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lib/libc/stdlib/strtonum.3

.\" Copyright (c) 2004 Ted Unangst .\" Copyright (c) 2004 Ted Unangst
.\" Copyright 2023 Oxide Computer Company
.\" .\"
.\" Permission to use, copy, modify, and distribute this software for any .\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above .\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies. .\" copyright notice and this permission notice appear in all copies.
.\" .\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES .\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF .\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR .\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES .\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN .\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\" .\"
.\" $OpenBSD: strtonum.3,v 1.13 2006/04/25 05:15:42 tedu Exp $ .\" $OpenBSD: strtonum.3,v 1.13 2006/04/25 05:15:42 tedu Exp $
.\" .\"
.Dd April 29, 2004 .Dd December 16, 2025
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You (or whoever pushes the commit) can set this to the current date when it goes in

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.Dt STRTONUM 3 .Dt STRTONUM 3
.Os .Os
.Sh NAME .Sh NAME
.Nm strtonum .Nm strtonum ,
.Nm strtonumx
.Nd "reliably convert string value to an integer" .Nd "reliably convert string value to an integer"
.Sh SYNOPSIS .Sh SYNOPSIS
.In stdlib.h .In stdlib.h
.Ft long long .Ft long long
.Fo strtonum .Fo strtonum
.Fa "const char *nptr" .Fa "const char *nptr"
.Fa "long long minval" .Fa "long long minval"
.Fa "long long maxval" .Fa "long long maxval"
.Fa "const char **errstr" .Fa "const char **errstr"
.Fc .Fc
.Ft long long
.Fo strtonumx
.Fa "const char *nptr"
.Fa "long long minval"
.Fa "long long maxval"
.Fa "const char **errstr"
.Fa "int base"
.Fc
.Sh DESCRIPTION .Sh DESCRIPTION
The The
.Fn strtonum .Fn strtonum
function converts the string in and
.Fn strtonumx
functions convert the string in
.Fa nptr .Fa nptr
to a to a
.Vt "long long" .Vt "long long"
value. value.
The These functions were designed to facilitate safe, robust programming and
.Fn strtonum overcome the shortcomings of the
function was designed to facilitate safe, robust programming
and overcome the shortcomings of the
.Xr atoi 3 .Xr atoi 3
and and
.Xr strtol 3 .Xr strtol 3
family of interfaces. family of interfaces.
.Pp .Pp
The string may begin with an arbitrary amount of whitespace The string may begin with an arbitrary amount of whitespace
(as determined by .Pq as determined by Xr isspace 3
.Xr isspace 3 )
followed by a single optional followed by a single optional
.Ql + .Ql +
or or
.Ql - .Ql -
sign. sign.
.Pp .Pp
The remainder of the string is converted to a The remainder of the string is converted to a
.Vt "long long" .Vt "long long"
value according to base 10. value according to base 10
.Pq for Fn strtonum
or the provided base
.Pq for Fn strtonumx .
.Pp .Pp
The value obtained is then checked against the provided The value obtained is then checked against the provided
.Fa minval .Fa minval
and and
.Fa maxval .Fa maxval
bounds. bounds.
If If
.Fa errstr .Fa errstr
is non-null, is non-null,
.Fn strtonum .Fn strtonum
stores an error string in and
.Fn strtonumx
store an error string in
.Fa *errstr .Fa *errstr
indicating the failure. indicating the failure.
.Pp
For
.Fn strtonumx
the value of
.Ar base
is interpreted in the same way as described in
.Xr strtoll 3 .
In particular, if the value of
.Ar base
is 0, then the expected form of
.Ar nptr
is that of a decimal constant, octal constant or hexadecimal constant, any of
which may be preceded by a + or - sign.
.Sh RETURN VALUES .Sh RETURN VALUES
The The
.Fn strtonum .Fn strtonum
function returns the result of the conversion, and
.Fn strtonumx
