generated with the **'**
pseudo-random number generator command.
This is a **non-portable extension**.
## Strings
The following commands control strings.
dc(1) can work with both numbers and strings, and registers (see the
**REGISTERS** section) can hold both strings and numbers. dc(1) always knows
whether the contents of a register are a string or a number.
While arithmetic operations have to have numbers, and will print an error if
given a string, other commands accept strings.
Strings can also be executed as macros. For example, if the string **[1pR]** is
executed as a macro, then the code **1pR** is executed, meaning that the **1**
will be printed with a newline after and then popped from the stack.
**\[**_characters_**\]**
: Makes a string containing *characters* and pushes it onto the stack.
If there are brackets (**\[** and **\]**) in the string, then they must be
balanced. Unbalanced brackets can be escaped using a backslash (**\\**)
character.
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the (first)
backslash is not.
**a**
: The value on top of the stack is popped.
If it is a number, it is truncated and its absolute value is taken. The
result mod **UCHAR_MAX+1** is calculated. If that result is **0**, push an
empty string; otherwise, push a one-character string where the character is
the result of the mod interpreted as an ASCII character.
If it is a string, then a new string is made. If the original string is
empty, the new string is empty. If it is not, then the first character of
the original string is used to create the new string as a one-character
string. The new string is then pushed onto the stack.
This is a **non-portable extension**.
**x**
: Pops a value off of the top of the stack.
If it is a number, it is pushed back onto the stack.
If it is a string, it is executed as a macro.
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
**\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is greater than the second, then the contents of register
*r* are executed.
For example, **0 1>a** will execute the contents of register **a**, and
**1 0>a** will not.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not greater than the second (less than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is less than the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not less than the second (greater than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is equal to the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not equal to the second, then the contents of register
*r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**?**
: Reads a line from the **stdin** and executes it. This is to allow macros to
request input from users.
**q**
: During execution of a macro, this exits the execution of that macro and the
execution of the macro that executed it. If there are no macros, or only one
macro executing, dc(1) exits.
**Q**
: Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack. If the number
of levels to pop is greater than the number of executing macros, dc(1)
exits.
## Status
These commands query status of the stack or its top value.
**Z**
: Pops a value off of the stack.
If it is a number, calculates the number of significant decimal digits it
has and pushes the result.
If it is a string, pushes the number of characters the string has.
**X**
: Pops a value off of the stack.
If it is a number, pushes the *scale* of the value onto the stack.
If it is a string, pushes **0**.
**z**
: Pushes the current stack depth (before execution of this command).
## Arrays
These commands manipulate arrays.
**:***r*
: Pops the top two values off of the stack. The second value will be stored in
the array *r* (see the **REGISTERS** section), indexed by the first value.
**;***r*
: Pops the value on top of the stack and uses it as an index into the array
*r*. The selected value is then pushed onto the stack.
# REGISTERS
Registers are names that can store strings, numbers, and arrays. (Number/string
registers do not interfere with array registers.)
Each register is also its own stack, so the current register value is the top of
the stack for the register. All registers, when first referenced, have one value
(**0**) in their stack.
In non-extended register mode, a register name is just the single character that
follows any command that needs a register name. The only exception is a newline
(**'\\n'**); it is a parse error for a newline to be used as a register name.
## Extended Register Mode
Unlike most other dc(1) implentations, this dc(1) provides nearly unlimited
amounts of registers, if extended register mode is enabled.
If extended register mode is enabled (**-x** or **--extended-register**
command-line arguments are given), then normal single character registers are
used *unless* the character immediately following a command that needs a
register name is a space (according to **isspace()**) and not a newline
(**'\\n'**).
In that case, the register name is found according to the regex
**\[a-z\]\[a-z0-9\_\]\*** (like bc(1) identifiers), and it is a parse error if
the next non-space characters do not match that regex.
# RESET
When dc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any macros that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
macros returned) is skipped.
Thus, when dc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
# PERFORMANCE
Most dc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This dc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **DC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **DC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**DC_BASE_DIGS**.
In addition, this dc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **DC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on dc(1):
**DC_LONG_BIT**
: The number of bits in the **long** type in the environment where dc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**DC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **DC_LONG_BIT**.
**DC_BASE_POW**
: The max decimal number that each large integer can store (see
**DC_BASE_DIGS**) plus **1**. Depends on **DC_BASE_DIGS**.
**DC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **DC_LONG_BIT**.
**DC_BASE_MAX**
: The maximum output base. Set at **DC_BASE_POW**.
**DC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**DC_SCALE_MAX**
: The maximum **scale**. Set at **DC_OVERFLOW_MAX-1**.
**DC_STRING_MAX**
: The maximum length of strings. Set at **DC_OVERFLOW_MAX-1**.
**DC_NAME_MAX**
: The maximum length of identifiers. Set at **DC_OVERFLOW_MAX-1**.
**DC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **DC_OVERFLOW_MAX-1**.
**DC_RAND_MAX**
: The maximum integer (inclusive) returned by the **'** command, if dc(1). Set
at **2\^DC_LONG_BIT-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**DC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
dc(1) recognizes the following environment variables:
**DC_ENV_ARGS**
: This is another way to give command-line arguments to dc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **DC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs. Another use would
be to use the **-e** option to set **scale** to a value other than **0**.
The code that parses **DC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some dc file.dc"** will be correctly parsed, but the string
**"/home/gavin/some \"dc\" file.dc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
- double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
+ double quotes as the outside quotes, as in **"some 'dc' file.dc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **DC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**DC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), dc(1) will output
lines to that length, including the backslash newline combo. The default
line length is **70**.
**DC_EXPR_EXIT**
: If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the **-e** and/or
**-f** command-line options (and any equivalents).
# EXIT STATUS
dc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, using a negative number as a bound for the pseudo-random number
generator, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**), places (**\@**), left shift (**H**), and right shift (**h**)
operators.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, and using a token where it is
invalid.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, and attempting an operation when
the stack has too few elements.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (dc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, dc(1) always exits
and returns **4**, no matter what mode dc(1) is in.
The other statuses will only be returned when dc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since dc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, dc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, dc(1) turns
on "TTY mode."
The prompt is enabled in TTY mode.
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause dc(1) to stop execution of the current input. If
dc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If dc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If dc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to dc(1) as it is executing a file, it
can seem as though dc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause dc(1) to clean up and exit, and it uses the
default handler for all other signals.
# LOCALES
This dc(1) ships with support for adding error messages for different locales
and thus, supports **LC_MESSAGS**.
# SEE ALSO
bc(1)
# STANDARDS
The dc(1) utility operators are compliant with the operators in the bc(1)
[IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1] specification.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHOR
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
diff --git a/contrib/bc/manuals/dc/HN.1 b/contrib/bc/manuals/dc/HN.1
index a3bf02dcd2b5..38efef021c64 100644
--- a/contrib/bc/manuals/dc/HN.1
+++ b/contrib/bc/manuals/dc/HN.1
@@ -1,1319 +1,1332 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "DC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "DC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH Name
.PP
dc - arbitrary-precision decimal reverse-Polish notation calculator
.SH SYNOPSIS
.PP
\f[B]dc\f[R] [\f[B]-hiPvVx\f[R]] [\f[B]\[en]version\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]no-prompt\f[R]] [\f[B]\[en]extended-register\f[R]]
[\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
dc(1) is an arbitrary-precision calculator.
It uses a stack (reverse Polish notation) to store numbers and results
of computations.
Arithmetic operations pop arguments off of the stack and push the
results.
.PP
If no files are given on the command-line as extra arguments (i.e., not
as \f[B]-f\f[R] or \f[B]\[en]file\f[R] arguments), then dc(1) reads from
\f[B]stdin\f[R].
Otherwise, those files are processed, and dc(1) will then exit.
.PP
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where \f[B]-e\f[R] (\f[B]\[en]expression\f[R]) and
\f[B]-f\f[R] (\f[B]\[en]file\f[R]) arguments cause dc(1) to execute them
and exit.
The reason for this is that this dc(1) allows users to set arguments in
the environment variable \f[B]DC_ENV_ARGS\f[R] (see the \f[B]ENVIRONMENT
VARIABLES\f[R] section).
Any expressions given on the command-line should be used to set up a
standard environment.
For example, if a user wants the \f[B]scale\f[R] always set to
\f[B]10\f[R], they can set \f[B]DC_ENV_ARGS\f[R] to \f[B]-e 10k\f[R],
and this dc(1) will always start with a \f[B]scale\f[R] of \f[B]10\f[R].
.PP
If users want to have dc(1) exit after processing all input from
\f[B]-e\f[R] and \f[B]-f\f[R] arguments (and their equivalents), then
they can just simply add \f[B]-e q\f[R] as the last command-line
argument or define the environment variable \f[B]DC_EXPR_EXIT\f[R].
.SH OPTIONS
.PP
The following are the options that dc(1) accepts.
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
Disables the prompt in TTY mode.
(The prompt is only enabled in TTY mode.
See the \f[B]TTY MODE\f[R] section) This is mostly for those users that
do not want a prompt or are not used to having them in dc(1).
Most of those users would want to put this option in
\f[B]DC_ENV_ARGS\f[R].
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-x\f[R] \f[B]\[en]extended-register\f[R]
Enables extended register mode.
See the \f[I]Extended Register Mode\f[R] subsection of the
\f[B]REGISTERS\f[R] section for more information.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]DC_ENV_ARGS\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]dc >&-\f[R], it will quit with an error.
This is done so that dc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]dc 2>&-\f[R], it will quit with an error.
This is done so that dc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
Each item in the input source code, either a number (see the
\f[B]NUMBERS\f[R] section) or a command (see the \f[B]COMMANDS\f[R]
section), is processed and executed, in order.
Input is processed immediately when entered.
.PP
\f[B]ibase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to interpret constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]ibase\f[R] is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in dc(1)
programs with the \f[B]T\f[R] command.
.PP
\f[B]obase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]DC_BASE_MAX\f[R] and
can be queried with the \f[B]U\f[R] command.
The min allowable value for \f[B]obase\f[R] is \f[B]0\f[R].
If \f[B]obase\f[R] is \f[B]0\f[R], values are output in scientific
notation, and if \f[B]obase\f[R] is \f[B]1\f[R], values are output in
engineering notation.
Otherwise, values are output in the specified base.
.PP
Outputting in scientific and engineering notations are \f[B]non-portable
extensions\f[R].
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a register (see the \f[B]REGISTERS\f[R] section) that sets the
precision of any operations (with exceptions).
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] can be queried in dc(1)
programs with the \f[B]V\f[R] command.
.PP
\f[B]seed\f[R] is a register containing the current seed for the
pseudo-random number generator.
If the current value of \f[B]seed\f[R] is queried and stored, then if it
is assigned to \f[B]seed\f[R] later, the pseudo-random number generator
is guaranteed to produce the same sequence of pseudo-random numbers that
were generated after the value of \f[B]seed\f[R] was first queried.
.PP
Multiple values assigned to \f[B]seed\f[R] can produce the same sequence
of pseudo-random numbers.
Likewise, when a value is assigned to \f[B]seed\f[R], it is not
guaranteed that querying \f[B]seed\f[R] immediately after will return
the same value.
In addition, the value of \f[B]seed\f[R] will change after any call to
the \f[B]\[cq]\f[R] command or the \f[B]\[dq]\f[R] command that does not
get receive a value of \f[B]0\f[R] or \f[B]1\f[R].
The maximum integer returned by the \f[B]\[cq]\f[R] command can be
queried with the \f[B]W\f[R] command.
.PP
\f[B]Note\f[R]: The values returned by the pseudo-random number
generator with the \f[B]\[cq]\f[R] and \f[B]\[dq]\f[R] commands are
guaranteed to \f[B]NOT\f[R] be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator.
However, they \f[I]are\f[R] guaranteed to be reproducible with identical
\f[B]seed\f[R] values.
-This means that the pseudo-random values from bc(1) should only be used
+This means that the pseudo-random values from dc(1) should only be used
where a reproducible stream of pseudo-random numbers is
\f[I]ESSENTIAL\f[R].
In any other case, use a non-seeded pseudo-random number generator.
.PP
The pseudo-random number generator, \f[B]seed\f[R], and all associated
operations are \f[B]non-portable extensions\f[R].
.SS Comments
.PP
Comments go from \f[B]#\f[R] until, and not including, the next newline.
This is a \f[B]non-portable extension\f[R].
.SH NUMBERS
.PP
Numbers are strings made up of digits, uppercase letters up to
\f[B]F\f[R], and at most \f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]DC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]F\f[R] alone always equals decimal \f[B]15\f[R].
.PP
In addition, dc(1) accepts numbers in scientific notation.
These have the form \f[B]<number>e<integer>\f[R].
The exponent (the portion after the \f[B]e\f[R]) must be an integer.
An example is \f[B]1.89237e9\f[R], which is equal to
\f[B]1892370000\f[R].
Negative exponents are also allowed, so \f[B]4.2890e_3\f[R] is equal to
\f[B]0.0042890\f[R].
.PP
\f[B]WARNING\f[R]: Both the number and the exponent in scientific
notation are interpreted according to the current \f[B]ibase\f[R], but
the number is still multiplied by \f[B]10\[ha]exponent\f[R] regardless
of the current \f[B]ibase\f[R].
For example, if \f[B]ibase\f[R] is \f[B]16\f[R] and dc(1) is given the
number string \f[B]FFeA\f[R], the resulting decimal number will be
\f[B]2550000000000\f[R], and if dc(1) is given the number string
\f[B]10e_4\f[R], the resulting decimal number will be \f[B]0.0016\f[R].
.PP
Accepting input as scientific notation is a \f[B]non-portable
extension\f[R].
.SH COMMANDS
.PP
The valid commands are listed below.
.SS Printing
.PP
These commands are used for printing.
.PP
Note that both scientific notation and engineering notation are
available for printing numbers.
Scientific notation is activated by assigning \f[B]0\f[R] to
\f[B]obase\f[R] using \f[B]0o\f[R], and engineering notation is
activated by assigning \f[B]1\f[R] to \f[B]obase\f[R] using
\f[B]1o\f[R].
To deactivate them, just assign a different value to \f[B]obase\f[R].
.PP
Printing numbers in scientific notation and/or engineering notation is a
\f[B]non-portable extension\f[R].
.TP
\f[B]p\f[R]
Prints the value on top of the stack, whether number or string, and
prints a newline after.
.RS
.PP
This does not alter the stack.
.RE
.TP
\f[B]n\f[R]
Prints the value on top of the stack, whether number or string, and pops
it off of the stack.
.TP
\f[B]P\f[R]
Pops a value off the stack.
.RS
.PP
If the value is a number, it is truncated and the absolute value of the
result is printed as though \f[B]obase\f[R] is \f[B]UCHAR_MAX+1\f[R] and
each digit is interpreted as an ASCII character, making it a byte
stream.
.PP
If the value is a string, it is printed without a trailing newline.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]f\f[R]
Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
.RS
.PP
Users should use this command when they get lost.
.RE
.SS Arithmetic
.PP
These are the commands used for arithmetic.
.TP
\f[B]+\f[R]
The top two values are popped off the stack, added, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]-\f[R]
The top two values are popped off the stack, subtracted, and the result
is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]*\f[R]
The top two values are popped off the stack, multiplied, and the result
is pushed onto the stack.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The top two values are popped off the stack, divided, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]%\f[R]
The top two values are popped off the stack, remaindered, and the result
is pushed onto the stack.
.RS
.PP
Remaindering is equivalent to 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R], and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]\[ti]\f[R]
The top two values are popped off the stack, divided and remaindered,
and the results (divided first, remainder second) are pushed onto the
stack.
This is equivalent to \f[B]x y / x y %\f[R] except that \f[B]x\f[R] and
\f[B]y\f[R] are only evaluated once.
.RS
.PP
The first value popped off of the stack must be non-zero.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
.RE
.TP
\f[B]v\f[R]
The top value is popped off the stack, its square root is computed, and
the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The value popped off of the stack must be non-negative.
.RE
.TP
\f[B]_\f[R]
If this command \f[I]immediately\f[R] precedes a number (i.e., no spaces
or other commands), then that number is input as a negative number.
.RS
.PP
Otherwise, the top value on the stack is popped and copied, and the copy
is negated and pushed onto the stack.
This behavior without a number is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]b\f[R]
The top value is popped off the stack, and if it is zero, it is pushed
back onto the stack.
Otherwise, its absolute value is pushed onto the stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]|\f[R]
The top three values are popped off the stack, a modular exponentiation
is computed, and the result is pushed onto the stack.
.RS
.PP
The first value popped is used as the reduction modulus and must be an
integer and non-zero.
The second value popped is used as the exponent and must be an integer
and non-negative.
The third value popped is the base and must be an integer.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]$\f[R]
The top value is popped off the stack and copied, and the copy is
truncated and pushed onto the stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[at]\f[R]
The top two values are popped off the stack, and the precision of the
second is set to the value of the first, whether by truncation or
extension.
.RS
.PP
The first value popped off of the stack must be an integer and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]H\f[R]
The top two values are popped off the stack, and the second is shifted
left (radix shifted right) to the value of the first.
.RS
.PP
The first value popped off of the stack must be an integer and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]h\f[R]
The top two values are popped off the stack, and the second is shifted
right (radix shifted left) to the value of the first.
.RS
.PP
The first value popped off of the stack must be an integer and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]G\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if they are equal, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]N\f[R]
The top value is popped off of the stack, and if it a \f[B]0\f[R], a
\f[B]1\f[R] is pushed; otherwise, a \f[B]0\f[R] is pushed.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B](\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]{\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than or equal to the second,
or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B])\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]}\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than or equal to the
second, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]M\f[R]
The top two values are popped off of the stack.
If they are both non-zero, a \f[B]1\f[R] is pushed onto the stack.
If either of them is zero, or both of them are, then a \f[B]0\f[R] is
pushed onto the stack.
.RS
.PP
This is like the \f[B]&&\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]m\f[R]
The top two values are popped off of the stack.
If at least one of them is non-zero, a \f[B]1\f[R] is pushed onto the
stack.
If both of them are zero, then a \f[B]0\f[R] is pushed onto the stack.
.RS
.PP
This is like the \f[B]||\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Pseudo-Random Number Generator
.PP
dc(1) has a built-in pseudo-random number generator.
These commands query the pseudo-random number generator.
(See Parameters for more information about the \f[B]seed\f[R] value that
controls the pseudo-random number generator.)
.PP
The pseudo-random number generator is guaranteed to \f[B]NOT\f[R] be
cryptographically secure.
.TP
\f[B]\[cq]\f[R]
Generates an integer between 0 and \f[B]DC_RAND_MAX\f[R], inclusive (see
the \f[B]LIMITS\f[R] section).
.RS
.PP
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[dq]\f[R]
Pops a value off of the stack, which is used as an \f[B]exclusive\f[R]
upper bound on the integer that will be generated.
If the bound is negative or is a non-integer, an error is raised, and
dc(1) resets (see the \f[B]RESET\f[R] section) while \f[B]seed\f[R]
remains unchanged.
If the bound is larger than \f[B]DC_RAND_MAX\f[R], the higher bound is
honored by generating several pseudo-random integers, multiplying them
by appropriate powers of \f[B]DC_RAND_MAX+1\f[R], and adding them
together.
Thus, the size of integer that can be generated with this command is
unbounded.
Using this command will change the value of \f[B]seed\f[R], unless the
operand is \f[B]0\f[R] or \f[B]1\f[R].
In that case, \f[B]0\f[R] is pushed onto the stack, and \f[B]seed\f[R]
is \f[I]not\f[R] changed.
.RS
.PP
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Stack Control
.PP
These commands control the stack.
.TP
\f[B]c\f[R]
Removes all items from (\[lq]clears\[rq]) the stack.
.TP
\f[B]d\f[R]
Copies the item on top of the stack (\[lq]duplicates\[rq]) and pushes
the copy onto the stack.
.TP
\f[B]r\f[R]
Swaps (\[lq]reverses\[rq]) the two top items on the stack.
.TP
\f[B]R\f[R]
Pops (\[lq]removes\[rq]) the top value from the stack.
.SS Register Control
.PP
These commands control registers (see the \f[B]REGISTERS\f[R] section).
.TP
\f[B]s\f[R]\f[I]r\f[R]
Pops the value off the top of the stack and stores it into register
\f[I]r\f[R].
.TP
\f[B]l\f[R]\f[I]r\f[R]
Copies the value in register \f[I]r\f[R] and pushes it onto the stack.
This does not alter the contents of \f[I]r\f[R].
.TP
\f[B]S\f[R]\f[I]r\f[R]
Pops the value off the top of the (main) stack and pushes it onto the
stack of register \f[I]r\f[R].
The previous value of the register becomes inaccessible.
.TP
\f[B]L\f[R]\f[I]r\f[R]
Pops the value off the top of the stack for register \f[I]r\f[R] and
push it onto the main stack.
The previous value in the stack for register \f[I]r\f[R], if any, is now
accessible via the \f[B]l\f[R]\f[I]r\f[R] command.
.SS Parameters
.PP
These commands control the values of \f[B]ibase\f[R], \f[B]obase\f[R],
\f[B]scale\f[R], and \f[B]seed\f[R].
Also see the \f[B]SYNTAX\f[R] section.
.TP
\f[B]i\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]ibase\f[R], which must be between \f[B]2\f[R] and \f[B]16\f[R],
inclusive.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]o\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]obase\f[R], which must be between \f[B]0\f[R] and
\f[B]DC_BASE_MAX\f[R], inclusive (see the \f[B]LIMITS\f[R] section and
the \f[B]NUMBERS\f[R] section).
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]k\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]scale\f[R], which must be non-negative.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]j\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]seed\f[R].
The meaning of \f[B]seed\f[R] is dependent on the current pseudo-random
number generator but is guaranteed to not change except for new major
versions.
.RS
.PP
The \f[I]scale\f[R] and sign of the value may be significant.
.PP
If a previously used \f[B]seed\f[R] value is used again, the
pseudo-random number generator is guaranteed to produce the same
sequence of pseudo-random numbers as it did when the \f[B]seed\f[R]
value was previously used.
.PP
The exact value assigned to \f[B]seed\f[R] is not guaranteed to be
returned if the \f[B]J\f[R] command is used.
However, if \f[B]seed\f[R] \f[I]does\f[R] return a different value, both
values, when assigned to \f[B]seed\f[R], are guaranteed to produce the
same sequence of pseudo-random numbers.
This means that certain values assigned to \f[B]seed\f[R] will not
produce unique sequences of pseudo-random numbers.
.PP
There is no limit to the length (number of significant decimal digits)
or \f[I]scale\f[R] of the value that can be assigned to \f[B]seed\f[R].
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]I\f[R]
Pushes the current value of \f[B]ibase\f[R] onto the main stack.
.TP
\f[B]O\f[R]
Pushes the current value of \f[B]obase\f[R] onto the main stack.
.TP
\f[B]K\f[R]
Pushes the current value of \f[B]scale\f[R] onto the main stack.
.TP
\f[B]J\f[R]
Pushes the current value of \f[B]seed\f[R] onto the main stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]T\f[R]
Pushes the maximum allowable value of \f[B]ibase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]U\f[R]
Pushes the maximum allowable value of \f[B]obase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]V\f[R]
Pushes the maximum allowable value of \f[B]scale\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]W\f[R]
Pushes the maximum (inclusive) integer that can be generated with the
\f[B]\[cq]\f[R] pseudo-random number generator command.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Strings
.PP
The following commands control strings.
.PP
dc(1) can work with both numbers and strings, and registers (see the
\f[B]REGISTERS\f[R] section) can hold both strings and numbers.
dc(1) always knows whether the contents of a register are a string or a
number.
.PP
While arithmetic operations have to have numbers, and will print an
error if given a string, other commands accept strings.
.PP
Strings can also be executed as macros.
For example, if the string \f[B][1pR]\f[R] is executed as a macro, then
the code \f[B]1pR\f[R] is executed, meaning that the \f[B]1\f[R] will be
printed with a newline after and then popped from the stack.
.TP
\f[B][\f[R]_characters_\f[B]]\f[R]
Makes a string containing \f[I]characters\f[R] and pushes it onto the
stack.
.RS
.PP
If there are brackets (\f[B][\f[R] and \f[B]]\f[R]) in the string, then
they must be balanced.
Unbalanced brackets can be escaped using a backslash (\f[B]\[rs]\f[R])
character.
.PP
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the
(first) backslash is not.
.RE
.TP
\f[B]a\f[R]
The value on top of the stack is popped.
.RS
.PP
If it is a number, it is truncated and its absolute value is taken.
The result mod \f[B]UCHAR_MAX+1\f[R] is calculated.
If that result is \f[B]0\f[R], push an empty string; otherwise, push a
one-character string where the character is the result of the mod
interpreted as an ASCII character.
.PP
If it is a string, then a new string is made.
If the original string is empty, the new string is empty.
If it is not, then the first character of the original string is used to
create the new string as a one-character string.
The new string is then pushed onto the stack.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]x\f[R]
Pops a value off of the top of the stack.
.RS
.PP
If it is a number, it is pushed back onto the stack.
.PP
If it is a string, it is executed as a macro.
.PP
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is greater than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
For example, \f[B]0 1>a\f[R] will execute the contents of register
\f[B]a\f[R], and \f[B]1 0>a\f[R] will not.
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not greater than the second (less than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is less than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not less than the second (greater than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is equal to the second, then the contents of register
\f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not equal to the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]?\f[R]
Reads a line from the \f[B]stdin\f[R] and executes it.
This is to allow macros to request input from users.
.TP
\f[B]q\f[R]
During execution of a macro, this exits the execution of that macro and
the execution of the macro that executed it.
If there are no macros, or only one macro executing, dc(1) exits.
.TP
\f[B]Q\f[R]
Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack.
If the number of levels to pop is greater than the number of executing
macros, dc(1) exits.
.SS Status
.PP
These commands query status of the stack or its top value.
.TP
\f[B]Z\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, calculates the number of significant decimal digits
it has and pushes the result.
.PP
If it is a string, pushes the number of characters the string has.
.RE
.TP
\f[B]X\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, pushes the \f[I]scale\f[R] of the value onto the
stack.
.PP
If it is a string, pushes \f[B]0\f[R].
.RE
.TP
\f[B]z\f[R]
Pushes the current stack depth (before execution of this command).
.SS Arrays
.PP
These commands manipulate arrays.
.TP
\f[B]:\f[R]\f[I]r\f[R]
Pops the top two values off of the stack.
The second value will be stored in the array \f[I]r\f[R] (see the
\f[B]REGISTERS\f[R] section), indexed by the first value.
.TP
\f[B];\f[R]\f[I]r\f[R]
Pops the value on top of the stack and uses it as an index into the
array \f[I]r\f[R].
The selected value is then pushed onto the stack.
.SH REGISTERS
.PP
Registers are names that can store strings, numbers, and arrays.
(Number/string registers do not interfere with array registers.)
.PP
Each register is also its own stack, so the current register value is
the top of the stack for the register.
All registers, when first referenced, have one value (\f[B]0\f[R]) in
their stack.
.PP
In non-extended register mode, a register name is just the single
character that follows any command that needs a register name.
The only exception is a newline (\f[B]`\[rs]n'\f[R]); it is a parse
error for a newline to be used as a register name.
.SS Extended Register Mode
.PP
Unlike most other dc(1) implentations, this dc(1) provides nearly
unlimited amounts of registers, if extended register mode is enabled.
.PP
If extended register mode is enabled (\f[B]-x\f[R] or
\f[B]\[en]extended-register\f[R] command-line arguments are given), then
normal single character registers are used \f[I]unless\f[R] the
character immediately following a command that needs a register name is
a space (according to \f[B]isspace()\f[R]) and not a newline
(\f[B]`\[rs]n'\f[R]).
.PP
In that case, the register name is found according to the regex
\f[B][a-z][a-z0-9_]*\f[R] (like bc(1) identifiers), and it is a parse
error if the next non-space characters do not match that regex.
.SH RESET
.PP
When dc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any macros that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all macros returned) is skipped.
.PP
Thus, when dc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.SH PERFORMANCE
.PP
Most dc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This dc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]DC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]DC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]DC_BASE_DIGS\f[R].
.PP
In addition, this dc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]DC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on dc(1):
.TP
\f[B]DC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
dc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]DC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]DC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]DC_BASE_DIGS\f[R].
.TP
\f[B]DC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]DC_BASE_POW\f[R].
.TP
\f[B]DC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]DC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_RAND_MAX\f[R]
The maximum integer (inclusive) returned by the \f[B]\[cq]\f[R] command,
if dc(1).
Set at \f[B]2\[ha]DC_LONG_BIT-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]DC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
dc(1) recognizes the following environment variables:
.TP
\f[B]DC_ENV_ARGS\f[R]
This is another way to give command-line arguments to dc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]DC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs.
Another use would be to use the \f[B]-e\f[R] option to set
\f[B]scale\f[R] to a value other than \f[B]0\f[R].
.RS
.PP
The code that parses \f[B]DC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some dc file.dc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]dc\[dq] file.dc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
-in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
+in \f[B]\[rq]some `dc' file.dc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]DC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]DC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), dc(1) will output lines to that length,
including the backslash newline combo.
The default line length is \f[B]70\f[R].
.TP
\f[B]DC_EXPR_EXIT\f[R]
If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the
\f[B]-e\f[R] and/or \f[B]-f\f[R] command-line options (and any
equivalents).
.SH EXIT STATUS
.PP
dc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, using a negative number as a bound for the
pseudo-random number generator, attempting to convert a negative number
to a hardware integer, overflow when converting a number to a hardware
integer, and attempting to use a non-integer where an integer is
required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]), places (\f[B]\[at]\f[R]), left shift
(\f[B]H\f[R]), and right shift (\f[B]h\f[R]) operators.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, and using a
token where it is invalid.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, and attempting an operation when the
stack has too few elements.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (dc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, dc(1)
always exits and returns \f[B]4\f[R], no matter what mode dc(1) is in.
.PP
The other statuses will only be returned when dc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
dc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, dc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, dc(1) turns on \[lq]TTY mode.\[rq]
.PP
The prompt is enabled in TTY mode.
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause dc(1) to stop execution of the
current input.
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If dc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If dc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to dc(1) as it is
executing a file, it can seem as though dc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause dc(1) to clean up and
exit, and it uses the default handler for all other signals.
.SH SEE ALSO
.PP
bc(1)
.SH STANDARDS
.PP
The dc(1) utility operators are compliant with the operators in the
bc(1) IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHOR
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/dc/HN.1.md b/contrib/bc/manuals/dc/HN.1.md
index fb225f2f9558..6248037980d9 100644
--- a/contrib/bc/manuals/dc/HN.1.md
+++ b/contrib/bc/manuals/dc/HN.1.md
@@ -1,1180 +1,1189 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# Name
dc - arbitrary-precision decimal reverse-Polish notation calculator
# SYNOPSIS
**dc** [**-hiPvVx**] [**--version**] [**--help**] [**--interactive**] [**--no-prompt**] [**--extended-register**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...] [*file*...]
# DESCRIPTION
dc(1) is an arbitrary-precision calculator. It uses a stack (reverse Polish
notation) to store numbers and results of computations. Arithmetic operations
pop arguments off of the stack and push the results.
If no files are given on the command-line as extra arguments (i.e., not as
**-f** or **--file** arguments), then dc(1) reads from **stdin**. Otherwise,
those files are processed, and dc(1) will then exit.
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where **-e** (**--expression**) and **-f** (**--file**)
arguments cause dc(1) to execute them and exit. The reason for this is that this
dc(1) allows users to set arguments in the environment variable **DC_ENV_ARGS**
(see the **ENVIRONMENT VARIABLES** section). Any expressions given on the
command-line should be used to set up a standard environment. For example, if a
user wants the **scale** always set to **10**, they can set **DC_ENV_ARGS** to
**-e 10k**, and this dc(1) will always start with a **scale** of **10**.
If users want to have dc(1) exit after processing all input from **-e** and
**-f** arguments (and their equivalents), then they can just simply add **-e q**
as the last command-line argument or define the environment variable
**DC_EXPR_EXIT**.
# OPTIONS
The following are the options that dc(1) accepts.
**-h**, **--help**
: Prints a usage message and quits.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-P**, **--no-prompt**
: Disables the prompt in TTY mode. (The prompt is only enabled in TTY mode.
See the **TTY MODE** section) This is mostly for those users that do not
want a prompt or are not used to having them in dc(1). Most of those users
would want to put this option in **DC_ENV_ARGS**.
This is a **non-portable extension**.
**-x** **--extended-register**
: Enables extended register mode. See the *Extended Register Mode* subsection
of the **REGISTERS** section for more information.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **DC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **dc <file> >&-**, it will quit with an error. This
is done so that dc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **dc <file> 2>&-**, it will quit with an error. This
is done so that dc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
Each item in the input source code, either a number (see the **NUMBERS**
section) or a command (see the **COMMANDS** section), is processed and executed,
in order. Input is processed immediately when entered.
**ibase** is a register (see the **REGISTERS** section) that determines how to
interpret constant numbers. It is the "input" base, or the number base used for
interpreting input numbers. **ibase** is initially **10**. The max allowable
value for **ibase** is **16**. The min allowable value for **ibase** is **2**.
The max allowable value for **ibase** can be queried in dc(1) programs with the
**T** command.
**obase** is a register (see the **REGISTERS** section) that determines how to
output results. It is the "output" base, or the number base used for outputting
numbers. **obase** is initially **10**. The max allowable value for **obase** is
**DC_BASE_MAX** and can be queried with the **U** command. The min allowable
value for **obase** is **0**. If **obase** is **0**, values are output in
scientific notation, and if **obase** is **1**, values are output in engineering
notation. Otherwise, values are output in the specified base.
Outputting in scientific and engineering notations are **non-portable
extensions**.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a register (see the
**REGISTERS** section) that sets the precision of any operations (with
exceptions). **scale** is initially **0**. **scale** cannot be negative. The max
allowable value for **scale** can be queried in dc(1) programs with the **V**
command.
**seed** is a register containing the current seed for the pseudo-random number
generator. If the current value of **seed** is queried and stored, then if it is
assigned to **seed** later, the pseudo-random number generator is guaranteed to
produce the same sequence of pseudo-random numbers that were generated after the
value of **seed** was first queried.
Multiple values assigned to **seed** can produce the same sequence of
pseudo-random numbers. Likewise, when a value is assigned to **seed**, it is not
guaranteed that querying **seed** immediately after will return the same value.
In addition, the value of **seed** will change after any call to the **'**
command or the **"** command that does not get receive a value of **0** or
**1**. The maximum integer returned by the **'** command can be queried with the
**W** command.
**Note**: The values returned by the pseudo-random number generator with the
**'** and **"** commands are guaranteed to **NOT** be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator. However,
they *are* guaranteed to be reproducible with identical **seed** values. This
-means that the pseudo-random values from bc(1) should only be used where a
+means that the pseudo-random values from dc(1) should only be used where a
reproducible stream of pseudo-random numbers is *ESSENTIAL*. In any other case,
use a non-seeded pseudo-random number generator.
The pseudo-random number generator, **seed**, and all associated operations are
**non-portable extensions**.
## Comments
Comments go from **#** until, and not including, the next newline. This is a
**non-portable extension**.
# NUMBERS
Numbers are strings made up of digits, uppercase letters up to **F**, and at
most **1** period for a radix. Numbers can have up to **DC_NUM_MAX** digits.
Uppercase letters are equal to **9** + their position in the alphabet (i.e.,
**A** equals **10**, or **9+1**). If a digit or letter makes no sense with the
current value of **ibase**, they are set to the value of the highest valid digit
in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **F** alone always equals decimal
**15**.
In addition, dc(1) accepts numbers in scientific notation. These have the form
**\<number\>e\<integer\>**. The exponent (the portion after the **e**) must be
an integer. An example is **1.89237e9**, which is equal to **1892370000**.
Negative exponents are also allowed, so **4.2890e_3** is equal to **0.0042890**.
**WARNING**: Both the number and the exponent in scientific notation are
interpreted according to the current **ibase**, but the number is still
multiplied by **10\^exponent** regardless of the current **ibase**. For example,
if **ibase** is **16** and dc(1) is given the number string **FFeA**, the
resulting decimal number will be **2550000000000**, and if dc(1) is given the
number string **10e_4**, the resulting decimal number will be **0.0016**.
Accepting input as scientific notation is a **non-portable extension**.
# COMMANDS
The valid commands are listed below.
## Printing
These commands are used for printing.
Note that both scientific notation and engineering notation are available for
printing numbers. Scientific notation is activated by assigning **0** to
**obase** using **0o**, and engineering notation is activated by assigning **1**
to **obase** using **1o**. To deactivate them, just assign a different value to
**obase**.
Printing numbers in scientific notation and/or engineering notation is a
**non-portable extension**.
**p**
: Prints the value on top of the stack, whether number or string, and prints a
newline after.
This does not alter the stack.
**n**
: Prints the value on top of the stack, whether number or string, and pops it
off of the stack.
**P**
: Pops a value off the stack.
If the value is a number, it is truncated and the absolute value of the
result is printed as though **obase** is **UCHAR_MAX+1** and each digit is
interpreted as an ASCII character, making it a byte stream.
If the value is a string, it is printed without a trailing newline.
This is a **non-portable extension**.
**f**
: Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
Users should use this command when they get lost.
## Arithmetic
These are the commands used for arithmetic.
**+**
: The top two values are popped off the stack, added, and the result is pushed
onto the stack. The *scale* of the result is equal to the max *scale* of
both operands.
**-**
: The top two values are popped off the stack, subtracted, and the result is
pushed onto the stack. The *scale* of the result is equal to the max
*scale* of both operands.
**\***
: The top two values are popped off the stack, multiplied, and the result is
pushed onto the stack. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result
is equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The top two values are popped off the stack, divided, and the result is
pushed onto the stack. The *scale* of the result is equal to **scale**.
The first value popped off of the stack must be non-zero.
**%**
: The top two values are popped off the stack, remaindered, and the result is
pushed onto the stack.
Remaindering is equivalent to 1) Computing **a/b** to current **scale**, and
2) Using the result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The first value popped off of the stack must be non-zero.
**~**
: The top two values are popped off the stack, divided and remaindered, and
the results (divided first, remainder second) are pushed onto the stack.
This is equivalent to **x y / x y %** except that **x** and **y** are only
evaluated once.
The first value popped off of the stack must be non-zero.
This is a **non-portable extension**.
**\^**
: The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack. The *scale* of
the result is equal to **scale**.
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
**v**
: The top value is popped off the stack, its square root is computed, and the
result is pushed onto the stack. The *scale* of the result is equal to
**scale**.
The value popped off of the stack must be non-negative.
**\_**
: If this command *immediately* precedes a number (i.e., no spaces or other
commands), then that number is input as a negative number.
Otherwise, the top value on the stack is popped and copied, and the copy is
negated and pushed onto the stack. This behavior without a number is a
**non-portable extension**.
**b**
: The top value is popped off the stack, and if it is zero, it is pushed back
onto the stack. Otherwise, its absolute value is pushed onto the stack.
This is a **non-portable extension**.
**|**
: The top three values are popped off the stack, a modular exponentiation is
computed, and the result is pushed onto the stack.
The first value popped is used as the reduction modulus and must be an
integer and non-zero. The second value popped is used as the exponent and
must be an integer and non-negative. The third value popped is the base and
must be an integer.
This is a **non-portable extension**.
**\$**
: The top value is popped off the stack and copied, and the copy is truncated
and pushed onto the stack.
This is a **non-portable extension**.
**\@**
: The top two values are popped off the stack, and the precision of the second
is set to the value of the first, whether by truncation or extension.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**H**
: The top two values are popped off the stack, and the second is shifted left
(radix shifted right) to the value of the first.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**h**
: The top two values are popped off the stack, and the second is shifted right
(radix shifted left) to the value of the first.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**G**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if they are equal, or **0** otherwise.
This is a **non-portable extension**.
**N**
: The top value is popped off of the stack, and if it a **0**, a **1** is
pushed; otherwise, a **0** is pushed.
This is a **non-portable extension**.
**(**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than the second, or **0** otherwise.
This is a **non-portable extension**.
**{**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than or equal to the second, or **0**
otherwise.
This is a **non-portable extension**.
**)**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than the second, or **0** otherwise.
This is a **non-portable extension**.
**}**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than or equal to the second, or
**0** otherwise.
This is a **non-portable extension**.
**M**
: The top two values are popped off of the stack. If they are both non-zero, a
**1** is pushed onto the stack. If either of them is zero, or both of them
are, then a **0** is pushed onto the stack.
This is like the **&&** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
**m**
: The top two values are popped off of the stack. If at least one of them is
non-zero, a **1** is pushed onto the stack. If both of them are zero, then a
**0** is pushed onto the stack.
This is like the **||** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
## Pseudo-Random Number Generator
dc(1) has a built-in pseudo-random number generator. These commands query the
pseudo-random number generator. (See Parameters for more information about the
**seed** value that controls the pseudo-random number generator.)
The pseudo-random number generator is guaranteed to **NOT** be
cryptographically secure.
**'**
: Generates an integer between 0 and **DC_RAND_MAX**, inclusive (see the
**LIMITS** section).
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
This is a **non-portable extension**.
**"**
: Pops a value off of the stack, which is used as an **exclusive** upper bound
on the integer that will be generated. If the bound is negative or is a
non-integer, an error is raised, and dc(1) resets (see the **RESET**
section) while **seed** remains unchanged. If the bound is larger than
**DC_RAND_MAX**, the higher bound is honored by generating several
pseudo-random integers, multiplying them by appropriate powers of
**DC_RAND_MAX+1**, and adding them together. Thus, the size of integer that
can be generated with this command is unbounded. Using this command will
change the value of **seed**, unless the operand is **0** or **1**. In that
case, **0** is pushed onto the stack, and **seed** is *not* changed.
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
This is a **non-portable extension**.
## Stack Control
These commands control the stack.
**c**
: Removes all items from ("clears") the stack.
**d**
: Copies the item on top of the stack ("duplicates") and pushes the copy onto
the stack.
**r**
: Swaps ("reverses") the two top items on the stack.
**R**
: Pops ("removes") the top value from the stack.
## Register Control
These commands control registers (see the **REGISTERS** section).
**s***r*
: Pops the value off the top of the stack and stores it into register *r*.
**l***r*
: Copies the value in register *r* and pushes it onto the stack. This does not
alter the contents of *r*.
**S***r*
: Pops the value off the top of the (main) stack and pushes it onto the stack
of register *r*. The previous value of the register becomes inaccessible.
**L***r*
: Pops the value off the top of the stack for register *r* and push it onto
the main stack. The previous value in the stack for register *r*, if any, is
now accessible via the **l***r* command.
## Parameters
These commands control the values of **ibase**, **obase**, **scale**, and
**seed**. Also see the **SYNTAX** section.
**i**
: Pops the value off of the top of the stack and uses it to set **ibase**,
which must be between **2** and **16**, inclusive.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**o**
: Pops the value off of the top of the stack and uses it to set **obase**,
which must be between **0** and **DC_BASE_MAX**, inclusive (see the
**LIMITS** section and the **NUMBERS** section).
If the value on top of the stack has any *scale*, the *scale* is ignored.
**k**
: Pops the value off of the top of the stack and uses it to set **scale**,
which must be non-negative.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**j**
: Pops the value off of the top of the stack and uses it to set **seed**. The
meaning of **seed** is dependent on the current pseudo-random number
generator but is guaranteed to not change except for new major versions.
The *scale* and sign of the value may be significant.
If a previously used **seed** value is used again, the pseudo-random number
generator is guaranteed to produce the same sequence of pseudo-random
numbers as it did when the **seed** value was previously used.
The exact value assigned to **seed** is not guaranteed to be returned if the
**J** command is used. However, if **seed** *does* return a different value,
both values, when assigned to **seed**, are guaranteed to produce the same
sequence of pseudo-random numbers. This means that certain values assigned
to **seed** will not produce unique sequences of pseudo-random numbers.
There is no limit to the length (number of significant decimal digits) or
*scale* of the value that can be assigned to **seed**.
This is a **non-portable extension**.
**I**
: Pushes the current value of **ibase** onto the main stack.
**O**
: Pushes the current value of **obase** onto the main stack.
**K**
: Pushes the current value of **scale** onto the main stack.
**J**
: Pushes the current value of **seed** onto the main stack.
This is a **non-portable extension**.
**T**
: Pushes the maximum allowable value of **ibase** onto the main stack.
This is a **non-portable extension**.
**U**
: Pushes the maximum allowable value of **obase** onto the main stack.
This is a **non-portable extension**.
**V**
: Pushes the maximum allowable value of **scale** onto the main stack.
This is a **non-portable extension**.
**W**
: Pushes the maximum (inclusive) integer that can be generated with the **'**
pseudo-random number generator command.