functions return the result of the conversion,
unless the value would exceed the provided bounds or is invalid. unless the value would exceed the provided bounds or is invalid.
On error, 0 is returned, On error, 0 is returned,
.Va errno .Va errno
is set, and is set, and
.Fa errstr .Fa errstr
will point to an error message. will point to an error message.
On success, On success,
.Fa *errstr .Fa *errstr
will be set to will be set to
.Dv NULL ; .Dv NULL ;
this fact can be used to differentiate this fact can be used to differentiate
a successful return of 0 from an error. a successful return of 0 from an error.
.Sh EXAMPLES .Sh EXAMPLES
Using Using
.Fn strtonum .Fn strtonum
and
.Fn strtonumx
correctly is meant to be simpler than the alternative functions. correctly is meant to be simpler than the alternative functions.
.Bd -literal -offset indent .Bd -literal -offset indent
int iterations; int iterations;
const char *errstr; const char *errstr;
iterations = strtonum(optarg, 1, 64, &errstr); iterations = strtonum(optarg, 1, 64, &errstr);
if (errstr != NULL) if (errstr != NULL)
errx(1, "number of iterations is %s: %s", errstr, optarg); errx(1, "number of iterations is %s: %s", errstr, optarg);
.Ed .Ed
.Pp .Pp
The above example will guarantee that the value of iterations is between The above example will guarantee that the value of iterations is between
1 and 64 (inclusive). 1 and 64 (inclusive).
.Sh ERRORS .Sh ERRORS
.Bl -tag -width Er .Bl -tag -width Er
.It Bq Er ERANGE .It Bq Er ERANGE
The given string was out of range. The given string was out of range.
.It Bq Er EINVAL .It Bq Er EINVAL
The given string did not consist solely of digit characters. The given string did not consist solely of digit characters
.Pq for Fn strtonum ,
or characters which are valid in the given base
.Pq for Fn strtonumx .
.It Bq Er EINVAL .It Bq Er EINVAL
The supplied The supplied
.Fa minval .Fa minval
was larger than was larger than
.Fa maxval . .Fa maxval .
.El .El
.Pp .Pp
If an error occurs, If an error occurs,
.Fa errstr .Fa errstr
will be set to one of the following strings: will be set to one of the following strings:
.Pp .Pp
.Bl -tag -width ".Li too large" -compact .Bl -tag -width ".Li too large" -compact
.It Li "too large" .It Qq too large
The result was larger than the provided maximum value. The result was larger than the provided maximum value.
.It Li "too small" .It Qq too small
The result was smaller than the provided minimum value. The result was smaller than the provided minimum value.
.It Li invalid .It Qq invalid
The string did not consist solely of digit characters. The string did not consist solely of characters valid in the specified base
.Pq or base 10 for Fn strtonum .
.It Qq unparsable; invalid base specified
The specified base was outside the permitted range.
.El .El
.Sh SEE ALSO .Sh SEE ALSO
.Xr atof 3 , .Xr atof 3 ,
.Xr atoi 3 , .Xr atoi 3 ,
.Xr atol 3 , .Xr atol 3 ,
.Xr atoll 3 , .Xr atoll 3 ,
.Xr sscanf 3 , .Xr sscanf 3 ,
.Xr strtod 3 , .Xr strtod 3 ,
Show All 10 Lines
and and
.Xr strtol 3 , .Xr strtol 3 ,
are either impossible or difficult to use safely. are either impossible or difficult to use safely.
.Sh HISTORY .Sh HISTORY
The The
.Fn strtonum .Fn strtonum
function first appeared in function first appeared in
.Ox 3.6 . .Ox 3.6 .
The
.Fn strtonumx
function first appeared in illumos in 2023.
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We prefer to use version numbers here.

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illumos doesn't have versions or version numbers. If it helps I can try to find the exact date the commit went into illumos-gate.

rosenfeld_grumpf.hope-2000.org: illumos doesn't have versions or version numbers. If it helps I can try to find the exact date…