This is a **non-portable extension**.
## Strings
The following commands control strings.
dc(1) can work with both numbers and strings, and registers (see the
**REGISTERS** section) can hold both strings and numbers. dc(1) always knows
whether the contents of a register are a string or a number.
While arithmetic operations have to have numbers, and will print an error if
given a string, other commands accept strings.
Strings can also be executed as macros. For example, if the string **[1pR]** is
executed as a macro, then the code **1pR** is executed, meaning that the **1**
will be printed with a newline after and then popped from the stack.
**\[**_characters_**\]**
: Makes a string containing *characters* and pushes it onto the stack.
If there are brackets (**\[** and **\]**) in the string, then they must be
balanced. Unbalanced brackets can be escaped using a backslash (**\\**)
character.
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the (first)
backslash is not.
**a**
: The value on top of the stack is popped.
If it is a number, it is truncated and its absolute value is taken. The
result mod **UCHAR_MAX+1** is calculated. If that result is **0**, push an
empty string; otherwise, push a one-character string where the character is
the result of the mod interpreted as an ASCII character.
If it is a string, then a new string is made. If the original string is
empty, the new string is empty. If it is not, then the first character of
the original string is used to create the new string as a one-character
string. The new string is then pushed onto the stack.
This is a **non-portable extension**.
**x**
: Pops a value off of the top of the stack.
If it is a number, it is pushed back onto the stack.
If it is a string, it is executed as a macro.
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
**\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is greater than the second, then the contents of register
*r* are executed.
For example, **0 1>a** will execute the contents of register **a**, and
**1 0>a** will not.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not greater than the second (less than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is less than the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not less than the second (greater than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is equal to the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not equal to the second, then the contents of register
*r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**?**
: Reads a line from the **stdin** and executes it. This is to allow macros to
request input from users.
**q**
: During execution of a macro, this exits the execution of that macro and the
execution of the macro that executed it. If there are no macros, or only one
macro executing, dc(1) exits.
**Q**
: Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack. If the number
of levels to pop is greater than the number of executing macros, dc(1)
exits.
## Status
These commands query status of the stack or its top value.
**Z**
: Pops a value off of the stack.
If it is a number, calculates the number of significant decimal digits it
has and pushes the result.
If it is a string, pushes the number of characters the string has.
**X**
: Pops a value off of the stack.
If it is a number, pushes the *scale* of the value onto the stack.
If it is a string, pushes **0**.
**z**
: Pushes the current stack depth (before execution of this command).
## Arrays
These commands manipulate arrays.
**:***r*
: Pops the top two values off of the stack. The second value will be stored in
the array *r* (see the **REGISTERS** section), indexed by the first value.
**;***r*
: Pops the value on top of the stack and uses it as an index into the array
*r*. The selected value is then pushed onto the stack.
# REGISTERS
Registers are names that can store strings, numbers, and arrays. (Number/string
registers do not interfere with array registers.)
Each register is also its own stack, so the current register value is the top of
the stack for the register. All registers, when first referenced, have one value
(**0**) in their stack.
In non-extended register mode, a register name is just the single character that
follows any command that needs a register name. The only exception is a newline
(**'\\n'**); it is a parse error for a newline to be used as a register name.
## Extended Register Mode
Unlike most other dc(1) implentations, this dc(1) provides nearly unlimited
amounts of registers, if extended register mode is enabled.
If extended register mode is enabled (**-x** or **--extended-register**
command-line arguments are given), then normal single character registers are
used *unless* the character immediately following a command that needs a
register name is a space (according to **isspace()**) and not a newline
(**'\\n'**).
In that case, the register name is found according to the regex
**\[a-z\]\[a-z0-9\_\]\*** (like bc(1) identifiers), and it is a parse error if
the next non-space characters do not match that regex.
# RESET
When dc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any macros that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
macros returned) is skipped.
Thus, when dc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
# PERFORMANCE
Most dc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This dc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **DC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **DC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**DC_BASE_DIGS**.
In addition, this dc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **DC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on dc(1):
**DC_LONG_BIT**
: The number of bits in the **long** type in the environment where dc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**DC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **DC_LONG_BIT**.
**DC_BASE_POW**
: The max decimal number that each large integer can store (see
**DC_BASE_DIGS**) plus **1**. Depends on **DC_BASE_DIGS**.
**DC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **DC_LONG_BIT**.
**DC_BASE_MAX**
: The maximum output base. Set at **DC_BASE_POW**.
**DC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**DC_SCALE_MAX**
: The maximum **scale**. Set at **DC_OVERFLOW_MAX-1**.
**DC_STRING_MAX**
: The maximum length of strings. Set at **DC_OVERFLOW_MAX-1**.
**DC_NAME_MAX**
: The maximum length of identifiers. Set at **DC_OVERFLOW_MAX-1**.
**DC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **DC_OVERFLOW_MAX-1**.
**DC_RAND_MAX**
: The maximum integer (inclusive) returned by the **'** command, if dc(1). Set
at **2\^DC_LONG_BIT-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**DC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
dc(1) recognizes the following environment variables:
**DC_ENV_ARGS**
: This is another way to give command-line arguments to dc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **DC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs. Another use would
be to use the **-e** option to set **scale** to a value other than **0**.
The code that parses **DC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some dc file.dc"** will be correctly parsed, but the string
**"/home/gavin/some \"dc\" file.dc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
- double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
+ double quotes as the outside quotes, as in **"some 'dc' file.dc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **DC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**DC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), dc(1) will output
lines to that length, including the backslash newline combo. The default
line length is **70**.
**DC_EXPR_EXIT**
: If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the **-e** and/or
**-f** command-line options (and any equivalents).
# EXIT STATUS
dc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, using a negative number as a bound for the pseudo-random number
generator, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**), places (**\@**), left shift (**H**), and right shift (**h**)
operators.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, and using a token where it is
invalid.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, and attempting an operation when
the stack has too few elements.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (dc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, dc(1) always exits
and returns **4**, no matter what mode dc(1) is in.
The other statuses will only be returned when dc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since dc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, dc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, dc(1) turns
on "TTY mode."
The prompt is enabled in TTY mode.
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause dc(1) to stop execution of the current input. If
dc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If dc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If dc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to dc(1) as it is executing a file, it
can seem as though dc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause dc(1) to clean up and exit, and it uses the
default handler for all other signals.
# SEE ALSO
bc(1)
# STANDARDS
The dc(1) utility operators are compliant with the operators in the bc(1)
[IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1] specification.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHOR
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
diff --git a/contrib/bc/manuals/dc/HNP.1 b/contrib/bc/manuals/dc/HNP.1
index 1bb8ea6a2de8..bb103564f3ca 100644
--- a/contrib/bc/manuals/dc/HNP.1
+++ b/contrib/bc/manuals/dc/HNP.1
@@ -1,1312 +1,1325 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "DC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "DC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH Name
.PP
dc - arbitrary-precision decimal reverse-Polish notation calculator
.SH SYNOPSIS
.PP
\f[B]dc\f[R] [\f[B]-hiPvVx\f[R]] [\f[B]\[en]version\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]no-prompt\f[R]] [\f[B]\[en]extended-register\f[R]]
[\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
dc(1) is an arbitrary-precision calculator.
It uses a stack (reverse Polish notation) to store numbers and results
of computations.
Arithmetic operations pop arguments off of the stack and push the
results.
.PP
If no files are given on the command-line as extra arguments (i.e., not
as \f[B]-f\f[R] or \f[B]\[en]file\f[R] arguments), then dc(1) reads from
\f[B]stdin\f[R].
Otherwise, those files are processed, and dc(1) will then exit.
.PP
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where \f[B]-e\f[R] (\f[B]\[en]expression\f[R]) and
\f[B]-f\f[R] (\f[B]\[en]file\f[R]) arguments cause dc(1) to execute them
and exit.
The reason for this is that this dc(1) allows users to set arguments in
the environment variable \f[B]DC_ENV_ARGS\f[R] (see the \f[B]ENVIRONMENT
VARIABLES\f[R] section).
Any expressions given on the command-line should be used to set up a
standard environment.
For example, if a user wants the \f[B]scale\f[R] always set to
\f[B]10\f[R], they can set \f[B]DC_ENV_ARGS\f[R] to \f[B]-e 10k\f[R],
and this dc(1) will always start with a \f[B]scale\f[R] of \f[B]10\f[R].
.PP
If users want to have dc(1) exit after processing all input from
\f[B]-e\f[R] and \f[B]-f\f[R] arguments (and their equivalents), then
they can just simply add \f[B]-e q\f[R] as the last command-line
argument or define the environment variable \f[B]DC_EXPR_EXIT\f[R].
.SH OPTIONS
.PP
The following are the options that dc(1) accepts.
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
This option is a no-op.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-x\f[R] \f[B]\[en]extended-register\f[R]
Enables extended register mode.
See the \f[I]Extended Register Mode\f[R] subsection of the
\f[B]REGISTERS\f[R] section for more information.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]DC_ENV_ARGS\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]dc >&-\f[R], it will quit with an error.
This is done so that dc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]dc 2>&-\f[R], it will quit with an error.
This is done so that dc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
Each item in the input source code, either a number (see the
\f[B]NUMBERS\f[R] section) or a command (see the \f[B]COMMANDS\f[R]
section), is processed and executed, in order.
Input is processed immediately when entered.
.PP
\f[B]ibase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to interpret constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]ibase\f[R] is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in dc(1)
programs with the \f[B]T\f[R] command.
.PP
\f[B]obase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]DC_BASE_MAX\f[R] and
can be queried with the \f[B]U\f[R] command.
The min allowable value for \f[B]obase\f[R] is \f[B]0\f[R].
If \f[B]obase\f[R] is \f[B]0\f[R], values are output in scientific
notation, and if \f[B]obase\f[R] is \f[B]1\f[R], values are output in
engineering notation.
Otherwise, values are output in the specified base.
.PP
Outputting in scientific and engineering notations are \f[B]non-portable
extensions\f[R].
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a register (see the \f[B]REGISTERS\f[R] section) that sets the
precision of any operations (with exceptions).
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] can be queried in dc(1)
programs with the \f[B]V\f[R] command.
.PP
\f[B]seed\f[R] is a register containing the current seed for the
pseudo-random number generator.
If the current value of \f[B]seed\f[R] is queried and stored, then if it
is assigned to \f[B]seed\f[R] later, the pseudo-random number generator
is guaranteed to produce the same sequence of pseudo-random numbers that
were generated after the value of \f[B]seed\f[R] was first queried.
.PP
Multiple values assigned to \f[B]seed\f[R] can produce the same sequence
of pseudo-random numbers.
Likewise, when a value is assigned to \f[B]seed\f[R], it is not
guaranteed that querying \f[B]seed\f[R] immediately after will return
the same value.
In addition, the value of \f[B]seed\f[R] will change after any call to
the \f[B]\[cq]\f[R] command or the \f[B]\[dq]\f[R] command that does not
get receive a value of \f[B]0\f[R] or \f[B]1\f[R].
The maximum integer returned by the \f[B]\[cq]\f[R] command can be
queried with the \f[B]W\f[R] command.
.PP
\f[B]Note\f[R]: The values returned by the pseudo-random number
generator with the \f[B]\[cq]\f[R] and \f[B]\[dq]\f[R] commands are
guaranteed to \f[B]NOT\f[R] be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator.
However, they \f[I]are\f[R] guaranteed to be reproducible with identical
\f[B]seed\f[R] values.
-This means that the pseudo-random values from bc(1) should only be used
+This means that the pseudo-random values from dc(1) should only be used
where a reproducible stream of pseudo-random numbers is
\f[I]ESSENTIAL\f[R].
In any other case, use a non-seeded pseudo-random number generator.
.PP
The pseudo-random number generator, \f[B]seed\f[R], and all associated
operations are \f[B]non-portable extensions\f[R].
.SS Comments
.PP
Comments go from \f[B]#\f[R] until, and not including, the next newline.
This is a \f[B]non-portable extension\f[R].
.SH NUMBERS
.PP
Numbers are strings made up of digits, uppercase letters up to
\f[B]F\f[R], and at most \f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]DC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]F\f[R] alone always equals decimal \f[B]15\f[R].
.PP
In addition, dc(1) accepts numbers in scientific notation.
These have the form \f[B]<number>e<integer>\f[R].
The exponent (the portion after the \f[B]e\f[R]) must be an integer.
An example is \f[B]1.89237e9\f[R], which is equal to
\f[B]1892370000\f[R].
Negative exponents are also allowed, so \f[B]4.2890e_3\f[R] is equal to
\f[B]0.0042890\f[R].
.PP
\f[B]WARNING\f[R]: Both the number and the exponent in scientific
notation are interpreted according to the current \f[B]ibase\f[R], but
the number is still multiplied by \f[B]10\[ha]exponent\f[R] regardless
of the current \f[B]ibase\f[R].
For example, if \f[B]ibase\f[R] is \f[B]16\f[R] and dc(1) is given the
number string \f[B]FFeA\f[R], the resulting decimal number will be
\f[B]2550000000000\f[R], and if dc(1) is given the number string
\f[B]10e_4\f[R], the resulting decimal number will be \f[B]0.0016\f[R].
.PP
Accepting input as scientific notation is a \f[B]non-portable
extension\f[R].
.SH COMMANDS
.PP
The valid commands are listed below.
.SS Printing
.PP
These commands are used for printing.
.PP
Note that both scientific notation and engineering notation are
available for printing numbers.
Scientific notation is activated by assigning \f[B]0\f[R] to
\f[B]obase\f[R] using \f[B]0o\f[R], and engineering notation is
activated by assigning \f[B]1\f[R] to \f[B]obase\f[R] using
\f[B]1o\f[R].
To deactivate them, just assign a different value to \f[B]obase\f[R].
.PP
Printing numbers in scientific notation and/or engineering notation is a
\f[B]non-portable extension\f[R].
.TP
\f[B]p\f[R]
Prints the value on top of the stack, whether number or string, and
prints a newline after.
.RS
.PP
This does not alter the stack.
.RE
.TP
\f[B]n\f[R]
Prints the value on top of the stack, whether number or string, and pops
it off of the stack.
.TP
\f[B]P\f[R]
Pops a value off the stack.
.RS
.PP
If the value is a number, it is truncated and the absolute value of the
result is printed as though \f[B]obase\f[R] is \f[B]UCHAR_MAX+1\f[R] and
each digit is interpreted as an ASCII character, making it a byte
stream.
.PP
If the value is a string, it is printed without a trailing newline.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]f\f[R]
Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
.RS
.PP
Users should use this command when they get lost.
.RE
.SS Arithmetic
.PP
These are the commands used for arithmetic.
.TP
\f[B]+\f[R]
The top two values are popped off the stack, added, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]-\f[R]
The top two values are popped off the stack, subtracted, and the result
is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]*\f[R]
The top two values are popped off the stack, multiplied, and the result
is pushed onto the stack.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The top two values are popped off the stack, divided, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]%\f[R]
The top two values are popped off the stack, remaindered, and the result
is pushed onto the stack.
.RS
.PP
Remaindering is equivalent to 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R], and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]\[ti]\f[R]
The top two values are popped off the stack, divided and remaindered,
and the results (divided first, remainder second) are pushed onto the
stack.
This is equivalent to \f[B]x y / x y %\f[R] except that \f[B]x\f[R] and
\f[B]y\f[R] are only evaluated once.
.RS
.PP
The first value popped off of the stack must be non-zero.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
.RE
.TP
\f[B]v\f[R]
The top value is popped off the stack, its square root is computed, and
the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The value popped off of the stack must be non-negative.
.RE
.TP
\f[B]_\f[R]
If this command \f[I]immediately\f[R] precedes a number (i.e., no spaces
or other commands), then that number is input as a negative number.
.RS
.PP
Otherwise, the top value on the stack is popped and copied, and the copy
is negated and pushed onto the stack.
This behavior without a number is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]b\f[R]
The top value is popped off the stack, and if it is zero, it is pushed
back onto the stack.
Otherwise, its absolute value is pushed onto the stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]|\f[R]
The top three values are popped off the stack, a modular exponentiation
is computed, and the result is pushed onto the stack.
.RS
.PP
The first value popped is used as the reduction modulus and must be an
integer and non-zero.
The second value popped is used as the exponent and must be an integer
and non-negative.
The third value popped is the base and must be an integer.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]$\f[R]
The top value is popped off the stack and copied, and the copy is
truncated and pushed onto the stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[at]\f[R]
The top two values are popped off the stack, and the precision of the
second is set to the value of the first, whether by truncation or
extension.
.RS
.PP
The first value popped off of the stack must be an integer and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]H\f[R]
The top two values are popped off the stack, and the second is shifted
left (radix shifted right) to the value of the first.
.RS
.PP
The first value popped off of the stack must be an integer and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]h\f[R]
The top two values are popped off the stack, and the second is shifted
right (radix shifted left) to the value of the first.
.RS
.PP
The first value popped off of the stack must be an integer and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]G\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if they are equal, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]N\f[R]
The top value is popped off of the stack, and if it a \f[B]0\f[R], a
\f[B]1\f[R] is pushed; otherwise, a \f[B]0\f[R] is pushed.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B](\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]{\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than or equal to the second,
or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B])\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]}\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than or equal to the
second, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]M\f[R]
The top two values are popped off of the stack.
If they are both non-zero, a \f[B]1\f[R] is pushed onto the stack.
If either of them is zero, or both of them are, then a \f[B]0\f[R] is
pushed onto the stack.
.RS
.PP
This is like the \f[B]&&\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]m\f[R]
The top two values are popped off of the stack.
If at least one of them is non-zero, a \f[B]1\f[R] is pushed onto the
stack.
If both of them are zero, then a \f[B]0\f[R] is pushed onto the stack.
.RS
.PP
This is like the \f[B]||\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Pseudo-Random Number Generator
.PP
dc(1) has a built-in pseudo-random number generator.
These commands query the pseudo-random number generator.
(See Parameters for more information about the \f[B]seed\f[R] value that
controls the pseudo-random number generator.)
.PP
The pseudo-random number generator is guaranteed to \f[B]NOT\f[R] be
cryptographically secure.
.TP
\f[B]\[cq]\f[R]
Generates an integer between 0 and \f[B]DC_RAND_MAX\f[R], inclusive (see
the \f[B]LIMITS\f[R] section).
.RS
.PP
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[dq]\f[R]
Pops a value off of the stack, which is used as an \f[B]exclusive\f[R]
upper bound on the integer that will be generated.
If the bound is negative or is a non-integer, an error is raised, and
dc(1) resets (see the \f[B]RESET\f[R] section) while \f[B]seed\f[R]
remains unchanged.
If the bound is larger than \f[B]DC_RAND_MAX\f[R], the higher bound is
honored by generating several pseudo-random integers, multiplying them
by appropriate powers of \f[B]DC_RAND_MAX+1\f[R], and adding them
together.
Thus, the size of integer that can be generated with this command is
unbounded.
Using this command will change the value of \f[B]seed\f[R], unless the
operand is \f[B]0\f[R] or \f[B]1\f[R].
In that case, \f[B]0\f[R] is pushed onto the stack, and \f[B]seed\f[R]
is \f[I]not\f[R] changed.
.RS
.PP
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Stack Control
.PP
These commands control the stack.
.TP
\f[B]c\f[R]
Removes all items from (\[lq]clears\[rq]) the stack.
.TP
\f[B]d\f[R]
Copies the item on top of the stack (\[lq]duplicates\[rq]) and pushes
the copy onto the stack.
.TP
\f[B]r\f[R]
Swaps (\[lq]reverses\[rq]) the two top items on the stack.
.TP
\f[B]R\f[R]
Pops (\[lq]removes\[rq]) the top value from the stack.
.SS Register Control
.PP
These commands control registers (see the \f[B]REGISTERS\f[R] section).
.TP
\f[B]s\f[R]\f[I]r\f[R]
Pops the value off the top of the stack and stores it into register
\f[I]r\f[R].
.TP
\f[B]l\f[R]\f[I]r\f[R]
Copies the value in register \f[I]r\f[R] and pushes it onto the stack.
This does not alter the contents of \f[I]r\f[R].
.TP
\f[B]S\f[R]\f[I]r\f[R]
Pops the value off the top of the (main) stack and pushes it onto the
stack of register \f[I]r\f[R].
The previous value of the register becomes inaccessible.
.TP
\f[B]L\f[R]\f[I]r\f[R]
Pops the value off the top of the stack for register \f[I]r\f[R] and
push it onto the main stack.
The previous value in the stack for register \f[I]r\f[R], if any, is now
accessible via the \f[B]l\f[R]\f[I]r\f[R] command.
.SS Parameters
.PP
These commands control the values of \f[B]ibase\f[R], \f[B]obase\f[R],
\f[B]scale\f[R], and \f[B]seed\f[R].
Also see the \f[B]SYNTAX\f[R] section.
.TP
\f[B]i\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]ibase\f[R], which must be between \f[B]2\f[R] and \f[B]16\f[R],
inclusive.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]o\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]obase\f[R], which must be between \f[B]0\f[R] and
\f[B]DC_BASE_MAX\f[R], inclusive (see the \f[B]LIMITS\f[R] section and
the \f[B]NUMBERS\f[R] section).
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]k\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]scale\f[R], which must be non-negative.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]j\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]seed\f[R].
The meaning of \f[B]seed\f[R] is dependent on the current pseudo-random
number generator but is guaranteed to not change except for new major
versions.
.RS
.PP
The \f[I]scale\f[R] and sign of the value may be significant.
.PP
If a previously used \f[B]seed\f[R] value is used again, the
pseudo-random number generator is guaranteed to produce the same
sequence of pseudo-random numbers as it did when the \f[B]seed\f[R]
value was previously used.
.PP
The exact value assigned to \f[B]seed\f[R] is not guaranteed to be
returned if the \f[B]J\f[R] command is used.
However, if \f[B]seed\f[R] \f[I]does\f[R] return a different value, both
values, when assigned to \f[B]seed\f[R], are guaranteed to produce the
same sequence of pseudo-random numbers.
This means that certain values assigned to \f[B]seed\f[R] will not
produce unique sequences of pseudo-random numbers.
.PP
There is no limit to the length (number of significant decimal digits)
or \f[I]scale\f[R] of the value that can be assigned to \f[B]seed\f[R].
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]I\f[R]
Pushes the current value of \f[B]ibase\f[R] onto the main stack.
.TP
\f[B]O\f[R]
Pushes the current value of \f[B]obase\f[R] onto the main stack.
.TP
\f[B]K\f[R]
Pushes the current value of \f[B]scale\f[R] onto the main stack.
.TP
\f[B]J\f[R]
Pushes the current value of \f[B]seed\f[R] onto the main stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]T\f[R]
Pushes the maximum allowable value of \f[B]ibase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]U\f[R]
Pushes the maximum allowable value of \f[B]obase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]V\f[R]
Pushes the maximum allowable value of \f[B]scale\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]W\f[R]
Pushes the maximum (inclusive) integer that can be generated with the
\f[B]\[cq]\f[R] pseudo-random number generator command.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Strings
.PP
The following commands control strings.
.PP
dc(1) can work with both numbers and strings, and registers (see the
\f[B]REGISTERS\f[R] section) can hold both strings and numbers.
dc(1) always knows whether the contents of a register are a string or a
number.
.PP
While arithmetic operations have to have numbers, and will print an
error if given a string, other commands accept strings.
.PP
Strings can also be executed as macros.
For example, if the string \f[B][1pR]\f[R] is executed as a macro, then
the code \f[B]1pR\f[R] is executed, meaning that the \f[B]1\f[R] will be
printed with a newline after and then popped from the stack.
.TP
\f[B][\f[R]_characters_\f[B]]\f[R]
Makes a string containing \f[I]characters\f[R] and pushes it onto the
stack.
.RS
.PP
If there are brackets (\f[B][\f[R] and \f[B]]\f[R]) in the string, then
they must be balanced.
Unbalanced brackets can be escaped using a backslash (\f[B]\[rs]\f[R])
character.
.PP
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the
(first) backslash is not.
.RE
.TP
\f[B]a\f[R]
The value on top of the stack is popped.
.RS
.PP
If it is a number, it is truncated and its absolute value is taken.
The result mod \f[B]UCHAR_MAX+1\f[R] is calculated.
If that result is \f[B]0\f[R], push an empty string; otherwise, push a
one-character string where the character is the result of the mod
interpreted as an ASCII character.
.PP
If it is a string, then a new string is made.
If the original string is empty, the new string is empty.
If it is not, then the first character of the original string is used to
create the new string as a one-character string.
The new string is then pushed onto the stack.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]x\f[R]
Pops a value off of the top of the stack.
.RS
.PP
If it is a number, it is pushed back onto the stack.
.PP
If it is a string, it is executed as a macro.
.PP
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is greater than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
For example, \f[B]0 1>a\f[R] will execute the contents of register
\f[B]a\f[R], and \f[B]1 0>a\f[R] will not.
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not greater than the second (less than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is less than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not less than the second (greater than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is equal to the second, then the contents of register
\f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not equal to the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]?\f[R]
Reads a line from the \f[B]stdin\f[R] and executes it.
This is to allow macros to request input from users.
.TP
\f[B]q\f[R]
During execution of a macro, this exits the execution of that macro and
the execution of the macro that executed it.
If there are no macros, or only one macro executing, dc(1) exits.
.TP
\f[B]Q\f[R]
Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack.
If the number of levels to pop is greater than the number of executing
macros, dc(1) exits.
.SS Status
.PP
These commands query status of the stack or its top value.
.TP
\f[B]Z\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, calculates the number of significant decimal digits
it has and pushes the result.
.PP
If it is a string, pushes the number of characters the string has.
.RE
.TP
\f[B]X\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, pushes the \f[I]scale\f[R] of the value onto the
stack.
.PP
If it is a string, pushes \f[B]0\f[R].
.RE
.TP
\f[B]z\f[R]
Pushes the current stack depth (before execution of this command).
.SS Arrays
.PP
These commands manipulate arrays.
.TP
\f[B]:\f[R]\f[I]r\f[R]
Pops the top two values off of the stack.
The second value will be stored in the array \f[I]r\f[R] (see the
\f[B]REGISTERS\f[R] section), indexed by the first value.
.TP
\f[B];\f[R]\f[I]r\f[R]
Pops the value on top of the stack and uses it as an index into the
array \f[I]r\f[R].
The selected value is then pushed onto the stack.
.SH REGISTERS
.PP
Registers are names that can store strings, numbers, and arrays.
(Number/string registers do not interfere with array registers.)
.PP
Each register is also its own stack, so the current register value is
the top of the stack for the register.
All registers, when first referenced, have one value (\f[B]0\f[R]) in
their stack.
.PP
In non-extended register mode, a register name is just the single
character that follows any command that needs a register name.
The only exception is a newline (\f[B]`\[rs]n'\f[R]); it is a parse
error for a newline to be used as a register name.
.SS Extended Register Mode
.PP
Unlike most other dc(1) implentations, this dc(1) provides nearly
unlimited amounts of registers, if extended register mode is enabled.
.PP
If extended register mode is enabled (\f[B]-x\f[R] or
\f[B]\[en]extended-register\f[R] command-line arguments are given), then
normal single character registers are used \f[I]unless\f[R] the
character immediately following a command that needs a register name is
a space (according to \f[B]isspace()\f[R]) and not a newline
(\f[B]`\[rs]n'\f[R]).
.PP
In that case, the register name is found according to the regex
\f[B][a-z][a-z0-9_]*\f[R] (like bc(1) identifiers), and it is a parse
error if the next non-space characters do not match that regex.
.SH RESET
.PP
When dc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any macros that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all macros returned) is skipped.
.PP
Thus, when dc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.SH PERFORMANCE
.PP
Most dc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This dc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]DC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]DC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]DC_BASE_DIGS\f[R].
.PP
In addition, this dc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]DC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on dc(1):
.TP
\f[B]DC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
dc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]DC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]DC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]DC_BASE_DIGS\f[R].
.TP
\f[B]DC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]DC_BASE_POW\f[R].
.TP
\f[B]DC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]DC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_RAND_MAX\f[R]
The maximum integer (inclusive) returned by the \f[B]\[cq]\f[R] command,
if dc(1).
Set at \f[B]2\[ha]DC_LONG_BIT-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]DC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
dc(1) recognizes the following environment variables:
.TP
\f[B]DC_ENV_ARGS\f[R]
This is another way to give command-line arguments to dc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]DC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs.
Another use would be to use the \f[B]-e\f[R] option to set
\f[B]scale\f[R] to a value other than \f[B]0\f[R].
.RS
.PP
The code that parses \f[B]DC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some dc file.dc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]dc\[dq] file.dc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
-in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
+in \f[B]\[rq]some `dc' file.dc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]DC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]DC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), dc(1) will output lines to that length,
including the backslash newline combo.
The default line length is \f[B]70\f[R].
.TP
\f[B]DC_EXPR_EXIT\f[R]
If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the
\f[B]-e\f[R] and/or \f[B]-f\f[R] command-line options (and any
equivalents).
.SH EXIT STATUS
.PP
dc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, using a negative number as a bound for the
pseudo-random number generator, attempting to convert a negative number
to a hardware integer, overflow when converting a number to a hardware
integer, and attempting to use a non-integer where an integer is
required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]), places (\f[B]\[at]\f[R]), left shift
(\f[B]H\f[R]), and right shift (\f[B]h\f[R]) operators.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, and using a
token where it is invalid.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, and attempting an operation when the
stack has too few elements.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (dc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, dc(1)
always exits and returns \f[B]4\f[R], no matter what mode dc(1) is in.
.PP
The other statuses will only be returned when dc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
dc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, dc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, dc(1) turns on \[lq]TTY mode.\[rq]
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause dc(1) to stop execution of the
current input.
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If dc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If dc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to dc(1) as it is
executing a file, it can seem as though dc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause dc(1) to clean up and
exit, and it uses the default handler for all other signals.
.SH SEE ALSO
.PP
bc(1)
.SH STANDARDS
.PP
The dc(1) utility operators are compliant with the operators in the
bc(1) IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHOR
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/dc/HNP.1.md b/contrib/bc/manuals/dc/HNP.1.md
index 78c37f2a177e..54d5957b6d93 100644
--- a/contrib/bc/manuals/dc/HNP.1.md
+++ b/contrib/bc/manuals/dc/HNP.1.md
@@ -1,1175 +1,1184 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# Name
dc - arbitrary-precision decimal reverse-Polish notation calculator
# SYNOPSIS
**dc** [**-hiPvVx**] [**--version**] [**--help**] [**--interactive**] [**--no-prompt**] [**--extended-register**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...] [*file*...]
# DESCRIPTION
dc(1) is an arbitrary-precision calculator. It uses a stack (reverse Polish
notation) to store numbers and results of computations. Arithmetic operations
pop arguments off of the stack and push the results.
If no files are given on the command-line as extra arguments (i.e., not as
**-f** or **--file** arguments), then dc(1) reads from **stdin**. Otherwise,
those files are processed, and dc(1) will then exit.
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where **-e** (**--expression**) and **-f** (**--file**)
arguments cause dc(1) to execute them and exit. The reason for this is that this
dc(1) allows users to set arguments in the environment variable **DC_ENV_ARGS**
(see the **ENVIRONMENT VARIABLES** section). Any expressions given on the
command-line should be used to set up a standard environment. For example, if a
user wants the **scale** always set to **10**, they can set **DC_ENV_ARGS** to
**-e 10k**, and this dc(1) will always start with a **scale** of **10**.
If users want to have dc(1) exit after processing all input from **-e** and
**-f** arguments (and their equivalents), then they can just simply add **-e q**
as the last command-line argument or define the environment variable
**DC_EXPR_EXIT**.
# OPTIONS
The following are the options that dc(1) accepts.
**-h**, **--help**
: Prints a usage message and quits.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-P**, **--no-prompt**
: This option is a no-op.
This is a **non-portable extension**.
**-x** **--extended-register**
: Enables extended register mode. See the *Extended Register Mode* subsection
of the **REGISTERS** section for more information.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **DC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **dc <file> >&-**, it will quit with an error. This
is done so that dc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **dc <file> 2>&-**, it will quit with an error. This
is done so that dc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
Each item in the input source code, either a number (see the **NUMBERS**
section) or a command (see the **COMMANDS** section), is processed and executed,
in order. Input is processed immediately when entered.
**ibase** is a register (see the **REGISTERS** section) that determines how to
interpret constant numbers. It is the "input" base, or the number base used for
interpreting input numbers. **ibase** is initially **10**. The max allowable
value for **ibase** is **16**. The min allowable value for **ibase** is **2**.
The max allowable value for **ibase** can be queried in dc(1) programs with the
**T** command.
**obase** is a register (see the **REGISTERS** section) that determines how to
output results. It is the "output" base, or the number base used for outputting
numbers. **obase** is initially **10**. The max allowable value for **obase** is
**DC_BASE_MAX** and can be queried with the **U** command. The min allowable
value for **obase** is **0**. If **obase** is **0**, values are output in
scientific notation, and if **obase** is **1**, values are output in engineering
notation. Otherwise, values are output in the specified base.
Outputting in scientific and engineering notations are **non-portable
extensions**.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a register (see the
**REGISTERS** section) that sets the precision of any operations (with
exceptions). **scale** is initially **0**. **scale** cannot be negative. The max
allowable value for **scale** can be queried in dc(1) programs with the **V**
command.
**seed** is a register containing the current seed for the pseudo-random number
generator. If the current value of **seed** is queried and stored, then if it is
assigned to **seed** later, the pseudo-random number generator is guaranteed to
produce the same sequence of pseudo-random numbers that were generated after the
value of **seed** was first queried.
Multiple values assigned to **seed** can produce the same sequence of
pseudo-random numbers. Likewise, when a value is assigned to **seed**, it is not
guaranteed that querying **seed** immediately after will return the same value.
In addition, the value of **seed** will change after any call to the **'**
command or the **"** command that does not get receive a value of **0** or
**1**. The maximum integer returned by the **'** command can be queried with the
**W** command.
**Note**: The values returned by the pseudo-random number generator with the
**'** and **"** commands are guaranteed to **NOT** be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator. However,
they *are* guaranteed to be reproducible with identical **seed** values. This
-means that the pseudo-random values from bc(1) should only be used where a
+means that the pseudo-random values from dc(1) should only be used where a
reproducible stream of pseudo-random numbers is *ESSENTIAL*. In any other case,
use a non-seeded pseudo-random number generator.
The pseudo-random number generator, **seed**, and all associated operations are
**non-portable extensions**.
## Comments
Comments go from **#** until, and not including, the next newline. This is a
**non-portable extension**.
# NUMBERS
Numbers are strings made up of digits, uppercase letters up to **F**, and at
most **1** period for a radix. Numbers can have up to **DC_NUM_MAX** digits.
Uppercase letters are equal to **9** + their position in the alphabet (i.e.,
**A** equals **10**, or **9+1**). If a digit or letter makes no sense with the
current value of **ibase**, they are set to the value of the highest valid digit
in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **F** alone always equals decimal
**15**.
In addition, dc(1) accepts numbers in scientific notation. These have the form
**\<number\>e\<integer\>**. The exponent (the portion after the **e**) must be
an integer. An example is **1.89237e9**, which is equal to **1892370000**.
Negative exponents are also allowed, so **4.2890e_3** is equal to **0.0042890**.
**WARNING**: Both the number and the exponent in scientific notation are
interpreted according to the current **ibase**, but the number is still
multiplied by **10\^exponent** regardless of the current **ibase**. For example,
if **ibase** is **16** and dc(1) is given the number string **FFeA**, the
resulting decimal number will be **2550000000000**, and if dc(1) is given the
number string **10e_4**, the resulting decimal number will be **0.0016**.
Accepting input as scientific notation is a **non-portable extension**.
# COMMANDS
The valid commands are listed below.
## Printing
These commands are used for printing.
Note that both scientific notation and engineering notation are available for
printing numbers. Scientific notation is activated by assigning **0** to
**obase** using **0o**, and engineering notation is activated by assigning **1**
to **obase** using **1o**. To deactivate them, just assign a different value to
**obase**.
Printing numbers in scientific notation and/or engineering notation is a
**non-portable extension**.
**p**
: Prints the value on top of the stack, whether number or string, and prints a
newline after.
This does not alter the stack.
**n**
: Prints the value on top of the stack, whether number or string, and pops it
off of the stack.
**P**
: Pops a value off the stack.
If the value is a number, it is truncated and the absolute value of the
result is printed as though **obase** is **UCHAR_MAX+1** and each digit is
interpreted as an ASCII character, making it a byte stream.
If the value is a string, it is printed without a trailing newline.
This is a **non-portable extension**.
**f**
: Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
Users should use this command when they get lost.
## Arithmetic
These are the commands used for arithmetic.
**+**
: The top two values are popped off the stack, added, and the result is pushed
onto the stack. The *scale* of the result is equal to the max *scale* of
both operands.
**-**
: The top two values are popped off the stack, subtracted, and the result is
pushed onto the stack. The *scale* of the result is equal to the max
*scale* of both operands.
**\***
: The top two values are popped off the stack, multiplied, and the result is
pushed onto the stack. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result
is equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The top two values are popped off the stack, divided, and the result is
pushed onto the stack. The *scale* of the result is equal to **scale**.
The first value popped off of the stack must be non-zero.
**%**
: The top two values are popped off the stack, remaindered, and the result is
pushed onto the stack.
Remaindering is equivalent to 1) Computing **a/b** to current **scale**, and
2) Using the result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The first value popped off of the stack must be non-zero.
**~**
: The top two values are popped off the stack, divided and remaindered, and
the results (divided first, remainder second) are pushed onto the stack.
This is equivalent to **x y / x y %** except that **x** and **y** are only
evaluated once.
The first value popped off of the stack must be non-zero.
This is a **non-portable extension**.
**\^**
: The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack. The *scale* of
the result is equal to **scale**.
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
**v**
: The top value is popped off the stack, its square root is computed, and the
result is pushed onto the stack. The *scale* of the result is equal to
**scale**.
The value popped off of the stack must be non-negative.
**\_**
: If this command *immediately* precedes a number (i.e., no spaces or other
commands), then that number is input as a negative number.
Otherwise, the top value on the stack is popped and copied, and the copy is
negated and pushed onto the stack. This behavior without a number is a
**non-portable extension**.
**b**
: The top value is popped off the stack, and if it is zero, it is pushed back
onto the stack. Otherwise, its absolute value is pushed onto the stack.
This is a **non-portable extension**.
**|**
: The top three values are popped off the stack, a modular exponentiation is
computed, and the result is pushed onto the stack.
The first value popped is used as the reduction modulus and must be an
integer and non-zero. The second value popped is used as the exponent and
must be an integer and non-negative. The third value popped is the base and
must be an integer.
This is a **non-portable extension**.
**\$**
: The top value is popped off the stack and copied, and the copy is truncated
and pushed onto the stack.
This is a **non-portable extension**.
**\@**
: The top two values are popped off the stack, and the precision of the second
is set to the value of the first, whether by truncation or extension.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**H**
: The top two values are popped off the stack, and the second is shifted left
(radix shifted right) to the value of the first.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**h**
: The top two values are popped off the stack, and the second is shifted right
(radix shifted left) to the value of the first.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**G**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if they are equal, or **0** otherwise.
This is a **non-portable extension**.
**N**
: The top value is popped off of the stack, and if it a **0**, a **1** is
pushed; otherwise, a **0** is pushed.
This is a **non-portable extension**.
**(**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than the second, or **0** otherwise.
This is a **non-portable extension**.
**{**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than or equal to the second, or **0**
otherwise.
This is a **non-portable extension**.
**)**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than the second, or **0** otherwise.
This is a **non-portable extension**.
**}**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than or equal to the second, or
**0** otherwise.
This is a **non-portable extension**.
**M**
: The top two values are popped off of the stack. If they are both non-zero, a
**1** is pushed onto the stack. If either of them is zero, or both of them
are, then a **0** is pushed onto the stack.
This is like the **&&** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
**m**
: The top two values are popped off of the stack. If at least one of them is
non-zero, a **1** is pushed onto the stack. If both of them are zero, then a
**0** is pushed onto the stack.
This is like the **||** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
## Pseudo-Random Number Generator
dc(1) has a built-in pseudo-random number generator. These commands query the
pseudo-random number generator. (See Parameters for more information about the
**seed** value that controls the pseudo-random number generator.)
The pseudo-random number generator is guaranteed to **NOT** be
cryptographically secure.
**'**
: Generates an integer between 0 and **DC_RAND_MAX**, inclusive (see the
**LIMITS** section).
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
This is a **non-portable extension**.
**"**
: Pops a value off of the stack, which is used as an **exclusive** upper bound
on the integer that will be generated. If the bound is negative or is a
non-integer, an error is raised, and dc(1) resets (see the **RESET**
section) while **seed** remains unchanged. If the bound is larger than
**DC_RAND_MAX**, the higher bound is honored by generating several
pseudo-random integers, multiplying them by appropriate powers of
**DC_RAND_MAX+1**, and adding them together. Thus, the size of integer that
can be generated with this command is unbounded. Using this command will
change the value of **seed**, unless the operand is **0** or **1**. In that
case, **0** is pushed onto the stack, and **seed** is *not* changed.
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
This is a **non-portable extension**.
## Stack Control
These commands control the stack.
**c**
: Removes all items from ("clears") the stack.
**d**
: Copies the item on top of the stack ("duplicates") and pushes the copy onto
the stack.
**r**
: Swaps ("reverses") the two top items on the stack.
**R**
: Pops ("removes") the top value from the stack.
## Register Control
These commands control registers (see the **REGISTERS** section).
**s***r*
: Pops the value off the top of the stack and stores it into register *r*.
**l***r*
: Copies the value in register *r* and pushes it onto the stack. This does not
alter the contents of *r*.
**S***r*
: Pops the value off the top of the (main) stack and pushes it onto the stack
of register *r*. The previous value of the register becomes inaccessible.
**L***r*
: Pops the value off the top of the stack for register *r* and push it onto
the main stack. The previous value in the stack for register *r*, if any, is
now accessible via the **l***r* command.
## Parameters
These commands control the values of **ibase**, **obase**, **scale**, and
**seed**. Also see the **SYNTAX** section.
**i**
: Pops the value off of the top of the stack and uses it to set **ibase**,
which must be between **2** and **16**, inclusive.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**o**
: Pops the value off of the top of the stack and uses it to set **obase**,
which must be between **0** and **DC_BASE_MAX**, inclusive (see the
**LIMITS** section and the **NUMBERS** section).
If the value on top of the stack has any *scale*, the *scale* is ignored.
**k**
: Pops the value off of the top of the stack and uses it to set **scale**,
which must be non-negative.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**j**
: Pops the value off of the top of the stack and uses it to set **seed**. The
meaning of **seed** is dependent on the current pseudo-random number
generator but is guaranteed to not change except for new major versions.
The *scale* and sign of the value may be significant.
If a previously used **seed** value is used again, the pseudo-random number
generator is guaranteed to produce the same sequence of pseudo-random
numbers as it did when the **seed** value was previously used.
The exact value assigned to **seed** is not guaranteed to be returned if the
**J** command is used. However, if **seed** *does* return a different value,
both values, when assigned to **seed**, are guaranteed to produce the same
sequence of pseudo-random numbers. This means that certain values assigned
to **seed** will not produce unique sequences of pseudo-random numbers.
There is no limit to the length (number of significant decimal digits) or
*scale* of the value that can be assigned to **seed**.
This is a **non-portable extension**.
**I**
: Pushes the current value of **ibase** onto the main stack.
**O**
: Pushes the current value of **obase** onto the main stack.
**K**
: Pushes the current value of **scale** onto the main stack.
**J**
: Pushes the current value of **seed** onto the main stack.
This is a **non-portable extension**.
**T**
: Pushes the maximum allowable value of **ibase** onto the main stack.
This is a **non-portable extension**.
**U**
: Pushes the maximum allowable value of **obase** onto the main stack.
This is a **non-portable extension**.
**V**
: Pushes the maximum allowable value of **scale** onto the main stack.
This is a **non-portable extension**.
**W**
: Pushes the maximum (inclusive) integer that can be generated with the **'**
pseudo-random number generator command.
This is a **non-portable extension**.
## Strings
The following commands control strings.
dc(1) can work with both numbers and strings, and registers (see the
**REGISTERS** section) can hold both strings and numbers. dc(1) always knows
whether the contents of a register are a string or a number.
While arithmetic operations have to have numbers, and will print an error if
given a string, other commands accept strings.
Strings can also be executed as macros. For example, if the string **[1pR]** is
executed as a macro, then the code **1pR** is executed, meaning that the **1**
will be printed with a newline after and then popped from the stack.
**\[**_characters_**\]**
: Makes a string containing *characters* and pushes it onto the stack.
If there are brackets (**\[** and **\]**) in the string, then they must be
balanced. Unbalanced brackets can be escaped using a backslash (**\\**)
character.
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the (first)
backslash is not.
**a**
: The value on top of the stack is popped.
If it is a number, it is truncated and its absolute value is taken. The
result mod **UCHAR_MAX+1** is calculated. If that result is **0**, push an
empty string; otherwise, push a one-character string where the character is
the result of the mod interpreted as an ASCII character.
If it is a string, then a new string is made. If the original string is
empty, the new string is empty. If it is not, then the first character of
the original string is used to create the new string as a one-character
string. The new string is then pushed onto the stack.
This is a **non-portable extension**.
**x**
: Pops a value off of the top of the stack.
If it is a number, it is pushed back onto the stack.
If it is a string, it is executed as a macro.
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
**\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is greater than the second, then the contents of register
*r* are executed.
For example, **0 1>a** will execute the contents of register **a**, and
**1 0>a** will not.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not greater than the second (less than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is less than the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not less than the second (greater than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is equal to the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not equal to the second, then the contents of register
*r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**?**
: Reads a line from the **stdin** and executes it. This is to allow macros to
request input from users.
**q**
: During execution of a macro, this exits the execution of that macro and the
execution of the macro that executed it. If there are no macros, or only one
macro executing, dc(1) exits.
**Q**
: Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack. If the number
of levels to pop is greater than the number of executing macros, dc(1)
exits.
## Status
These commands query status of the stack or its top value.
**Z**
: Pops a value off of the stack.
If it is a number, calculates the number of significant decimal digits it
has and pushes the result.
If it is a string, pushes the number of characters the string has.
**X**
: Pops a value off of the stack.
If it is a number, pushes the *scale* of the value onto the stack.
If it is a string, pushes **0**.
**z**
: Pushes the current stack depth (before execution of this command).
## Arrays
These commands manipulate arrays.
**:***r*
: Pops the top two values off of the stack. The second value will be stored in
the array *r* (see the **REGISTERS** section), indexed by the first value.
**;***r*
: Pops the value on top of the stack and uses it as an index into the array
*r*. The selected value is then pushed onto the stack.
# REGISTERS
Registers are names that can store strings, numbers, and arrays. (Number/string
registers do not interfere with array registers.)
Each register is also its own stack, so the current register value is the top of
the stack for the register. All registers, when first referenced, have one value
(**0**) in their stack.
In non-extended register mode, a register name is just the single character that
follows any command that needs a register name. The only exception is a newline
(**'\\n'**); it is a parse error for a newline to be used as a register name.
## Extended Register Mode
Unlike most other dc(1) implentations, this dc(1) provides nearly unlimited
amounts of registers, if extended register mode is enabled.
If extended register mode is enabled (**-x** or **--extended-register**
command-line arguments are given), then normal single character registers are
used *unless* the character immediately following a command that needs a
register name is a space (according to **isspace()**) and not a newline
(**'\\n'**).
In that case, the register name is found according to the regex
**\[a-z\]\[a-z0-9\_\]\*** (like bc(1) identifiers), and it is a parse error if
the next non-space characters do not match that regex.
# RESET
When dc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any macros that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
macros returned) is skipped.
Thus, when dc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
# PERFORMANCE
Most dc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This dc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **DC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **DC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**DC_BASE_DIGS**.
In addition, this dc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **DC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on dc(1):
**DC_LONG_BIT**
: The number of bits in the **long** type in the environment where dc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**DC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **DC_LONG_BIT**.
**DC_BASE_POW**
: The max decimal number that each large integer can store (see
**DC_BASE_DIGS**) plus **1**. Depends on **DC_BASE_DIGS**.
**DC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **DC_LONG_BIT**.
**DC_BASE_MAX**
: The maximum output base. Set at **DC_BASE_POW**.
**DC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**DC_SCALE_MAX**
: The maximum **scale**. Set at **DC_OVERFLOW_MAX-1**.
**DC_STRING_MAX**
: The maximum length of strings. Set at **DC_OVERFLOW_MAX-1**.
**DC_NAME_MAX**
: The maximum length of identifiers. Set at **DC_OVERFLOW_MAX-1**.
**DC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **DC_OVERFLOW_MAX-1**.
**DC_RAND_MAX**
: The maximum integer (inclusive) returned by the **'** command, if dc(1). Set
at **2\^DC_LONG_BIT-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**DC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
dc(1) recognizes the following environment variables:
**DC_ENV_ARGS**
: This is another way to give command-line arguments to dc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **DC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs. Another use would
be to use the **-e** option to set **scale** to a value other than **0**.
The code that parses **DC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some dc file.dc"** will be correctly parsed, but the string
**"/home/gavin/some \"dc\" file.dc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
- double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
+ double quotes as the outside quotes, as in **"some 'dc' file.dc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **DC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**DC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), dc(1) will output
lines to that length, including the backslash newline combo. The default
line length is **70**.
**DC_EXPR_EXIT**
: If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the **-e** and/or
**-f** command-line options (and any equivalents).
# EXIT STATUS
dc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, using a negative number as a bound for the pseudo-random number
generator, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**), places (**\@**), left shift (**H**), and right shift (**h**)
operators.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, and using a token where it is
invalid.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, and attempting an operation when
the stack has too few elements.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (dc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, dc(1) always exits
and returns **4**, no matter what mode dc(1) is in.
The other statuses will only be returned when dc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since dc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, dc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, dc(1) turns
on "TTY mode."
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause dc(1) to stop execution of the current input. If
dc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If dc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If dc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to dc(1) as it is executing a file, it
can seem as though dc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause dc(1) to clean up and exit, and it uses the
default handler for all other signals.
# SEE ALSO
bc(1)
# STANDARDS
The dc(1) utility operators are compliant with the operators in the bc(1)
[IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1] specification.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHOR
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
diff --git a/contrib/bc/manuals/dc/HP.1 b/contrib/bc/manuals/dc/HP.1
index 51d477f4a8e7..abbf1b24da1d 100644
--- a/contrib/bc/manuals/dc/HP.1
+++ b/contrib/bc/manuals/dc/HP.1
@@ -1,1316 +1,1329 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "DC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "DC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH Name
.PP
dc - arbitrary-precision decimal reverse-Polish notation calculator
.SH SYNOPSIS
.PP
\f[B]dc\f[R] [\f[B]-hiPvVx\f[R]] [\f[B]\[en]version\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]no-prompt\f[R]] [\f[B]\[en]extended-register\f[R]]
[\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
dc(1) is an arbitrary-precision calculator.
It uses a stack (reverse Polish notation) to store numbers and results
of computations.
Arithmetic operations pop arguments off of the stack and push the
results.
.PP
If no files are given on the command-line as extra arguments (i.e., not
as \f[B]-f\f[R] or \f[B]\[en]file\f[R] arguments), then dc(1) reads from
\f[B]stdin\f[R].
Otherwise, those files are processed, and dc(1) will then exit.
.PP
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where \f[B]-e\f[R] (\f[B]\[en]expression\f[R]) and
\f[B]-f\f[R] (\f[B]\[en]file\f[R]) arguments cause dc(1) to execute them
and exit.
The reason for this is that this dc(1) allows users to set arguments in
the environment variable \f[B]DC_ENV_ARGS\f[R] (see the \f[B]ENVIRONMENT
VARIABLES\f[R] section).
Any expressions given on the command-line should be used to set up a
standard environment.
For example, if a user wants the \f[B]scale\f[R] always set to
\f[B]10\f[R], they can set \f[B]DC_ENV_ARGS\f[R] to \f[B]-e 10k\f[R],
and this dc(1) will always start with a \f[B]scale\f[R] of \f[B]10\f[R].
.PP
If users want to have dc(1) exit after processing all input from
\f[B]-e\f[R] and \f[B]-f\f[R] arguments (and their equivalents), then
they can just simply add \f[B]-e q\f[R] as the last command-line
argument or define the environment variable \f[B]DC_EXPR_EXIT\f[R].
.SH OPTIONS
.PP
The following are the options that dc(1) accepts.
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
This option is a no-op.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-x\f[R] \f[B]\[en]extended-register\f[R]
Enables extended register mode.
See the \f[I]Extended Register Mode\f[R] subsection of the
\f[B]REGISTERS\f[R] section for more information.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]DC_ENV_ARGS\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]dc >&-\f[R], it will quit with an error.
This is done so that dc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]dc 2>&-\f[R], it will quit with an error.
This is done so that dc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
Each item in the input source code, either a number (see the
\f[B]NUMBERS\f[R] section) or a command (see the \f[B]COMMANDS\f[R]
section), is processed and executed, in order.
Input is processed immediately when entered.
.PP
\f[B]ibase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to interpret constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]ibase\f[R] is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in dc(1)
programs with the \f[B]T\f[R] command.
.PP
\f[B]obase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]DC_BASE_MAX\f[R] and
can be queried with the \f[B]U\f[R] command.
The min allowable value for \f[B]obase\f[R] is \f[B]0\f[R].
If \f[B]obase\f[R] is \f[B]0\f[R], values are output in scientific
notation, and if \f[B]obase\f[R] is \f[B]1\f[R], values are output in
engineering notation.
Otherwise, values are output in the specified base.
.PP
Outputting in scientific and engineering notations are \f[B]non-portable
extensions\f[R].
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a register (see the \f[B]REGISTERS\f[R] section) that sets the
precision of any operations (with exceptions).
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] can be queried in dc(1)
programs with the \f[B]V\f[R] command.
.PP
\f[B]seed\f[R] is a register containing the current seed for the
pseudo-random number generator.
If the current value of \f[B]seed\f[R] is queried and stored, then if it
is assigned to \f[B]seed\f[R] later, the pseudo-random number generator
is guaranteed to produce the same sequence of pseudo-random numbers that
were generated after the value of \f[B]seed\f[R] was first queried.
.PP
Multiple values assigned to \f[B]seed\f[R] can produce the same sequence
of pseudo-random numbers.
Likewise, when a value is assigned to \f[B]seed\f[R], it is not
guaranteed that querying \f[B]seed\f[R] immediately after will return
the same value.
In addition, the value of \f[B]seed\f[R] will change after any call to
the \f[B]\[cq]\f[R] command or the \f[B]\[dq]\f[R] command that does not
get receive a value of \f[B]0\f[R] or \f[B]1\f[R].
The maximum integer returned by the \f[B]\[cq]\f[R] command can be
queried with the \f[B]W\f[R] command.
.PP
\f[B]Note\f[R]: The values returned by the pseudo-random number
generator with the \f[B]\[cq]\f[R] and \f[B]\[dq]\f[R] commands are
guaranteed to \f[B]NOT\f[R] be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator.
However, they \f[I]are\f[R] guaranteed to be reproducible with identical
\f[B]seed\f[R] values.
-This means that the pseudo-random values from bc(1) should only be used
+This means that the pseudo-random values from dc(1) should only be used
where a reproducible stream of pseudo-random numbers is
\f[I]ESSENTIAL\f[R].
In any other case, use a non-seeded pseudo-random number generator.
.PP
The pseudo-random number generator, \f[B]seed\f[R], and all associated
operations are \f[B]non-portable extensions\f[R].
.SS Comments
.PP
Comments go from \f[B]#\f[R] until, and not including, the next newline.
This is a \f[B]non-portable extension\f[R].
.SH NUMBERS
.PP
Numbers are strings made up of digits, uppercase letters up to
\f[B]F\f[R], and at most \f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]DC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]F\f[R] alone always equals decimal \f[B]15\f[R].
.PP
In addition, dc(1) accepts numbers in scientific notation.
These have the form \f[B]<number>e<integer>\f[R].
The exponent (the portion after the \f[B]e\f[R]) must be an integer.
An example is \f[B]1.89237e9\f[R], which is equal to
\f[B]1892370000\f[R].
Negative exponents are also allowed, so \f[B]4.2890e_3\f[R] is equal to
\f[B]0.0042890\f[R].
.PP
\f[B]WARNING\f[R]: Both the number and the exponent in scientific
notation are interpreted according to the current \f[B]ibase\f[R], but
the number is still multiplied by \f[B]10\[ha]exponent\f[R] regardless
of the current \f[B]ibase\f[R].
For example, if \f[B]ibase\f[R] is \f[B]16\f[R] and dc(1) is given the
number string \f[B]FFeA\f[R], the resulting decimal number will be
\f[B]2550000000000\f[R], and if dc(1) is given the number string
\f[B]10e_4\f[R], the resulting decimal number will be \f[B]0.0016\f[R].
.PP
Accepting input as scientific notation is a \f[B]non-portable
extension\f[R].
.SH COMMANDS
.PP
The valid commands are listed below.
.SS Printing
.PP
These commands are used for printing.
.PP
Note that both scientific notation and engineering notation are
available for printing numbers.
Scientific notation is activated by assigning \f[B]0\f[R] to
\f[B]obase\f[R] using \f[B]0o\f[R], and engineering notation is
activated by assigning \f[B]1\f[R] to \f[B]obase\f[R] using
\f[B]1o\f[R].
To deactivate them, just assign a different value to \f[B]obase\f[R].
.PP
Printing numbers in scientific notation and/or engineering notation is a
\f[B]non-portable extension\f[R].
.TP
\f[B]p\f[R]
Prints the value on top of the stack, whether number or string, and
prints a newline after.
.RS
.PP
This does not alter the stack.
.RE
.TP
\f[B]n\f[R]
Prints the value on top of the stack, whether number or string, and pops
it off of the stack.
.TP
\f[B]P\f[R]
Pops a value off the stack.
.RS
.PP
If the value is a number, it is truncated and the absolute value of the
result is printed as though \f[B]obase\f[R] is \f[B]UCHAR_MAX+1\f[R] and
each digit is interpreted as an ASCII character, making it a byte
stream.
.PP
If the value is a string, it is printed without a trailing newline.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]f\f[R]
Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
.RS
.PP
Users should use this command when they get lost.
.RE
.SS Arithmetic
.PP
These are the commands used for arithmetic.
.TP
\f[B]+\f[R]
The top two values are popped off the stack, added, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]-\f[R]
The top two values are popped off the stack, subtracted, and the result
is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]*\f[R]
The top two values are popped off the stack, multiplied, and the result
is pushed onto the stack.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The top two values are popped off the stack, divided, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]%\f[R]
The top two values are popped off the stack, remaindered, and the result
is pushed onto the stack.
.RS
.PP
Remaindering is equivalent to 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R], and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]\[ti]\f[R]
The top two values are popped off the stack, divided and remaindered,
and the results (divided first, remainder second) are pushed onto the
stack.
This is equivalent to \f[B]x y / x y %\f[R] except that \f[B]x\f[R] and
\f[B]y\f[R] are only evaluated once.
.RS
.PP
The first value popped off of the stack must be non-zero.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
.RE
.TP
\f[B]v\f[R]
The top value is popped off the stack, its square root is computed, and
the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The value popped off of the stack must be non-negative.
.RE
.TP
\f[B]_\f[R]
If this command \f[I]immediately\f[R] precedes a number (i.e., no spaces
or other commands), then that number is input as a negative number.
.RS
.PP
Otherwise, the top value on the stack is popped and copied, and the copy
is negated and pushed onto the stack.
This behavior without a number is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]b\f[R]
The top value is popped off the stack, and if it is zero, it is pushed
back onto the stack.
Otherwise, its absolute value is pushed onto the stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]|\f[R]
The top three values are popped off the stack, a modular exponentiation
is computed, and the result is pushed onto the stack.
.RS
.PP
The first value popped is used as the reduction modulus and must be an
integer and non-zero.
The second value popped is used as the exponent and must be an integer
and non-negative.
The third value popped is the base and must be an integer.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]$\f[R]
The top value is popped off the stack and copied, and the copy is
truncated and pushed onto the stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[at]\f[R]
The top two values are popped off the stack, and the precision of the
second is set to the value of the first, whether by truncation or
extension.
.RS
.PP
The first value popped off of the stack must be an integer and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]H\f[R]
The top two values are popped off the stack, and the second is shifted
left (radix shifted right) to the value of the first.
.RS
.PP
The first value popped off of the stack must be an integer and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]h\f[R]
The top two values are popped off the stack, and the second is shifted
right (radix shifted left) to the value of the first.
.RS
.PP
The first value popped off of the stack must be an integer and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]G\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if they are equal, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]N\f[R]
The top value is popped off of the stack, and if it a \f[B]0\f[R], a
\f[B]1\f[R] is pushed; otherwise, a \f[B]0\f[R] is pushed.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B](\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]{\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than or equal to the second,
or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B])\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]}\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than or equal to the
second, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]M\f[R]
The top two values are popped off of the stack.
If they are both non-zero, a \f[B]1\f[R] is pushed onto the stack.
If either of them is zero, or both of them are, then a \f[B]0\f[R] is
pushed onto the stack.
.RS
.PP
This is like the \f[B]&&\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]m\f[R]
The top two values are popped off of the stack.
If at least one of them is non-zero, a \f[B]1\f[R] is pushed onto the
stack.
If both of them are zero, then a \f[B]0\f[R] is pushed onto the stack.
.RS
.PP
This is like the \f[B]||\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Pseudo-Random Number Generator
.PP
dc(1) has a built-in pseudo-random number generator.
These commands query the pseudo-random number generator.
(See Parameters for more information about the \f[B]seed\f[R] value that
controls the pseudo-random number generator.)
.PP
The pseudo-random number generator is guaranteed to \f[B]NOT\f[R] be
cryptographically secure.
.TP
\f[B]\[cq]\f[R]
Generates an integer between 0 and \f[B]DC_RAND_MAX\f[R], inclusive (see
the \f[B]LIMITS\f[R] section).
.RS
.PP
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[dq]\f[R]
Pops a value off of the stack, which is used as an \f[B]exclusive\f[R]
upper bound on the integer that will be generated.
If the bound is negative or is a non-integer, an error is raised, and
dc(1) resets (see the \f[B]RESET\f[R] section) while \f[B]seed\f[R]
remains unchanged.
If the bound is larger than \f[B]DC_RAND_MAX\f[R], the higher bound is
honored by generating several pseudo-random integers, multiplying them
by appropriate powers of \f[B]DC_RAND_MAX+1\f[R], and adding them
together.
Thus, the size of integer that can be generated with this command is
unbounded.
Using this command will change the value of \f[B]seed\f[R], unless the
operand is \f[B]0\f[R] or \f[B]1\f[R].
In that case, \f[B]0\f[R] is pushed onto the stack, and \f[B]seed\f[R]
is \f[I]not\f[R] changed.
.RS
.PP
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Stack Control
.PP
These commands control the stack.
.TP
\f[B]c\f[R]
Removes all items from (\[lq]clears\[rq]) the stack.
.TP
\f[B]d\f[R]
Copies the item on top of the stack (\[lq]duplicates\[rq]) and pushes
the copy onto the stack.
.TP
\f[B]r\f[R]
Swaps (\[lq]reverses\[rq]) the two top items on the stack.
.TP
\f[B]R\f[R]
Pops (\[lq]removes\[rq]) the top value from the stack.
.SS Register Control
.PP
These commands control registers (see the \f[B]REGISTERS\f[R] section).
.TP
\f[B]s\f[R]\f[I]r\f[R]
Pops the value off the top of the stack and stores it into register
\f[I]r\f[R].
.TP
\f[B]l\f[R]\f[I]r\f[R]
Copies the value in register \f[I]r\f[R] and pushes it onto the stack.
This does not alter the contents of \f[I]r\f[R].
.TP
\f[B]S\f[R]\f[I]r\f[R]
Pops the value off the top of the (main) stack and pushes it onto the
stack of register \f[I]r\f[R].
The previous value of the register becomes inaccessible.
.TP
\f[B]L\f[R]\f[I]r\f[R]
Pops the value off the top of the stack for register \f[I]r\f[R] and
push it onto the main stack.
The previous value in the stack for register \f[I]r\f[R], if any, is now
accessible via the \f[B]l\f[R]\f[I]r\f[R] command.
.SS Parameters
.PP
These commands control the values of \f[B]ibase\f[R], \f[B]obase\f[R],
\f[B]scale\f[R], and \f[B]seed\f[R].
Also see the \f[B]SYNTAX\f[R] section.
.TP
\f[B]i\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]ibase\f[R], which must be between \f[B]2\f[R] and \f[B]16\f[R],
inclusive.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]o\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]obase\f[R], which must be between \f[B]0\f[R] and
\f[B]DC_BASE_MAX\f[R], inclusive (see the \f[B]LIMITS\f[R] section and
the \f[B]NUMBERS\f[R] section).
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]k\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]scale\f[R], which must be non-negative.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]j\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]seed\f[R].
The meaning of \f[B]seed\f[R] is dependent on the current pseudo-random
number generator but is guaranteed to not change except for new major
versions.
.RS
.PP
The \f[I]scale\f[R] and sign of the value may be significant.
.PP
If a previously used \f[B]seed\f[R] value is used again, the
pseudo-random number generator is guaranteed to produce the same
sequence of pseudo-random numbers as it did when the \f[B]seed\f[R]
value was previously used.
.PP
The exact value assigned to \f[B]seed\f[R] is not guaranteed to be
returned if the \f[B]J\f[R] command is used.
However, if \f[B]seed\f[R] \f[I]does\f[R] return a different value, both
values, when assigned to \f[B]seed\f[R], are guaranteed to produce the
same sequence of pseudo-random numbers.
This means that certain values assigned to \f[B]seed\f[R] will not
produce unique sequences of pseudo-random numbers.
.PP
There is no limit to the length (number of significant decimal digits)
or \f[I]scale\f[R] of the value that can be assigned to \f[B]seed\f[R].
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]I\f[R]
Pushes the current value of \f[B]ibase\f[R] onto the main stack.
.TP
\f[B]O\f[R]
Pushes the current value of \f[B]obase\f[R] onto the main stack.
.TP
\f[B]K\f[R]
Pushes the current value of \f[B]scale\f[R] onto the main stack.
.TP
\f[B]J\f[R]
Pushes the current value of \f[B]seed\f[R] onto the main stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]T\f[R]
Pushes the maximum allowable value of \f[B]ibase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]U\f[R]
Pushes the maximum allowable value of \f[B]obase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]V\f[R]
Pushes the maximum allowable value of \f[B]scale\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]W\f[R]
Pushes the maximum (inclusive) integer that can be generated with the
\f[B]\[cq]\f[R] pseudo-random number generator command.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Strings
.PP
The following commands control strings.
.PP
dc(1) can work with both numbers and strings, and registers (see the
\f[B]REGISTERS\f[R] section) can hold both strings and numbers.
dc(1) always knows whether the contents of a register are a string or a
number.
.PP
While arithmetic operations have to have numbers, and will print an
error if given a string, other commands accept strings.
.PP
Strings can also be executed as macros.
For example, if the string \f[B][1pR]\f[R] is executed as a macro, then
the code \f[B]1pR\f[R] is executed, meaning that the \f[B]1\f[R] will be
printed with a newline after and then popped from the stack.
.TP
\f[B][\f[R]_characters_\f[B]]\f[R]
Makes a string containing \f[I]characters\f[R] and pushes it onto the
stack.
.RS
.PP
If there are brackets (\f[B][\f[R] and \f[B]]\f[R]) in the string, then
they must be balanced.
Unbalanced brackets can be escaped using a backslash (\f[B]\[rs]\f[R])
character.
.PP
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the
(first) backslash is not.
.RE
.TP
\f[B]a\f[R]
The value on top of the stack is popped.
.RS
.PP
If it is a number, it is truncated and its absolute value is taken.
The result mod \f[B]UCHAR_MAX+1\f[R] is calculated.
If that result is \f[B]0\f[R], push an empty string; otherwise, push a
one-character string where the character is the result of the mod
interpreted as an ASCII character.
.PP
If it is a string, then a new string is made.
If the original string is empty, the new string is empty.
If it is not, then the first character of the original string is used to
create the new string as a one-character string.
The new string is then pushed onto the stack.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]x\f[R]
Pops a value off of the top of the stack.
.RS
.PP
If it is a number, it is pushed back onto the stack.
.PP
If it is a string, it is executed as a macro.
.PP
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is greater than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
For example, \f[B]0 1>a\f[R] will execute the contents of register
\f[B]a\f[R], and \f[B]1 0>a\f[R] will not.
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not greater than the second (less than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is less than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not less than the second (greater than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is equal to the second, then the contents of register
\f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not equal to the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]?\f[R]
Reads a line from the \f[B]stdin\f[R] and executes it.
This is to allow macros to request input from users.
.TP
\f[B]q\f[R]
During execution of a macro, this exits the execution of that macro and
the execution of the macro that executed it.
If there are no macros, or only one macro executing, dc(1) exits.
.TP
\f[B]Q\f[R]
Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack.
If the number of levels to pop is greater than the number of executing
macros, dc(1) exits.
.SS Status
.PP
These commands query status of the stack or its top value.
.TP
\f[B]Z\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, calculates the number of significant decimal digits
it has and pushes the result.
.PP
If it is a string, pushes the number of characters the string has.
.RE
.TP
\f[B]X\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, pushes the \f[I]scale\f[R] of the value onto the
stack.
.PP
If it is a string, pushes \f[B]0\f[R].
.RE
.TP
\f[B]z\f[R]
Pushes the current stack depth (before execution of this command).
.SS Arrays
.PP
These commands manipulate arrays.
.TP
\f[B]:\f[R]\f[I]r\f[R]
Pops the top two values off of the stack.
The second value will be stored in the array \f[I]r\f[R] (see the
\f[B]REGISTERS\f[R] section), indexed by the first value.
.TP
\f[B];\f[R]\f[I]r\f[R]
Pops the value on top of the stack and uses it as an index into the
array \f[I]r\f[R].
The selected value is then pushed onto the stack.
.SH REGISTERS
.PP
Registers are names that can store strings, numbers, and arrays.
(Number/string registers do not interfere with array registers.)
.PP
Each register is also its own stack, so the current register value is
the top of the stack for the register.
All registers, when first referenced, have one value (\f[B]0\f[R]) in
their stack.
.PP
In non-extended register mode, a register name is just the single
character that follows any command that needs a register name.
The only exception is a newline (\f[B]`\[rs]n'\f[R]); it is a parse
error for a newline to be used as a register name.
.SS Extended Register Mode
.PP
Unlike most other dc(1) implentations, this dc(1) provides nearly
unlimited amounts of registers, if extended register mode is enabled.
.PP
If extended register mode is enabled (\f[B]-x\f[R] or
\f[B]\[en]extended-register\f[R] command-line arguments are given), then
normal single character registers are used \f[I]unless\f[R] the
character immediately following a command that needs a register name is
a space (according to \f[B]isspace()\f[R]) and not a newline
(\f[B]`\[rs]n'\f[R]).
.PP
In that case, the register name is found according to the regex
\f[B][a-z][a-z0-9_]*\f[R] (like bc(1) identifiers), and it is a parse
error if the next non-space characters do not match that regex.
.SH RESET
.PP
When dc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any macros that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all macros returned) is skipped.
.PP
Thus, when dc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.SH PERFORMANCE
.PP
Most dc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This dc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]DC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]DC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]DC_BASE_DIGS\f[R].
.PP
In addition, this dc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]DC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on dc(1):
.TP
\f[B]DC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
dc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]DC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]DC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]DC_BASE_DIGS\f[R].
.TP
\f[B]DC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]DC_BASE_POW\f[R].
.TP
\f[B]DC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]DC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_RAND_MAX\f[R]
The maximum integer (inclusive) returned by the \f[B]\[cq]\f[R] command,
if dc(1).
Set at \f[B]2\[ha]DC_LONG_BIT-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]DC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
dc(1) recognizes the following environment variables:
.TP
\f[B]DC_ENV_ARGS\f[R]
This is another way to give command-line arguments to dc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]DC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs.
Another use would be to use the \f[B]-e\f[R] option to set
\f[B]scale\f[R] to a value other than \f[B]0\f[R].
.RS
.PP
The code that parses \f[B]DC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some dc file.dc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]dc\[dq] file.dc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
-in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
+in \f[B]\[rq]some `dc' file.dc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]DC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]DC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), dc(1) will output lines to that length,
including the backslash newline combo.
The default line length is \f[B]70\f[R].
.TP
\f[B]DC_EXPR_EXIT\f[R]
If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the
\f[B]-e\f[R] and/or \f[B]-f\f[R] command-line options (and any
equivalents).
.SH EXIT STATUS
.PP
dc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, using a negative number as a bound for the
pseudo-random number generator, attempting to convert a negative number
to a hardware integer, overflow when converting a number to a hardware
integer, and attempting to use a non-integer where an integer is
required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]), places (\f[B]\[at]\f[R]), left shift
(\f[B]H\f[R]), and right shift (\f[B]h\f[R]) operators.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, and using a
token where it is invalid.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, and attempting an operation when the
stack has too few elements.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (dc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, dc(1)
always exits and returns \f[B]4\f[R], no matter what mode dc(1) is in.
.PP
The other statuses will only be returned when dc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
dc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, dc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, dc(1) turns on \[lq]TTY mode.\[rq]
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause dc(1) to stop execution of the
current input.
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If dc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If dc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to dc(1) as it is
executing a file, it can seem as though dc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause dc(1) to clean up and
exit, and it uses the default handler for all other signals.
.SH LOCALES
.PP
This dc(1) ships with support for adding error messages for different
locales and thus, supports \f[B]LC_MESSAGS\f[R].
.SH SEE ALSO
.PP
bc(1)
.SH STANDARDS
.PP
The dc(1) utility operators are compliant with the operators in the
bc(1) IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHOR
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/dc/HP.1.md b/contrib/bc/manuals/dc/HP.1.md
index d9865db53bdf..25e690f6f0e5 100644
--- a/contrib/bc/manuals/dc/HP.1.md
+++ b/contrib/bc/manuals/dc/HP.1.md
@@ -1,1180 +1,1189 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# Name
dc - arbitrary-precision decimal reverse-Polish notation calculator
# SYNOPSIS
**dc** [**-hiPvVx**] [**--version**] [**--help**] [**--interactive**] [**--no-prompt**] [**--extended-register**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...] [*file*...]
# DESCRIPTION
dc(1) is an arbitrary-precision calculator. It uses a stack (reverse Polish
notation) to store numbers and results of computations. Arithmetic operations
pop arguments off of the stack and push the results.
If no files are given on the command-line as extra arguments (i.e., not as
**-f** or **--file** arguments), then dc(1) reads from **stdin**. Otherwise,
those files are processed, and dc(1) will then exit.
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where **-e** (**--expression**) and **-f** (**--file**)
arguments cause dc(1) to execute them and exit. The reason for this is that this
dc(1) allows users to set arguments in the environment variable **DC_ENV_ARGS**
(see the **ENVIRONMENT VARIABLES** section). Any expressions given on the
command-line should be used to set up a standard environment. For example, if a
user wants the **scale** always set to **10**, they can set **DC_ENV_ARGS** to
**-e 10k**, and this dc(1) will always start with a **scale** of **10**.
If users want to have dc(1) exit after processing all input from **-e** and
**-f** arguments (and their equivalents), then they can just simply add **-e q**
as the last command-line argument or define the environment variable
**DC_EXPR_EXIT**.
# OPTIONS
The following are the options that dc(1) accepts.
**-h**, **--help**
: Prints a usage message and quits.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-P**, **--no-prompt**
: This option is a no-op.
This is a **non-portable extension**.
**-x** **--extended-register**
: Enables extended register mode. See the *Extended Register Mode* subsection
of the **REGISTERS** section for more information.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **DC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **dc <file> >&-**, it will quit with an error. This
is done so that dc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **dc <file> 2>&-**, it will quit with an error. This
is done so that dc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
Each item in the input source code, either a number (see the **NUMBERS**
section) or a command (see the **COMMANDS** section), is processed and executed,
in order. Input is processed immediately when entered.
**ibase** is a register (see the **REGISTERS** section) that determines how to
interpret constant numbers. It is the "input" base, or the number base used for
interpreting input numbers. **ibase** is initially **10**. The max allowable
value for **ibase** is **16**. The min allowable value for **ibase** is **2**.
The max allowable value for **ibase** can be queried in dc(1) programs with the
**T** command.
**obase** is a register (see the **REGISTERS** section) that determines how to
output results. It is the "output" base, or the number base used for outputting
numbers. **obase** is initially **10**. The max allowable value for **obase** is
**DC_BASE_MAX** and can be queried with the **U** command. The min allowable
value for **obase** is **0**. If **obase** is **0**, values are output in
scientific notation, and if **obase** is **1**, values are output in engineering
notation. Otherwise, values are output in the specified base.
Outputting in scientific and engineering notations are **non-portable
extensions**.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a register (see the
**REGISTERS** section) that sets the precision of any operations (with
exceptions). **scale** is initially **0**. **scale** cannot be negative. The max
allowable value for **scale** can be queried in dc(1) programs with the **V**
command.
**seed** is a register containing the current seed for the pseudo-random number
generator. If the current value of **seed** is queried and stored, then if it is
assigned to **seed** later, the pseudo-random number generator is guaranteed to
produce the same sequence of pseudo-random numbers that were generated after the
value of **seed** was first queried.
Multiple values assigned to **seed** can produce the same sequence of
pseudo-random numbers. Likewise, when a value is assigned to **seed**, it is not
guaranteed that querying **seed** immediately after will return the same value.
In addition, the value of **seed** will change after any call to the **'**
command or the **"** command that does not get receive a value of **0** or
**1**. The maximum integer returned by the **'** command can be queried with the
**W** command.
**Note**: The values returned by the pseudo-random number generator with the
**'** and **"** commands are guaranteed to **NOT** be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator. However,
they *are* guaranteed to be reproducible with identical **seed** values. This
-means that the pseudo-random values from bc(1) should only be used where a
+means that the pseudo-random values from dc(1) should only be used where a
reproducible stream of pseudo-random numbers is *ESSENTIAL*. In any other case,
use a non-seeded pseudo-random number generator.
The pseudo-random number generator, **seed**, and all associated operations are
**non-portable extensions**.
## Comments
Comments go from **#** until, and not including, the next newline. This is a
**non-portable extension**.
# NUMBERS
Numbers are strings made up of digits, uppercase letters up to **F**, and at
most **1** period for a radix. Numbers can have up to **DC_NUM_MAX** digits.
Uppercase letters are equal to **9** + their position in the alphabet (i.e.,
**A** equals **10**, or **9+1**). If a digit or letter makes no sense with the
current value of **ibase**, they are set to the value of the highest valid digit
in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **F** alone always equals decimal
**15**.
In addition, dc(1) accepts numbers in scientific notation. These have the form
**\<number\>e\<integer\>**. The exponent (the portion after the **e**) must be
an integer. An example is **1.89237e9**, which is equal to **1892370000**.
Negative exponents are also allowed, so **4.2890e_3** is equal to **0.0042890**.
**WARNING**: Both the number and the exponent in scientific notation are
interpreted according to the current **ibase**, but the number is still
multiplied by **10\^exponent** regardless of the current **ibase**. For example,
if **ibase** is **16** and dc(1) is given the number string **FFeA**, the
resulting decimal number will be **2550000000000**, and if dc(1) is given the
number string **10e_4**, the resulting decimal number will be **0.0016**.
Accepting input as scientific notation is a **non-portable extension**.
# COMMANDS
The valid commands are listed below.
## Printing
These commands are used for printing.
Note that both scientific notation and engineering notation are available for
printing numbers. Scientific notation is activated by assigning **0** to
**obase** using **0o**, and engineering notation is activated by assigning **1**
to **obase** using **1o**. To deactivate them, just assign a different value to
**obase**.
Printing numbers in scientific notation and/or engineering notation is a
**non-portable extension**.
**p**
: Prints the value on top of the stack, whether number or string, and prints a
newline after.
This does not alter the stack.
**n**
: Prints the value on top of the stack, whether number or string, and pops it
off of the stack.
**P**
: Pops a value off the stack.
If the value is a number, it is truncated and the absolute value of the
result is printed as though **obase** is **UCHAR_MAX+1** and each digit is
interpreted as an ASCII character, making it a byte stream.
If the value is a string, it is printed without a trailing newline.
This is a **non-portable extension**.
**f**
: Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
Users should use this command when they get lost.
## Arithmetic
These are the commands used for arithmetic.
**+**
: The top two values are popped off the stack, added, and the result is pushed
onto the stack. The *scale* of the result is equal to the max *scale* of
both operands.
**-**
: The top two values are popped off the stack, subtracted, and the result is
pushed onto the stack. The *scale* of the result is equal to the max
*scale* of both operands.
**\***
: The top two values are popped off the stack, multiplied, and the result is
pushed onto the stack. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result
is equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The top two values are popped off the stack, divided, and the result is
pushed onto the stack. The *scale* of the result is equal to **scale**.
The first value popped off of the stack must be non-zero.
**%**
: The top two values are popped off the stack, remaindered, and the result is
pushed onto the stack.
Remaindering is equivalent to 1) Computing **a/b** to current **scale**, and
2) Using the result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The first value popped off of the stack must be non-zero.
**~**
: The top two values are popped off the stack, divided and remaindered, and
the results (divided first, remainder second) are pushed onto the stack.
This is equivalent to **x y / x y %** except that **x** and **y** are only
evaluated once.
The first value popped off of the stack must be non-zero.
This is a **non-portable extension**.
**\^**
: The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack. The *scale* of
the result is equal to **scale**.
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
**v**
: The top value is popped off the stack, its square root is computed, and the
result is pushed onto the stack. The *scale* of the result is equal to
**scale**.
The value popped off of the stack must be non-negative.
**\_**
: If this command *immediately* precedes a number (i.e., no spaces or other
commands), then that number is input as a negative number.
Otherwise, the top value on the stack is popped and copied, and the copy is
negated and pushed onto the stack. This behavior without a number is a
**non-portable extension**.
**b**
: The top value is popped off the stack, and if it is zero, it is pushed back
onto the stack. Otherwise, its absolute value is pushed onto the stack.
This is a **non-portable extension**.
**|**
: The top three values are popped off the stack, a modular exponentiation is
computed, and the result is pushed onto the stack.
The first value popped is used as the reduction modulus and must be an
integer and non-zero. The second value popped is used as the exponent and
must be an integer and non-negative. The third value popped is the base and
must be an integer.
This is a **non-portable extension**.
**\$**
: The top value is popped off the stack and copied, and the copy is truncated
and pushed onto the stack.
This is a **non-portable extension**.
**\@**
: The top two values are popped off the stack, and the precision of the second
is set to the value of the first, whether by truncation or extension.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**H**
: The top two values are popped off the stack, and the second is shifted left
(radix shifted right) to the value of the first.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**h**
: The top two values are popped off the stack, and the second is shifted right
(radix shifted left) to the value of the first.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**G**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if they are equal, or **0** otherwise.
This is a **non-portable extension**.
**N**
: The top value is popped off of the stack, and if it a **0**, a **1** is
pushed; otherwise, a **0** is pushed.
This is a **non-portable extension**.
**(**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than the second, or **0** otherwise.
This is a **non-portable extension**.
**{**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than or equal to the second, or **0**
otherwise.
This is a **non-portable extension**.
**)**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than the second, or **0** otherwise.
This is a **non-portable extension**.
**}**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than or equal to the second, or
**0** otherwise.
This is a **non-portable extension**.
**M**
: The top two values are popped off of the stack. If they are both non-zero, a
**1** is pushed onto the stack. If either of them is zero, or both of them
are, then a **0** is pushed onto the stack.
This is like the **&&** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
**m**
: The top two values are popped off of the stack. If at least one of them is
non-zero, a **1** is pushed onto the stack. If both of them are zero, then a
**0** is pushed onto the stack.
This is like the **||** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
## Pseudo-Random Number Generator
dc(1) has a built-in pseudo-random number generator. These commands query the
pseudo-random number generator. (See Parameters for more information about the
**seed** value that controls the pseudo-random number generator.)
The pseudo-random number generator is guaranteed to **NOT** be
cryptographically secure.
**'**
: Generates an integer between 0 and **DC_RAND_MAX**, inclusive (see the
**LIMITS** section).
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
This is a **non-portable extension**.
**"**
: Pops a value off of the stack, which is used as an **exclusive** upper bound
on the integer that will be generated. If the bound is negative or is a
non-integer, an error is raised, and dc(1) resets (see the **RESET**
section) while **seed** remains unchanged. If the bound is larger than
**DC_RAND_MAX**, the higher bound is honored by generating several
pseudo-random integers, multiplying them by appropriate powers of
**DC_RAND_MAX+1**, and adding them together. Thus, the size of integer that
can be generated with this command is unbounded. Using this command will
change the value of **seed**, unless the operand is **0** or **1**. In that
case, **0** is pushed onto the stack, and **seed** is *not* changed.
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
This is a **non-portable extension**.
## Stack Control
These commands control the stack.
**c**
: Removes all items from ("clears") the stack.
**d**
: Copies the item on top of the stack ("duplicates") and pushes the copy onto
the stack.
**r**
: Swaps ("reverses") the two top items on the stack.
**R**
: Pops ("removes") the top value from the stack.
## Register Control
These commands control registers (see the **REGISTERS** section).
**s***r*
: Pops the value off the top of the stack and stores it into register *r*.
**l***r*
: Copies the value in register *r* and pushes it onto the stack. This does not
alter the contents of *r*.
**S***r*
: Pops the value off the top of the (main) stack and pushes it onto the stack
of register *r*. The previous value of the register becomes inaccessible.
**L***r*
: Pops the value off the top of the stack for register *r* and push it onto
the main stack. The previous value in the stack for register *r*, if any, is
now accessible via the **l***r* command.
## Parameters
These commands control the values of **ibase**, **obase**, **scale**, and
**seed**. Also see the **SYNTAX** section.
**i**
: Pops the value off of the top of the stack and uses it to set **ibase**,
which must be between **2** and **16**, inclusive.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**o**
: Pops the value off of the top of the stack and uses it to set **obase**,
which must be between **0** and **DC_BASE_MAX**, inclusive (see the
**LIMITS** section and the **NUMBERS** section).
If the value on top of the stack has any *scale*, the *scale* is ignored.
**k**
: Pops the value off of the top of the stack and uses it to set **scale**,
which must be non-negative.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**j**
: Pops the value off of the top of the stack and uses it to set **seed**. The
meaning of **seed** is dependent on the current pseudo-random number
generator but is guaranteed to not change except for new major versions.
The *scale* and sign of the value may be significant.
If a previously used **seed** value is used again, the pseudo-random number
generator is guaranteed to produce the same sequence of pseudo-random
numbers as it did when the **seed** value was previously used.
The exact value assigned to **seed** is not guaranteed to be returned if the
**J** command is used. However, if **seed** *does* return a different value,
both values, when assigned to **seed**, are guaranteed to produce the same
sequence of pseudo-random numbers. This means that certain values assigned
to **seed** will not produce unique sequences of pseudo-random numbers.
There is no limit to the length (number of significant decimal digits) or
*scale* of the value that can be assigned to **seed**.
This is a **non-portable extension**.
**I**
: Pushes the current value of **ibase** onto the main stack.
**O**
: Pushes the current value of **obase** onto the main stack.
**K**
: Pushes the current value of **scale** onto the main stack.
**J**
: Pushes the current value of **seed** onto the main stack.
This is a **non-portable extension**.
**T**
: Pushes the maximum allowable value of **ibase** onto the main stack.
This is a **non-portable extension**.
**U**
: Pushes the maximum allowable value of **obase** onto the main stack.
This is a **non-portable extension**.
**V**
: Pushes the maximum allowable value of **scale** onto the main stack.
This is a **non-portable extension**.
**W**
: Pushes the maximum (inclusive) integer that can be generated with the **'**
pseudo-random number generator command.
This is a **non-portable extension**.
## Strings
The following commands control strings.
dc(1) can work with both numbers and strings, and registers (see the
**REGISTERS** section) can hold both strings and numbers. dc(1) always knows
whether the contents of a register are a string or a number.
While arithmetic operations have to have numbers, and will print an error if
given a string, other commands accept strings.
Strings can also be executed as macros. For example, if the string **[1pR]** is
executed as a macro, then the code **1pR** is executed, meaning that the **1**
will be printed with a newline after and then popped from the stack.
**\[**_characters_**\]**
: Makes a string containing *characters* and pushes it onto the stack.
If there are brackets (**\[** and **\]**) in the string, then they must be
balanced. Unbalanced brackets can be escaped using a backslash (**\\**)
character.
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the (first)
backslash is not.
**a**
: The value on top of the stack is popped.
If it is a number, it is truncated and its absolute value is taken. The
result mod **UCHAR_MAX+1** is calculated. If that result is **0**, push an
empty string; otherwise, push a one-character string where the character is
the result of the mod interpreted as an ASCII character.
If it is a string, then a new string is made. If the original string is
empty, the new string is empty. If it is not, then the first character of
the original string is used to create the new string as a one-character
string. The new string is then pushed onto the stack.
This is a **non-portable extension**.
**x**
: Pops a value off of the top of the stack.
If it is a number, it is pushed back onto the stack.
If it is a string, it is executed as a macro.
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
**\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is greater than the second, then the contents of register
*r* are executed.
For example, **0 1>a** will execute the contents of register **a**, and
**1 0>a** will not.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not greater than the second (less than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is less than the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not less than the second (greater than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is equal to the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not equal to the second, then the contents of register
*r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**?**
: Reads a line from the **stdin** and executes it. This is to allow macros to
request input from users.
**q**
: During execution of a macro, this exits the execution of that macro and the
execution of the macro that executed it. If there are no macros, or only one
macro executing, dc(1) exits.
**Q**
: Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack. If the number
of levels to pop is greater than the number of executing macros, dc(1)
exits.
## Status
These commands query status of the stack or its top value.
**Z**
: Pops a value off of the stack.
If it is a number, calculates the number of significant decimal digits it
has and pushes the result.
If it is a string, pushes the number of characters the string has.
**X**
: Pops a value off of the stack.
If it is a number, pushes the *scale* of the value onto the stack.
If it is a string, pushes **0**.
**z**
: Pushes the current stack depth (before execution of this command).
## Arrays
These commands manipulate arrays.
**:***r*
: Pops the top two values off of the stack. The second value will be stored in
the array *r* (see the **REGISTERS** section), indexed by the first value.
**;***r*
: Pops the value on top of the stack and uses it as an index into the array
*r*. The selected value is then pushed onto the stack.
# REGISTERS
Registers are names that can store strings, numbers, and arrays. (Number/string
registers do not interfere with array registers.)
Each register is also its own stack, so the current register value is the top of
the stack for the register. All registers, when first referenced, have one value
(**0**) in their stack.
In non-extended register mode, a register name is just the single character that
follows any command that needs a register name. The only exception is a newline
(**'\\n'**); it is a parse error for a newline to be used as a register name.
## Extended Register Mode
Unlike most other dc(1) implentations, this dc(1) provides nearly unlimited
amounts of registers, if extended register mode is enabled.
If extended register mode is enabled (**-x** or **--extended-register**
command-line arguments are given), then normal single character registers are
used *unless* the character immediately following a command that needs a
register name is a space (according to **isspace()**) and not a newline
(**'\\n'**).
In that case, the register name is found according to the regex
**\[a-z\]\[a-z0-9\_\]\*** (like bc(1) identifiers), and it is a parse error if
the next non-space characters do not match that regex.
# RESET
When dc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any macros that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
macros returned) is skipped.
Thus, when dc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
# PERFORMANCE
Most dc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This dc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **DC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **DC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**DC_BASE_DIGS**.
In addition, this dc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **DC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on dc(1):
**DC_LONG_BIT**
: The number of bits in the **long** type in the environment where dc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**DC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **DC_LONG_BIT**.
**DC_BASE_POW**
: The max decimal number that each large integer can store (see
**DC_BASE_DIGS**) plus **1**. Depends on **DC_BASE_DIGS**.
**DC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **DC_LONG_BIT**.
**DC_BASE_MAX**
: The maximum output base. Set at **DC_BASE_POW**.
**DC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**DC_SCALE_MAX**
: The maximum **scale**. Set at **DC_OVERFLOW_MAX-1**.
**DC_STRING_MAX**
: The maximum length of strings. Set at **DC_OVERFLOW_MAX-1**.
**DC_NAME_MAX**
: The maximum length of identifiers. Set at **DC_OVERFLOW_MAX-1**.
**DC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **DC_OVERFLOW_MAX-1**.
**DC_RAND_MAX**
: The maximum integer (inclusive) returned by the **'** command, if dc(1). Set
at **2\^DC_LONG_BIT-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**DC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
dc(1) recognizes the following environment variables:
**DC_ENV_ARGS**
: This is another way to give command-line arguments to dc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **DC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs. Another use would
be to use the **-e** option to set **scale** to a value other than **0**.
The code that parses **DC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some dc file.dc"** will be correctly parsed, but the string
**"/home/gavin/some \"dc\" file.dc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
- double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
+ double quotes as the outside quotes, as in **"some 'dc' file.dc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **DC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**DC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), dc(1) will output
lines to that length, including the backslash newline combo. The default
line length is **70**.
**DC_EXPR_EXIT**
: If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the **-e** and/or
**-f** command-line options (and any equivalents).
# EXIT STATUS
dc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, using a negative number as a bound for the pseudo-random number
generator, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**), places (**\@**), left shift (**H**), and right shift (**h**)
operators.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, and using a token where it is
invalid.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, and attempting an operation when
the stack has too few elements.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (dc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, dc(1) always exits
and returns **4**, no matter what mode dc(1) is in.
The other statuses will only be returned when dc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since dc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, dc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, dc(1) turns
on "TTY mode."
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause dc(1) to stop execution of the current input. If
dc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If dc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If dc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to dc(1) as it is executing a file, it
can seem as though dc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause dc(1) to clean up and exit, and it uses the
default handler for all other signals.
# LOCALES
This dc(1) ships with support for adding error messages for different locales
and thus, supports **LC_MESSAGS**.
# SEE ALSO
bc(1)
# STANDARDS
The dc(1) utility operators are compliant with the operators in the bc(1)
[IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1] specification.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHOR
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
diff --git a/contrib/bc/manuals/dc/N.1 b/contrib/bc/manuals/dc/N.1
index 8f4718490813..e257c79bc9b7 100644
--- a/contrib/bc/manuals/dc/N.1
+++ b/contrib/bc/manuals/dc/N.1
@@ -1,1334 +1,1347 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "DC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "DC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH Name
.PP
dc - arbitrary-precision decimal reverse-Polish notation calculator
.SH SYNOPSIS
.PP
\f[B]dc\f[R] [\f[B]-hiPvVx\f[R]] [\f[B]\[en]version\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]no-prompt\f[R]] [\f[B]\[en]extended-register\f[R]]
[\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
dc(1) is an arbitrary-precision calculator.
It uses a stack (reverse Polish notation) to store numbers and results
of computations.
Arithmetic operations pop arguments off of the stack and push the
results.
.PP
If no files are given on the command-line as extra arguments (i.e., not
as \f[B]-f\f[R] or \f[B]\[en]file\f[R] arguments), then dc(1) reads from
\f[B]stdin\f[R].
Otherwise, those files are processed, and dc(1) will then exit.
.PP
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where \f[B]-e\f[R] (\f[B]\[en]expression\f[R]) and
\f[B]-f\f[R] (\f[B]\[en]file\f[R]) arguments cause dc(1) to execute them
and exit.
The reason for this is that this dc(1) allows users to set arguments in
the environment variable \f[B]DC_ENV_ARGS\f[R] (see the \f[B]ENVIRONMENT
VARIABLES\f[R] section).
Any expressions given on the command-line should be used to set up a
standard environment.
For example, if a user wants the \f[B]scale\f[R] always set to
\f[B]10\f[R], they can set \f[B]DC_ENV_ARGS\f[R] to \f[B]-e 10k\f[R],
and this dc(1) will always start with a \f[B]scale\f[R] of \f[B]10\f[R].
.PP
If users want to have dc(1) exit after processing all input from
\f[B]-e\f[R] and \f[B]-f\f[R] arguments (and their equivalents), then
they can just simply add \f[B]-e q\f[R] as the last command-line
argument or define the environment variable \f[B]DC_EXPR_EXIT\f[R].
.SH OPTIONS
.PP
The following are the options that dc(1) accepts.
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
Disables the prompt in TTY mode.
(The prompt is only enabled in TTY mode.
See the \f[B]TTY MODE\f[R] section) This is mostly for those users that
do not want a prompt or are not used to having them in dc(1).
Most of those users would want to put this option in
\f[B]DC_ENV_ARGS\f[R].
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-x\f[R] \f[B]\[en]extended-register\f[R]
Enables extended register mode.
See the \f[I]Extended Register Mode\f[R] subsection of the
\f[B]REGISTERS\f[R] section for more information.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]DC_ENV_ARGS\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]dc >&-\f[R], it will quit with an error.
This is done so that dc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]dc 2>&-\f[R], it will quit with an error.
This is done so that dc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
Each item in the input source code, either a number (see the
\f[B]NUMBERS\f[R] section) or a command (see the \f[B]COMMANDS\f[R]
section), is processed and executed, in order.
Input is processed immediately when entered.
.PP
\f[B]ibase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to interpret constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]ibase\f[R] is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in dc(1)
programs with the \f[B]T\f[R] command.
.PP
\f[B]obase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]DC_BASE_MAX\f[R] and
can be queried with the \f[B]U\f[R] command.
The min allowable value for \f[B]obase\f[R] is \f[B]0\f[R].
If \f[B]obase\f[R] is \f[B]0\f[R], values are output in scientific
notation, and if \f[B]obase\f[R] is \f[B]1\f[R], values are output in
engineering notation.
Otherwise, values are output in the specified base.
.PP
Outputting in scientific and engineering notations are \f[B]non-portable
extensions\f[R].
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a register (see the \f[B]REGISTERS\f[R] section) that sets the
precision of any operations (with exceptions).
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] can be queried in dc(1)
programs with the \f[B]V\f[R] command.
.PP
\f[B]seed\f[R] is a register containing the current seed for the
pseudo-random number generator.
If the current value of \f[B]seed\f[R] is queried and stored, then if it
is assigned to \f[B]seed\f[R] later, the pseudo-random number generator
is guaranteed to produce the same sequence of pseudo-random numbers that
were generated after the value of \f[B]seed\f[R] was first queried.
.PP
Multiple values assigned to \f[B]seed\f[R] can produce the same sequence
of pseudo-random numbers.
Likewise, when a value is assigned to \f[B]seed\f[R], it is not
guaranteed that querying \f[B]seed\f[R] immediately after will return
the same value.
In addition, the value of \f[B]seed\f[R] will change after any call to
the \f[B]\[cq]\f[R] command or the \f[B]\[dq]\f[R] command that does not
get receive a value of \f[B]0\f[R] or \f[B]1\f[R].
The maximum integer returned by the \f[B]\[cq]\f[R] command can be
queried with the \f[B]W\f[R] command.
.PP
\f[B]Note\f[R]: The values returned by the pseudo-random number
generator with the \f[B]\[cq]\f[R] and \f[B]\[dq]\f[R] commands are
guaranteed to \f[B]NOT\f[R] be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator.
However, they \f[I]are\f[R] guaranteed to be reproducible with identical
\f[B]seed\f[R] values.
-This means that the pseudo-random values from bc(1) should only be used
+This means that the pseudo-random values from dc(1) should only be used
where a reproducible stream of pseudo-random numbers is
\f[I]ESSENTIAL\f[R].
In any other case, use a non-seeded pseudo-random number generator.
.PP
The pseudo-random number generator, \f[B]seed\f[R], and all associated
operations are \f[B]non-portable extensions\f[R].
.SS Comments
.PP
Comments go from \f[B]#\f[R] until, and not including, the next newline.
This is a \f[B]non-portable extension\f[R].
.SH NUMBERS
.PP
Numbers are strings made up of digits, uppercase letters up to
\f[B]F\f[R], and at most \f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]DC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]F\f[R] alone always equals decimal \f[B]15\f[R].
.PP
In addition, dc(1) accepts numbers in scientific notation.
These have the form \f[B]<number>e<integer>\f[R].
The exponent (the portion after the \f[B]e\f[R]) must be an integer.
An example is \f[B]1.89237e9\f[R], which is equal to
\f[B]1892370000\f[R].
Negative exponents are also allowed, so \f[B]4.2890e_3\f[R] is equal to
\f[B]0.0042890\f[R].
.PP
\f[B]WARNING\f[R]: Both the number and the exponent in scientific
notation are interpreted according to the current \f[B]ibase\f[R], but
the number is still multiplied by \f[B]10\[ha]exponent\f[R] regardless
of the current \f[B]ibase\f[R].
For example, if \f[B]ibase\f[R] is \f[B]16\f[R] and dc(1) is given the
number string \f[B]FFeA\f[R], the resulting decimal number will be
\f[B]2550000000000\f[R], and if dc(1) is given the number string
\f[B]10e_4\f[R], the resulting decimal number will be \f[B]0.0016\f[R].
.PP
Accepting input as scientific notation is a \f[B]non-portable
extension\f[R].
.SH COMMANDS
.PP
The valid commands are listed below.
.SS Printing
.PP
These commands are used for printing.
.PP
Note that both scientific notation and engineering notation are
available for printing numbers.
Scientific notation is activated by assigning \f[B]0\f[R] to
\f[B]obase\f[R] using \f[B]0o\f[R], and engineering notation is
activated by assigning \f[B]1\f[R] to \f[B]obase\f[R] using
\f[B]1o\f[R].
To deactivate them, just assign a different value to \f[B]obase\f[R].
.PP
Printing numbers in scientific notation and/or engineering notation is a
\f[B]non-portable extension\f[R].
.TP
\f[B]p\f[R]
Prints the value on top of the stack, whether number or string, and
prints a newline after.
.RS
.PP
This does not alter the stack.
.RE
.TP
\f[B]n\f[R]
Prints the value on top of the stack, whether number or string, and pops
it off of the stack.
.TP
\f[B]P\f[R]
Pops a value off the stack.
.RS
.PP
If the value is a number, it is truncated and the absolute value of the
result is printed as though \f[B]obase\f[R] is \f[B]UCHAR_MAX+1\f[R] and
each digit is interpreted as an ASCII character, making it a byte
stream.
.PP
If the value is a string, it is printed without a trailing newline.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]f\f[R]
Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
.RS
.PP
Users should use this command when they get lost.
.RE
.SS Arithmetic
.PP
These are the commands used for arithmetic.
.TP
\f[B]+\f[R]
The top two values are popped off the stack, added, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]-\f[R]
The top two values are popped off the stack, subtracted, and the result
is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]*\f[R]
The top two values are popped off the stack, multiplied, and the result
is pushed onto the stack.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The top two values are popped off the stack, divided, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]%\f[R]
The top two values are popped off the stack, remaindered, and the result
is pushed onto the stack.
.RS
.PP
Remaindering is equivalent to 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R], and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]\[ti]\f[R]
The top two values are popped off the stack, divided and remaindered,
and the results (divided first, remainder second) are pushed onto the
stack.
This is equivalent to \f[B]x y / x y %\f[R] except that \f[B]x\f[R] and
\f[B]y\f[R] are only evaluated once.
.RS
.PP
The first value popped off of the stack must be non-zero.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
.RE
.TP
\f[B]v\f[R]
The top value is popped off the stack, its square root is computed, and
the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The value popped off of the stack must be non-negative.
.RE
.TP
\f[B]_\f[R]
If this command \f[I]immediately\f[R] precedes a number (i.e., no spaces
or other commands), then that number is input as a negative number.
.RS
.PP
Otherwise, the top value on the stack is popped and copied, and the copy
is negated and pushed onto the stack.
This behavior without a number is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]b\f[R]
The top value is popped off the stack, and if it is zero, it is pushed
back onto the stack.
Otherwise, its absolute value is pushed onto the stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]|\f[R]
The top three values are popped off the stack, a modular exponentiation
is computed, and the result is pushed onto the stack.
.RS
.PP
The first value popped is used as the reduction modulus and must be an
integer and non-zero.
The second value popped is used as the exponent and must be an integer
and non-negative.
The third value popped is the base and must be an integer.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]$\f[R]
The top value is popped off the stack and copied, and the copy is
truncated and pushed onto the stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[at]\f[R]
The top two values are popped off the stack, and the precision of the
second is set to the value of the first, whether by truncation or
extension.
.RS
.PP
The first value popped off of the stack must be an integer and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]H\f[R]
The top two values are popped off the stack, and the second is shifted
left (radix shifted right) to the value of the first.
.RS
.PP
The first value popped off of the stack must be an integer and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]h\f[R]
The top two values are popped off the stack, and the second is shifted
right (radix shifted left) to the value of the first.
.RS
.PP
The first value popped off of the stack must be an integer and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]G\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if they are equal, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]N\f[R]
The top value is popped off of the stack, and if it a \f[B]0\f[R], a
\f[B]1\f[R] is pushed; otherwise, a \f[B]0\f[R] is pushed.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B](\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]{\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than or equal to the second,
or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B])\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]}\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than or equal to the
second, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]M\f[R]
The top two values are popped off of the stack.
If they are both non-zero, a \f[B]1\f[R] is pushed onto the stack.
If either of them is zero, or both of them are, then a \f[B]0\f[R] is
pushed onto the stack.
.RS
.PP
This is like the \f[B]&&\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]m\f[R]
The top two values are popped off of the stack.
If at least one of them is non-zero, a \f[B]1\f[R] is pushed onto the
stack.
If both of them are zero, then a \f[B]0\f[R] is pushed onto the stack.
.RS
.PP
This is like the \f[B]||\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Pseudo-Random Number Generator
.PP
dc(1) has a built-in pseudo-random number generator.
These commands query the pseudo-random number generator.
(See Parameters for more information about the \f[B]seed\f[R] value that
controls the pseudo-random number generator.)
.PP
The pseudo-random number generator is guaranteed to \f[B]NOT\f[R] be
cryptographically secure.
.TP
\f[B]\[cq]\f[R]
Generates an integer between 0 and \f[B]DC_RAND_MAX\f[R], inclusive (see
the \f[B]LIMITS\f[R] section).
.RS
.PP
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[dq]\f[R]
Pops a value off of the stack, which is used as an \f[B]exclusive\f[R]
upper bound on the integer that will be generated.
If the bound is negative or is a non-integer, an error is raised, and
dc(1) resets (see the \f[B]RESET\f[R] section) while \f[B]seed\f[R]
remains unchanged.
If the bound is larger than \f[B]DC_RAND_MAX\f[R], the higher bound is
honored by generating several pseudo-random integers, multiplying them
by appropriate powers of \f[B]DC_RAND_MAX+1\f[R], and adding them
together.
Thus, the size of integer that can be generated with this command is
unbounded.
Using this command will change the value of \f[B]seed\f[R], unless the
operand is \f[B]0\f[R] or \f[B]1\f[R].
In that case, \f[B]0\f[R] is pushed onto the stack, and \f[B]seed\f[R]
is \f[I]not\f[R] changed.
.RS
.PP
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Stack Control
.PP
These commands control the stack.
.TP
\f[B]c\f[R]
Removes all items from (\[lq]clears\[rq]) the stack.
.TP
\f[B]d\f[R]
Copies the item on top of the stack (\[lq]duplicates\[rq]) and pushes
the copy onto the stack.
.TP
\f[B]r\f[R]
Swaps (\[lq]reverses\[rq]) the two top items on the stack.
.TP
\f[B]R\f[R]
Pops (\[lq]removes\[rq]) the top value from the stack.
.SS Register Control
.PP
These commands control registers (see the \f[B]REGISTERS\f[R] section).
.TP
\f[B]s\f[R]\f[I]r\f[R]
Pops the value off the top of the stack and stores it into register
\f[I]r\f[R].
.TP
\f[B]l\f[R]\f[I]r\f[R]
Copies the value in register \f[I]r\f[R] and pushes it onto the stack.
This does not alter the contents of \f[I]r\f[R].
.TP
\f[B]S\f[R]\f[I]r\f[R]
Pops the value off the top of the (main) stack and pushes it onto the
stack of register \f[I]r\f[R].
The previous value of the register becomes inaccessible.
.TP
\f[B]L\f[R]\f[I]r\f[R]
Pops the value off the top of the stack for register \f[I]r\f[R] and
push it onto the main stack.
The previous value in the stack for register \f[I]r\f[R], if any, is now
accessible via the \f[B]l\f[R]\f[I]r\f[R] command.
.SS Parameters
.PP
These commands control the values of \f[B]ibase\f[R], \f[B]obase\f[R],
\f[B]scale\f[R], and \f[B]seed\f[R].
Also see the \f[B]SYNTAX\f[R] section.
.TP
\f[B]i\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]ibase\f[R], which must be between \f[B]2\f[R] and \f[B]16\f[R],
inclusive.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]o\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]obase\f[R], which must be between \f[B]0\f[R] and
\f[B]DC_BASE_MAX\f[R], inclusive (see the \f[B]LIMITS\f[R] section and
the \f[B]NUMBERS\f[R] section).
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]k\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]scale\f[R], which must be non-negative.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]j\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]seed\f[R].
The meaning of \f[B]seed\f[R] is dependent on the current pseudo-random
number generator but is guaranteed to not change except for new major
versions.
.RS
.PP
The \f[I]scale\f[R] and sign of the value may be significant.
.PP
If a previously used \f[B]seed\f[R] value is used again, the
pseudo-random number generator is guaranteed to produce the same
sequence of pseudo-random numbers as it did when the \f[B]seed\f[R]
value was previously used.
.PP
The exact value assigned to \f[B]seed\f[R] is not guaranteed to be
returned if the \f[B]J\f[R] command is used.
However, if \f[B]seed\f[R] \f[I]does\f[R] return a different value, both
values, when assigned to \f[B]seed\f[R], are guaranteed to produce the
same sequence of pseudo-random numbers.
This means that certain values assigned to \f[B]seed\f[R] will not
produce unique sequences of pseudo-random numbers.
.PP
There is no limit to the length (number of significant decimal digits)
or \f[I]scale\f[R] of the value that can be assigned to \f[B]seed\f[R].
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]I\f[R]
Pushes the current value of \f[B]ibase\f[R] onto the main stack.
.TP
\f[B]O\f[R]
Pushes the current value of \f[B]obase\f[R] onto the main stack.
.TP
\f[B]K\f[R]
Pushes the current value of \f[B]scale\f[R] onto the main stack.
.TP
\f[B]J\f[R]
Pushes the current value of \f[B]seed\f[R] onto the main stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]T\f[R]
Pushes the maximum allowable value of \f[B]ibase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]U\f[R]
Pushes the maximum allowable value of \f[B]obase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]V\f[R]
Pushes the maximum allowable value of \f[B]scale\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]W\f[R]
Pushes the maximum (inclusive) integer that can be generated with the
\f[B]\[cq]\f[R] pseudo-random number generator command.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Strings
.PP
The following commands control strings.
.PP
dc(1) can work with both numbers and strings, and registers (see the
\f[B]REGISTERS\f[R] section) can hold both strings and numbers.
dc(1) always knows whether the contents of a register are a string or a
number.
.PP
While arithmetic operations have to have numbers, and will print an
error if given a string, other commands accept strings.
.PP
Strings can also be executed as macros.
For example, if the string \f[B][1pR]\f[R] is executed as a macro, then
the code \f[B]1pR\f[R] is executed, meaning that the \f[B]1\f[R] will be
printed with a newline after and then popped from the stack.
.TP
\f[B][\f[R]_characters_\f[B]]\f[R]
Makes a string containing \f[I]characters\f[R] and pushes it onto the
stack.
.RS
.PP
If there are brackets (\f[B][\f[R] and \f[B]]\f[R]) in the string, then
they must be balanced.
Unbalanced brackets can be escaped using a backslash (\f[B]\[rs]\f[R])
character.
.PP
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the
(first) backslash is not.
.RE
.TP
\f[B]a\f[R]
The value on top of the stack is popped.
.RS
.PP
If it is a number, it is truncated and its absolute value is taken.
The result mod \f[B]UCHAR_MAX+1\f[R] is calculated.
If that result is \f[B]0\f[R], push an empty string; otherwise, push a
one-character string where the character is the result of the mod
interpreted as an ASCII character.
.PP
If it is a string, then a new string is made.
If the original string is empty, the new string is empty.
If it is not, then the first character of the original string is used to
create the new string as a one-character string.
The new string is then pushed onto the stack.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]x\f[R]
Pops a value off of the top of the stack.
.RS
.PP
If it is a number, it is pushed back onto the stack.
.PP
If it is a string, it is executed as a macro.
.PP
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is greater than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
For example, \f[B]0 1>a\f[R] will execute the contents of register
\f[B]a\f[R], and \f[B]1 0>a\f[R] will not.
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not greater than the second (less than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is less than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not less than the second (greater than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is equal to the second, then the contents of register
\f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not equal to the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]?\f[R]
Reads a line from the \f[B]stdin\f[R] and executes it.
This is to allow macros to request input from users.
.TP
\f[B]q\f[R]
During execution of a macro, this exits the execution of that macro and
the execution of the macro that executed it.
If there are no macros, or only one macro executing, dc(1) exits.
.TP
\f[B]Q\f[R]
Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack.
If the number of levels to pop is greater than the number of executing
macros, dc(1) exits.
.SS Status
.PP
These commands query status of the stack or its top value.
.TP
\f[B]Z\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, calculates the number of significant decimal digits
it has and pushes the result.
.PP
If it is a string, pushes the number of characters the string has.
.RE
.TP
\f[B]X\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, pushes the \f[I]scale\f[R] of the value onto the
stack.
.PP
If it is a string, pushes \f[B]0\f[R].
.RE
.TP
\f[B]z\f[R]
Pushes the current stack depth (before execution of this command).
.SS Arrays
.PP
These commands manipulate arrays.
.TP
\f[B]:\f[R]\f[I]r\f[R]
Pops the top two values off of the stack.
The second value will be stored in the array \f[I]r\f[R] (see the
\f[B]REGISTERS\f[R] section), indexed by the first value.
.TP
\f[B];\f[R]\f[I]r\f[R]
Pops the value on top of the stack and uses it as an index into the
array \f[I]r\f[R].
The selected value is then pushed onto the stack.
.SH REGISTERS
.PP
Registers are names that can store strings, numbers, and arrays.
(Number/string registers do not interfere with array registers.)
.PP
Each register is also its own stack, so the current register value is
the top of the stack for the register.
All registers, when first referenced, have one value (\f[B]0\f[R]) in
their stack.
.PP
In non-extended register mode, a register name is just the single
character that follows any command that needs a register name.
The only exception is a newline (\f[B]`\[rs]n'\f[R]); it is a parse
error for a newline to be used as a register name.
.SS Extended Register Mode
.PP
Unlike most other dc(1) implentations, this dc(1) provides nearly
unlimited amounts of registers, if extended register mode is enabled.
.PP
If extended register mode is enabled (\f[B]-x\f[R] or
\f[B]\[en]extended-register\f[R] command-line arguments are given), then
normal single character registers are used \f[I]unless\f[R] the
character immediately following a command that needs a register name is
a space (according to \f[B]isspace()\f[R]) and not a newline
(\f[B]`\[rs]n'\f[R]).
.PP
In that case, the register name is found according to the regex
\f[B][a-z][a-z0-9_]*\f[R] (like bc(1) identifiers), and it is a parse
error if the next non-space characters do not match that regex.
.SH RESET
.PP
When dc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any macros that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all macros returned) is skipped.
.PP
Thus, when dc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.SH PERFORMANCE
.PP
Most dc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This dc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]DC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]DC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]DC_BASE_DIGS\f[R].
.PP
In addition, this dc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]DC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on dc(1):
.TP
\f[B]DC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
dc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]DC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]DC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]DC_BASE_DIGS\f[R].
.TP
\f[B]DC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]DC_BASE_POW\f[R].
.TP
\f[B]DC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]DC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_RAND_MAX\f[R]
The maximum integer (inclusive) returned by the \f[B]\[cq]\f[R] command,
if dc(1).
Set at \f[B]2\[ha]DC_LONG_BIT-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]DC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
dc(1) recognizes the following environment variables:
.TP
\f[B]DC_ENV_ARGS\f[R]
This is another way to give command-line arguments to dc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]DC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs.
Another use would be to use the \f[B]-e\f[R] option to set
\f[B]scale\f[R] to a value other than \f[B]0\f[R].
.RS
.PP
The code that parses \f[B]DC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some dc file.dc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]dc\[dq] file.dc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
-in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
+in \f[B]\[rq]some `dc' file.dc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]DC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]DC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), dc(1) will output lines to that length,
including the backslash newline combo.
The default line length is \f[B]70\f[R].
.TP
\f[B]DC_EXPR_EXIT\f[R]
If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the
\f[B]-e\f[R] and/or \f[B]-f\f[R] command-line options (and any
equivalents).
.SH EXIT STATUS
.PP
dc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, using a negative number as a bound for the
pseudo-random number generator, attempting to convert a negative number
to a hardware integer, overflow when converting a number to a hardware
integer, and attempting to use a non-integer where an integer is
required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]), places (\f[B]\[at]\f[R]), left shift
(\f[B]H\f[R]), and right shift (\f[B]h\f[R]) operators.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, and using a
token where it is invalid.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, and attempting an operation when the
stack has too few elements.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (dc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, dc(1)
always exits and returns \f[B]4\f[R], no matter what mode dc(1) is in.
.PP
The other statuses will only be returned when dc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
dc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, dc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, dc(1) turns on \[lq]TTY mode.\[rq]
.PP
TTY mode is required for history to be enabled (see the \f[B]COMMAND
LINE HISTORY\f[R] section).
It is also required to enable special handling for \f[B]SIGINT\f[R]
signals.
.PP
The prompt is enabled in TTY mode.
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause dc(1) to stop execution of the
current input.
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If dc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If dc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to dc(1) as it is
executing a file, it can seem as though dc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause dc(1) to clean up and
exit, and it uses the default handler for all other signals.
The one exception is \f[B]SIGHUP\f[R]; in that case, when dc(1) is in
TTY mode, a \f[B]SIGHUP\f[R] will cause dc(1) to clean up and exit.
.SH COMMAND LINE HISTORY
.PP
dc(1) supports interactive command-line editing.
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), history is
enabled.
Previous lines can be recalled and edited with the arrow keys.
.PP
\f[B]Note\f[R]: tabs are converted to 8 spaces.
.SH SEE ALSO
.PP
bc(1)
.SH STANDARDS
.PP
The dc(1) utility operators are compliant with the operators in the
bc(1) IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHOR
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/dc/N.1.md b/contrib/bc/manuals/dc/N.1.md
index a79c482c8244..1d9d1d6f64ed 100644
--- a/contrib/bc/manuals/dc/N.1.md
+++ b/contrib/bc/manuals/dc/N.1.md
@@ -1,1193 +1,1202 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# Name
dc - arbitrary-precision decimal reverse-Polish notation calculator
# SYNOPSIS
**dc** [**-hiPvVx**] [**--version**] [**--help**] [**--interactive**] [**--no-prompt**] [**--extended-register**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...] [*file*...]
# DESCRIPTION
dc(1) is an arbitrary-precision calculator. It uses a stack (reverse Polish
notation) to store numbers and results of computations. Arithmetic operations
pop arguments off of the stack and push the results.
If no files are given on the command-line as extra arguments (i.e., not as
**-f** or **--file** arguments), then dc(1) reads from **stdin**. Otherwise,
those files are processed, and dc(1) will then exit.
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where **-e** (**--expression**) and **-f** (**--file**)
arguments cause dc(1) to execute them and exit. The reason for this is that this
dc(1) allows users to set arguments in the environment variable **DC_ENV_ARGS**
(see the **ENVIRONMENT VARIABLES** section). Any expressions given on the
command-line should be used to set up a standard environment. For example, if a
user wants the **scale** always set to **10**, they can set **DC_ENV_ARGS** to
**-e 10k**, and this dc(1) will always start with a **scale** of **10**.
If users want to have dc(1) exit after processing all input from **-e** and
**-f** arguments (and their equivalents), then they can just simply add **-e q**
as the last command-line argument or define the environment variable
**DC_EXPR_EXIT**.
# OPTIONS
The following are the options that dc(1) accepts.
**-h**, **--help**
: Prints a usage message and quits.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-P**, **--no-prompt**
: Disables the prompt in TTY mode. (The prompt is only enabled in TTY mode.
See the **TTY MODE** section) This is mostly for those users that do not
want a prompt or are not used to having them in dc(1). Most of those users
would want to put this option in **DC_ENV_ARGS**.
This is a **non-portable extension**.
**-x** **--extended-register**
: Enables extended register mode. See the *Extended Register Mode* subsection
of the **REGISTERS** section for more information.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **DC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **dc <file> >&-**, it will quit with an error. This
is done so that dc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **dc <file> 2>&-**, it will quit with an error. This
is done so that dc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
Each item in the input source code, either a number (see the **NUMBERS**
section) or a command (see the **COMMANDS** section), is processed and executed,
in order. Input is processed immediately when entered.
**ibase** is a register (see the **REGISTERS** section) that determines how to
interpret constant numbers. It is the "input" base, or the number base used for
interpreting input numbers. **ibase** is initially **10**. The max allowable
value for **ibase** is **16**. The min allowable value for **ibase** is **2**.
The max allowable value for **ibase** can be queried in dc(1) programs with the
**T** command.
**obase** is a register (see the **REGISTERS** section) that determines how to
output results. It is the "output" base, or the number base used for outputting
numbers. **obase** is initially **10**. The max allowable value for **obase** is
**DC_BASE_MAX** and can be queried with the **U** command. The min allowable
value for **obase** is **0**. If **obase** is **0**, values are output in
scientific notation, and if **obase** is **1**, values are output in engineering
notation. Otherwise, values are output in the specified base.
Outputting in scientific and engineering notations are **non-portable
extensions**.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a register (see the
**REGISTERS** section) that sets the precision of any operations (with
exceptions). **scale** is initially **0**. **scale** cannot be negative. The max
allowable value for **scale** can be queried in dc(1) programs with the **V**
command.
**seed** is a register containing the current seed for the pseudo-random number
generator. If the current value of **seed** is queried and stored, then if it is
assigned to **seed** later, the pseudo-random number generator is guaranteed to
produce the same sequence of pseudo-random numbers that were generated after the
value of **seed** was first queried.
Multiple values assigned to **seed** can produce the same sequence of
pseudo-random numbers. Likewise, when a value is assigned to **seed**, it is not
guaranteed that querying **seed** immediately after will return the same value.
In addition, the value of **seed** will change after any call to the **'**
command or the **"** command that does not get receive a value of **0** or
**1**. The maximum integer returned by the **'** command can be queried with the
**W** command.
**Note**: The values returned by the pseudo-random number generator with the
**'** and **"** commands are guaranteed to **NOT** be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator. However,
they *are* guaranteed to be reproducible with identical **seed** values. This
-means that the pseudo-random values from bc(1) should only be used where a
+means that the pseudo-random values from dc(1) should only be used where a
reproducible stream of pseudo-random numbers is *ESSENTIAL*. In any other case,
use a non-seeded pseudo-random number generator.
The pseudo-random number generator, **seed**, and all associated operations are
**non-portable extensions**.
## Comments
Comments go from **#** until, and not including, the next newline. This is a
**non-portable extension**.
# NUMBERS
Numbers are strings made up of digits, uppercase letters up to **F**, and at
most **1** period for a radix. Numbers can have up to **DC_NUM_MAX** digits.
Uppercase letters are equal to **9** + their position in the alphabet (i.e.,
**A** equals **10**, or **9+1**). If a digit or letter makes no sense with the
current value of **ibase**, they are set to the value of the highest valid digit
in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **F** alone always equals decimal
**15**.
In addition, dc(1) accepts numbers in scientific notation. These have the form
**\<number\>e\<integer\>**. The exponent (the portion after the **e**) must be
an integer. An example is **1.89237e9**, which is equal to **1892370000**.
Negative exponents are also allowed, so **4.2890e_3** is equal to **0.0042890**.
**WARNING**: Both the number and the exponent in scientific notation are
interpreted according to the current **ibase**, but the number is still
multiplied by **10\^exponent** regardless of the current **ibase**. For example,
if **ibase** is **16** and dc(1) is given the number string **FFeA**, the
resulting decimal number will be **2550000000000**, and if dc(1) is given the
number string **10e_4**, the resulting decimal number will be **0.0016**.
Accepting input as scientific notation is a **non-portable extension**.
# COMMANDS
The valid commands are listed below.
## Printing
These commands are used for printing.
Note that both scientific notation and engineering notation are available for
printing numbers. Scientific notation is activated by assigning **0** to
**obase** using **0o**, and engineering notation is activated by assigning **1**
to **obase** using **1o**. To deactivate them, just assign a different value to
**obase**.
Printing numbers in scientific notation and/or engineering notation is a
**non-portable extension**.
**p**
: Prints the value on top of the stack, whether number or string, and prints a
newline after.
This does not alter the stack.
**n**
: Prints the value on top of the stack, whether number or string, and pops it
off of the stack.
**P**
: Pops a value off the stack.
If the value is a number, it is truncated and the absolute value of the
result is printed as though **obase** is **UCHAR_MAX+1** and each digit is
interpreted as an ASCII character, making it a byte stream.
If the value is a string, it is printed without a trailing newline.
This is a **non-portable extension**.
**f**
: Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
Users should use this command when they get lost.
## Arithmetic
These are the commands used for arithmetic.
**+**
: The top two values are popped off the stack, added, and the result is pushed
onto the stack. The *scale* of the result is equal to the max *scale* of
both operands.
**-**
: The top two values are popped off the stack, subtracted, and the result is
pushed onto the stack. The *scale* of the result is equal to the max
*scale* of both operands.
**\***
: The top two values are popped off the stack, multiplied, and the result is
pushed onto the stack. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result
is equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The top two values are popped off the stack, divided, and the result is
pushed onto the stack. The *scale* of the result is equal to **scale**.
The first value popped off of the stack must be non-zero.
**%**
: The top two values are popped off the stack, remaindered, and the result is
pushed onto the stack.
Remaindering is equivalent to 1) Computing **a/b** to current **scale**, and
2) Using the result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The first value popped off of the stack must be non-zero.
**~**
: The top two values are popped off the stack, divided and remaindered, and
the results (divided first, remainder second) are pushed onto the stack.
This is equivalent to **x y / x y %** except that **x** and **y** are only
evaluated once.
The first value popped off of the stack must be non-zero.
This is a **non-portable extension**.
**\^**
: The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack. The *scale* of
the result is equal to **scale**.
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
**v**
: The top value is popped off the stack, its square root is computed, and the
result is pushed onto the stack. The *scale* of the result is equal to
**scale**.
The value popped off of the stack must be non-negative.
**\_**
: If this command *immediately* precedes a number (i.e., no spaces or other
commands), then that number is input as a negative number.
Otherwise, the top value on the stack is popped and copied, and the copy is
negated and pushed onto the stack. This behavior without a number is a
**non-portable extension**.
**b**
: The top value is popped off the stack, and if it is zero, it is pushed back
onto the stack. Otherwise, its absolute value is pushed onto the stack.
This is a **non-portable extension**.
**|**
: The top three values are popped off the stack, a modular exponentiation is
computed, and the result is pushed onto the stack.
The first value popped is used as the reduction modulus and must be an
integer and non-zero. The second value popped is used as the exponent and
must be an integer and non-negative. The third value popped is the base and
must be an integer.
This is a **non-portable extension**.
**\$**
: The top value is popped off the stack and copied, and the copy is truncated
and pushed onto the stack.
This is a **non-portable extension**.
**\@**
: The top two values are popped off the stack, and the precision of the second
is set to the value of the first, whether by truncation or extension.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**H**
: The top two values are popped off the stack, and the second is shifted left
(radix shifted right) to the value of the first.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**h**
: The top two values are popped off the stack, and the second is shifted right
(radix shifted left) to the value of the first.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**G**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if they are equal, or **0** otherwise.
This is a **non-portable extension**.
**N**
: The top value is popped off of the stack, and if it a **0**, a **1** is
pushed; otherwise, a **0** is pushed.
This is a **non-portable extension**.
**(**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than the second, or **0** otherwise.
This is a **non-portable extension**.
**{**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than or equal to the second, or **0**
otherwise.
This is a **non-portable extension**.
**)**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than the second, or **0** otherwise.
This is a **non-portable extension**.
**}**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than or equal to the second, or
**0** otherwise.
This is a **non-portable extension**.
**M**
: The top two values are popped off of the stack. If they are both non-zero, a
**1** is pushed onto the stack. If either of them is zero, or both of them
are, then a **0** is pushed onto the stack.
This is like the **&&** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
**m**
: The top two values are popped off of the stack. If at least one of them is
non-zero, a **1** is pushed onto the stack. If both of them are zero, then a
**0** is pushed onto the stack.
This is like the **||** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
## Pseudo-Random Number Generator
dc(1) has a built-in pseudo-random number generator. These commands query the
pseudo-random number generator. (See Parameters for more information about the
**seed** value that controls the pseudo-random number generator.)
The pseudo-random number generator is guaranteed to **NOT** be
cryptographically secure.
**'**
: Generates an integer between 0 and **DC_RAND_MAX**, inclusive (see the
**LIMITS** section).
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
This is a **non-portable extension**.
**"**
: Pops a value off of the stack, which is used as an **exclusive** upper bound
on the integer that will be generated. If the bound is negative or is a
non-integer, an error is raised, and dc(1) resets (see the **RESET**
section) while **seed** remains unchanged. If the bound is larger than
**DC_RAND_MAX**, the higher bound is honored by generating several
pseudo-random integers, multiplying them by appropriate powers of
**DC_RAND_MAX+1**, and adding them together. Thus, the size of integer that
can be generated with this command is unbounded. Using this command will
change the value of **seed**, unless the operand is **0** or **1**. In that
case, **0** is pushed onto the stack, and **seed** is *not* changed.
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
This is a **non-portable extension**.
## Stack Control
These commands control the stack.
**c**
: Removes all items from ("clears") the stack.
**d**
: Copies the item on top of the stack ("duplicates") and pushes the copy onto
the stack.
**r**
: Swaps ("reverses") the two top items on the stack.
**R**
: Pops ("removes") the top value from the stack.
## Register Control
These commands control registers (see the **REGISTERS** section).
**s***r*
: Pops the value off the top of the stack and stores it into register *r*.
**l***r*
: Copies the value in register *r* and pushes it onto the stack. This does not
alter the contents of *r*.
**S***r*
: Pops the value off the top of the (main) stack and pushes it onto the stack
of register *r*. The previous value of the register becomes inaccessible.
**L***r*
: Pops the value off the top of the stack for register *r* and push it onto
the main stack. The previous value in the stack for register *r*, if any, is
now accessible via the **l***r* command.
## Parameters
These commands control the values of **ibase**, **obase**, **scale**, and
**seed**. Also see the **SYNTAX** section.
**i**
: Pops the value off of the top of the stack and uses it to set **ibase**,
which must be between **2** and **16**, inclusive.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**o**
: Pops the value off of the top of the stack and uses it to set **obase**,
which must be between **0** and **DC_BASE_MAX**, inclusive (see the
**LIMITS** section and the **NUMBERS** section).
If the value on top of the stack has any *scale*, the *scale* is ignored.
**k**
: Pops the value off of the top of the stack and uses it to set **scale**,
which must be non-negative.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**j**
: Pops the value off of the top of the stack and uses it to set **seed**. The
meaning of **seed** is dependent on the current pseudo-random number
generator but is guaranteed to not change except for new major versions.
The *scale* and sign of the value may be significant.
If a previously used **seed** value is used again, the pseudo-random number
generator is guaranteed to produce the same sequence of pseudo-random
numbers as it did when the **seed** value was previously used.
The exact value assigned to **seed** is not guaranteed to be returned if the
**J** command is used. However, if **seed** *does* return a different value,
both values, when assigned to **seed**, are guaranteed to produce the same
sequence of pseudo-random numbers. This means that certain values assigned
to **seed** will not produce unique sequences of pseudo-random numbers.
There is no limit to the length (number of significant decimal digits) or
*scale* of the value that can be assigned to **seed**.
This is a **non-portable extension**.
**I**
: Pushes the current value of **ibase** onto the main stack.
**O**
: Pushes the current value of **obase** onto the main stack.
**K**
: Pushes the current value of **scale** onto the main stack.
**J**
: Pushes the current value of **seed** onto the main stack.
This is a **non-portable extension**.
**T**
: Pushes the maximum allowable value of **ibase** onto the main stack.
This is a **non-portable extension**.
**U**
: Pushes the maximum allowable value of **obase** onto the main stack.
This is a **non-portable extension**.
**V**
: Pushes the maximum allowable value of **scale** onto the main stack.
This is a **non-portable extension**.
**W**
: Pushes the maximum (inclusive) integer that can be generated with the **'**
pseudo-random number generator command.
This is a **non-portable extension**.
## Strings
The following commands control strings.
dc(1) can work with both numbers and strings, and registers (see the
**REGISTERS** section) can hold both strings and numbers. dc(1) always knows
whether the contents of a register are a string or a number.
While arithmetic operations have to have numbers, and will print an error if
given a string, other commands accept strings.
Strings can also be executed as macros. For example, if the string **[1pR]** is
executed as a macro, then the code **1pR** is executed, meaning that the **1**
will be printed with a newline after and then popped from the stack.
**\[**_characters_**\]**
: Makes a string containing *characters* and pushes it onto the stack.
If there are brackets (**\[** and **\]**) in the string, then they must be
balanced. Unbalanced brackets can be escaped using a backslash (**\\**)
character.
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the (first)
backslash is not.
**a**
: The value on top of the stack is popped.
If it is a number, it is truncated and its absolute value is taken. The
result mod **UCHAR_MAX+1** is calculated. If that result is **0**, push an
empty string; otherwise, push a one-character string where the character is
the result of the mod interpreted as an ASCII character.
If it is a string, then a new string is made. If the original string is
empty, the new string is empty. If it is not, then the first character of
the original string is used to create the new string as a one-character
string. The new string is then pushed onto the stack.
This is a **non-portable extension**.
**x**
: Pops a value off of the top of the stack.
If it is a number, it is pushed back onto the stack.
If it is a string, it is executed as a macro.
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
**\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is greater than the second, then the contents of register
*r* are executed.
For example, **0 1>a** will execute the contents of register **a**, and
**1 0>a** will not.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not greater than the second (less than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is less than the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not less than the second (greater than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is equal to the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not equal to the second, then the contents of register
*r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**?**
: Reads a line from the **stdin** and executes it. This is to allow macros to
request input from users.
**q**
: During execution of a macro, this exits the execution of that macro and the
execution of the macro that executed it. If there are no macros, or only one
macro executing, dc(1) exits.
**Q**
: Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack. If the number
of levels to pop is greater than the number of executing macros, dc(1)
exits.
## Status
These commands query status of the stack or its top value.
**Z**
: Pops a value off of the stack.
If it is a number, calculates the number of significant decimal digits it
has and pushes the result.
If it is a string, pushes the number of characters the string has.
**X**
: Pops a value off of the stack.
If it is a number, pushes the *scale* of the value onto the stack.
If it is a string, pushes **0**.
**z**
: Pushes the current stack depth (before execution of this command).
## Arrays
These commands manipulate arrays.
**:***r*
: Pops the top two values off of the stack. The second value will be stored in
the array *r* (see the **REGISTERS** section), indexed by the first value.
**;***r*
: Pops the value on top of the stack and uses it as an index into the array
*r*. The selected value is then pushed onto the stack.
# REGISTERS
Registers are names that can store strings, numbers, and arrays. (Number/string
registers do not interfere with array registers.)
Each register is also its own stack, so the current register value is the top of
the stack for the register. All registers, when first referenced, have one value
(**0**) in their stack.
In non-extended register mode, a register name is just the single character that
follows any command that needs a register name. The only exception is a newline
(**'\\n'**); it is a parse error for a newline to be used as a register name.
## Extended Register Mode
Unlike most other dc(1) implentations, this dc(1) provides nearly unlimited
amounts of registers, if extended register mode is enabled.
If extended register mode is enabled (**-x** or **--extended-register**
command-line arguments are given), then normal single character registers are
used *unless* the character immediately following a command that needs a
register name is a space (according to **isspace()**) and not a newline
(**'\\n'**).
In that case, the register name is found according to the regex
**\[a-z\]\[a-z0-9\_\]\*** (like bc(1) identifiers), and it is a parse error if
the next non-space characters do not match that regex.
# RESET
When dc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any macros that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
macros returned) is skipped.
Thus, when dc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
# PERFORMANCE
Most dc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This dc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **DC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **DC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**DC_BASE_DIGS**.
In addition, this dc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **DC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on dc(1):
**DC_LONG_BIT**
: The number of bits in the **long** type in the environment where dc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**DC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **DC_LONG_BIT**.
**DC_BASE_POW**
: The max decimal number that each large integer can store (see
**DC_BASE_DIGS**) plus **1**. Depends on **DC_BASE_DIGS**.
**DC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **DC_LONG_BIT**.
**DC_BASE_MAX**
: The maximum output base. Set at **DC_BASE_POW**.
**DC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**DC_SCALE_MAX**
: The maximum **scale**. Set at **DC_OVERFLOW_MAX-1**.
**DC_STRING_MAX**
: The maximum length of strings. Set at **DC_OVERFLOW_MAX-1**.
**DC_NAME_MAX**
: The maximum length of identifiers. Set at **DC_OVERFLOW_MAX-1**.
**DC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **DC_OVERFLOW_MAX-1**.
**DC_RAND_MAX**
: The maximum integer (inclusive) returned by the **'** command, if dc(1). Set
at **2\^DC_LONG_BIT-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**DC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
dc(1) recognizes the following environment variables:
**DC_ENV_ARGS**
: This is another way to give command-line arguments to dc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **DC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs. Another use would
be to use the **-e** option to set **scale** to a value other than **0**.
The code that parses **DC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some dc file.dc"** will be correctly parsed, but the string
**"/home/gavin/some \"dc\" file.dc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
- double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
+ double quotes as the outside quotes, as in **"some 'dc' file.dc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **DC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**DC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), dc(1) will output
lines to that length, including the backslash newline combo. The default
line length is **70**.
**DC_EXPR_EXIT**
: If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the **-e** and/or
**-f** command-line options (and any equivalents).
# EXIT STATUS
dc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, using a negative number as a bound for the pseudo-random number
generator, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**), places (**\@**), left shift (**H**), and right shift (**h**)
operators.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, and using a token where it is
invalid.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, and attempting an operation when
the stack has too few elements.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (dc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, dc(1) always exits
and returns **4**, no matter what mode dc(1) is in.
The other statuses will only be returned when dc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since dc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, dc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, dc(1) turns
on "TTY mode."
TTY mode is required for history to be enabled (see the **COMMAND LINE HISTORY**
section). It is also required to enable special handling for **SIGINT** signals.
The prompt is enabled in TTY mode.
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause dc(1) to stop execution of the current input. If
dc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If dc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If dc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to dc(1) as it is executing a file, it
can seem as though dc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause dc(1) to clean up and exit, and it uses the
default handler for all other signals. The one exception is **SIGHUP**; in that
case, when dc(1) is in TTY mode, a **SIGHUP** will cause dc(1) to clean up and
exit.
# COMMAND LINE HISTORY
dc(1) supports interactive command-line editing. If dc(1) is in TTY mode (see
the **TTY MODE** section), history is enabled. Previous lines can be recalled
and edited with the arrow keys.
**Note**: tabs are converted to 8 spaces.
# SEE ALSO
bc(1)
# STANDARDS
The dc(1) utility operators are compliant with the operators in the bc(1)
[IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1] specification.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHOR
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
diff --git a/contrib/bc/manuals/dc/NP.1 b/contrib/bc/manuals/dc/NP.1
index 30e6333389c6..7c799d0ee25b 100644
--- a/contrib/bc/manuals/dc/NP.1
+++ b/contrib/bc/manuals/dc/NP.1
@@ -1,1327 +1,1340 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "DC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "DC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH Name
.PP
dc - arbitrary-precision decimal reverse-Polish notation calculator
.SH SYNOPSIS
.PP
\f[B]dc\f[R] [\f[B]-hiPvVx\f[R]] [\f[B]\[en]version\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]no-prompt\f[R]] [\f[B]\[en]extended-register\f[R]]
[\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
dc(1) is an arbitrary-precision calculator.
It uses a stack (reverse Polish notation) to store numbers and results
of computations.
Arithmetic operations pop arguments off of the stack and push the
results.
.PP
If no files are given on the command-line as extra arguments (i.e., not
as \f[B]-f\f[R] or \f[B]\[en]file\f[R] arguments), then dc(1) reads from
\f[B]stdin\f[R].
Otherwise, those files are processed, and dc(1) will then exit.
.PP
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where \f[B]-e\f[R] (\f[B]\[en]expression\f[R]) and
\f[B]-f\f[R] (\f[B]\[en]file\f[R]) arguments cause dc(1) to execute them
and exit.
The reason for this is that this dc(1) allows users to set arguments in
the environment variable \f[B]DC_ENV_ARGS\f[R] (see the \f[B]ENVIRONMENT
VARIABLES\f[R] section).
Any expressions given on the command-line should be used to set up a
standard environment.
For example, if a user wants the \f[B]scale\f[R] always set to
\f[B]10\f[R], they can set \f[B]DC_ENV_ARGS\f[R] to \f[B]-e 10k\f[R],
and this dc(1) will always start with a \f[B]scale\f[R] of \f[B]10\f[R].
.PP
If users want to have dc(1) exit after processing all input from
\f[B]-e\f[R] and \f[B]-f\f[R] arguments (and their equivalents), then
they can just simply add \f[B]-e q\f[R] as the last command-line
argument or define the environment variable \f[B]DC_EXPR_EXIT\f[R].
.SH OPTIONS
.PP
The following are the options that dc(1) accepts.
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
This option is a no-op.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-x\f[R] \f[B]\[en]extended-register\f[R]
Enables extended register mode.
See the \f[I]Extended Register Mode\f[R] subsection of the
\f[B]REGISTERS\f[R] section for more information.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]DC_ENV_ARGS\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]dc >&-\f[R], it will quit with an error.
This is done so that dc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]dc 2>&-\f[R], it will quit with an error.
This is done so that dc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
Each item in the input source code, either a number (see the
\f[B]NUMBERS\f[R] section) or a command (see the \f[B]COMMANDS\f[R]
section), is processed and executed, in order.
Input is processed immediately when entered.
.PP
\f[B]ibase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to interpret constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]ibase\f[R] is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in dc(1)
programs with the \f[B]T\f[R] command.
.PP
\f[B]obase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]DC_BASE_MAX\f[R] and
can be queried with the \f[B]U\f[R] command.
The min allowable value for \f[B]obase\f[R] is \f[B]0\f[R].
If \f[B]obase\f[R] is \f[B]0\f[R], values are output in scientific
notation, and if \f[B]obase\f[R] is \f[B]1\f[R], values are output in
engineering notation.
Otherwise, values are output in the specified base.
.PP
Outputting in scientific and engineering notations are \f[B]non-portable
extensions\f[R].
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a register (see the \f[B]REGISTERS\f[R] section) that sets the
precision of any operations (with exceptions).
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] can be queried in dc(1)
programs with the \f[B]V\f[R] command.
.PP
\f[B]seed\f[R] is a register containing the current seed for the
pseudo-random number generator.
If the current value of \f[B]seed\f[R] is queried and stored, then if it
is assigned to \f[B]seed\f[R] later, the pseudo-random number generator
is guaranteed to produce the same sequence of pseudo-random numbers that
were generated after the value of \f[B]seed\f[R] was first queried.
.PP
Multiple values assigned to \f[B]seed\f[R] can produce the same sequence
of pseudo-random numbers.
Likewise, when a value is assigned to \f[B]seed\f[R], it is not
guaranteed that querying \f[B]seed\f[R] immediately after will return
the same value.
In addition, the value of \f[B]seed\f[R] will change after any call to
the \f[B]\[cq]\f[R] command or the \f[B]\[dq]\f[R] command that does not
get receive a value of \f[B]0\f[R] or \f[B]1\f[R].
The maximum integer returned by the \f[B]\[cq]\f[R] command can be
queried with the \f[B]W\f[R] command.
.PP
\f[B]Note\f[R]: The values returned by the pseudo-random number
generator with the \f[B]\[cq]\f[R] and \f[B]\[dq]\f[R] commands are
guaranteed to \f[B]NOT\f[R] be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator.
However, they \f[I]are\f[R] guaranteed to be reproducible with identical
\f[B]seed\f[R] values.
-This means that the pseudo-random values from bc(1) should only be used
+This means that the pseudo-random values from dc(1) should only be used
where a reproducible stream of pseudo-random numbers is
\f[I]ESSENTIAL\f[R].
In any other case, use a non-seeded pseudo-random number generator.
.PP
The pseudo-random number generator, \f[B]seed\f[R], and all associated
operations are \f[B]non-portable extensions\f[R].
.SS Comments
.PP
Comments go from \f[B]#\f[R] until, and not including, the next newline.
This is a \f[B]non-portable extension\f[R].
.SH NUMBERS
.PP
Numbers are strings made up of digits, uppercase letters up to
\f[B]F\f[R], and at most \f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]DC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]F\f[R] alone always equals decimal \f[B]15\f[R].
.PP
In addition, dc(1) accepts numbers in scientific notation.
These have the form \f[B]<number>e<integer>\f[R].
The exponent (the portion after the \f[B]e\f[R]) must be an integer.
An example is \f[B]1.89237e9\f[R], which is equal to
\f[B]1892370000\f[R].
Negative exponents are also allowed, so \f[B]4.2890e_3\f[R] is equal to
\f[B]0.0042890\f[R].
.PP
\f[B]WARNING\f[R]: Both the number and the exponent in scientific
notation are interpreted according to the current \f[B]ibase\f[R], but
the number is still multiplied by \f[B]10\[ha]exponent\f[R] regardless
of the current \f[B]ibase\f[R].
For example, if \f[B]ibase\f[R] is \f[B]16\f[R] and dc(1) is given the
number string \f[B]FFeA\f[R], the resulting decimal number will be
\f[B]2550000000000\f[R], and if dc(1) is given the number string
\f[B]10e_4\f[R], the resulting decimal number will be \f[B]0.0016\f[R].
.PP
Accepting input as scientific notation is a \f[B]non-portable
extension\f[R].
.SH COMMANDS
.PP
The valid commands are listed below.
.SS Printing
.PP
These commands are used for printing.
.PP
Note that both scientific notation and engineering notation are
available for printing numbers.
Scientific notation is activated by assigning \f[B]0\f[R] to
\f[B]obase\f[R] using \f[B]0o\f[R], and engineering notation is
activated by assigning \f[B]1\f[R] to \f[B]obase\f[R] using
\f[B]1o\f[R].
To deactivate them, just assign a different value to \f[B]obase\f[R].
.PP
Printing numbers in scientific notation and/or engineering notation is a
\f[B]non-portable extension\f[R].
.TP
\f[B]p\f[R]
Prints the value on top of the stack, whether number or string, and
prints a newline after.
.RS
.PP
This does not alter the stack.
.RE
.TP
\f[B]n\f[R]
Prints the value on top of the stack, whether number or string, and pops
it off of the stack.
.TP
\f[B]P\f[R]
Pops a value off the stack.
.RS
.PP
If the value is a number, it is truncated and the absolute value of the
result is printed as though \f[B]obase\f[R] is \f[B]UCHAR_MAX+1\f[R] and
each digit is interpreted as an ASCII character, making it a byte
stream.
.PP
If the value is a string, it is printed without a trailing newline.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]f\f[R]
Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
.RS
.PP
Users should use this command when they get lost.
.RE
.SS Arithmetic
.PP
These are the commands used for arithmetic.
.TP
\f[B]+\f[R]
The top two values are popped off the stack, added, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]-\f[R]
The top two values are popped off the stack, subtracted, and the result
is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]*\f[R]
The top two values are popped off the stack, multiplied, and the result
is pushed onto the stack.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The top two values are popped off the stack, divided, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]%\f[R]
The top two values are popped off the stack, remaindered, and the result
is pushed onto the stack.
.RS
.PP
Remaindering is equivalent to 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R], and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]\[ti]\f[R]
The top two values are popped off the stack, divided and remaindered,
and the results (divided first, remainder second) are pushed onto the
stack.
This is equivalent to \f[B]x y / x y %\f[R] except that \f[B]x\f[R] and
\f[B]y\f[R] are only evaluated once.
.RS
.PP
The first value popped off of the stack must be non-zero.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
.RE
.TP
\f[B]v\f[R]
The top value is popped off the stack, its square root is computed, and
the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The value popped off of the stack must be non-negative.
.RE
.TP
\f[B]_\f[R]
If this command \f[I]immediately\f[R] precedes a number (i.e., no spaces
or other commands), then that number is input as a negative number.
.RS
.PP
Otherwise, the top value on the stack is popped and copied, and the copy
is negated and pushed onto the stack.
This behavior without a number is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]b\f[R]
The top value is popped off the stack, and if it is zero, it is pushed
back onto the stack.
Otherwise, its absolute value is pushed onto the stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]|\f[R]
The top three values are popped off the stack, a modular exponentiation
is computed, and the result is pushed onto the stack.
.RS
.PP
The first value popped is used as the reduction modulus and must be an
integer and non-zero.
The second value popped is used as the exponent and must be an integer
and non-negative.
The third value popped is the base and must be an integer.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]$\f[R]
The top value is popped off the stack and copied, and the copy is
truncated and pushed onto the stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[at]\f[R]
The top two values are popped off the stack, and the precision of the
second is set to the value of the first, whether by truncation or
extension.
.RS
.PP
The first value popped off of the stack must be an integer and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]H\f[R]
The top two values are popped off the stack, and the second is shifted
left (radix shifted right) to the value of the first.
.RS
.PP
The first value popped off of the stack must be an integer and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]h\f[R]
The top two values are popped off the stack, and the second is shifted
right (radix shifted left) to the value of the first.
.RS
.PP
The first value popped off of the stack must be an integer and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]G\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if they are equal, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]N\f[R]
The top value is popped off of the stack, and if it a \f[B]0\f[R], a
\f[B]1\f[R] is pushed; otherwise, a \f[B]0\f[R] is pushed.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B](\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]{\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than or equal to the second,
or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B])\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]}\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than or equal to the
second, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]M\f[R]
The top two values are popped off of the stack.
If they are both non-zero, a \f[B]1\f[R] is pushed onto the stack.
If either of them is zero, or both of them are, then a \f[B]0\f[R] is
pushed onto the stack.
.RS
.PP
This is like the \f[B]&&\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]m\f[R]
The top two values are popped off of the stack.
If at least one of them is non-zero, a \f[B]1\f[R] is pushed onto the
stack.
If both of them are zero, then a \f[B]0\f[R] is pushed onto the stack.
.RS
.PP
This is like the \f[B]||\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Pseudo-Random Number Generator
.PP
dc(1) has a built-in pseudo-random number generator.
These commands query the pseudo-random number generator.
(See Parameters for more information about the \f[B]seed\f[R] value that
controls the pseudo-random number generator.)
.PP
The pseudo-random number generator is guaranteed to \f[B]NOT\f[R] be
cryptographically secure.
.TP
\f[B]\[cq]\f[R]
Generates an integer between 0 and \f[B]DC_RAND_MAX\f[R], inclusive (see
the \f[B]LIMITS\f[R] section).
.RS
.PP
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[dq]\f[R]
Pops a value off of the stack, which is used as an \f[B]exclusive\f[R]
upper bound on the integer that will be generated.
If the bound is negative or is a non-integer, an error is raised, and
dc(1) resets (see the \f[B]RESET\f[R] section) while \f[B]seed\f[R]
remains unchanged.
If the bound is larger than \f[B]DC_RAND_MAX\f[R], the higher bound is
honored by generating several pseudo-random integers, multiplying them
by appropriate powers of \f[B]DC_RAND_MAX+1\f[R], and adding them
together.
Thus, the size of integer that can be generated with this command is
unbounded.
Using this command will change the value of \f[B]seed\f[R], unless the
operand is \f[B]0\f[R] or \f[B]1\f[R].
In that case, \f[B]0\f[R] is pushed onto the stack, and \f[B]seed\f[R]
is \f[I]not\f[R] changed.
.RS
.PP
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Stack Control
.PP
These commands control the stack.
.TP
\f[B]c\f[R]
Removes all items from (\[lq]clears\[rq]) the stack.
.TP
\f[B]d\f[R]
Copies the item on top of the stack (\[lq]duplicates\[rq]) and pushes
the copy onto the stack.
.TP
\f[B]r\f[R]
Swaps (\[lq]reverses\[rq]) the two top items on the stack.
.TP
\f[B]R\f[R]
Pops (\[lq]removes\[rq]) the top value from the stack.
.SS Register Control
.PP
These commands control registers (see the \f[B]REGISTERS\f[R] section).
.TP
\f[B]s\f[R]\f[I]r\f[R]
Pops the value off the top of the stack and stores it into register
\f[I]r\f[R].
.TP
\f[B]l\f[R]\f[I]r\f[R]
Copies the value in register \f[I]r\f[R] and pushes it onto the stack.
This does not alter the contents of \f[I]r\f[R].
.TP
\f[B]S\f[R]\f[I]r\f[R]
Pops the value off the top of the (main) stack and pushes it onto the
stack of register \f[I]r\f[R].
The previous value of the register becomes inaccessible.
.TP
\f[B]L\f[R]\f[I]r\f[R]
Pops the value off the top of the stack for register \f[I]r\f[R] and
push it onto the main stack.
The previous value in the stack for register \f[I]r\f[R], if any, is now
accessible via the \f[B]l\f[R]\f[I]r\f[R] command.
.SS Parameters
.PP
These commands control the values of \f[B]ibase\f[R], \f[B]obase\f[R],
\f[B]scale\f[R], and \f[B]seed\f[R].
Also see the \f[B]SYNTAX\f[R] section.
.TP
\f[B]i\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]ibase\f[R], which must be between \f[B]2\f[R] and \f[B]16\f[R],
inclusive.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]o\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]obase\f[R], which must be between \f[B]0\f[R] and
\f[B]DC_BASE_MAX\f[R], inclusive (see the \f[B]LIMITS\f[R] section and
the \f[B]NUMBERS\f[R] section).
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]k\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]scale\f[R], which must be non-negative.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]j\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]seed\f[R].
The meaning of \f[B]seed\f[R] is dependent on the current pseudo-random
number generator but is guaranteed to not change except for new major
versions.
.RS
.PP
The \f[I]scale\f[R] and sign of the value may be significant.
.PP
If a previously used \f[B]seed\f[R] value is used again, the
pseudo-random number generator is guaranteed to produce the same
sequence of pseudo-random numbers as it did when the \f[B]seed\f[R]
value was previously used.
.PP
The exact value assigned to \f[B]seed\f[R] is not guaranteed to be
returned if the \f[B]J\f[R] command is used.
However, if \f[B]seed\f[R] \f[I]does\f[R] return a different value, both
values, when assigned to \f[B]seed\f[R], are guaranteed to produce the
same sequence of pseudo-random numbers.
This means that certain values assigned to \f[B]seed\f[R] will not
produce unique sequences of pseudo-random numbers.
.PP
There is no limit to the length (number of significant decimal digits)
or \f[I]scale\f[R] of the value that can be assigned to \f[B]seed\f[R].
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]I\f[R]
Pushes the current value of \f[B]ibase\f[R] onto the main stack.
.TP
\f[B]O\f[R]
Pushes the current value of \f[B]obase\f[R] onto the main stack.
.TP
\f[B]K\f[R]
Pushes the current value of \f[B]scale\f[R] onto the main stack.
.TP
\f[B]J\f[R]
Pushes the current value of \f[B]seed\f[R] onto the main stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]T\f[R]
Pushes the maximum allowable value of \f[B]ibase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]U\f[R]
Pushes the maximum allowable value of \f[B]obase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]V\f[R]
Pushes the maximum allowable value of \f[B]scale\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]W\f[R]
Pushes the maximum (inclusive) integer that can be generated with the
\f[B]\[cq]\f[R] pseudo-random number generator command.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Strings
.PP
The following commands control strings.
.PP
dc(1) can work with both numbers and strings, and registers (see the
\f[B]REGISTERS\f[R] section) can hold both strings and numbers.
dc(1) always knows whether the contents of a register are a string or a
number.
.PP
While arithmetic operations have to have numbers, and will print an
error if given a string, other commands accept strings.
.PP
Strings can also be executed as macros.
For example, if the string \f[B][1pR]\f[R] is executed as a macro, then
the code \f[B]1pR\f[R] is executed, meaning that the \f[B]1\f[R] will be
printed with a newline after and then popped from the stack.
.TP
\f[B][\f[R]_characters_\f[B]]\f[R]
Makes a string containing \f[I]characters\f[R] and pushes it onto the
stack.
.RS
.PP
If there are brackets (\f[B][\f[R] and \f[B]]\f[R]) in the string, then
they must be balanced.
Unbalanced brackets can be escaped using a backslash (\f[B]\[rs]\f[R])
character.
.PP
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the
(first) backslash is not.
.RE
.TP
\f[B]a\f[R]
The value on top of the stack is popped.
.RS
.PP
If it is a number, it is truncated and its absolute value is taken.
The result mod \f[B]UCHAR_MAX+1\f[R] is calculated.
If that result is \f[B]0\f[R], push an empty string; otherwise, push a
one-character string where the character is the result of the mod
interpreted as an ASCII character.
.PP
If it is a string, then a new string is made.
If the original string is empty, the new string is empty.
If it is not, then the first character of the original string is used to
create the new string as a one-character string.
The new string is then pushed onto the stack.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]x\f[R]
Pops a value off of the top of the stack.
.RS
.PP
If it is a number, it is pushed back onto the stack.
.PP
If it is a string, it is executed as a macro.
.PP
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is greater than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
For example, \f[B]0 1>a\f[R] will execute the contents of register
\f[B]a\f[R], and \f[B]1 0>a\f[R] will not.
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not greater than the second (less than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is less than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not less than the second (greater than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is equal to the second, then the contents of register
\f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not equal to the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]?\f[R]
Reads a line from the \f[B]stdin\f[R] and executes it.
This is to allow macros to request input from users.
.TP
\f[B]q\f[R]
During execution of a macro, this exits the execution of that macro and
the execution of the macro that executed it.
If there are no macros, or only one macro executing, dc(1) exits.
.TP
\f[B]Q\f[R]
Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack.
If the number of levels to pop is greater than the number of executing
macros, dc(1) exits.
.SS Status
.PP
These commands query status of the stack or its top value.
.TP
\f[B]Z\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, calculates the number of significant decimal digits
it has and pushes the result.
.PP
If it is a string, pushes the number of characters the string has.
.RE
.TP
\f[B]X\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, pushes the \f[I]scale\f[R] of the value onto the
stack.
.PP
If it is a string, pushes \f[B]0\f[R].
.RE
.TP
\f[B]z\f[R]
Pushes the current stack depth (before execution of this command).
.SS Arrays
.PP
These commands manipulate arrays.
.TP
\f[B]:\f[R]\f[I]r\f[R]
Pops the top two values off of the stack.
The second value will be stored in the array \f[I]r\f[R] (see the
\f[B]REGISTERS\f[R] section), indexed by the first value.
.TP
\f[B];\f[R]\f[I]r\f[R]
Pops the value on top of the stack and uses it as an index into the
array \f[I]r\f[R].
The selected value is then pushed onto the stack.
.SH REGISTERS
.PP
Registers are names that can store strings, numbers, and arrays.
(Number/string registers do not interfere with array registers.)
.PP
Each register is also its own stack, so the current register value is
the top of the stack for the register.
All registers, when first referenced, have one value (\f[B]0\f[R]) in
their stack.
.PP
In non-extended register mode, a register name is just the single
character that follows any command that needs a register name.
The only exception is a newline (\f[B]`\[rs]n'\f[R]); it is a parse
error for a newline to be used as a register name.
.SS Extended Register Mode
.PP
Unlike most other dc(1) implentations, this dc(1) provides nearly
unlimited amounts of registers, if extended register mode is enabled.
.PP
If extended register mode is enabled (\f[B]-x\f[R] or
\f[B]\[en]extended-register\f[R] command-line arguments are given), then
normal single character registers are used \f[I]unless\f[R] the
character immediately following a command that needs a register name is
a space (according to \f[B]isspace()\f[R]) and not a newline
(\f[B]`\[rs]n'\f[R]).
.PP
In that case, the register name is found according to the regex
\f[B][a-z][a-z0-9_]*\f[R] (like bc(1) identifiers), and it is a parse
error if the next non-space characters do not match that regex.
.SH RESET
.PP
When dc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any macros that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all macros returned) is skipped.
.PP
Thus, when dc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.SH PERFORMANCE
.PP
Most dc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This dc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]DC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]DC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]DC_BASE_DIGS\f[R].
.PP
In addition, this dc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]DC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on dc(1):
.TP
\f[B]DC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
dc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]DC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]DC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]DC_BASE_DIGS\f[R].
.TP
\f[B]DC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]DC_BASE_POW\f[R].
.TP
\f[B]DC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]DC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_RAND_MAX\f[R]
The maximum integer (inclusive) returned by the \f[B]\[cq]\f[R] command,
if dc(1).
Set at \f[B]2\[ha]DC_LONG_BIT-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]DC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
dc(1) recognizes the following environment variables:
.TP
\f[B]DC_ENV_ARGS\f[R]
This is another way to give command-line arguments to dc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]DC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs.
Another use would be to use the \f[B]-e\f[R] option to set
\f[B]scale\f[R] to a value other than \f[B]0\f[R].
.RS
.PP
The code that parses \f[B]DC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some dc file.dc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]dc\[dq] file.dc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
-in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
+in \f[B]\[rq]some `dc' file.dc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]DC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]DC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), dc(1) will output lines to that length,
including the backslash newline combo.
The default line length is \f[B]70\f[R].
.TP
\f[B]DC_EXPR_EXIT\f[R]
If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the
\f[B]-e\f[R] and/or \f[B]-f\f[R] command-line options (and any
equivalents).
.SH EXIT STATUS
.PP
dc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, using a negative number as a bound for the
pseudo-random number generator, attempting to convert a negative number
to a hardware integer, overflow when converting a number to a hardware
integer, and attempting to use a non-integer where an integer is
required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]), places (\f[B]\[at]\f[R]), left shift
(\f[B]H\f[R]), and right shift (\f[B]h\f[R]) operators.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, and using a
token where it is invalid.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, and attempting an operation when the
stack has too few elements.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (dc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, dc(1)
always exits and returns \f[B]4\f[R], no matter what mode dc(1) is in.
.PP
The other statuses will only be returned when dc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
dc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, dc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, dc(1) turns on \[lq]TTY mode.\[rq]
.PP
TTY mode is required for history to be enabled (see the \f[B]COMMAND
LINE HISTORY\f[R] section).
It is also required to enable special handling for \f[B]SIGINT\f[R]
signals.
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause dc(1) to stop execution of the
current input.
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If dc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If dc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to dc(1) as it is
executing a file, it can seem as though dc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause dc(1) to clean up and
exit, and it uses the default handler for all other signals.
The one exception is \f[B]SIGHUP\f[R]; in that case, when dc(1) is in
TTY mode, a \f[B]SIGHUP\f[R] will cause dc(1) to clean up and exit.
.SH COMMAND LINE HISTORY
.PP
dc(1) supports interactive command-line editing.
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), history is
enabled.
Previous lines can be recalled and edited with the arrow keys.
.PP
\f[B]Note\f[R]: tabs are converted to 8 spaces.
.SH SEE ALSO
.PP
bc(1)
.SH STANDARDS
.PP
The dc(1) utility operators are compliant with the operators in the
bc(1) IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHOR
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/dc/NP.1.md b/contrib/bc/manuals/dc/NP.1.md
index 74057fb80afc..60cc89078876 100644
--- a/contrib/bc/manuals/dc/NP.1.md
+++ b/contrib/bc/manuals/dc/NP.1.md
@@ -1,1188 +1,1197 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# Name
dc - arbitrary-precision decimal reverse-Polish notation calculator
# SYNOPSIS
**dc** [**-hiPvVx**] [**--version**] [**--help**] [**--interactive**] [**--no-prompt**] [**--extended-register**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...] [*file*...]
# DESCRIPTION
dc(1) is an arbitrary-precision calculator. It uses a stack (reverse Polish
notation) to store numbers and results of computations. Arithmetic operations
pop arguments off of the stack and push the results.
If no files are given on the command-line as extra arguments (i.e., not as
**-f** or **--file** arguments), then dc(1) reads from **stdin**. Otherwise,
those files are processed, and dc(1) will then exit.
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where **-e** (**--expression**) and **-f** (**--file**)
arguments cause dc(1) to execute them and exit. The reason for this is that this
dc(1) allows users to set arguments in the environment variable **DC_ENV_ARGS**
(see the **ENVIRONMENT VARIABLES** section). Any expressions given on the
command-line should be used to set up a standard environment. For example, if a
user wants the **scale** always set to **10**, they can set **DC_ENV_ARGS** to
**-e 10k**, and this dc(1) will always start with a **scale** of **10**.
If users want to have dc(1) exit after processing all input from **-e** and
**-f** arguments (and their equivalents), then they can just simply add **-e q**
as the last command-line argument or define the environment variable
**DC_EXPR_EXIT**.
# OPTIONS
The following are the options that dc(1) accepts.
**-h**, **--help**
: Prints a usage message and quits.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-P**, **--no-prompt**
: This option is a no-op.
This is a **non-portable extension**.
**-x** **--extended-register**
: Enables extended register mode. See the *Extended Register Mode* subsection
of the **REGISTERS** section for more information.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **DC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **dc <file> >&-**, it will quit with an error. This
is done so that dc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **dc <file> 2>&-**, it will quit with an error. This
is done so that dc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
Each item in the input source code, either a number (see the **NUMBERS**
section) or a command (see the **COMMANDS** section), is processed and executed,
in order. Input is processed immediately when entered.
**ibase** is a register (see the **REGISTERS** section) that determines how to
interpret constant numbers. It is the "input" base, or the number base used for
interpreting input numbers. **ibase** is initially **10**. The max allowable
value for **ibase** is **16**. The min allowable value for **ibase** is **2**.
The max allowable value for **ibase** can be queried in dc(1) programs with the
**T** command.
**obase** is a register (see the **REGISTERS** section) that determines how to
output results. It is the "output" base, or the number base used for outputting
numbers. **obase** is initially **10**. The max allowable value for **obase** is
**DC_BASE_MAX** and can be queried with the **U** command. The min allowable
value for **obase** is **0**. If **obase** is **0**, values are output in
scientific notation, and if **obase** is **1**, values are output in engineering
notation. Otherwise, values are output in the specified base.
Outputting in scientific and engineering notations are **non-portable
extensions**.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a register (see the
**REGISTERS** section) that sets the precision of any operations (with
exceptions). **scale** is initially **0**. **scale** cannot be negative. The max
allowable value for **scale** can be queried in dc(1) programs with the **V**
command.
**seed** is a register containing the current seed for the pseudo-random number
generator. If the current value of **seed** is queried and stored, then if it is
assigned to **seed** later, the pseudo-random number generator is guaranteed to
produce the same sequence of pseudo-random numbers that were generated after the
value of **seed** was first queried.
Multiple values assigned to **seed** can produce the same sequence of
pseudo-random numbers. Likewise, when a value is assigned to **seed**, it is not
guaranteed that querying **seed** immediately after will return the same value.
In addition, the value of **seed** will change after any call to the **'**
command or the **"** command that does not get receive a value of **0** or
**1**. The maximum integer returned by the **'** command can be queried with the
**W** command.
**Note**: The values returned by the pseudo-random number generator with the
**'** and **"** commands are guaranteed to **NOT** be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator. However,
they *are* guaranteed to be reproducible with identical **seed** values. This
-means that the pseudo-random values from bc(1) should only be used where a
+means that the pseudo-random values from dc(1) should only be used where a
reproducible stream of pseudo-random numbers is *ESSENTIAL*. In any other case,
use a non-seeded pseudo-random number generator.
The pseudo-random number generator, **seed**, and all associated operations are
**non-portable extensions**.
## Comments
Comments go from **#** until, and not including, the next newline. This is a
**non-portable extension**.
# NUMBERS
Numbers are strings made up of digits, uppercase letters up to **F**, and at
most **1** period for a radix. Numbers can have up to **DC_NUM_MAX** digits.
Uppercase letters are equal to **9** + their position in the alphabet (i.e.,
**A** equals **10**, or **9+1**). If a digit or letter makes no sense with the
current value of **ibase**, they are set to the value of the highest valid digit
in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **F** alone always equals decimal
**15**.
In addition, dc(1) accepts numbers in scientific notation. These have the form
**\<number\>e\<integer\>**. The exponent (the portion after the **e**) must be
an integer. An example is **1.89237e9**, which is equal to **1892370000**.
Negative exponents are also allowed, so **4.2890e_3** is equal to **0.0042890**.
**WARNING**: Both the number and the exponent in scientific notation are
interpreted according to the current **ibase**, but the number is still
multiplied by **10\^exponent** regardless of the current **ibase**. For example,
if **ibase** is **16** and dc(1) is given the number string **FFeA**, the
resulting decimal number will be **2550000000000**, and if dc(1) is given the
number string **10e_4**, the resulting decimal number will be **0.0016**.
Accepting input as scientific notation is a **non-portable extension**.
# COMMANDS
The valid commands are listed below.
## Printing
These commands are used for printing.
Note that both scientific notation and engineering notation are available for
printing numbers. Scientific notation is activated by assigning **0** to
**obase** using **0o**, and engineering notation is activated by assigning **1**
to **obase** using **1o**. To deactivate them, just assign a different value to
**obase**.
Printing numbers in scientific notation and/or engineering notation is a
**non-portable extension**.
**p**
: Prints the value on top of the stack, whether number or string, and prints a
newline after.
This does not alter the stack.
**n**
: Prints the value on top of the stack, whether number or string, and pops it
off of the stack.
**P**
: Pops a value off the stack.
If the value is a number, it is truncated and the absolute value of the
result is printed as though **obase** is **UCHAR_MAX+1** and each digit is
interpreted as an ASCII character, making it a byte stream.
If the value is a string, it is printed without a trailing newline.
This is a **non-portable extension**.
**f**
: Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
Users should use this command when they get lost.
## Arithmetic
These are the commands used for arithmetic.
**+**
: The top two values are popped off the stack, added, and the result is pushed
onto the stack. The *scale* of the result is equal to the max *scale* of
both operands.
**-**
: The top two values are popped off the stack, subtracted, and the result is
pushed onto the stack. The *scale* of the result is equal to the max
*scale* of both operands.
**\***
: The top two values are popped off the stack, multiplied, and the result is
pushed onto the stack. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result
is equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The top two values are popped off the stack, divided, and the result is
pushed onto the stack. The *scale* of the result is equal to **scale**.
The first value popped off of the stack must be non-zero.
**%**
: The top two values are popped off the stack, remaindered, and the result is
pushed onto the stack.
Remaindering is equivalent to 1) Computing **a/b** to current **scale**, and
2) Using the result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The first value popped off of the stack must be non-zero.
**~**
: The top two values are popped off the stack, divided and remaindered, and
the results (divided first, remainder second) are pushed onto the stack.
This is equivalent to **x y / x y %** except that **x** and **y** are only
evaluated once.
The first value popped off of the stack must be non-zero.
This is a **non-portable extension**.
**\^**
: The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack. The *scale* of
the result is equal to **scale**.
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
**v**
: The top value is popped off the stack, its square root is computed, and the
result is pushed onto the stack. The *scale* of the result is equal to
**scale**.
The value popped off of the stack must be non-negative.
**\_**
: If this command *immediately* precedes a number (i.e., no spaces or other
commands), then that number is input as a negative number.
Otherwise, the top value on the stack is popped and copied, and the copy is
negated and pushed onto the stack. This behavior without a number is a
**non-portable extension**.
**b**
: The top value is popped off the stack, and if it is zero, it is pushed back
onto the stack. Otherwise, its absolute value is pushed onto the stack.
This is a **non-portable extension**.
**|**
: The top three values are popped off the stack, a modular exponentiation is
computed, and the result is pushed onto the stack.
The first value popped is used as the reduction modulus and must be an
integer and non-zero. The second value popped is used as the exponent and
must be an integer and non-negative. The third value popped is the base and
must be an integer.
This is a **non-portable extension**.
**\$**
: The top value is popped off the stack and copied, and the copy is truncated
and pushed onto the stack.
This is a **non-portable extension**.
**\@**
: The top two values are popped off the stack, and the precision of the second
is set to the value of the first, whether by truncation or extension.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**H**
: The top two values are popped off the stack, and the second is shifted left
(radix shifted right) to the value of the first.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**h**
: The top two values are popped off the stack, and the second is shifted right
(radix shifted left) to the value of the first.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**G**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if they are equal, or **0** otherwise.
This is a **non-portable extension**.
**N**
: The top value is popped off of the stack, and if it a **0**, a **1** is
pushed; otherwise, a **0** is pushed.
This is a **non-portable extension**.
**(**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than the second, or **0** otherwise.
This is a **non-portable extension**.
**{**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than or equal to the second, or **0**
otherwise.
This is a **non-portable extension**.
**)**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than the second, or **0** otherwise.
This is a **non-portable extension**.
**}**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than or equal to the second, or
**0** otherwise.
This is a **non-portable extension**.
**M**
: The top two values are popped off of the stack. If they are both non-zero, a
**1** is pushed onto the stack. If either of them is zero, or both of them
are, then a **0** is pushed onto the stack.
This is like the **&&** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
**m**
: The top two values are popped off of the stack. If at least one of them is
non-zero, a **1** is pushed onto the stack. If both of them are zero, then a
**0** is pushed onto the stack.
This is like the **||** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
## Pseudo-Random Number Generator
dc(1) has a built-in pseudo-random number generator. These commands query the
pseudo-random number generator. (See Parameters for more information about the
**seed** value that controls the pseudo-random number generator.)
The pseudo-random number generator is guaranteed to **NOT** be
cryptographically secure.
**'**
: Generates an integer between 0 and **DC_RAND_MAX**, inclusive (see the
**LIMITS** section).
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
This is a **non-portable extension**.
**"**
: Pops a value off of the stack, which is used as an **exclusive** upper bound
on the integer that will be generated. If the bound is negative or is a
non-integer, an error is raised, and dc(1) resets (see the **RESET**
section) while **seed** remains unchanged. If the bound is larger than
**DC_RAND_MAX**, the higher bound is honored by generating several
pseudo-random integers, multiplying them by appropriate powers of
**DC_RAND_MAX+1**, and adding them together. Thus, the size of integer that
can be generated with this command is unbounded. Using this command will
change the value of **seed**, unless the operand is **0** or **1**. In that
case, **0** is pushed onto the stack, and **seed** is *not* changed.
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
This is a **non-portable extension**.
## Stack Control
These commands control the stack.
**c**
: Removes all items from ("clears") the stack.
**d**
: Copies the item on top of the stack ("duplicates") and pushes the copy onto
the stack.
**r**
: Swaps ("reverses") the two top items on the stack.
**R**
: Pops ("removes") the top value from the stack.
## Register Control
These commands control registers (see the **REGISTERS** section).
**s***r*
: Pops the value off the top of the stack and stores it into register *r*.
**l***r*
: Copies the value in register *r* and pushes it onto the stack. This does not
alter the contents of *r*.
**S***r*
: Pops the value off the top of the (main) stack and pushes it onto the stack
of register *r*. The previous value of the register becomes inaccessible.
**L***r*
: Pops the value off the top of the stack for register *r* and push it onto
the main stack. The previous value in the stack for register *r*, if any, is
now accessible via the **l***r* command.
## Parameters
These commands control the values of **ibase**, **obase**, **scale**, and
**seed**. Also see the **SYNTAX** section.
**i**
: Pops the value off of the top of the stack and uses it to set **ibase**,
which must be between **2** and **16**, inclusive.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**o**
: Pops the value off of the top of the stack and uses it to set **obase**,
which must be between **0** and **DC_BASE_MAX**, inclusive (see the
**LIMITS** section and the **NUMBERS** section).
If the value on top of the stack has any *scale*, the *scale* is ignored.
**k**
: Pops the value off of the top of the stack and uses it to set **scale**,
which must be non-negative.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**j**
: Pops the value off of the top of the stack and uses it to set **seed**. The
meaning of **seed** is dependent on the current pseudo-random number
generator but is guaranteed to not change except for new major versions.
The *scale* and sign of the value may be significant.
If a previously used **seed** value is used again, the pseudo-random number
generator is guaranteed to produce the same sequence of pseudo-random
numbers as it did when the **seed** value was previously used.
The exact value assigned to **seed** is not guaranteed to be returned if the
**J** command is used. However, if **seed** *does* return a different value,
both values, when assigned to **seed**, are guaranteed to produce the same
sequence of pseudo-random numbers. This means that certain values assigned
to **seed** will not produce unique sequences of pseudo-random numbers.
There is no limit to the length (number of significant decimal digits) or
*scale* of the value that can be assigned to **seed**.
This is a **non-portable extension**.
**I**
: Pushes the current value of **ibase** onto the main stack.
**O**
: Pushes the current value of **obase** onto the main stack.
**K**
: Pushes the current value of **scale** onto the main stack.
**J**
: Pushes the current value of **seed** onto the main stack.
This is a **non-portable extension**.
**T**
: Pushes the maximum allowable value of **ibase** onto the main stack.
This is a **non-portable extension**.
**U**
: Pushes the maximum allowable value of **obase** onto the main stack.
This is a **non-portable extension**.
**V**
: Pushes the maximum allowable value of **scale** onto the main stack.
This is a **non-portable extension**.
**W**
: Pushes the maximum (inclusive) integer that can be generated with the **'**
pseudo-random number generator command.
This is a **non-portable extension**.
## Strings
The following commands control strings.
dc(1) can work with both numbers and strings, and registers (see the
**REGISTERS** section) can hold both strings and numbers. dc(1) always knows
whether the contents of a register are a string or a number.
While arithmetic operations have to have numbers, and will print an error if
given a string, other commands accept strings.
Strings can also be executed as macros. For example, if the string **[1pR]** is
executed as a macro, then the code **1pR** is executed, meaning that the **1**
will be printed with a newline after and then popped from the stack.
**\[**_characters_**\]**
: Makes a string containing *characters* and pushes it onto the stack.
If there are brackets (**\[** and **\]**) in the string, then they must be
balanced. Unbalanced brackets can be escaped using a backslash (**\\**)
character.
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the (first)
backslash is not.
**a**
: The value on top of the stack is popped.
If it is a number, it is truncated and its absolute value is taken. The
result mod **UCHAR_MAX+1** is calculated. If that result is **0**, push an
empty string; otherwise, push a one-character string where the character is
the result of the mod interpreted as an ASCII character.
If it is a string, then a new string is made. If the original string is
empty, the new string is empty. If it is not, then the first character of
the original string is used to create the new string as a one-character
string. The new string is then pushed onto the stack.
This is a **non-portable extension**.
**x**
: Pops a value off of the top of the stack.
If it is a number, it is pushed back onto the stack.
If it is a string, it is executed as a macro.
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
**\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is greater than the second, then the contents of register
*r* are executed.
For example, **0 1>a** will execute the contents of register **a**, and
**1 0>a** will not.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not greater than the second (less than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is less than the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not less than the second (greater than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is equal to the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not equal to the second, then the contents of register
*r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**?**
: Reads a line from the **stdin** and executes it. This is to allow macros to
request input from users.
**q**
: During execution of a macro, this exits the execution of that macro and the
execution of the macro that executed it. If there are no macros, or only one
macro executing, dc(1) exits.
**Q**
: Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack. If the number
of levels to pop is greater than the number of executing macros, dc(1)
exits.
## Status
These commands query status of the stack or its top value.
**Z**
: Pops a value off of the stack.
If it is a number, calculates the number of significant decimal digits it
has and pushes the result.
If it is a string, pushes the number of characters the string has.
**X**
: Pops a value off of the stack.
If it is a number, pushes the *scale* of the value onto the stack.
If it is a string, pushes **0**.
**z**
: Pushes the current stack depth (before execution of this command).
## Arrays
These commands manipulate arrays.
**:***r*
: Pops the top two values off of the stack. The second value will be stored in
the array *r* (see the **REGISTERS** section), indexed by the first value.
**;***r*
: Pops the value on top of the stack and uses it as an index into the array
*r*. The selected value is then pushed onto the stack.
# REGISTERS
Registers are names that can store strings, numbers, and arrays. (Number/string
registers do not interfere with array registers.)
Each register is also its own stack, so the current register value is the top of
the stack for the register. All registers, when first referenced, have one value
(**0**) in their stack.
In non-extended register mode, a register name is just the single character that
follows any command that needs a register name. The only exception is a newline
(**'\\n'**); it is a parse error for a newline to be used as a register name.
## Extended Register Mode
Unlike most other dc(1) implentations, this dc(1) provides nearly unlimited
amounts of registers, if extended register mode is enabled.
If extended register mode is enabled (**-x** or **--extended-register**
command-line arguments are given), then normal single character registers are
used *unless* the character immediately following a command that needs a
register name is a space (according to **isspace()**) and not a newline
(**'\\n'**).
In that case, the register name is found according to the regex
**\[a-z\]\[a-z0-9\_\]\*** (like bc(1) identifiers), and it is a parse error if
the next non-space characters do not match that regex.
# RESET
When dc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any macros that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
macros returned) is skipped.
Thus, when dc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
# PERFORMANCE
Most dc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This dc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **DC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **DC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**DC_BASE_DIGS**.
In addition, this dc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **DC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on dc(1):
**DC_LONG_BIT**
: The number of bits in the **long** type in the environment where dc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**DC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **DC_LONG_BIT**.
**DC_BASE_POW**
: The max decimal number that each large integer can store (see
**DC_BASE_DIGS**) plus **1**. Depends on **DC_BASE_DIGS**.
**DC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **DC_LONG_BIT**.
**DC_BASE_MAX**
: The maximum output base. Set at **DC_BASE_POW**.
**DC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**DC_SCALE_MAX**
: The maximum **scale**. Set at **DC_OVERFLOW_MAX-1**.
**DC_STRING_MAX**
: The maximum length of strings. Set at **DC_OVERFLOW_MAX-1**.
**DC_NAME_MAX**
: The maximum length of identifiers. Set at **DC_OVERFLOW_MAX-1**.
**DC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **DC_OVERFLOW_MAX-1**.
**DC_RAND_MAX**
: The maximum integer (inclusive) returned by the **'** command, if dc(1). Set
at **2\^DC_LONG_BIT-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**DC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
dc(1) recognizes the following environment variables:
**DC_ENV_ARGS**
: This is another way to give command-line arguments to dc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **DC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs. Another use would
be to use the **-e** option to set **scale** to a value other than **0**.
The code that parses **DC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some dc file.dc"** will be correctly parsed, but the string
**"/home/gavin/some \"dc\" file.dc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
- double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
+ double quotes as the outside quotes, as in **"some 'dc' file.dc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **DC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**DC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), dc(1) will output
lines to that length, including the backslash newline combo. The default
line length is **70**.
**DC_EXPR_EXIT**
: If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the **-e** and/or
**-f** command-line options (and any equivalents).
# EXIT STATUS
dc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, using a negative number as a bound for the pseudo-random number
generator, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**), places (**\@**), left shift (**H**), and right shift (**h**)
operators.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, and using a token where it is
invalid.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, and attempting an operation when
the stack has too few elements.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (dc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, dc(1) always exits
and returns **4**, no matter what mode dc(1) is in.
The other statuses will only be returned when dc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since dc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, dc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, dc(1) turns
on "TTY mode."
TTY mode is required for history to be enabled (see the **COMMAND LINE HISTORY**
section). It is also required to enable special handling for **SIGINT** signals.
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause dc(1) to stop execution of the current input. If
dc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If dc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If dc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to dc(1) as it is executing a file, it
can seem as though dc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause dc(1) to clean up and exit, and it uses the
default handler for all other signals. The one exception is **SIGHUP**; in that
case, when dc(1) is in TTY mode, a **SIGHUP** will cause dc(1) to clean up and
exit.
# COMMAND LINE HISTORY
dc(1) supports interactive command-line editing. If dc(1) is in TTY mode (see
the **TTY MODE** section), history is enabled. Previous lines can be recalled
and edited with the arrow keys.
**Note**: tabs are converted to 8 spaces.
# SEE ALSO
bc(1)
# STANDARDS
The dc(1) utility operators are compliant with the operators in the bc(1)
[IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1] specification.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHOR
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
diff --git a/contrib/bc/manuals/dc/P.1 b/contrib/bc/manuals/dc/P.1
index dbbee3e905c0..b28e0dadda48 100644
--- a/contrib/bc/manuals/dc/P.1
+++ b/contrib/bc/manuals/dc/P.1
@@ -1,1331 +1,1344 @@
.\"
.\" SPDX-License-Identifier: BSD-2-Clause
.\"
.\" Copyright (c) 2018-2021 Gavin D. Howard and contributors.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" * Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\"
.\" * Redistributions in binary form must reproduce the above copyright notice,
.\" this list of conditions and the following disclaimer in the documentation
.\" and/or other materials provided with the distribution.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.\"
-.TH "DC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "DC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
.SH Name
.PP
dc - arbitrary-precision decimal reverse-Polish notation calculator
.SH SYNOPSIS
.PP
\f[B]dc\f[R] [\f[B]-hiPvVx\f[R]] [\f[B]\[en]version\f[R]]
[\f[B]\[en]help\f[R]] [\f[B]\[en]interactive\f[R]]
[\f[B]\[en]no-prompt\f[R]] [\f[B]\[en]extended-register\f[R]]
[\f[B]-e\f[R] \f[I]expr\f[R]]
[\f[B]\[en]expression\f[R]=\f[I]expr\f[R]\&...] [\f[B]-f\f[R]
\f[I]file\f[R]\&...] [\f[B]-file\f[R]=\f[I]file\f[R]\&...]
[\f[I]file\f[R]\&...]
.SH DESCRIPTION
.PP
dc(1) is an arbitrary-precision calculator.
It uses a stack (reverse Polish notation) to store numbers and results
of computations.
Arithmetic operations pop arguments off of the stack and push the
results.
.PP
If no files are given on the command-line as extra arguments (i.e., not
as \f[B]-f\f[R] or \f[B]\[en]file\f[R] arguments), then dc(1) reads from
\f[B]stdin\f[R].
Otherwise, those files are processed, and dc(1) will then exit.
.PP
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where \f[B]-e\f[R] (\f[B]\[en]expression\f[R]) and
\f[B]-f\f[R] (\f[B]\[en]file\f[R]) arguments cause dc(1) to execute them
and exit.
The reason for this is that this dc(1) allows users to set arguments in
the environment variable \f[B]DC_ENV_ARGS\f[R] (see the \f[B]ENVIRONMENT
VARIABLES\f[R] section).
Any expressions given on the command-line should be used to set up a
standard environment.
For example, if a user wants the \f[B]scale\f[R] always set to
\f[B]10\f[R], they can set \f[B]DC_ENV_ARGS\f[R] to \f[B]-e 10k\f[R],
and this dc(1) will always start with a \f[B]scale\f[R] of \f[B]10\f[R].
.PP
If users want to have dc(1) exit after processing all input from
\f[B]-e\f[R] and \f[B]-f\f[R] arguments (and their equivalents), then
they can just simply add \f[B]-e q\f[R] as the last command-line
argument or define the environment variable \f[B]DC_EXPR_EXIT\f[R].
.SH OPTIONS
.PP
The following are the options that dc(1) accepts.
.TP
\f[B]-h\f[R], \f[B]\[en]help\f[R]
Prints a usage message and quits.
.TP
\f[B]-v\f[R], \f[B]-V\f[R], \f[B]\[en]version\f[R]
Print the version information (copyright header) and exit.
.TP
\f[B]-i\f[R], \f[B]\[en]interactive\f[R]
Forces interactive mode.
(See the \f[B]INTERACTIVE MODE\f[R] section.)
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-P\f[R], \f[B]\[en]no-prompt\f[R]
This option is a no-op.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-x\f[R] \f[B]\[en]extended-register\f[R]
Enables extended register mode.
See the \f[I]Extended Register Mode\f[R] subsection of the
\f[B]REGISTERS\f[R] section for more information.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-e\f[R] \f[I]expr\f[R], \f[B]\[en]expression\f[R]=\f[I]expr\f[R]
Evaluates \f[I]expr\f[R].
If multiple expressions are given, they are evaluated in order.
If files are given as well (see below), the expressions and files are
evaluated in the order given.
This means that if a file is given before an expression, the file is
read in and evaluated first.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
-\f[B]-f\f[R] or \f[B]\[en]file\f[R].
+\f[B]-f\f[R] or \f[B]\[en]file\f[R], whether on the command-line or in
+\f[B]DC_ENV_ARGS\f[R].
+However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]-f\f[R] \f[I]file\f[R], \f[B]\[en]file\f[R]=\f[I]file\f[R]
Reads in \f[I]file\f[R] and evaluates it, line by line, as though it
were read through \f[B]stdin\f[R].
If expressions are also given (see above), the expressions are evaluated
in the order given.
.RS
.PP
-After processing all expressions and files, dc(1) will exit, unless
+If this option is given on the command-line (i.e., not in
+\f[B]DC_ENV_ARGS\f[R], see the \f[B]ENVIRONMENT VARIABLES\f[R] section),
+then after processing all expressions and files, dc(1) will exit, unless
\f[B]-\f[R] (\f[B]stdin\f[R]) was given as an argument at least once to
\f[B]-f\f[R] or \f[B]\[en]file\f[R].
However, if any other \f[B]-e\f[R], \f[B]\[en]expression\f[R],
-\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after that,
-bc(1) will give a fatal error and exit.
+\f[B]-f\f[R], or \f[B]\[en]file\f[R] arguments are given after
+\f[B]-f-\f[R] or equivalent is given, dc(1) will give a fatal error and
+exit.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.PP
All long options are \f[B]non-portable extensions\f[R].
.SH STDOUT
.PP
Any non-error output is written to \f[B]stdout\f[R].
+In addition, if history (see the \f[B]HISTORY\f[R] section) and the
+prompt (see the \f[B]TTY MODE\f[R] section) are enabled, both are output
+to \f[B]stdout\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stdout\f[R], so if \f[B]stdout\f[R] is closed, as in
\f[B]dc >&-\f[R], it will quit with an error.
This is done so that dc(1) can report problems when \f[B]stdout\f[R] is
redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stdout\f[R] to \f[B]/dev/null\f[R].
.SH STDERR
.PP
Any error output is written to \f[B]stderr\f[R].
.PP
\f[B]Note\f[R]: Unlike other dc(1) implementations, this dc(1) will
issue a fatal error (see the \f[B]EXIT STATUS\f[R] section) if it cannot
write to \f[B]stderr\f[R], so if \f[B]stderr\f[R] is closed, as in
\f[B]dc 2>&-\f[R], it will quit with an error.
This is done so that dc(1) can exit with an error code when
\f[B]stderr\f[R] is redirected to a file.
.PP
If there are scripts that depend on the behavior of other dc(1)
implementations, it is recommended that those scripts be changed to
redirect \f[B]stderr\f[R] to \f[B]/dev/null\f[R].
.SH SYNTAX
.PP
Each item in the input source code, either a number (see the
\f[B]NUMBERS\f[R] section) or a command (see the \f[B]COMMANDS\f[R]
section), is processed and executed, in order.
Input is processed immediately when entered.
.PP
\f[B]ibase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to interpret constant numbers.
It is the \[lq]input\[rq] base, or the number base used for interpreting
input numbers.
\f[B]ibase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]ibase\f[R] is \f[B]16\f[R].
The min allowable value for \f[B]ibase\f[R] is \f[B]2\f[R].
The max allowable value for \f[B]ibase\f[R] can be queried in dc(1)
programs with the \f[B]T\f[R] command.
.PP
\f[B]obase\f[R] is a register (see the \f[B]REGISTERS\f[R] section) that
determines how to output results.
It is the \[lq]output\[rq] base, or the number base used for outputting
numbers.
\f[B]obase\f[R] is initially \f[B]10\f[R].
The max allowable value for \f[B]obase\f[R] is \f[B]DC_BASE_MAX\f[R] and
can be queried with the \f[B]U\f[R] command.
The min allowable value for \f[B]obase\f[R] is \f[B]0\f[R].
If \f[B]obase\f[R] is \f[B]0\f[R], values are output in scientific
notation, and if \f[B]obase\f[R] is \f[B]1\f[R], values are output in
engineering notation.
Otherwise, values are output in the specified base.
.PP
Outputting in scientific and engineering notations are \f[B]non-portable
extensions\f[R].
.PP
The \f[I]scale\f[R] of an expression is the number of digits in the
result of the expression right of the decimal point, and \f[B]scale\f[R]
is a register (see the \f[B]REGISTERS\f[R] section) that sets the
precision of any operations (with exceptions).
\f[B]scale\f[R] is initially \f[B]0\f[R].
\f[B]scale\f[R] cannot be negative.
The max allowable value for \f[B]scale\f[R] can be queried in dc(1)
programs with the \f[B]V\f[R] command.
.PP
\f[B]seed\f[R] is a register containing the current seed for the
pseudo-random number generator.
If the current value of \f[B]seed\f[R] is queried and stored, then if it
is assigned to \f[B]seed\f[R] later, the pseudo-random number generator
is guaranteed to produce the same sequence of pseudo-random numbers that
were generated after the value of \f[B]seed\f[R] was first queried.
.PP
Multiple values assigned to \f[B]seed\f[R] can produce the same sequence
of pseudo-random numbers.
Likewise, when a value is assigned to \f[B]seed\f[R], it is not
guaranteed that querying \f[B]seed\f[R] immediately after will return
the same value.
In addition, the value of \f[B]seed\f[R] will change after any call to
the \f[B]\[cq]\f[R] command or the \f[B]\[dq]\f[R] command that does not
get receive a value of \f[B]0\f[R] or \f[B]1\f[R].
The maximum integer returned by the \f[B]\[cq]\f[R] command can be
queried with the \f[B]W\f[R] command.
.PP
\f[B]Note\f[R]: The values returned by the pseudo-random number
generator with the \f[B]\[cq]\f[R] and \f[B]\[dq]\f[R] commands are
guaranteed to \f[B]NOT\f[R] be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator.
However, they \f[I]are\f[R] guaranteed to be reproducible with identical
\f[B]seed\f[R] values.
-This means that the pseudo-random values from bc(1) should only be used
+This means that the pseudo-random values from dc(1) should only be used
where a reproducible stream of pseudo-random numbers is
\f[I]ESSENTIAL\f[R].
In any other case, use a non-seeded pseudo-random number generator.
.PP
The pseudo-random number generator, \f[B]seed\f[R], and all associated
operations are \f[B]non-portable extensions\f[R].
.SS Comments
.PP
Comments go from \f[B]#\f[R] until, and not including, the next newline.
This is a \f[B]non-portable extension\f[R].
.SH NUMBERS
.PP
Numbers are strings made up of digits, uppercase letters up to
\f[B]F\f[R], and at most \f[B]1\f[R] period for a radix.
Numbers can have up to \f[B]DC_NUM_MAX\f[R] digits.
Uppercase letters are equal to \f[B]9\f[R] + their position in the
alphabet (i.e., \f[B]A\f[R] equals \f[B]10\f[R], or \f[B]9+1\f[R]).
If a digit or letter makes no sense with the current value of
\f[B]ibase\f[R], they are set to the value of the highest valid digit in
\f[B]ibase\f[R].
.PP
Single-character numbers (i.e., \f[B]A\f[R] alone) take the value that
they would have if they were valid digits, regardless of the value of
\f[B]ibase\f[R].
This means that \f[B]A\f[R] alone always equals decimal \f[B]10\f[R] and
\f[B]F\f[R] alone always equals decimal \f[B]15\f[R].
.PP
In addition, dc(1) accepts numbers in scientific notation.
These have the form \f[B]<number>e<integer>\f[R].
The exponent (the portion after the \f[B]e\f[R]) must be an integer.
An example is \f[B]1.89237e9\f[R], which is equal to
\f[B]1892370000\f[R].
Negative exponents are also allowed, so \f[B]4.2890e_3\f[R] is equal to
\f[B]0.0042890\f[R].
.PP
\f[B]WARNING\f[R]: Both the number and the exponent in scientific
notation are interpreted according to the current \f[B]ibase\f[R], but
the number is still multiplied by \f[B]10\[ha]exponent\f[R] regardless
of the current \f[B]ibase\f[R].
For example, if \f[B]ibase\f[R] is \f[B]16\f[R] and dc(1) is given the
number string \f[B]FFeA\f[R], the resulting decimal number will be
\f[B]2550000000000\f[R], and if dc(1) is given the number string
\f[B]10e_4\f[R], the resulting decimal number will be \f[B]0.0016\f[R].
.PP
Accepting input as scientific notation is a \f[B]non-portable
extension\f[R].
.SH COMMANDS
.PP
The valid commands are listed below.
.SS Printing
.PP
These commands are used for printing.
.PP
Note that both scientific notation and engineering notation are
available for printing numbers.
Scientific notation is activated by assigning \f[B]0\f[R] to
\f[B]obase\f[R] using \f[B]0o\f[R], and engineering notation is
activated by assigning \f[B]1\f[R] to \f[B]obase\f[R] using
\f[B]1o\f[R].
To deactivate them, just assign a different value to \f[B]obase\f[R].
.PP
Printing numbers in scientific notation and/or engineering notation is a
\f[B]non-portable extension\f[R].
.TP
\f[B]p\f[R]
Prints the value on top of the stack, whether number or string, and
prints a newline after.
.RS
.PP
This does not alter the stack.
.RE
.TP
\f[B]n\f[R]
Prints the value on top of the stack, whether number or string, and pops
it off of the stack.
.TP
\f[B]P\f[R]
Pops a value off the stack.
.RS
.PP
If the value is a number, it is truncated and the absolute value of the
result is printed as though \f[B]obase\f[R] is \f[B]UCHAR_MAX+1\f[R] and
each digit is interpreted as an ASCII character, making it a byte
stream.
.PP
If the value is a string, it is printed without a trailing newline.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]f\f[R]
Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
.RS
.PP
Users should use this command when they get lost.
.RE
.SS Arithmetic
.PP
These are the commands used for arithmetic.
.TP
\f[B]+\f[R]
The top two values are popped off the stack, added, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]-\f[R]
The top two values are popped off the stack, subtracted, and the result
is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to the max \f[I]scale\f[R] of
both operands.
.TP
\f[B]*\f[R]
The top two values are popped off the stack, multiplied, and the result
is pushed onto the stack.
If \f[B]a\f[R] is the \f[I]scale\f[R] of the first expression and
\f[B]b\f[R] is the \f[I]scale\f[R] of the second expression, the
\f[I]scale\f[R] of the result is equal to
\f[B]min(a+b,max(scale,a,b))\f[R] where \f[B]min()\f[R] and
\f[B]max()\f[R] return the obvious values.
.TP
\f[B]/\f[R]
The top two values are popped off the stack, divided, and the result is
pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]%\f[R]
The top two values are popped off the stack, remaindered, and the result
is pushed onto the stack.
.RS
.PP
Remaindering is equivalent to 1) Computing \f[B]a/b\f[R] to current
\f[B]scale\f[R], and 2) Using the result of step 1 to calculate
\f[B]a-(a/b)*b\f[R] to \f[I]scale\f[R]
\f[B]max(scale+scale(b),scale(a))\f[R].
.PP
The first value popped off of the stack must be non-zero.
.RE
.TP
\f[B]\[ti]\f[R]
The top two values are popped off the stack, divided and remaindered,
and the results (divided first, remainder second) are pushed onto the
stack.
This is equivalent to \f[B]x y / x y %\f[R] except that \f[B]x\f[R] and
\f[B]y\f[R] are only evaluated once.
.RS
.PP
The first value popped off of the stack must be non-zero.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[ha]\f[R]
The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
.RE
.TP
\f[B]v\f[R]
The top value is popped off the stack, its square root is computed, and
the result is pushed onto the stack.
The \f[I]scale\f[R] of the result is equal to \f[B]scale\f[R].
.RS
.PP
The value popped off of the stack must be non-negative.
.RE
.TP
\f[B]_\f[R]
If this command \f[I]immediately\f[R] precedes a number (i.e., no spaces
or other commands), then that number is input as a negative number.
.RS
.PP
Otherwise, the top value on the stack is popped and copied, and the copy
is negated and pushed onto the stack.
This behavior without a number is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]b\f[R]
The top value is popped off the stack, and if it is zero, it is pushed
back onto the stack.
Otherwise, its absolute value is pushed onto the stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]|\f[R]
The top three values are popped off the stack, a modular exponentiation
is computed, and the result is pushed onto the stack.
.RS
.PP
The first value popped is used as the reduction modulus and must be an
integer and non-zero.
The second value popped is used as the exponent and must be an integer
and non-negative.
The third value popped is the base and must be an integer.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]$\f[R]
The top value is popped off the stack and copied, and the copy is
truncated and pushed onto the stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[at]\f[R]
The top two values are popped off the stack, and the precision of the
second is set to the value of the first, whether by truncation or
extension.
.RS
.PP
The first value popped off of the stack must be an integer and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]H\f[R]
The top two values are popped off the stack, and the second is shifted
left (radix shifted right) to the value of the first.
.RS
.PP
The first value popped off of the stack must be an integer and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]h\f[R]
The top two values are popped off the stack, and the second is shifted
right (radix shifted left) to the value of the first.
.RS
.PP
The first value popped off of the stack must be an integer and
non-negative.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]G\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if they are equal, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]N\f[R]
The top value is popped off of the stack, and if it a \f[B]0\f[R], a
\f[B]1\f[R] is pushed; otherwise, a \f[B]0\f[R] is pushed.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B](\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]{\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is less than or equal to the second,
or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B])\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than the second, or
\f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]}\f[R]
The top two values are popped off of the stack, they are compared, and a
\f[B]1\f[R] is pushed if the first is greater than or equal to the
second, or \f[B]0\f[R] otherwise.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]M\f[R]
The top two values are popped off of the stack.
If they are both non-zero, a \f[B]1\f[R] is pushed onto the stack.
If either of them is zero, or both of them are, then a \f[B]0\f[R] is
pushed onto the stack.
.RS
.PP
This is like the \f[B]&&\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]m\f[R]
The top two values are popped off of the stack.
If at least one of them is non-zero, a \f[B]1\f[R] is pushed onto the
stack.
If both of them are zero, then a \f[B]0\f[R] is pushed onto the stack.
.RS
.PP
This is like the \f[B]||\f[R] operator in bc(1), and it is \f[I]not\f[R]
a short-circuit operator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Pseudo-Random Number Generator
.PP
dc(1) has a built-in pseudo-random number generator.
These commands query the pseudo-random number generator.
(See Parameters for more information about the \f[B]seed\f[R] value that
controls the pseudo-random number generator.)
.PP
The pseudo-random number generator is guaranteed to \f[B]NOT\f[R] be
cryptographically secure.
.TP
\f[B]\[cq]\f[R]
Generates an integer between 0 and \f[B]DC_RAND_MAX\f[R], inclusive (see
the \f[B]LIMITS\f[R] section).
.RS
.PP
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]\[dq]\f[R]
Pops a value off of the stack, which is used as an \f[B]exclusive\f[R]
upper bound on the integer that will be generated.
If the bound is negative or is a non-integer, an error is raised, and
dc(1) resets (see the \f[B]RESET\f[R] section) while \f[B]seed\f[R]
remains unchanged.
If the bound is larger than \f[B]DC_RAND_MAX\f[R], the higher bound is
honored by generating several pseudo-random integers, multiplying them
by appropriate powers of \f[B]DC_RAND_MAX+1\f[R], and adding them
together.
Thus, the size of integer that can be generated with this command is
unbounded.
Using this command will change the value of \f[B]seed\f[R], unless the
operand is \f[B]0\f[R] or \f[B]1\f[R].
In that case, \f[B]0\f[R] is pushed onto the stack, and \f[B]seed\f[R]
is \f[I]not\f[R] changed.
.RS
.PP
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Stack Control
.PP
These commands control the stack.
.TP
\f[B]c\f[R]
Removes all items from (\[lq]clears\[rq]) the stack.
.TP
\f[B]d\f[R]
Copies the item on top of the stack (\[lq]duplicates\[rq]) and pushes
the copy onto the stack.
.TP
\f[B]r\f[R]
Swaps (\[lq]reverses\[rq]) the two top items on the stack.
.TP
\f[B]R\f[R]
Pops (\[lq]removes\[rq]) the top value from the stack.
.SS Register Control
.PP
These commands control registers (see the \f[B]REGISTERS\f[R] section).
.TP
\f[B]s\f[R]\f[I]r\f[R]
Pops the value off the top of the stack and stores it into register
\f[I]r\f[R].
.TP
\f[B]l\f[R]\f[I]r\f[R]
Copies the value in register \f[I]r\f[R] and pushes it onto the stack.
This does not alter the contents of \f[I]r\f[R].
.TP
\f[B]S\f[R]\f[I]r\f[R]
Pops the value off the top of the (main) stack and pushes it onto the
stack of register \f[I]r\f[R].
The previous value of the register becomes inaccessible.
.TP
\f[B]L\f[R]\f[I]r\f[R]
Pops the value off the top of the stack for register \f[I]r\f[R] and
push it onto the main stack.
The previous value in the stack for register \f[I]r\f[R], if any, is now
accessible via the \f[B]l\f[R]\f[I]r\f[R] command.
.SS Parameters
.PP
These commands control the values of \f[B]ibase\f[R], \f[B]obase\f[R],
\f[B]scale\f[R], and \f[B]seed\f[R].
Also see the \f[B]SYNTAX\f[R] section.
.TP
\f[B]i\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]ibase\f[R], which must be between \f[B]2\f[R] and \f[B]16\f[R],
inclusive.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]o\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]obase\f[R], which must be between \f[B]0\f[R] and
\f[B]DC_BASE_MAX\f[R], inclusive (see the \f[B]LIMITS\f[R] section and
the \f[B]NUMBERS\f[R] section).
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]k\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]scale\f[R], which must be non-negative.
.RS
.PP
If the value on top of the stack has any \f[I]scale\f[R], the
\f[I]scale\f[R] is ignored.
.RE
.TP
\f[B]j\f[R]
Pops the value off of the top of the stack and uses it to set
\f[B]seed\f[R].
The meaning of \f[B]seed\f[R] is dependent on the current pseudo-random
number generator but is guaranteed to not change except for new major
versions.
.RS
.PP
The \f[I]scale\f[R] and sign of the value may be significant.
.PP
If a previously used \f[B]seed\f[R] value is used again, the
pseudo-random number generator is guaranteed to produce the same
sequence of pseudo-random numbers as it did when the \f[B]seed\f[R]
value was previously used.
.PP
The exact value assigned to \f[B]seed\f[R] is not guaranteed to be
returned if the \f[B]J\f[R] command is used.
However, if \f[B]seed\f[R] \f[I]does\f[R] return a different value, both
values, when assigned to \f[B]seed\f[R], are guaranteed to produce the
same sequence of pseudo-random numbers.
This means that certain values assigned to \f[B]seed\f[R] will not
produce unique sequences of pseudo-random numbers.
.PP
There is no limit to the length (number of significant decimal digits)
or \f[I]scale\f[R] of the value that can be assigned to \f[B]seed\f[R].
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]I\f[R]
Pushes the current value of \f[B]ibase\f[R] onto the main stack.
.TP
\f[B]O\f[R]
Pushes the current value of \f[B]obase\f[R] onto the main stack.
.TP
\f[B]K\f[R]
Pushes the current value of \f[B]scale\f[R] onto the main stack.
.TP
\f[B]J\f[R]
Pushes the current value of \f[B]seed\f[R] onto the main stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]T\f[R]
Pushes the maximum allowable value of \f[B]ibase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]U\f[R]
Pushes the maximum allowable value of \f[B]obase\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]V\f[R]
Pushes the maximum allowable value of \f[B]scale\f[R] onto the main
stack.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]W\f[R]
Pushes the maximum (inclusive) integer that can be generated with the
\f[B]\[cq]\f[R] pseudo-random number generator command.
.RS
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.SS Strings
.PP
The following commands control strings.
.PP
dc(1) can work with both numbers and strings, and registers (see the
\f[B]REGISTERS\f[R] section) can hold both strings and numbers.
dc(1) always knows whether the contents of a register are a string or a
number.
.PP
While arithmetic operations have to have numbers, and will print an
error if given a string, other commands accept strings.
.PP
Strings can also be executed as macros.
For example, if the string \f[B][1pR]\f[R] is executed as a macro, then
the code \f[B]1pR\f[R] is executed, meaning that the \f[B]1\f[R] will be
printed with a newline after and then popped from the stack.
.TP
\f[B][\f[R]_characters_\f[B]]\f[R]
Makes a string containing \f[I]characters\f[R] and pushes it onto the
stack.
.RS
.PP
If there are brackets (\f[B][\f[R] and \f[B]]\f[R]) in the string, then
they must be balanced.
Unbalanced brackets can be escaped using a backslash (\f[B]\[rs]\f[R])
character.
.PP
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the
(first) backslash is not.
.RE
.TP
\f[B]a\f[R]
The value on top of the stack is popped.
.RS
.PP
If it is a number, it is truncated and its absolute value is taken.
The result mod \f[B]UCHAR_MAX+1\f[R] is calculated.
If that result is \f[B]0\f[R], push an empty string; otherwise, push a
one-character string where the character is the result of the mod
interpreted as an ASCII character.
.PP
If it is a string, then a new string is made.
If the original string is empty, the new string is empty.
If it is not, then the first character of the original string is used to
create the new string as a one-character string.
The new string is then pushed onto the stack.
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]x\f[R]
Pops a value off of the top of the stack.
.RS
.PP
If it is a number, it is pushed back onto the stack.
.PP
If it is a string, it is executed as a macro.
.PP
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is greater than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
For example, \f[B]0 1>a\f[R] will execute the contents of register
\f[B]a\f[R], and \f[B]1 0>a\f[R] will not.
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not greater than the second (less than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!>\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is less than the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not less than the second (greater than or equal
to), then the contents of register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!<\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is equal to the second, then the contents of register
\f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]
Pops two values off of the stack that must be numbers and compares them.
If the first value is not equal to the second, then the contents of
register \f[I]r\f[R] are executed.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.RE
.TP
\f[B]!=\f[R]\f[I]r\f[R]\f[B]e\f[R]\f[I]s\f[R]
Like the above, but will execute register \f[I]s\f[R] if the comparison
fails.
.RS
.PP
If either or both of the values are not numbers, dc(1) will raise an
error and reset (see the \f[B]RESET\f[R] section).
.PP
This is a \f[B]non-portable extension\f[R].
.RE
.TP
\f[B]?\f[R]
Reads a line from the \f[B]stdin\f[R] and executes it.
This is to allow macros to request input from users.
.TP
\f[B]q\f[R]
During execution of a macro, this exits the execution of that macro and
the execution of the macro that executed it.
If there are no macros, or only one macro executing, dc(1) exits.
.TP
\f[B]Q\f[R]
Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack.
If the number of levels to pop is greater than the number of executing
macros, dc(1) exits.
.SS Status
.PP
These commands query status of the stack or its top value.
.TP
\f[B]Z\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, calculates the number of significant decimal digits
it has and pushes the result.
.PP
If it is a string, pushes the number of characters the string has.
.RE
.TP
\f[B]X\f[R]
Pops a value off of the stack.
.RS
.PP
If it is a number, pushes the \f[I]scale\f[R] of the value onto the
stack.
.PP
If it is a string, pushes \f[B]0\f[R].
.RE
.TP
\f[B]z\f[R]
Pushes the current stack depth (before execution of this command).
.SS Arrays
.PP
These commands manipulate arrays.
.TP
\f[B]:\f[R]\f[I]r\f[R]
Pops the top two values off of the stack.
The second value will be stored in the array \f[I]r\f[R] (see the
\f[B]REGISTERS\f[R] section), indexed by the first value.
.TP
\f[B];\f[R]\f[I]r\f[R]
Pops the value on top of the stack and uses it as an index into the
array \f[I]r\f[R].
The selected value is then pushed onto the stack.
.SH REGISTERS
.PP
Registers are names that can store strings, numbers, and arrays.
(Number/string registers do not interfere with array registers.)
.PP
Each register is also its own stack, so the current register value is
the top of the stack for the register.
All registers, when first referenced, have one value (\f[B]0\f[R]) in
their stack.
.PP
In non-extended register mode, a register name is just the single
character that follows any command that needs a register name.
The only exception is a newline (\f[B]`\[rs]n'\f[R]); it is a parse
error for a newline to be used as a register name.
.SS Extended Register Mode
.PP
Unlike most other dc(1) implentations, this dc(1) provides nearly
unlimited amounts of registers, if extended register mode is enabled.
.PP
If extended register mode is enabled (\f[B]-x\f[R] or
\f[B]\[en]extended-register\f[R] command-line arguments are given), then
normal single character registers are used \f[I]unless\f[R] the
character immediately following a command that needs a register name is
a space (according to \f[B]isspace()\f[R]) and not a newline
(\f[B]`\[rs]n'\f[R]).
.PP
In that case, the register name is found according to the regex
\f[B][a-z][a-z0-9_]*\f[R] (like bc(1) identifiers), and it is a parse
error if the next non-space characters do not match that regex.
.SH RESET
.PP
When dc(1) encounters an error or a signal that it has a non-default
handler for, it resets.
This means that several things happen.
.PP
First, any macros that are executing are stopped and popped off the
stack.
The behavior is not unlike that of exceptions in programming languages.
Then the execution point is set so that any code waiting to execute
(after all macros returned) is skipped.
.PP
Thus, when dc(1) resets, it skips any remaining code waiting to be
executed.
Then, if it is interactive mode, and the error was not a fatal error
(see the \f[B]EXIT STATUS\f[R] section), it asks for more input;
otherwise, it exits with the appropriate return code.
.SH PERFORMANCE
.PP
Most dc(1) implementations use \f[B]char\f[R] types to calculate the
value of \f[B]1\f[R] decimal digit at a time, but that can be slow.
This dc(1) does something different.
.PP
It uses large integers to calculate more than \f[B]1\f[R] decimal digit
at a time.
If built in a environment where \f[B]DC_LONG_BIT\f[R] (see the
\f[B]LIMITS\f[R] section) is \f[B]64\f[R], then each integer has
\f[B]9\f[R] decimal digits.
If built in an environment where \f[B]DC_LONG_BIT\f[R] is \f[B]32\f[R]
then each integer has \f[B]4\f[R] decimal digits.
This value (the number of decimal digits per large integer) is called
\f[B]DC_BASE_DIGS\f[R].
.PP
In addition, this dc(1) uses an even larger integer for overflow
checking.
This integer type depends on the value of \f[B]DC_LONG_BIT\f[R], but is
always at least twice as large as the integer type used to store digits.
.SH LIMITS
.PP
The following are the limits on dc(1):
.TP
\f[B]DC_LONG_BIT\f[R]
The number of bits in the \f[B]long\f[R] type in the environment where
dc(1) was built.
This determines how many decimal digits can be stored in a single large
integer (see the \f[B]PERFORMANCE\f[R] section).
.TP
\f[B]DC_BASE_DIGS\f[R]
The number of decimal digits per large integer (see the
\f[B]PERFORMANCE\f[R] section).
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_POW\f[R]
The max decimal number that each large integer can store (see
\f[B]DC_BASE_DIGS\f[R]) plus \f[B]1\f[R].
Depends on \f[B]DC_BASE_DIGS\f[R].
.TP
\f[B]DC_OVERFLOW_MAX\f[R]
The max number that the overflow type (see the \f[B]PERFORMANCE\f[R]
section) can hold.
Depends on \f[B]DC_LONG_BIT\f[R].
.TP
\f[B]DC_BASE_MAX\f[R]
The maximum output base.
Set at \f[B]DC_BASE_POW\f[R].
.TP
\f[B]DC_DIM_MAX\f[R]
The maximum size of arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.TP
\f[B]DC_SCALE_MAX\f[R]
The maximum \f[B]scale\f[R].
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_STRING_MAX\f[R]
The maximum length of strings.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NAME_MAX\f[R]
The maximum length of identifiers.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_NUM_MAX\f[R]
The maximum length of a number (in decimal digits), which includes
digits after the decimal point.
Set at \f[B]DC_OVERFLOW_MAX-1\f[R].
.TP
\f[B]DC_RAND_MAX\f[R]
The maximum integer (inclusive) returned by the \f[B]\[cq]\f[R] command,
if dc(1).
Set at \f[B]2\[ha]DC_LONG_BIT-1\f[R].
.TP
Exponent
The maximum allowable exponent (positive or negative).
Set at \f[B]DC_OVERFLOW_MAX\f[R].
.TP
Number of vars
The maximum number of vars/arrays.
Set at \f[B]SIZE_MAX-1\f[R].
.PP
These limits are meant to be effectively non-existent; the limits are so
large (at least on 64-bit machines) that there should not be any point
at which they become a problem.
In fact, memory should be exhausted before these limits should be hit.
.SH ENVIRONMENT VARIABLES
.PP
dc(1) recognizes the following environment variables:
.TP
\f[B]DC_ENV_ARGS\f[R]
This is another way to give command-line arguments to dc(1).
They should be in the same format as all other command-line arguments.
These are always processed first, so any files given in
\f[B]DC_ENV_ARGS\f[R] will be processed before arguments and files given
on the command-line.
This gives the user the ability to set up \[lq]standard\[rq] options and
files to be used at every invocation.
The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs.
Another use would be to use the \f[B]-e\f[R] option to set
\f[B]scale\f[R] to a value other than \f[B]0\f[R].
.RS
.PP
The code that parses \f[B]DC_ENV_ARGS\f[R] will correctly handle quoted
arguments, but it does not understand escape sequences.
For example, the string \f[B]\[lq]/home/gavin/some dc file.dc\[rq]\f[R]
will be correctly parsed, but the string \f[B]\[lq]/home/gavin/some
\[dq]dc\[dq] file.dc\[rq]\f[R] will include the backslashes.
.PP
The quote parsing will handle either kind of quotes, \f[B]\[cq]\f[R] or
\f[B]\[lq]\f[R]. Thus, if you have a file with any number of single
quotes in the name, you can use double quotes as the outside quotes, as
-in \f[B]\[rq]some `bc' file.bc\[dq]\f[R], and vice versa if you have a
+in \f[B]\[rq]some `dc' file.dc\[dq]\f[R], and vice versa if you have a
file with double quotes.
However, handling a file with both kinds of quotes in
\f[B]DC_ENV_ARGS\f[R] is not supported due to the complexity of the
parsing, though such files are still supported on the command-line where
the parsing is done by the shell.
.RE
.TP
\f[B]DC_LINE_LENGTH\f[R]
If this environment variable exists and contains an integer that is
greater than \f[B]1\f[R] and is less than \f[B]UINT16_MAX\f[R]
(\f[B]2\[ha]16-1\f[R]), dc(1) will output lines to that length,
including the backslash newline combo.
The default line length is \f[B]70\f[R].
.TP
\f[B]DC_EXPR_EXIT\f[R]
If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the
\f[B]-e\f[R] and/or \f[B]-f\f[R] command-line options (and any
equivalents).
.SH EXIT STATUS
.PP
dc(1) returns the following exit statuses:
.TP
\f[B]0\f[R]
No error.
.TP
\f[B]1\f[R]
A math error occurred.
This follows standard practice of using \f[B]1\f[R] for expected errors,
since math errors will happen in the process of normal execution.
.RS
.PP
Math errors include divide by \f[B]0\f[R], taking the square root of a
negative number, using a negative number as a bound for the
pseudo-random number generator, attempting to convert a negative number
to a hardware integer, overflow when converting a number to a hardware
integer, and attempting to use a non-integer where an integer is
required.
.PP
Converting to a hardware integer happens for the second operand of the
power (\f[B]\[ha]\f[R]), places (\f[B]\[at]\f[R]), left shift
(\f[B]H\f[R]), and right shift (\f[B]h\f[R]) operators.
.RE
.TP
\f[B]2\f[R]
A parse error occurred.
.RS
.PP
Parse errors include unexpected \f[B]EOF\f[R], using an invalid
character, failing to find the end of a string or comment, and using a
token where it is invalid.
.RE
.TP
\f[B]3\f[R]
A runtime error occurred.
.RS
.PP
Runtime errors include assigning an invalid number to \f[B]ibase\f[R],
\f[B]obase\f[R], or \f[B]scale\f[R]; give a bad expression to a
\f[B]read()\f[R] call, calling \f[B]read()\f[R] inside of a
\f[B]read()\f[R] call, type errors, and attempting an operation when the
stack has too few elements.
.RE
.TP
\f[B]4\f[R]
A fatal error occurred.
.RS
.PP
Fatal errors include memory allocation errors, I/O errors, failing to
open files, attempting to use files that do not have only ASCII
characters (dc(1) only accepts ASCII characters), attempting to open a
directory as a file, and giving invalid command-line options.
.RE
.PP
The exit status \f[B]4\f[R] is special; when a fatal error occurs, dc(1)
always exits and returns \f[B]4\f[R], no matter what mode dc(1) is in.
.PP
The other statuses will only be returned when dc(1) is not in
interactive mode (see the \f[B]INTERACTIVE MODE\f[R] section), since
dc(1) resets its state (see the \f[B]RESET\f[R] section) and accepts
more input when one of those errors occurs in interactive mode.
This is also the case when interactive mode is forced by the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.PP
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the
\f[B]-i\f[R] flag or \f[B]\[en]interactive\f[R] option.
.SH INTERACTIVE MODE
.PP
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both \f[B]stdin\f[R]
and \f[B]stdout\f[R] are hooked to a terminal, but the \f[B]-i\f[R] flag
and \f[B]\[en]interactive\f[R] option can turn it on in other cases.
.PP
In interactive mode, dc(1) attempts to recover from errors (see the
\f[B]RESET\f[R] section), and in normal execution, flushes
\f[B]stdout\f[R] as soon as execution is done for the current input.
.SH TTY MODE
.PP
If \f[B]stdin\f[R], \f[B]stdout\f[R], and \f[B]stderr\f[R] are all
connected to a TTY, dc(1) turns on \[lq]TTY mode.\[rq]
.PP
TTY mode is required for history to be enabled (see the \f[B]COMMAND
LINE HISTORY\f[R] section).
It is also required to enable special handling for \f[B]SIGINT\f[R]
signals.
.PP
TTY mode is different from interactive mode because interactive mode is
required in the bc(1)
specification (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html),
and interactive mode requires only \f[B]stdin\f[R] and \f[B]stdout\f[R]
to be connected to a terminal.
.SH SIGNAL HANDLING
.PP
Sending a \f[B]SIGINT\f[R] will cause dc(1) to stop execution of the
current input.
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), it will
reset (see the \f[B]RESET\f[R] section).
Otherwise, it will clean up and exit.
.PP
Note that \[lq]current input\[rq] can mean one of two things.
If dc(1) is processing input from \f[B]stdin\f[R] in TTY mode, it will
ask for more input.
If dc(1) is processing input from a file in TTY mode, it will stop
processing the file and start processing the next file, if one exists,
or ask for input from \f[B]stdin\f[R] if no other file exists.
.PP
This means that if a \f[B]SIGINT\f[R] is sent to dc(1) as it is
executing a file, it can seem as though dc(1) did not respond to the
signal since it will immediately start executing the next file.
This is by design; most files that users execute when interacting with
dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file.
The rest of the files could still be executed without problem, allowing
the user to continue.
.PP
\f[B]SIGTERM\f[R] and \f[B]SIGQUIT\f[R] cause dc(1) to clean up and
exit, and it uses the default handler for all other signals.
The one exception is \f[B]SIGHUP\f[R]; in that case, when dc(1) is in
TTY mode, a \f[B]SIGHUP\f[R] will cause dc(1) to clean up and exit.
.SH COMMAND LINE HISTORY
.PP
dc(1) supports interactive command-line editing.
If dc(1) is in TTY mode (see the \f[B]TTY MODE\f[R] section), history is
enabled.
Previous lines can be recalled and edited with the arrow keys.
.PP
\f[B]Note\f[R]: tabs are converted to 8 spaces.
.SH LOCALES
.PP
This dc(1) ships with support for adding error messages for different
locales and thus, supports \f[B]LC_MESSAGS\f[R].
.SH SEE ALSO
.PP
bc(1)
.SH STANDARDS
.PP
The dc(1) utility operators are compliant with the operators in the
bc(1) IEEE Std 1003.1-2017
(\[lq]POSIX.1-2017\[rq]) (https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html)
specification.
.SH BUGS
.PP
None are known.
Report bugs at https://git.yzena.com/gavin/bc.
.SH AUTHOR
.PP
Gavin D.
Howard <gavin@yzena.com> and contributors.
diff --git a/contrib/bc/manuals/dc/P.1.md b/contrib/bc/manuals/dc/P.1.md
index 5d095faaa124..396a9873c517 100644
--- a/contrib/bc/manuals/dc/P.1.md
+++ b/contrib/bc/manuals/dc/P.1.md
@@ -1,1193 +1,1202 @@
<!---
SPDX-License-Identifier: BSD-2-Clause
Copyright (c) 2018-2021 Gavin D. Howard and contributors.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
POSSIBILITY OF SUCH DAMAGE.
-->
# Name
dc - arbitrary-precision decimal reverse-Polish notation calculator
# SYNOPSIS
**dc** [**-hiPvVx**] [**--version**] [**--help**] [**--interactive**] [**--no-prompt**] [**--extended-register**] [**-e** *expr*] [**--expression**=*expr*...] [**-f** *file*...] [**-file**=*file*...] [*file*...]
# DESCRIPTION
dc(1) is an arbitrary-precision calculator. It uses a stack (reverse Polish
notation) to store numbers and results of computations. Arithmetic operations
pop arguments off of the stack and push the results.
If no files are given on the command-line as extra arguments (i.e., not as
**-f** or **--file** arguments), then dc(1) reads from **stdin**. Otherwise,
those files are processed, and dc(1) will then exit.
This is different from the dc(1) on OpenBSD and possibly other dc(1)
implementations, where **-e** (**--expression**) and **-f** (**--file**)
arguments cause dc(1) to execute them and exit. The reason for this is that this
dc(1) allows users to set arguments in the environment variable **DC_ENV_ARGS**
(see the **ENVIRONMENT VARIABLES** section). Any expressions given on the
command-line should be used to set up a standard environment. For example, if a
user wants the **scale** always set to **10**, they can set **DC_ENV_ARGS** to
**-e 10k**, and this dc(1) will always start with a **scale** of **10**.
If users want to have dc(1) exit after processing all input from **-e** and
**-f** arguments (and their equivalents), then they can just simply add **-e q**
as the last command-line argument or define the environment variable
**DC_EXPR_EXIT**.
# OPTIONS
The following are the options that dc(1) accepts.
**-h**, **--help**
: Prints a usage message and quits.
**-v**, **-V**, **--version**
: Print the version information (copyright header) and exit.
**-i**, **--interactive**
: Forces interactive mode. (See the **INTERACTIVE MODE** section.)
This is a **non-portable extension**.
**-P**, **--no-prompt**
: This option is a no-op.
This is a **non-portable extension**.
**-x** **--extended-register**
: Enables extended register mode. See the *Extended Register Mode* subsection
of the **REGISTERS** section for more information.
This is a **non-portable extension**.
**-e** *expr*, **--expression**=*expr*
: Evaluates *expr*. If multiple expressions are given, they are evaluated in
order. If files are given as well (see below), the expressions and files are
evaluated in the order given. This means that if a file is given before an
expression, the file is read in and evaluated first.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**, whether on the
+ command-line or in **DC_ENV_ARGS**. However, if any other **-e**,
+ **--expression**, **-f**, or **--file** arguments are given after **-f-** or
+ equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
**-f** *file*, **--file**=*file*
: Reads in *file* and evaluates it, line by line, as though it were read
through **stdin**. If expressions are also given (see above), the
expressions are evaluated in the order given.
- After processing all expressions and files, dc(1) will exit, unless **-**
- (**stdin**) was given as an argument at least once to **-f** or **--file**.
- However, if any other **-e**, **--expression**, **-f**, or **--file**
- arguments are given after that, bc(1) will give a fatal error and exit.
+ If this option is given on the command-line (i.e., not in **DC_ENV_ARGS**,
+ see the **ENVIRONMENT VARIABLES** section), then after processing all
+ expressions and files, dc(1) will exit, unless **-** (**stdin**) was given
+ as an argument at least once to **-f** or **--file**. However, if any other
+ **-e**, **--expression**, **-f**, or **--file** arguments are given after
+ **-f-** or equivalent is given, dc(1) will give a fatal error and exit.
This is a **non-portable extension**.
All long options are **non-portable extensions**.
# STDOUT
-Any non-error output is written to **stdout**.
+Any non-error output is written to **stdout**. In addition, if history (see the
+**HISTORY** section) and the prompt (see the **TTY MODE** section) are enabled,
+both are output to **stdout**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stdout**, so if
**stdout** is closed, as in **dc <file> >&-**, it will quit with an error. This
is done so that dc(1) can report problems when **stdout** is redirected to a
file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stdout** to
**/dev/null**.
# STDERR
Any error output is written to **stderr**.
**Note**: Unlike other dc(1) implementations, this dc(1) will issue a fatal
error (see the **EXIT STATUS** section) if it cannot write to **stderr**, so if
**stderr** is closed, as in **dc <file> 2>&-**, it will quit with an error. This
is done so that dc(1) can exit with an error code when **stderr** is redirected
to a file.
If there are scripts that depend on the behavior of other dc(1) implementations,
it is recommended that those scripts be changed to redirect **stderr** to
**/dev/null**.
# SYNTAX
Each item in the input source code, either a number (see the **NUMBERS**
section) or a command (see the **COMMANDS** section), is processed and executed,
in order. Input is processed immediately when entered.
**ibase** is a register (see the **REGISTERS** section) that determines how to
interpret constant numbers. It is the "input" base, or the number base used for
interpreting input numbers. **ibase** is initially **10**. The max allowable
value for **ibase** is **16**. The min allowable value for **ibase** is **2**.
The max allowable value for **ibase** can be queried in dc(1) programs with the
**T** command.
**obase** is a register (see the **REGISTERS** section) that determines how to
output results. It is the "output" base, or the number base used for outputting
numbers. **obase** is initially **10**. The max allowable value for **obase** is
**DC_BASE_MAX** and can be queried with the **U** command. The min allowable
value for **obase** is **0**. If **obase** is **0**, values are output in
scientific notation, and if **obase** is **1**, values are output in engineering
notation. Otherwise, values are output in the specified base.
Outputting in scientific and engineering notations are **non-portable
extensions**.
The *scale* of an expression is the number of digits in the result of the
expression right of the decimal point, and **scale** is a register (see the
**REGISTERS** section) that sets the precision of any operations (with
exceptions). **scale** is initially **0**. **scale** cannot be negative. The max
allowable value for **scale** can be queried in dc(1) programs with the **V**
command.
**seed** is a register containing the current seed for the pseudo-random number
generator. If the current value of **seed** is queried and stored, then if it is
assigned to **seed** later, the pseudo-random number generator is guaranteed to
produce the same sequence of pseudo-random numbers that were generated after the
value of **seed** was first queried.
Multiple values assigned to **seed** can produce the same sequence of
pseudo-random numbers. Likewise, when a value is assigned to **seed**, it is not
guaranteed that querying **seed** immediately after will return the same value.
In addition, the value of **seed** will change after any call to the **'**
command or the **"** command that does not get receive a value of **0** or
**1**. The maximum integer returned by the **'** command can be queried with the
**W** command.
**Note**: The values returned by the pseudo-random number generator with the
**'** and **"** commands are guaranteed to **NOT** be cryptographically secure.
This is a consequence of using a seeded pseudo-random number generator. However,
they *are* guaranteed to be reproducible with identical **seed** values. This
-means that the pseudo-random values from bc(1) should only be used where a
+means that the pseudo-random values from dc(1) should only be used where a
reproducible stream of pseudo-random numbers is *ESSENTIAL*. In any other case,
use a non-seeded pseudo-random number generator.
The pseudo-random number generator, **seed**, and all associated operations are
**non-portable extensions**.
## Comments
Comments go from **#** until, and not including, the next newline. This is a
**non-portable extension**.
# NUMBERS
Numbers are strings made up of digits, uppercase letters up to **F**, and at
most **1** period for a radix. Numbers can have up to **DC_NUM_MAX** digits.
Uppercase letters are equal to **9** + their position in the alphabet (i.e.,
**A** equals **10**, or **9+1**). If a digit or letter makes no sense with the
current value of **ibase**, they are set to the value of the highest valid digit
in **ibase**.
Single-character numbers (i.e., **A** alone) take the value that they would have
if they were valid digits, regardless of the value of **ibase**. This means that
**A** alone always equals decimal **10** and **F** alone always equals decimal
**15**.
In addition, dc(1) accepts numbers in scientific notation. These have the form
**\<number\>e\<integer\>**. The exponent (the portion after the **e**) must be
an integer. An example is **1.89237e9**, which is equal to **1892370000**.
Negative exponents are also allowed, so **4.2890e_3** is equal to **0.0042890**.
**WARNING**: Both the number and the exponent in scientific notation are
interpreted according to the current **ibase**, but the number is still
multiplied by **10\^exponent** regardless of the current **ibase**. For example,
if **ibase** is **16** and dc(1) is given the number string **FFeA**, the
resulting decimal number will be **2550000000000**, and if dc(1) is given the
number string **10e_4**, the resulting decimal number will be **0.0016**.
Accepting input as scientific notation is a **non-portable extension**.
# COMMANDS
The valid commands are listed below.
## Printing
These commands are used for printing.
Note that both scientific notation and engineering notation are available for
printing numbers. Scientific notation is activated by assigning **0** to
**obase** using **0o**, and engineering notation is activated by assigning **1**
to **obase** using **1o**. To deactivate them, just assign a different value to
**obase**.
Printing numbers in scientific notation and/or engineering notation is a
**non-portable extension**.
**p**
: Prints the value on top of the stack, whether number or string, and prints a
newline after.
This does not alter the stack.
**n**
: Prints the value on top of the stack, whether number or string, and pops it
off of the stack.
**P**
: Pops a value off the stack.
If the value is a number, it is truncated and the absolute value of the
result is printed as though **obase** is **UCHAR_MAX+1** and each digit is
interpreted as an ASCII character, making it a byte stream.
If the value is a string, it is printed without a trailing newline.
This is a **non-portable extension**.
**f**
: Prints the entire contents of the stack, in order from newest to oldest,
without altering anything.
Users should use this command when they get lost.
## Arithmetic
These are the commands used for arithmetic.
**+**
: The top two values are popped off the stack, added, and the result is pushed
onto the stack. The *scale* of the result is equal to the max *scale* of
both operands.
**-**
: The top two values are popped off the stack, subtracted, and the result is
pushed onto the stack. The *scale* of the result is equal to the max
*scale* of both operands.
**\***
: The top two values are popped off the stack, multiplied, and the result is
pushed onto the stack. If **a** is the *scale* of the first expression and
**b** is the *scale* of the second expression, the *scale* of the result
is equal to **min(a+b,max(scale,a,b))** where **min()** and **max()** return
the obvious values.
**/**
: The top two values are popped off the stack, divided, and the result is
pushed onto the stack. The *scale* of the result is equal to **scale**.
The first value popped off of the stack must be non-zero.
**%**
: The top two values are popped off the stack, remaindered, and the result is
pushed onto the stack.
Remaindering is equivalent to 1) Computing **a/b** to current **scale**, and
2) Using the result of step 1 to calculate **a-(a/b)\*b** to *scale*
**max(scale+scale(b),scale(a))**.
The first value popped off of the stack must be non-zero.
**~**
: The top two values are popped off the stack, divided and remaindered, and
the results (divided first, remainder second) are pushed onto the stack.
This is equivalent to **x y / x y %** except that **x** and **y** are only
evaluated once.
The first value popped off of the stack must be non-zero.
This is a **non-portable extension**.
**\^**
: The top two values are popped off the stack, the second is raised to the
power of the first, and the result is pushed onto the stack. The *scale* of
the result is equal to **scale**.
The first value popped off of the stack must be an integer, and if that
value is negative, the second value popped off of the stack must be
non-zero.
**v**
: The top value is popped off the stack, its square root is computed, and the
result is pushed onto the stack. The *scale* of the result is equal to
**scale**.
The value popped off of the stack must be non-negative.
**\_**
: If this command *immediately* precedes a number (i.e., no spaces or other
commands), then that number is input as a negative number.
Otherwise, the top value on the stack is popped and copied, and the copy is
negated and pushed onto the stack. This behavior without a number is a
**non-portable extension**.
**b**
: The top value is popped off the stack, and if it is zero, it is pushed back
onto the stack. Otherwise, its absolute value is pushed onto the stack.
This is a **non-portable extension**.
**|**
: The top three values are popped off the stack, a modular exponentiation is
computed, and the result is pushed onto the stack.
The first value popped is used as the reduction modulus and must be an
integer and non-zero. The second value popped is used as the exponent and
must be an integer and non-negative. The third value popped is the base and
must be an integer.
This is a **non-portable extension**.
**\$**
: The top value is popped off the stack and copied, and the copy is truncated
and pushed onto the stack.
This is a **non-portable extension**.
**\@**
: The top two values are popped off the stack, and the precision of the second
is set to the value of the first, whether by truncation or extension.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**H**
: The top two values are popped off the stack, and the second is shifted left
(radix shifted right) to the value of the first.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**h**
: The top two values are popped off the stack, and the second is shifted right
(radix shifted left) to the value of the first.
The first value popped off of the stack must be an integer and non-negative.
This is a **non-portable extension**.
**G**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if they are equal, or **0** otherwise.
This is a **non-portable extension**.
**N**
: The top value is popped off of the stack, and if it a **0**, a **1** is
pushed; otherwise, a **0** is pushed.
This is a **non-portable extension**.
**(**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than the second, or **0** otherwise.
This is a **non-portable extension**.
**{**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is less than or equal to the second, or **0**
otherwise.
This is a **non-portable extension**.
**)**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than the second, or **0** otherwise.
This is a **non-portable extension**.
**}**
: The top two values are popped off of the stack, they are compared, and a
**1** is pushed if the first is greater than or equal to the second, or
**0** otherwise.
This is a **non-portable extension**.
**M**
: The top two values are popped off of the stack. If they are both non-zero, a
**1** is pushed onto the stack. If either of them is zero, or both of them
are, then a **0** is pushed onto the stack.
This is like the **&&** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
**m**
: The top two values are popped off of the stack. If at least one of them is
non-zero, a **1** is pushed onto the stack. If both of them are zero, then a
**0** is pushed onto the stack.
This is like the **||** operator in bc(1), and it is *not* a short-circuit
operator.
This is a **non-portable extension**.
## Pseudo-Random Number Generator
dc(1) has a built-in pseudo-random number generator. These commands query the
pseudo-random number generator. (See Parameters for more information about the
**seed** value that controls the pseudo-random number generator.)
The pseudo-random number generator is guaranteed to **NOT** be
cryptographically secure.
**'**
: Generates an integer between 0 and **DC_RAND_MAX**, inclusive (see the
**LIMITS** section).
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
This is a **non-portable extension**.
**"**
: Pops a value off of the stack, which is used as an **exclusive** upper bound
on the integer that will be generated. If the bound is negative or is a
non-integer, an error is raised, and dc(1) resets (see the **RESET**
section) while **seed** remains unchanged. If the bound is larger than
**DC_RAND_MAX**, the higher bound is honored by generating several
pseudo-random integers, multiplying them by appropriate powers of
**DC_RAND_MAX+1**, and adding them together. Thus, the size of integer that
can be generated with this command is unbounded. Using this command will
change the value of **seed**, unless the operand is **0** or **1**. In that
case, **0** is pushed onto the stack, and **seed** is *not* changed.
The generated integer is made as unbiased as possible, subject to the
limitations of the pseudo-random number generator.
This is a **non-portable extension**.
## Stack Control
These commands control the stack.
**c**
: Removes all items from ("clears") the stack.
**d**
: Copies the item on top of the stack ("duplicates") and pushes the copy onto
the stack.
**r**
: Swaps ("reverses") the two top items on the stack.
**R**
: Pops ("removes") the top value from the stack.
## Register Control
These commands control registers (see the **REGISTERS** section).
**s***r*
: Pops the value off the top of the stack and stores it into register *r*.
**l***r*
: Copies the value in register *r* and pushes it onto the stack. This does not
alter the contents of *r*.
**S***r*
: Pops the value off the top of the (main) stack and pushes it onto the stack
of register *r*. The previous value of the register becomes inaccessible.
**L***r*
: Pops the value off the top of the stack for register *r* and push it onto
the main stack. The previous value in the stack for register *r*, if any, is
now accessible via the **l***r* command.
## Parameters
These commands control the values of **ibase**, **obase**, **scale**, and
**seed**. Also see the **SYNTAX** section.
**i**
: Pops the value off of the top of the stack and uses it to set **ibase**,
which must be between **2** and **16**, inclusive.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**o**
: Pops the value off of the top of the stack and uses it to set **obase**,
which must be between **0** and **DC_BASE_MAX**, inclusive (see the
**LIMITS** section and the **NUMBERS** section).
If the value on top of the stack has any *scale*, the *scale* is ignored.
**k**
: Pops the value off of the top of the stack and uses it to set **scale**,
which must be non-negative.
If the value on top of the stack has any *scale*, the *scale* is ignored.
**j**
: Pops the value off of the top of the stack and uses it to set **seed**. The
meaning of **seed** is dependent on the current pseudo-random number
generator but is guaranteed to not change except for new major versions.
The *scale* and sign of the value may be significant.
If a previously used **seed** value is used again, the pseudo-random number
generator is guaranteed to produce the same sequence of pseudo-random
numbers as it did when the **seed** value was previously used.
The exact value assigned to **seed** is not guaranteed to be returned if the
**J** command is used. However, if **seed** *does* return a different value,
both values, when assigned to **seed**, are guaranteed to produce the same
sequence of pseudo-random numbers. This means that certain values assigned
to **seed** will not produce unique sequences of pseudo-random numbers.
There is no limit to the length (number of significant decimal digits) or
*scale* of the value that can be assigned to **seed**.
This is a **non-portable extension**.
**I**
: Pushes the current value of **ibase** onto the main stack.
**O**
: Pushes the current value of **obase** onto the main stack.
**K**
: Pushes the current value of **scale** onto the main stack.
**J**
: Pushes the current value of **seed** onto the main stack.
This is a **non-portable extension**.
**T**
: Pushes the maximum allowable value of **ibase** onto the main stack.
This is a **non-portable extension**.
**U**
: Pushes the maximum allowable value of **obase** onto the main stack.
This is a **non-portable extension**.
**V**
: Pushes the maximum allowable value of **scale** onto the main stack.
This is a **non-portable extension**.
**W**
: Pushes the maximum (inclusive) integer that can be generated with the **'**
pseudo-random number generator command.
This is a **non-portable extension**.
## Strings
The following commands control strings.
dc(1) can work with both numbers and strings, and registers (see the
**REGISTERS** section) can hold both strings and numbers. dc(1) always knows
whether the contents of a register are a string or a number.
While arithmetic operations have to have numbers, and will print an error if
given a string, other commands accept strings.
Strings can also be executed as macros. For example, if the string **[1pR]** is
executed as a macro, then the code **1pR** is executed, meaning that the **1**
will be printed with a newline after and then popped from the stack.
**\[**_characters_**\]**
: Makes a string containing *characters* and pushes it onto the stack.
If there are brackets (**\[** and **\]**) in the string, then they must be
balanced. Unbalanced brackets can be escaped using a backslash (**\\**)
character.
If there is a backslash character in the string, the character after it
(even another backslash) is put into the string verbatim, but the (first)
backslash is not.
**a**
: The value on top of the stack is popped.
If it is a number, it is truncated and its absolute value is taken. The
result mod **UCHAR_MAX+1** is calculated. If that result is **0**, push an
empty string; otherwise, push a one-character string where the character is
the result of the mod interpreted as an ASCII character.
If it is a string, then a new string is made. If the original string is
empty, the new string is empty. If it is not, then the first character of
the original string is used to create the new string as a one-character
string. The new string is then pushed onto the stack.
This is a **non-portable extension**.
**x**
: Pops a value off of the top of the stack.
If it is a number, it is pushed back onto the stack.
If it is a string, it is executed as a macro.
This behavior is the norm whenever a macro is executed, whether by this
command or by the conditional execution commands below.
**\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is greater than the second, then the contents of register
*r* are executed.
For example, **0 1>a** will execute the contents of register **a**, and
**1 0>a** will not.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\>***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not greater than the second (less than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\>***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is less than the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!\<***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not less than the second (greater than or equal to), then
the contents of register *r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!\<***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is equal to the second, then the contents of register *r*
are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**!=***r*
: Pops two values off of the stack that must be numbers and compares them. If
the first value is not equal to the second, then the contents of register
*r* are executed.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
**!=***r***e***s*
: Like the above, but will execute register *s* if the comparison fails.
If either or both of the values are not numbers, dc(1) will raise an error
and reset (see the **RESET** section).
This is a **non-portable extension**.
**?**
: Reads a line from the **stdin** and executes it. This is to allow macros to
request input from users.
**q**
: During execution of a macro, this exits the execution of that macro and the
execution of the macro that executed it. If there are no macros, or only one
macro executing, dc(1) exits.
**Q**
: Pops a value from the stack which must be non-negative and is used the
number of macro executions to pop off of the execution stack. If the number
of levels to pop is greater than the number of executing macros, dc(1)
exits.
## Status
These commands query status of the stack or its top value.
**Z**
: Pops a value off of the stack.
If it is a number, calculates the number of significant decimal digits it
has and pushes the result.
If it is a string, pushes the number of characters the string has.
**X**
: Pops a value off of the stack.
If it is a number, pushes the *scale* of the value onto the stack.
If it is a string, pushes **0**.
**z**
: Pushes the current stack depth (before execution of this command).
## Arrays
These commands manipulate arrays.
**:***r*
: Pops the top two values off of the stack. The second value will be stored in
the array *r* (see the **REGISTERS** section), indexed by the first value.
**;***r*
: Pops the value on top of the stack and uses it as an index into the array
*r*. The selected value is then pushed onto the stack.
# REGISTERS
Registers are names that can store strings, numbers, and arrays. (Number/string
registers do not interfere with array registers.)
Each register is also its own stack, so the current register value is the top of
the stack for the register. All registers, when first referenced, have one value
(**0**) in their stack.
In non-extended register mode, a register name is just the single character that
follows any command that needs a register name. The only exception is a newline
(**'\\n'**); it is a parse error for a newline to be used as a register name.
## Extended Register Mode
Unlike most other dc(1) implentations, this dc(1) provides nearly unlimited
amounts of registers, if extended register mode is enabled.
If extended register mode is enabled (**-x** or **--extended-register**
command-line arguments are given), then normal single character registers are
used *unless* the character immediately following a command that needs a
register name is a space (according to **isspace()**) and not a newline
(**'\\n'**).
In that case, the register name is found according to the regex
**\[a-z\]\[a-z0-9\_\]\*** (like bc(1) identifiers), and it is a parse error if
the next non-space characters do not match that regex.
# RESET
When dc(1) encounters an error or a signal that it has a non-default handler
for, it resets. This means that several things happen.
First, any macros that are executing are stopped and popped off the stack.
The behavior is not unlike that of exceptions in programming languages. Then
the execution point is set so that any code waiting to execute (after all
macros returned) is skipped.
Thus, when dc(1) resets, it skips any remaining code waiting to be executed.
Then, if it is interactive mode, and the error was not a fatal error (see the
**EXIT STATUS** section), it asks for more input; otherwise, it exits with the
appropriate return code.
# PERFORMANCE
Most dc(1) implementations use **char** types to calculate the value of **1**
decimal digit at a time, but that can be slow. This dc(1) does something
different.
It uses large integers to calculate more than **1** decimal digit at a time. If
built in a environment where **DC_LONG_BIT** (see the **LIMITS** section) is
**64**, then each integer has **9** decimal digits. If built in an environment
where **DC_LONG_BIT** is **32** then each integer has **4** decimal digits. This
value (the number of decimal digits per large integer) is called
**DC_BASE_DIGS**.
In addition, this dc(1) uses an even larger integer for overflow checking. This
integer type depends on the value of **DC_LONG_BIT**, but is always at least
twice as large as the integer type used to store digits.
# LIMITS
The following are the limits on dc(1):
**DC_LONG_BIT**
: The number of bits in the **long** type in the environment where dc(1) was
built. This determines how many decimal digits can be stored in a single
large integer (see the **PERFORMANCE** section).
**DC_BASE_DIGS**
: The number of decimal digits per large integer (see the **PERFORMANCE**
section). Depends on **DC_LONG_BIT**.
**DC_BASE_POW**
: The max decimal number that each large integer can store (see
**DC_BASE_DIGS**) plus **1**. Depends on **DC_BASE_DIGS**.
**DC_OVERFLOW_MAX**
: The max number that the overflow type (see the **PERFORMANCE** section) can
hold. Depends on **DC_LONG_BIT**.
**DC_BASE_MAX**
: The maximum output base. Set at **DC_BASE_POW**.
**DC_DIM_MAX**
: The maximum size of arrays. Set at **SIZE_MAX-1**.
**DC_SCALE_MAX**
: The maximum **scale**. Set at **DC_OVERFLOW_MAX-1**.
**DC_STRING_MAX**
: The maximum length of strings. Set at **DC_OVERFLOW_MAX-1**.
**DC_NAME_MAX**
: The maximum length of identifiers. Set at **DC_OVERFLOW_MAX-1**.
**DC_NUM_MAX**
: The maximum length of a number (in decimal digits), which includes digits
after the decimal point. Set at **DC_OVERFLOW_MAX-1**.
**DC_RAND_MAX**
: The maximum integer (inclusive) returned by the **'** command, if dc(1). Set
at **2\^DC_LONG_BIT-1**.
Exponent
: The maximum allowable exponent (positive or negative). Set at
**DC_OVERFLOW_MAX**.
Number of vars
: The maximum number of vars/arrays. Set at **SIZE_MAX-1**.
These limits are meant to be effectively non-existent; the limits are so large
(at least on 64-bit machines) that there should not be any point at which they
become a problem. In fact, memory should be exhausted before these limits should
be hit.
# ENVIRONMENT VARIABLES
dc(1) recognizes the following environment variables:
**DC_ENV_ARGS**
: This is another way to give command-line arguments to dc(1). They should be
in the same format as all other command-line arguments. These are always
processed first, so any files given in **DC_ENV_ARGS** will be processed
before arguments and files given on the command-line. This gives the user
the ability to set up "standard" options and files to be used at every
invocation. The most useful thing for such files to contain would be useful
functions that the user might want every time dc(1) runs. Another use would
be to use the **-e** option to set **scale** to a value other than **0**.
The code that parses **DC_ENV_ARGS** will correctly handle quoted arguments,
but it does not understand escape sequences. For example, the string
**"/home/gavin/some dc file.dc"** will be correctly parsed, but the string
**"/home/gavin/some \"dc\" file.dc"** will include the backslashes.
The quote parsing will handle either kind of quotes, **'** or **"**. Thus,
if you have a file with any number of single quotes in the name, you can use
- double quotes as the outside quotes, as in **"some 'bc' file.bc"**, and vice
+ double quotes as the outside quotes, as in **"some 'dc' file.dc"**, and vice
versa if you have a file with double quotes. However, handling a file with
both kinds of quotes in **DC_ENV_ARGS** is not supported due to the
complexity of the parsing, though such files are still supported on the
command-line where the parsing is done by the shell.
**DC_LINE_LENGTH**
: If this environment variable exists and contains an integer that is greater
than **1** and is less than **UINT16_MAX** (**2\^16-1**), dc(1) will output
lines to that length, including the backslash newline combo. The default
line length is **70**.
**DC_EXPR_EXIT**
: If this variable exists (no matter the contents), dc(1) will exit
immediately after executing expressions and files given by the **-e** and/or
**-f** command-line options (and any equivalents).
# EXIT STATUS
dc(1) returns the following exit statuses:
**0**
: No error.
**1**
: A math error occurred. This follows standard practice of using **1** for
expected errors, since math errors will happen in the process of normal
execution.
Math errors include divide by **0**, taking the square root of a negative
number, using a negative number as a bound for the pseudo-random number
generator, attempting to convert a negative number to a hardware integer,
overflow when converting a number to a hardware integer, and attempting to
use a non-integer where an integer is required.
Converting to a hardware integer happens for the second operand of the power
(**\^**), places (**\@**), left shift (**H**), and right shift (**h**)
operators.
**2**
: A parse error occurred.
Parse errors include unexpected **EOF**, using an invalid character, failing
to find the end of a string or comment, and using a token where it is
invalid.
**3**
: A runtime error occurred.
Runtime errors include assigning an invalid number to **ibase**, **obase**,
or **scale**; give a bad expression to a **read()** call, calling **read()**
inside of a **read()** call, type errors, and attempting an operation when
the stack has too few elements.
**4**
: A fatal error occurred.
Fatal errors include memory allocation errors, I/O errors, failing to open
files, attempting to use files that do not have only ASCII characters (dc(1)
only accepts ASCII characters), attempting to open a directory as a file,
and giving invalid command-line options.
The exit status **4** is special; when a fatal error occurs, dc(1) always exits
and returns **4**, no matter what mode dc(1) is in.
The other statuses will only be returned when dc(1) is not in interactive mode
(see the **INTERACTIVE MODE** section), since dc(1) resets its state (see the
**RESET** section) and accepts more input when one of those errors occurs in
interactive mode. This is also the case when interactive mode is forced by the
**-i** flag or **--interactive** option.
These exit statuses allow dc(1) to be used in shell scripting with error
checking, and its normal behavior can be forced by using the **-i** flag or
**--interactive** option.
# INTERACTIVE MODE
Like bc(1), dc(1) has an interactive mode and a non-interactive mode.
Interactive mode is turned on automatically when both **stdin** and **stdout**
are hooked to a terminal, but the **-i** flag and **--interactive** option can
turn it on in other cases.
In interactive mode, dc(1) attempts to recover from errors (see the **RESET**
section), and in normal execution, flushes **stdout** as soon as execution is
done for the current input.
# TTY MODE
If **stdin**, **stdout**, and **stderr** are all connected to a TTY, dc(1) turns
on "TTY mode."
TTY mode is required for history to be enabled (see the **COMMAND LINE HISTORY**
section). It is also required to enable special handling for **SIGINT** signals.
TTY mode is different from interactive mode because interactive mode is required
in the [bc(1) specification][1], and interactive mode requires only **stdin**
and **stdout** to be connected to a terminal.
# SIGNAL HANDLING
Sending a **SIGINT** will cause dc(1) to stop execution of the current input. If
dc(1) is in TTY mode (see the **TTY MODE** section), it will reset (see the
**RESET** section). Otherwise, it will clean up and exit.
Note that "current input" can mean one of two things. If dc(1) is processing
input from **stdin** in TTY mode, it will ask for more input. If dc(1) is
processing input from a file in TTY mode, it will stop processing the file and
start processing the next file, if one exists, or ask for input from **stdin**
if no other file exists.
This means that if a **SIGINT** is sent to dc(1) as it is executing a file, it
can seem as though dc(1) did not respond to the signal since it will immediately
start executing the next file. This is by design; most files that users execute
when interacting with dc(1) have function definitions, which are quick to parse.
If a file takes a long time to execute, there may be a bug in that file. The
rest of the files could still be executed without problem, allowing the user to
continue.
**SIGTERM** and **SIGQUIT** cause dc(1) to clean up and exit, and it uses the
default handler for all other signals. The one exception is **SIGHUP**; in that
case, when dc(1) is in TTY mode, a **SIGHUP** will cause dc(1) to clean up and
exit.
# COMMAND LINE HISTORY
dc(1) supports interactive command-line editing. If dc(1) is in TTY mode (see
the **TTY MODE** section), history is enabled. Previous lines can be recalled
and edited with the arrow keys.
**Note**: tabs are converted to 8 spaces.
# LOCALES
This dc(1) ships with support for adding error messages for different locales
and thus, supports **LC_MESSAGS**.
# SEE ALSO
bc(1)
# STANDARDS
The dc(1) utility operators are compliant with the operators in the bc(1)
[IEEE Std 1003.1-2017 (“POSIX.1-2017”)][1] specification.
# BUGS
None are known. Report bugs at https://git.yzena.com/gavin/bc.
# AUTHOR
Gavin D. Howard <gavin@yzena.com> and contributors.
[1]: https://pubs.opengroup.org/onlinepubs/9699919799/utilities/bc.html
diff --git a/contrib/bc/manuals/header_bc.txt b/contrib/bc/manuals/header_bc.txt
index bf8f772b6e0f..91e60bd4a984 100644
--- a/contrib/bc/manuals/header_bc.txt
+++ b/contrib/bc/manuals/header_bc.txt
@@ -1 +1 @@
-.TH "BC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "BC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
diff --git a/contrib/bc/manuals/header_bcl.txt b/contrib/bc/manuals/header_bcl.txt
index a017f0670a79..290cc7794143 100644
--- a/contrib/bc/manuals/header_bcl.txt
+++ b/contrib/bc/manuals/header_bcl.txt
@@ -1 +1 @@
-.TH "BCL" "3" "January 2021" "Gavin D. Howard" "Libraries Manual"
+.TH "BCL" "3" "February 2021" "Gavin D. Howard" "Libraries Manual"
diff --git a/contrib/bc/manuals/header_dc.txt b/contrib/bc/manuals/header_dc.txt
index 656210eb0a3a..787d492b3066 100644
--- a/contrib/bc/manuals/header_dc.txt
+++ b/contrib/bc/manuals/header_dc.txt
@@ -1 +1 @@
-.TH "DC" "1" "January 2021" "Gavin D. Howard" "General Commands Manual"
+.TH "DC" "1" "February 2021" "Gavin D. Howard" "General Commands Manual"
diff --git a/contrib/bc/release.sh b/contrib/bc/release.sh
index 5f55c0f8acda..902f26ef4d33 100755
--- a/contrib/bc/release.sh
+++ b/contrib/bc/release.sh
@@ -1,582 +1,582 @@
#! /bin/sh
#
# SPDX-License-Identifier: BSD-2-Clause
#
# Copyright (c) 2018-2021 Gavin D. Howard and contributors.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# * Redistributions of source code must retain the above copyright notice, this
# list of conditions and the following disclaimer.
#
# * Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
#
usage() {
printf 'usage: %s [run_tests] [generate_tests] [test_with_clang] [test_with_gcc] \n' "$script"
printf ' [run_sanitizers] [run_valgrind] [run_64_bit] [run_gen_script]\n'
exit 1
}
header() {
_header_msg="$1"
shift
printf '\n'
printf '*******************\n'
printf "$_header_msg"
printf '\n'
printf '*******************\n'
printf '\n'
}
do_make() {
make -j16 "$@"
}
configure() {
_configure_CFLAGS="$1"
shift
_configure_CC="$1"
shift
_configure_configure_flags="$1"
shift
_configure_GEN_HOST="$1"
shift
_configure_LONG_BIT="$1"
shift
if [ "$gen_tests" -eq 0 ]; then
_configure_configure_flags="-G $_configure_configure_flags"
fi
if [ "$_configure_CC" = "clang" ]; then
_configure_CFLAGS="$clang_flags $_configure_CFLAGS"
elif [ "$_configure_CC" = "gcc" ]; then
_configure_CFLAGS="$gcc_flags $_configure_CFLAGS"
fi
_configure_header=$(printf 'Running ./configure.sh %s ...' "$_configure_configure_flags")
_configure_header=$(printf "$_configure_header\n CC=\"%s\"\n" "$_configure_CC")
_configure_header=$(printf "$_configure_header\n CFLAGS=\"%s\"\n" "$_configure_CFLAGS")
_configure_header=$(printf "$_configure_header\n LONG_BIT=%s" "$_configure_LONG_BIT")
_configure_header=$(printf "$_configure_header\n GEN_HOST=%s" "$_configure_GEN_HOST")
header "$_configure_header"
CFLAGS="$_configure_CFLAGS" CC="$_configure_CC" GEN_HOST="$_configure_GEN_HOST" \
LONG_BIT="$_configure_LONG_BIT" ./configure.sh $_configure_configure_flags > /dev/null
}
build() {
_build_CFLAGS="$1"
shift
_build_CC="$1"
shift
_build_configure_flags="$1"
shift
_build_GEN_HOST="$1"
shift
_build_LONG_BIT="$1"
shift
configure "$_build_CFLAGS" "$_build_CC" "$_build_configure_flags" "$_build_GEN_HOST" "$_build_LONG_BIT"
_build_header=$(printf 'Building...\n CC=%s' "$_build_CC")
_build_header=$(printf "$_build_header\n CFLAGS=\"%s\"" "$_build_CFLAGS")
_build_header=$(printf "$_build_header\n LONG_BIT=%s" "$_build_LONG_BIT")
_build_header=$(printf "$_build_header\n GEN_HOST=%s" "$_build_GEN_HOST")
header "$_build_header"
do_make > /dev/null 2> "$scriptdir/.test.txt"
if [ -s "$scriptdir/.test.txt" ]; then
printf '%s generated warning(s):\n' "$_build_CC"
printf '\n'
cat "$scriptdir/.test.txt"
exit 1
fi
}
runtest() {
header "Running tests"
if [ "$#" -gt 0 ]; then
do_make "$@"
else
do_make test
fi
}
runconfigtests() {
_runconfigtests_CFLAGS="$1"
shift
_runconfigtests_CC="$1"
shift
_runconfigtests_configure_flags="$1"
shift
_runconfigtests_GEN_HOST="$1"
shift
_runconfigtests_LONG_BIT="$1"
shift
_runconfigtests_run_tests="$1"
shift
if [ "$_runconfigtests_run_tests" -ne 0 ]; then
_runconfigtests_header=$(printf 'Running tests with configure flags')
else
_runconfigtests_header=$(printf 'Building with configure flags')
fi
_runconfigtests_header=$(printf "$_runconfigtests_header \"%s\" ...\n" "$_runconfigtests_configure_flags")
_runconfigtests_header=$(printf "$_runconfigtests_header\n CC=%s\n" "$_runconfigseries_CC")
_runconfigtests_header=$(printf "$_runconfigtests_header\n CFLAGS=\"%s\"" "$_runconfigseries_CFLAGS")
_runconfigtests_header=$(printf "$_runconfigtests_header\n LONG_BIT=%s" "$_runconfigtests_LONG_BIT")
_runconfigtests_header=$(printf "$_runconfigtests_header\n GEN_HOST=%s" "$_runconfigtests_GEN_HOST")
header "$_runconfigtests_header"
build "$_runconfigtests_CFLAGS" "$_runconfigtests_CC" \
"$_runconfigtests_configure_flags" "$_runconfigtests_GEN_HOST" \
"$_runconfigtests_LONG_BIT"
if [ "$_runconfigtests_run_tests" -ne 0 ]; then
runtest
fi
do_make clean
build "$_runconfigtests_CFLAGS" "$_runconfigtests_CC" \
"$_runconfigtests_configure_flags -b" "$_runconfigtests_GEN_HOST" \
"$_runconfigtests_LONG_BIT"
if [ "$_runconfigtests_run_tests" -ne 0 ]; then
runtest
fi
do_make clean
build "$_runconfigtests_CFLAGS" "$_runconfigtests_CC" \
"$_runconfigtests_configure_flags -d" "$_runconfigtests_GEN_HOST" \
"$_runconfigtests_LONG_BIT"
if [ "$_runconfigtests_run_tests" -ne 0 ]; then
runtest
fi
do_make clean
}
runconfigseries() {
_runconfigseries_CFLAGS="$1"
shift
_runconfigseries_CC="$1"
shift
_runconfigseries_configure_flags="$1"
shift
_runconfigseries_run_tests="$1"
shift
if [ "$run_64_bit" -ne 0 ]; then
runconfigtests "$_runconfigseries_CFLAGS" "$_runconfigseries_CC" \
"$_runconfigseries_configure_flags" 1 64 "$_runconfigseries_run_tests"
if [ "$run_gen_script" -ne 0 ]; then
runconfigtests "$_runconfigseries_CFLAGS" "$_runconfigseries_CC" \
"$_runconfigseries_configure_flags" 0 64 "$_runconfigseries_run_tests"
fi
runconfigtests "$_runconfigseries_CFLAGS -DBC_RAND_BUILTIN=0" "$_runconfigseries_CC" \
"$_runconfigseries_configure_flags" 1 64 "$_runconfigseries_run_tests"
fi
runconfigtests "$_runconfigseries_CFLAGS" "$_runconfigseries_CC" \
"$_runconfigseries_configure_flags" 1 32 "$_runconfigseries_run_tests"
if [ "$run_gen_script" -ne 0 ]; then
runconfigtests "$_runconfigseries_CFLAGS" "$_runconfigseries_CC" \
"$_runconfigseries_configure_flags" 0 32 "$_runconfigseries_run_tests"
fi
}
runtestseries() {
_runtestseries_CFLAGS="$1"
shift
_runtestseries_CC="$1"
shift
_runtestseries_configure_flags="$1"
shift
_runtestseries_run_tests="$1"
shift
_runtestseries_flags="E H N P EH EN EP HN HP NP EHN EHP ENP HNP EHNP"
runconfigseries "$_runtestseries_CFLAGS" "$_runtestseries_CC" \
"$_runtestseries_configure_flags" "$_runtestseries_run_tests"
for f in $_runtestseries_flags; do
runconfigseries "$_runtestseries_CFLAGS" "$_runtestseries_CC" \
"$_runtestseries_configure_flags -$f" "$_runtestseries_run_tests"
done
}
runlibtests() {
_runlibtests_CFLAGS="$1"
shift
_runlibtests_CC="$1"
shift
_runlibtests_configure_flags="$1"
shift
_runlibtests_run_tests="$1"
shift
_runlibtests_configure_flags="$_runlibtests_configure_flags -a"
build "$_runlibtests_CFLAGS" "$_runlibtests_CC" "$_runlibtests_configure_flags" 1 64
if [ "$_runlibtests_run_tests" -ne 0 ]; then
runtest
fi
build "$_runlibtests_CFLAGS" "$_runlibtests_CC" "$_runlibtests_configure_flags" 1 32
if [ "$_runlibtests_run_tests" -ne 0 ]; then
runtest
fi
}
runtests() {
_runtests_CFLAGS="$1"
shift
_runtests_CC="$1"
shift
_runtests_configure_flags="$1"
shift
_runtests_run_tests="$1"
shift
runtestseries "-std=c99 $_runtests_CFLAGS" "$_runtests_CC" "$_runtests_configure_flags" "$_runtests_run_tests"
runtestseries "-std=c11 $_runtests_CFLAGS" "$_runtests_CC" "$_runtests_configure_flags" "$_runtests_run_tests"
}
karatsuba() {
header "Running Karatsuba tests"
do_make karatsuba_test
}
vg() {
header "Running valgrind"
if [ "$run_64_bit" -ne 0 ]; then
_vg_bits=64
else
_vg_bits=32
fi
build "$debug" "gcc" "-O0 -gv" "1" "$_vg_bits"
runtest test
do_make clean_config
build "$debug" "gcc" "-O0 -gvb" "1" "$_vg_bits"
runtest test
do_make clean_config
build "$debug" "gcc" "-O0 -gvd" "1" "$_vg_bits"
runtest test
do_make clean_config
}
debug() {
_debug_CC="$1"
shift
_debug_run_tests="$1"
shift
runtests "$debug" "$_debug_CC" "-g" "$_debug_run_tests"
if [ "$_debug_CC" = "clang" -a "$run_sanitizers" -ne 0 ]; then
runtests "$debug -fsanitize=undefined" "$_debug_CC" "-g" "$_debug_run_tests"
fi
runlibtests "$debug" "$_debug_CC" "-g" "$_debug_run_tests"
if [ "$_debug_CC" = "clang" -a "$run_sanitizers" -ne 0 ]; then
runlibtests "$debug -fsanitize=undefined" "$_debug_CC" "-g" "$_debug_run_tests"
fi
}
release() {
_release_CC="$1"
shift
_release_run_tests="$1"
shift
runtests "$release" "$_release_CC" "-O3" "$_release_run_tests"
runlibtests "$release" "$_release_CC" "-O3" "$_release_run_tests"
}
reldebug() {
_reldebug_CC="$1"
shift
_reldebug_run_tests="$1"
shift
runtests "$debug" "$_reldebug_CC" "-gO3" "$_reldebug_run_tests"
if [ "$_reldebug_CC" = "clang" -a "$run_sanitizers" -ne 0 ]; then
runtests "$debug -fsanitize=address" "$_reldebug_CC" "-gO3" "$_reldebug_run_tests"
runtests "$debug -fsanitize=memory" "$_reldebug_CC" "-gO3" "$_reldebug_run_tests"
fi
runlibtests "$debug" "$_reldebug_CC" "-gO3" "$_reldebug_run_tests"
if [ "$_reldebug_CC" = "clang" -a "$run_sanitizers" -ne 0 ]; then
runlibtests "$debug -fsanitize=address" "$_reldebug_CC" "-gO3" "$_reldebug_run_tests"
runlibtests "$debug -fsanitize=memory" "$_reldebug_CC" "-gO3" "$_reldebug_run_tests"
fi
}
minsize() {
_minsize_CC="$1"
shift
_minsize_run_tests="$1"
shift
runtests "$release" "$_minsize_CC" "-Os" "$_minsize_run_tests"
runlibtests "$release" "$_minsize_CC" "-Os" "$_minsize_run_tests"
}
build_set() {
_build_set_CC="$1"
shift
_build_set_run_tests="$1"
shift
debug "$_build_set_CC" "$_build_set_run_tests"
release "$_build_set_CC" "$_build_set_run_tests"
reldebug "$_build_set_CC" "$_build_set_run_tests"
minsize "$_build_set_CC" "$_build_set_run_tests"
}
clang_flags="-Weverything -Wno-padded -Wno-switch-enum -Wno-format-nonliteral"
clang_flags="$clang_flags -Wno-cast-align -Wno-missing-noreturn -Wno-disabled-macro-expansion"
clang_flags="$clang_flags -Wno-unreachable-code -Wno-unreachable-code-return"
clang_flags="$clang_flags -Wno-implicit-fallthrough"
gcc_flags="-Wno-maybe-uninitialized -Wno-clobbered"
cflags="-Wall -Wextra -Werror -pedantic -Wno-conditional-uninitialized"
debug="$cflags -fno-omit-frame-pointer"
release="$cflags -DNDEBUG"
set -e
script="$0"
scriptdir=$(dirname "$script")
if [ "$#" -gt 0 ]; then
run_tests="$1"
shift
else
run_tests=1
fi
if [ "$#" -gt 0 ]; then
gen_tests="$1"
shift
else
gen_tests=1
fi
if [ "$#" -gt 0 ]; then
test_with_clang="$1"
shift
else
test_with_clang=1
fi
if [ "$#" -gt 0 ]; then
test_with_gcc="$1"
shift
else
test_with_gcc=1
fi
if [ "$#" -gt 0 ]; then
run_sanitizers="$1"
shift
else
run_sanitizers=1
fi
if [ "$#" -gt 0 ]; then
run_valgrind="$1"
shift
else
run_valgrind=1
fi
if [ "$#" -gt 0 ]; then
run_64_bit="$1"
shift
else
run_64_bit=1
fi
if [ "$#" -gt 0 ]; then
run_gen_script="$1"
shift
else
run_gen_script=0
fi
if [ "$run_64_bit" -ne 0 ]; then
bits=64
else
bits=32
fi
cd "$scriptdir"
if [ "$test_with_clang" -ne 0 ]; then
defcc="clang"
elif [ "$test_with_gcc" -ne 0 ]; then
defcc="gcc"
else
defcc="c99"
fi
export ASAN_OPTIONS="abort_on_error=1,allocator_may_return_null=1"
export UBSAN_OPTIONS="print_stack_trace=1,silence_unsigned_overflow=1"
build "$debug" "$defcc" "-g" "1" "$bits"
header "Running math library under --standard"
printf 'quit\n' | bin/bc -ls
version=$(make version)
do_make clean_tests
if [ "$test_with_clang" -ne 0 ]; then
build_set "clang" "$run_tests"
fi
if [ "$test_with_gcc" -ne 0 ]; then
build_set "gcc" "$run_tests"
fi
if [ "$run_tests" -ne 0 ]; then
build "$release" "$defcc" "-O3" "1" "$bits"
karatsuba
if [ "$run_valgrind" -ne 0 -a "$test_with_gcc" -ne 0 ]; then
vg
fi
printf '\n'
printf 'Tests successful.\n'
set +e
command -v afl-gcc > /dev/null 2>&1
err="$?"
set -e
if [ "$err" -eq 0 ]; then
header "Configuring for afl-gcc..."
configure "$debug $gcc_flags -DBC_ENABLE_RAND=0" "afl-gcc" "-HNP -gO3" "1" "$bits"
printf '\n'
printf 'Run make\n'
printf '\n'
printf 'Then run %s/tests/randmath.py and the fuzzer.\n' "$scriptdir"
printf '\n'
printf 'Then run ASan on the fuzzer test cases with the following build:\n'
printf '\n'
printf ' CFLAGS="-fsanitize=address -fno-omit-frame-pointer -DBC_ENABLE_RAND=0" ./configure.sh -gO3 -HNPS\n'
printf ' make\n'
printf '\n'
printf 'Then run the GitHub release script as follows:\n'
printf '\n'
printf ' <github_release> %s release.sh RELEASE.md\\\n' "$version"
printf ' tests/afl.py tests/radamsa.sh tests/radamsa.txt tests/randmath.py \\\n'
- printf ' tests/bc/scripts/timeconst.bc\n'
+ printf ' tests/fuzzing/ tests/bc/scripts/timeconst.bc\n'
fi
fi
diff --git a/contrib/bc/src/args.c b/contrib/bc/src/args.c
index b26062c6caec..9c26b7c18790 100644
--- a/contrib/bc/src/args.c
+++ b/contrib/bc/src/args.c
@@ -1,219 +1,221 @@
/*
* *****************************************************************************
*
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (c) 2018-2021 Gavin D. Howard and contributors.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* *****************************************************************************
*
* Code for processing command-line arguments.
*
*/
#include <assert.h>
#include <ctype.h>
#include <stdbool.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <vector.h>
#include <read.h>
#include <args.h>
#include <opt.h>
static const BcOptLong bc_args_lopt[] = {
{ "expression", BC_OPT_REQUIRED, 'e' },
{ "file", BC_OPT_REQUIRED, 'f' },
{ "help", BC_OPT_NONE, 'h' },
{ "interactive", BC_OPT_NONE, 'i' },
{ "no-prompt", BC_OPT_NONE, 'P' },
#if BC_ENABLED
{ "global-stacks", BC_OPT_BC_ONLY, 'g' },
{ "mathlib", BC_OPT_BC_ONLY, 'l' },
{ "quiet", BC_OPT_BC_ONLY, 'q' },
{ "standard", BC_OPT_BC_ONLY, 's' },
{ "warn", BC_OPT_BC_ONLY, 'w' },
#endif // BC_ENABLED
{ "version", BC_OPT_NONE, 'v' },
{ "version", BC_OPT_NONE, 'V' },
#if DC_ENABLED
{ "extended-register", BC_OPT_DC_ONLY, 'x' },
#endif // DC_ENABLED
{ NULL, 0, 0 },
};
static void bc_args_exprs(const char *str) {
BC_SIG_ASSERT_LOCKED;
if (vm.exprs.v == NULL) bc_vec_init(&vm.exprs, sizeof(uchar), NULL);
bc_vec_concat(&vm.exprs, str);
bc_vec_concat(&vm.exprs, "\n");
}
static void bc_args_file(const char *file) {
char *buf;
BC_SIG_ASSERT_LOCKED;
vm.file = file;
bc_read_file(file, &buf);
bc_args_exprs(buf);
free(buf);
}
-void bc_args(int argc, char *argv[]) {
+void bc_args(int argc, char *argv[], bool exit_exprs) {
int c;
size_t i;
bool do_exit = false, version = false;
BcOpt opts;
BC_SIG_ASSERT_LOCKED;
bc_opt_init(&opts, argv);
while ((c = bc_opt_parse(&opts, bc_args_lopt)) != -1) {
switch (c) {
case 'e':
{
if (vm.no_exit_exprs)
bc_vm_verr(BC_ERR_FATAL_OPTION, "-e (--expression)");
bc_args_exprs(opts.optarg);
+ vm.exit_exprs = (exit_exprs || vm.exit_exprs);
break;
}
case 'f':
{
if (!strcmp(opts.optarg, "-")) vm.no_exit_exprs = true;
else {
if (vm.no_exit_exprs)
bc_vm_verr(BC_ERR_FATAL_OPTION, "-f (--file)");
bc_args_file(opts.optarg);
+ vm.exit_exprs = (exit_exprs || vm.exit_exprs);
}
break;
}
case 'h':
{
bc_vm_info(vm.help);
do_exit = true;
break;
}
case 'i':
{
vm.flags |= BC_FLAG_I;
break;
}
case 'P':
{
vm.flags |= BC_FLAG_P;
break;
}
#if BC_ENABLED
case 'g':
{
assert(BC_IS_BC);
vm.flags |= BC_FLAG_G;
break;
}
case 'l':
{
assert(BC_IS_BC);
vm.flags |= BC_FLAG_L;
break;
}
case 'q':
{
assert(BC_IS_BC);
// Do nothing.
break;
}
case 's':
{
assert(BC_IS_BC);
vm.flags |= BC_FLAG_S;
break;
}
case 'w':
{
assert(BC_IS_BC);
vm.flags |= BC_FLAG_W;
break;
}
#endif // BC_ENABLED
case 'V':
case 'v':
{
do_exit = version = true;
break;
}
#if DC_ENABLED
case 'x':
{
assert(BC_IS_DC);
vm.flags |= DC_FLAG_X;
break;
}
#endif // DC_ENABLED
#ifndef NDEBUG
// We shouldn't get here because bc_opt_error()/bc_vm_error() should
// longjmp() out.
case '?':
case ':':
default:
{
abort();
}
#endif // NDEBUG
}
}
if (version) bc_vm_info(NULL);
if (do_exit) exit((int) vm.status);
if (opts.optind < (size_t) argc && vm.files.v == NULL)
bc_vec_init(&vm.files, sizeof(char*), NULL);
for (i = opts.optind; i < (size_t) argc; ++i)
bc_vec_push(&vm.files, argv + i);
}
diff --git a/contrib/bc/src/vm.c b/contrib/bc/src/vm.c
index d363458bed58..87036c7b5c91 100644
--- a/contrib/bc/src/vm.c
+++ b/contrib/bc/src/vm.c
@@ -1,975 +1,975 @@
/*
* *****************************************************************************
*
* SPDX-License-Identifier: BSD-2-Clause
*
* Copyright (c) 2018-2021 Gavin D. Howard and contributors.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions are met:
*
* * Redistributions of source code must retain the above copyright notice, this
* list of conditions and the following disclaimer.
*
* * Redistributions in binary form must reproduce the above copyright notice,
* this list of conditions and the following disclaimer in the documentation
* and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
* *****************************************************************************
*
* Code common to all of bc and dc.
*
*/
#include <assert.h>
#include <ctype.h>
#include <errno.h>
#include <stdarg.h>
#include <string.h>
#include <signal.h>
#include <setjmp.h>
#ifndef _WIN32
#include <sys/types.h>
#include <unistd.h>
#else // _WIN32
#define WIN32_LEAN_AND_MEAN
#include <windows.h>
#include <io.h>
#endif // _WIN32
#include <vector.h>
#include <args.h>
#include <vm.h>
#include <read.h>
#include <bc.h>
char output_bufs[BC_VM_BUF_SIZE];
BcVm vm;
#if BC_DEBUG_CODE
BC_NORETURN void bc_vm_jmp(const char* f) {
#else // BC_DEBUG_CODE
BC_NORETURN void bc_vm_jmp(void) {
#endif
assert(BC_SIG_EXC);
BC_SIG_MAYLOCK;
#if BC_DEBUG_CODE
bc_file_puts(&vm.ferr, "Longjmp: ");
bc_file_puts(&vm.ferr, f);
bc_file_putchar(&vm.ferr, '\n');
bc_file_flush(&vm.ferr);
#endif // BC_DEBUG_CODE
#ifndef NDEBUG
assert(vm.jmp_bufs.len - (size_t) vm.sig_pop);
#endif // NDEBUG
if (vm.jmp_bufs.len == 0) abort();
if (vm.sig_pop) bc_vec_pop(&vm.jmp_bufs);
else vm.sig_pop = 1;
siglongjmp(*((sigjmp_buf*) bc_vec_top(&vm.jmp_bufs)), 1);
}
#if !BC_ENABLE_LIBRARY
static void bc_vm_sig(int sig) {
// There is already a signal in flight.
if (vm.status == (sig_atomic_t) BC_STATUS_QUIT || vm.sig) {
if (!BC_TTY || sig != SIGINT) vm.status = BC_STATUS_QUIT;
return;
}
if (BC_TTY && sig == SIGINT) {
int err = errno;
if (write(STDOUT_FILENO, vm.sigmsg, vm.siglen) != (ssize_t) vm.siglen)
vm.status = BC_STATUS_ERROR_FATAL;
else vm.sig = 1;
errno = err;
}
else vm.status = BC_STATUS_QUIT;
assert(vm.jmp_bufs.len);
if (!vm.sig_lock) BC_VM_JMP;
}
void bc_vm_info(const char* const help) {
BC_SIG_ASSERT_LOCKED;
bc_file_puts(&vm.fout, vm.name);
bc_file_putchar(&vm.fout, ' ');
bc_file_puts(&vm.fout, BC_VERSION);
bc_file_putchar(&vm.fout, '\n');
bc_file_puts(&vm.fout, bc_copyright);
if (help) {
bc_file_putchar(&vm.fout, '\n');
bc_file_printf(&vm.fout, help, vm.name, vm.name);
}
bc_file_flush(&vm.fout);
}
#endif // !BC_ENABLE_LIBRARY
#if !BC_ENABLE_LIBRARY && !BC_ENABLE_MEMCHECK
BC_NORETURN
#endif // !BC_ENABLE_LIBRARY && !BC_ENABLE_MEMCHECK
void bc_vm_fatalError(BcErr e) {
bc_vm_err(e);
#if !BC_ENABLE_LIBRARY && !BC_ENABLE_MEMCHECK
abort();
#endif // !BC_ENABLE_LIBRARY && !BC_ENABLE_MEMCHECK
}
#if BC_ENABLE_LIBRARY
void bc_vm_handleError(BcErr e) {
assert(e < BC_ERR_NELEMS);
assert(!vm.sig_pop);
BC_SIG_LOCK;
if (e <= BC_ERR_MATH_DIVIDE_BY_ZERO) {
vm.err = (BclError) (e - BC_ERR_MATH_NEGATIVE +
BCL_ERROR_MATH_NEGATIVE);
}
else if (vm.abrt) abort();
else if (e == BC_ERR_FATAL_ALLOC_ERR) vm.err = BCL_ERROR_FATAL_ALLOC_ERR;
else vm.err = BCL_ERROR_FATAL_UNKNOWN_ERR;
BC_VM_JMP;
}
#else // BC_ENABLE_LIBRARY
void bc_vm_handleError(BcErr e, size_t line, ...) {
BcStatus s;
va_list args;
uchar id = bc_err_ids[e];
const char* err_type = vm.err_ids[id];
sig_atomic_t lock;
assert(e < BC_ERR_NELEMS);
assert(!vm.sig_pop);
#if BC_ENABLED
if (!BC_S && e >= BC_ERR_POSIX_START) {
if (BC_W) {
// Make sure to not return an error.
id = UCHAR_MAX;
err_type = vm.err_ids[BC_ERR_IDX_WARN];
}
else return;
}
#endif // BC_ENABLED
BC_SIG_TRYLOCK(lock);
// Make sure all of stdout is written first.
s = bc_file_flushErr(&vm.fout);
if (BC_ERR(s == BC_STATUS_ERROR_FATAL)) {
vm.status = (sig_atomic_t) s;
BC_VM_JMP;
}
va_start(args, line);
bc_file_putchar(&vm.ferr, '\n');
bc_file_puts(&vm.ferr, err_type);
bc_file_putchar(&vm.ferr, ' ');
bc_file_vprintf(&vm.ferr, vm.err_msgs[e], args);
va_end(args);
if (BC_NO_ERR(vm.file)) {
// This is the condition for parsing vs runtime.
// If line is not 0, it is parsing.
if (line) {
bc_file_puts(&vm.ferr, "\n ");
bc_file_puts(&vm.ferr, vm.file);
bc_file_printf(&vm.ferr, bc_err_line, line);
}
else {
BcInstPtr *ip = bc_vec_item_rev(&vm.prog.stack, 0);
BcFunc *f = bc_vec_item(&vm.prog.fns, ip->func);
bc_file_puts(&vm.ferr, "\n ");
bc_file_puts(&vm.ferr, vm.func_header);
bc_file_putchar(&vm.ferr, ' ');
bc_file_puts(&vm.ferr, f->name);
#if BC_ENABLED
if (BC_IS_BC && ip->func != BC_PROG_MAIN &&
ip->func != BC_PROG_READ)
{
bc_file_puts(&vm.ferr, "()");
}
#endif // BC_ENABLED
}
}
bc_file_puts(&vm.ferr, "\n\n");
s = bc_file_flushErr(&vm.ferr);
#if !BC_ENABLE_MEMCHECK
// Because this function is called by a BC_NORETURN function when fatal
// errors happen, we need to make sure to exit on fatal errors. This will
// be faster anyway. This function *cannot jump when a fatal error occurs!*
if (BC_ERR(id == BC_ERR_IDX_FATAL || s == BC_STATUS_ERROR_FATAL))
exit(bc_vm_atexit((int) BC_STATUS_ERROR_FATAL));
#else // !BC_ENABLE_MEMCHECK
if (BC_ERR(s == BC_STATUS_ERROR_FATAL)) vm.status = (sig_atomic_t) s;
else
#endif // !BC_ENABLE_MEMCHECK
{
vm.status = (sig_atomic_t) (uchar) (id + 1);
}
if (BC_ERR(vm.status)) BC_VM_JMP;
BC_SIG_TRYUNLOCK(lock);
}
static void bc_vm_envArgs(const char* const env_args_name) {
char *env_args = getenv(env_args_name), *buf, *start;
char instr = '\0';
BC_SIG_ASSERT_LOCKED;
if (env_args == NULL) return;
start = buf = vm.env_args_buffer = bc_vm_strdup(env_args);
assert(buf != NULL);
bc_vec_init(&vm.env_args, sizeof(char*), NULL);
bc_vec_push(&vm.env_args, &env_args_name);
while (*buf) {
if (!isspace(*buf)) {
if (*buf == '"' || *buf == '\'') {
instr = *buf;
buf += 1;
if (*buf == instr) {
instr = '\0';
buf += 1;
continue;
}
}
bc_vec_push(&vm.env_args, &buf);
while (*buf && ((!instr && !isspace(*buf)) ||
(instr && *buf != instr)))
{
buf += 1;
}
if (*buf) {
if (instr) instr = '\0';
*buf = '\0';
buf += 1;
start = buf;
}
else if (instr) bc_vm_error(BC_ERR_FATAL_OPTION, 0, start);
}
else buf += 1;
}
// Make sure to push a NULL pointer at the end.
buf = NULL;
bc_vec_push(&vm.env_args, &buf);
- bc_args((int) vm.env_args.len - 1, bc_vec_item(&vm.env_args, 0));
+ bc_args((int) vm.env_args.len - 1, bc_vec_item(&vm.env_args, 0), false);
}
static size_t bc_vm_envLen(const char *var) {
char *lenv = getenv(var);
size_t i, len = BC_NUM_PRINT_WIDTH;
int num;
if (lenv == NULL) return len;
len = strlen(lenv);
for (num = 1, i = 0; num && i < len; ++i) num = isdigit(lenv[i]);
if (num) {
len = (size_t) atoi(lenv) - 1;
if (len < 2 || len >= UINT16_MAX) len = BC_NUM_PRINT_WIDTH;
}
else len = BC_NUM_PRINT_WIDTH;
return len;
}
#endif // BC_ENABLE_LIBRARY
void bc_vm_shutdown(void) {
BC_SIG_ASSERT_LOCKED;
#if BC_ENABLE_NLS
if (vm.catalog != BC_VM_INVALID_CATALOG) catclose(vm.catalog);
#endif // BC_ENABLE_NLS
#if BC_ENABLE_HISTORY
// This must always run to ensure that the terminal is back to normal.
if (BC_TTY) bc_history_free(&vm.history);
#endif // BC_ENABLE_HISTORY
#ifndef NDEBUG
#if !BC_ENABLE_LIBRARY
bc_vec_free(&vm.env_args);
free(vm.env_args_buffer);
bc_vec_free(&vm.files);
bc_vec_free(&vm.exprs);
bc_program_free(&vm.prog);
bc_parse_free(&vm.prs);
#endif // !BC_ENABLE_LIBRARY
bc_vm_freeTemps();
bc_vec_free(&vm.temps);
#endif // NDEBUG
#if !BC_ENABLE_LIBRARY
bc_file_free(&vm.fout);
bc_file_free(&vm.ferr);
#endif // !BC_ENABLE_LIBRARY
}
#if !defined(NDEBUG) || BC_ENABLE_LIBRARY
void bc_vm_freeTemps(void) {
size_t i;
for (i = 0; i < vm.temps.len; ++i) {
free(((BcNum*) bc_vec_item(&vm.temps, i))->num);
}
}
#endif // !defined(NDEBUG) || BC_ENABLE_LIBRARY
inline size_t bc_vm_arraySize(size_t n, size_t size) {
size_t res = n * size;
if (BC_ERR(res >= SIZE_MAX || (n != 0 && res / n != size)))
bc_vm_fatalError(BC_ERR_FATAL_ALLOC_ERR);
return res;
}
inline size_t bc_vm_growSize(size_t a, size_t b) {
size_t res = a + b;
if (BC_ERR(res >= SIZE_MAX || res < a || res < b))
bc_vm_fatalError(BC_ERR_FATAL_ALLOC_ERR);
return res;
}
void* bc_vm_malloc(size_t n) {
void* ptr;
BC_SIG_ASSERT_LOCKED;
ptr = malloc(n);
if (BC_ERR(ptr == NULL)) bc_vm_fatalError(BC_ERR_FATAL_ALLOC_ERR);
return ptr;
}
void* bc_vm_realloc(void *ptr, size_t n) {
void* temp;
BC_SIG_ASSERT_LOCKED;
temp = realloc(ptr, n);
if (BC_ERR(temp == NULL)) bc_vm_fatalError(BC_ERR_FATAL_ALLOC_ERR);
return temp;
}
char* bc_vm_strdup(const char *str) {
char *s;
BC_SIG_ASSERT_LOCKED;
s = strdup(str);
if (BC_ERR(s == NULL)) bc_vm_fatalError(BC_ERR_FATAL_ALLOC_ERR);
return s;
}
#if !BC_ENABLE_LIBRARY
void bc_vm_printf(const char *fmt, ...) {
va_list args;
BC_SIG_LOCK;
va_start(args, fmt);
bc_file_vprintf(&vm.fout, fmt, args);
va_end(args);
vm.nchars = 0;
BC_SIG_UNLOCK;
}
#endif // !BC_ENABLE_LIBRARY
void bc_vm_putchar(int c) {
#if BC_ENABLE_LIBRARY
bc_vec_pushByte(&vm.out, (uchar) c);
#else // BC_ENABLE_LIBRARY
bc_file_putchar(&vm.fout, (uchar) c);
vm.nchars = (c == '\n' ? 0 : vm.nchars + 1);
#endif // BC_ENABLE_LIBRARY
}
#if !BC_ENABLE_LIBRARY
static void bc_vm_clean(void) {
BcVec *fns = &vm.prog.fns;
BcFunc *f = bc_vec_item(fns, BC_PROG_MAIN);
BcInstPtr *ip = bc_vec_item(&vm.prog.stack, 0);
bool good = ((vm.status && vm.status != BC_STATUS_QUIT) || vm.sig);
if (good) bc_program_reset(&vm.prog);
#if BC_ENABLED
if (good && BC_IS_BC) good = !BC_PARSE_NO_EXEC(&vm.prs);
#endif // BC_ENABLED
#if DC_ENABLED
if (BC_IS_DC) {
size_t i;
good = true;
for (i = 0; good && i < vm.prog.results.len; ++i) {
BcResult *r = (BcResult*) bc_vec_item(&vm.prog.results, i);
good = BC_VM_SAFE_RESULT(r);
}
}
#endif // DC_ENABLED
// If this condition is true, we can get rid of strings,
// constants, and code. This is an idea from busybox.
if (good && vm.prog.stack.len == 1 && ip->idx == f->code.len) {
#if BC_ENABLED
if (BC_IS_BC) {
bc_vec_popAll(&f->labels);
bc_vec_popAll(&f->strs);
bc_vec_popAll(&f->consts);
}
#endif // BC_ENABLED
#if DC_ENABLED
// Note to self: you cannot delete strings and functions. Deal with it.
if (BC_IS_DC) bc_vec_popAll(vm.prog.consts);
#endif // DC_ENABLED
bc_vec_popAll(&f->code);
ip->idx = 0;
}
}
static void bc_vm_process(const char *text) {
bc_parse_text(&vm.prs, text);
do {
#if BC_ENABLED
if (vm.prs.l.t == BC_LEX_KW_DEFINE) vm.parse(&vm.prs);
#endif // BC_ENABLED
while (BC_PARSE_CAN_PARSE(vm.prs)) vm.parse(&vm.prs);
if(BC_IS_DC || !BC_PARSE_NO_EXEC(&vm.prs)) bc_program_exec(&vm.prog);
assert(BC_IS_DC || vm.prog.results.len == 0);
if (BC_I) bc_file_flush(&vm.fout);
} while (vm.prs.l.t != BC_LEX_EOF);
}
#if BC_ENABLED
static void bc_vm_endif(void) {
size_t i;
bool good;
if (BC_NO_ERR(!BC_PARSE_NO_EXEC(&vm.prs))) return;
good = true;
for (i = 0; good && i < vm.prs.flags.len; ++i) {
uint16_t flag = *((uint16_t*) bc_vec_item(&vm.prs.flags, i));
good = ((flag & BC_PARSE_FLAG_BRACE) != BC_PARSE_FLAG_BRACE);
}
if (good) {
while (BC_PARSE_IF_END(&vm.prs)) bc_vm_process("else {}");
}
else bc_parse_err(&vm.prs, BC_ERR_PARSE_BLOCK);
}
#endif // BC_ENABLED
static void bc_vm_file(const char *file) {
char *data = NULL;
assert(!vm.sig_pop);
bc_lex_file(&vm.prs.l, file);
BC_SIG_LOCK;
bc_read_file(file, &data);
BC_SETJMP_LOCKED(err);
BC_SIG_UNLOCK;
bc_vm_process(data);
#if BC_ENABLED
if (BC_IS_BC) bc_vm_endif();
#endif // BC_ENABLED
err:
BC_SIG_MAYLOCK;
free(data);
bc_vm_clean();
// bc_program_reset(), called by bc_vm_clean(), resets the status.
// We want it to clear the sig_pop variable in case it was set.
if (vm.status == (sig_atomic_t) BC_STATUS_SUCCESS) BC_LONGJMP_STOP;
BC_LONGJMP_CONT;
}
static void bc_vm_stdin(void) {
BcStatus s;
BcVec buf, buffer;
size_t string = 0;
bool comment = false, hash = false;
bc_lex_file(&vm.prs.l, bc_program_stdin_name);
BC_SIG_LOCK;
bc_vec_init(&buffer, sizeof(uchar), NULL);
bc_vec_init(&buf, sizeof(uchar), NULL);
bc_vec_pushByte(&buffer, '\0');
BC_SETJMP_LOCKED(err);
BC_SIG_UNLOCK;
restart:
// This loop is complex because the vm tries not to send any lines that end
// with a backslash to the parser. The reason for that is because the parser
// treats a backslash+newline combo as whitespace, per the bc spec. In that
// case, and for strings and comments, the parser will expect more stuff.
while ((!(s = bc_read_line(&buf, ">>> ")) ||
(vm.eof = (s == BC_STATUS_EOF))) && buf.len > 1)
{
char c2, *str = buf.v;
size_t i, len = buf.len - 1;
for (i = 0; i < len; ++i) {
bool notend = len > i + 1;
uchar c = (uchar) str[i];
hash = (!comment && !string && ((hash && c != '\n') ||
(!hash && c == '#')));
if (!hash && !comment && (i - 1 > len || str[i - 1] != '\\')) {
if (BC_IS_BC) string ^= (c == '"');
else if (c == ']') string -= 1;
else if (c == '[') string += 1;
}
if (BC_IS_BC && !hash && !string && notend) {
c2 = str[i + 1];
if (c == '/' && !comment && c2 == '*') {
comment = true;
i += 1;
}
else if (c == '*' && comment && c2 == '/') {
comment = false;
i += 1;
}
}
}
bc_vec_concat(&buffer, buf.v);
if (string || comment) continue;
if (len >= 2 && str[len - 2] == '\\' && str[len - 1] == '\n') continue;
#if BC_ENABLE_HISTORY
if (vm.history.stdin_has_data) continue;
#endif // BC_ENABLE_HISTORY
bc_vm_process(buffer.v);
bc_vec_empty(&buffer);
if (vm.eof) break;
else bc_vm_clean();
}
if (!BC_STATUS_IS_ERROR(s)) {
if (BC_ERR(comment))
bc_parse_err(&vm.prs, BC_ERR_PARSE_COMMENT);
else if (BC_ERR(string))
bc_parse_err(&vm.prs, BC_ERR_PARSE_STRING);
#if BC_ENABLED
else if (BC_IS_BC) bc_vm_endif();
#endif // BC_ENABLED
}
err:
BC_SIG_MAYLOCK;
bc_vm_clean();
#if !BC_ENABLE_MEMCHECK
assert(vm.status != BC_STATUS_ERROR_FATAL);
vm.status = vm.status == BC_STATUS_QUIT || !BC_I ?
vm.status : BC_STATUS_SUCCESS;
#else // !BC_ENABLE_MEMCHECK
vm.status = vm.status == BC_STATUS_ERROR_FATAL ||
vm.status == BC_STATUS_QUIT || !BC_I ?
vm.status : BC_STATUS_SUCCESS;
#endif // !BC_ENABLE_MEMCHECK
if (!vm.status && !vm.eof) {
bc_vec_empty(&buffer);
BC_LONGJMP_STOP;
BC_SIG_UNLOCK;
goto restart;
}
bc_vec_free(&buf);
bc_vec_free(&buffer);
BC_LONGJMP_CONT;
}
#if BC_ENABLED
static void bc_vm_load(const char *name, const char *text) {
bc_lex_file(&vm.prs.l, name);
bc_parse_text(&vm.prs, text);
while (vm.prs.l.t != BC_LEX_EOF) vm.parse(&vm.prs);
}
#endif // BC_ENABLED
static void bc_vm_defaultMsgs(void) {
size_t i;
vm.func_header = bc_err_func_header;
for (i = 0; i < BC_ERR_IDX_NELEMS + BC_ENABLED; ++i)
vm.err_ids[i] = bc_errs[i];
for (i = 0; i < BC_ERR_NELEMS; ++i) vm.err_msgs[i] = bc_err_msgs[i];
}
static void bc_vm_gettext(void) {
#if BC_ENABLE_NLS
uchar id = 0;
int set = 1, msg = 1;
size_t i;
if (vm.locale == NULL) {
vm.catalog = BC_VM_INVALID_CATALOG;
bc_vm_defaultMsgs();
return;
}
vm.catalog = catopen(BC_MAINEXEC, NL_CAT_LOCALE);
if (vm.catalog == BC_VM_INVALID_CATALOG) {
bc_vm_defaultMsgs();
return;
}
vm.func_header = catgets(vm.catalog, set, msg, bc_err_func_header);
for (set += 1; msg <= BC_ERR_IDX_NELEMS + BC_ENABLED; ++msg)
vm.err_ids[msg - 1] = catgets(vm.catalog, set, msg, bc_errs[msg - 1]);
i = 0;
id = bc_err_ids[i];
for (set = id + 3, msg = 1; i < BC_ERR_NELEMS; ++i, ++msg) {
if (id != bc_err_ids[i]) {
msg = 1;
id = bc_err_ids[i];
set = id + 3;
}
vm.err_msgs[i] = catgets(vm.catalog, set, msg, bc_err_msgs[i]);
}
#else // BC_ENABLE_NLS
bc_vm_defaultMsgs();
#endif // BC_ENABLE_NLS
}
static void bc_vm_exec(void) {
size_t i;
bool has_file = false;
BcVec buf;
#if BC_ENABLED
if (BC_IS_BC && (vm.flags & BC_FLAG_L)) {
bc_vm_load(bc_lib_name, bc_lib);
#if BC_ENABLE_EXTRA_MATH
if (!BC_IS_POSIX) bc_vm_load(bc_lib2_name, bc_lib2);
#endif // BC_ENABLE_EXTRA_MATH
}
#endif // BC_ENABLED
if (vm.exprs.len) {
size_t len = vm.exprs.len - 1;
bool more;
BC_SIG_LOCK;
bc_vec_init(&buf, sizeof(uchar), NULL);
#ifndef NDEBUG
BC_SETJMP_LOCKED(err);
#endif // NDEBUG
BC_SIG_UNLOCK;
bc_lex_file(&vm.prs.l, bc_program_exprs_name);
do {
more = bc_read_buf(&buf, vm.exprs.v, &len);
bc_vec_pushByte(&buf, '\0');
bc_vm_process(buf.v);
bc_vec_popAll(&buf);
} while (more);
BC_SIG_LOCK;
bc_vec_free(&buf);
#ifndef NDEBUG
BC_UNSETJMP;
#endif // NDEBUG
BC_SIG_UNLOCK;
- if (!vm.no_exit_exprs) return;
+ if (!vm.no_exit_exprs && vm.exit_exprs) return;
}
for (i = 0; i < vm.files.len; ++i) {
char *path = *((char**) bc_vec_item(&vm.files, i));
if (!strcmp(path, "")) continue;
has_file = true;
bc_vm_file(path);
}
#if BC_ENABLE_AFL
__AFL_INIT();
#endif // BC_ENABLE_AFL
if (BC_IS_BC || !has_file) bc_vm_stdin();
// These are all protected by ifndef NDEBUG because if these are needed, bc is
// going to exit anyway, and I see no reason to include this code in a release
// build when the OS is going to free all of the resources anyway.
#ifndef NDEBUG
return;
err:
BC_SIG_MAYLOCK;
bc_vec_free(&buf);
BC_LONGJMP_CONT;
#endif // NDEBUG
}
void bc_vm_boot(int argc, char *argv[], const char *env_len,
const char* const env_args)
{
int ttyin, ttyout, ttyerr;
struct sigaction sa;
BC_SIG_ASSERT_LOCKED;
ttyin = isatty(STDIN_FILENO);
ttyout = isatty(STDOUT_FILENO);
ttyerr = isatty(STDERR_FILENO);
vm.flags |= ttyin ? BC_FLAG_TTYIN : 0;
vm.flags |= (ttyin != 0 && ttyout != 0 && ttyerr != 0) ? BC_FLAG_TTY : 0;
vm.flags |= ttyin && ttyout ? BC_FLAG_I : 0;
sigemptyset(&sa.sa_mask);
sa.sa_handler = bc_vm_sig;
sa.sa_flags = SA_NODEFER;
sigaction(SIGTERM, &sa, NULL);
sigaction(SIGQUIT, &sa, NULL);
sigaction(SIGINT, &sa, NULL);
#if BC_ENABLE_HISTORY
if (BC_TTY) sigaction(SIGHUP, &sa, NULL);
#endif // BC_ENABLE_HISTORY
bc_vm_init();
vm.file = NULL;
bc_vm_gettext();
bc_file_init(&vm.ferr, STDERR_FILENO, output_bufs + BC_VM_STDOUT_BUF_SIZE,
BC_VM_STDERR_BUF_SIZE);
bc_file_init(&vm.fout, STDOUT_FILENO, output_bufs, BC_VM_STDOUT_BUF_SIZE);
vm.buf = output_bufs + BC_VM_STDOUT_BUF_SIZE + BC_VM_STDERR_BUF_SIZE;
vm.line_len = (uint16_t) bc_vm_envLen(env_len);
bc_vec_clear(&vm.files);
bc_vec_clear(&vm.exprs);
bc_program_init(&vm.prog);
bc_parse_init(&vm.prs, &vm.prog, BC_PROG_MAIN);
#if BC_ENABLE_HISTORY
if (BC_TTY) bc_history_init(&vm.history);
#endif // BC_ENABLE_HISTORY
#if BC_ENABLED
if (BC_IS_BC) vm.flags |= BC_FLAG_S * (getenv("POSIXLY_CORRECT") != NULL);
#endif // BC_ENABLED
bc_vm_envArgs(env_args);
- bc_args(argc, argv);
+ bc_args(argc, argv, true);
#if BC_ENABLED
if (BC_IS_POSIX) vm.flags &= ~(BC_FLAG_G);
#endif // BC_ENABLED
BC_SIG_UNLOCK;
bc_vm_exec();
}
#endif // !BC_ENABLE_LIBRARY
void bc_vm_init(void) {
BC_SIG_ASSERT_LOCKED;
memcpy(vm.max_num, bc_num_bigdigMax,
bc_num_bigdigMax_size * sizeof(BcDig));
memcpy(vm.max2_num, bc_num_bigdigMax2,
bc_num_bigdigMax2_size * sizeof(BcDig));
bc_num_setup(&vm.max, vm.max_num, BC_NUM_BIGDIG_LOG10);
bc_num_setup(&vm.max2, vm.max2_num, BC_NUM_BIGDIG_LOG10);
vm.max.len = bc_num_bigdigMax_size;
vm.max2.len = bc_num_bigdigMax2_size;
bc_vec_init(&vm.temps, sizeof(BcNum), NULL);
vm.maxes[BC_PROG_GLOBALS_IBASE] = BC_NUM_MAX_POSIX_IBASE;
vm.maxes[BC_PROG_GLOBALS_OBASE] = BC_MAX_OBASE;
vm.maxes[BC_PROG_GLOBALS_SCALE] = BC_MAX_SCALE;
#if BC_ENABLE_EXTRA_MATH && BC_ENABLE_RAND
vm.maxes[BC_PROG_MAX_RAND] = ((BcRand) 0) - 1;
#endif // BC_ENABLE_EXTRA_MATH && BC_ENABLE_RAND
#if BC_ENABLED
#if !BC_ENABLE_LIBRARY
if (BC_IS_BC && !BC_IS_POSIX)
#endif // !BC_ENABLE_LIBRARY
{
vm.maxes[BC_PROG_GLOBALS_IBASE] = BC_NUM_MAX_IBASE;
}
#endif // BC_ENABLED
}
#if BC_ENABLE_LIBRARY
void bc_vm_atexit(void) {
bc_vm_shutdown();
#ifndef NDEBUG
bc_vec_free(&vm.jmp_bufs);
#endif // NDEBUG
}
#else // BC_ENABLE_LIBRARY
int bc_vm_atexit(int status) {
int s = BC_STATUS_IS_ERROR(status) ? status : BC_STATUS_SUCCESS;
bc_vm_shutdown();
#ifndef NDEBUG
bc_vec_free(&vm.jmp_bufs);
#endif // NDEBUG
return s;
}
#endif // BC_ENABLE_LIBRARY
diff --git a/contrib/bc/tests/script.sh b/contrib/bc/tests/script.sh
index acd68f6d9bc3..b7c707ac88bf 100755
--- a/contrib/bc/tests/script.sh
+++ b/contrib/bc/tests/script.sh
@@ -1,171 +1,171 @@
#! /bin/sh
#
# SPDX-License-Identifier: BSD-2-Clause
#
# Copyright (c) 2018-2021 Gavin D. Howard and contributors.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions are met:
#
# * Redistributions of source code must retain the above copyright notice, this
# list of conditions and the following disclaimer.
#
# * Redistributions in binary form must reproduce the above copyright notice,
# this list of conditions and the following disclaimer in the documentation
# and/or other materials provided with the distribution.
#
# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
# AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
# IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
# ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
# LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
# CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
# SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
# INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
# CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
# ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
#
set -e
script="$0"
testdir=$(dirname "${script}")
. "$testdir/../functions.sh"
if [ "$#" -lt 2 ]; then
printf 'usage: %s dir script [run_extra_tests] [run_stack_tests] [generate_tests] [time_tests] [exec args...]\n' "$script"
exit 1
fi
d="$1"
shift
f="$1"
shift
if [ "$#" -gt 0 ]; then
run_extra_tests="$1"
shift
else
run_extra_tests=1
fi
if [ "$#" -gt 0 ]; then
run_stack_tests="$1"
shift
else
run_stack_tests=1
fi
if [ "$#" -gt 0 ]; then
generate="$1"
shift
else
generate=1
fi
if [ "$#" -gt 0 ]; then
time_tests="$1"
shift
else
time_tests=0
fi
if [ "$#" -gt 0 ]; then
exe="$1"
shift
else
exe="$testdir/../bin/$d"
fi
if [ "$d" = "bc" ]; then
if [ "$run_stack_tests" -ne 0 ]; then
options="-lgq"
else
options="-lq"
fi
halt="halt"
else
options="-x"
halt="q"
fi
scriptdir="$testdir/$d/scripts"
name="${f%.*}"
if [ "$f" = "timeconst.bc" ]; then
exit 0
fi
if [ "$run_extra_tests" -eq 0 ]; then
if [ "$f" = "rand.bc" ]; then
printf 'Skipping %s script: %s\n' "$d" "$f"
exit 0
fi
fi
if [ "$run_stack_tests" -eq 0 ]; then
if [ "$f" = "globals.bc" -o "$f" = "references.bc" -o "$f" = "rand.bc" ]; then
printf 'Skipping %s script: %s\n' "$d" "$f"
exit 0
fi
fi
out="$testdir/${d}_outputs/${name}_script_results.txt"
outdir=$(dirname "$out")
if [ ! -d "$outdir" ]; then
mkdir -p "$outdir"
fi
unset BC_ENV_ARGS
unset BC_LINE_LENGTH
unset DC_ENV_ARGS
unset DC_LINE_LENGTH
s="$scriptdir/$f"
orig="$testdir/$name.txt"
results="$scriptdir/$name.txt"
if [ -f "$orig" ]; then
res="$orig"
elif [ -f "$results" ]; then
res="$results"
elif [ "$generate" -eq 0 ]; then
- printf 'Skipping %s script %s\n' "$d" "$s"
+ printf 'Skipping %s script %s\n' "$d" "$f"
exit 0
else
printf 'Generating %s results...' "$f"
printf '%s\n' "$halt" | "$d" "$s" > "$results"
printf 'done\n'
res="$results"
fi
set +e
printf 'Running %s script %s...' "$d" "$f"
if [ "$time_tests" -ne 0 ]; then
printf '\n'
printf '%s\n' "$halt" | /usr/bin/time -p "$exe" "$@" $options "$s" > "$out"
err="$?"
printf '\n'
else
printf '%s\n' "$halt" | "$exe" "$@" $options "$s" > "$out"
err="$?"
fi
checktest "$d" "$err" "script $f" "$res" "$out"
rm -f "$out"
exec printf 'pass\n'