1.\"	$OpenBSD: isdigit.3,v 1.12 2017/09/05 03:16:13 schwarze Exp $
2.\"
3.\" Copyright (c) 1991 The Regents of the University of California.
4.\" Copyright (c) 2017 Ingo Schwarze <schwarze@openbsd.org>
5.\" All rights reserved.
6.\"
7.\" This code is derived from software contributed to Berkeley by
8.\" the American National Standards Committee X3, on Information
9.\" Processing Systems.
10.\"
11.\" Redistribution and use in source and binary forms, with or without
12.\" modification, are permitted provided that the following conditions
13.\" are met:
14.\" 1. Redistributions of source code must retain the above copyright
15.\"    notice, this list of conditions and the following disclaimer.
16.\" 2. Redistributions in binary form must reproduce the above copyright
17.\"    notice, this list of conditions and the following disclaimer in the
18.\"    documentation and/or other materials provided with the distribution.
19.\" 3. Neither the name of the University nor the names of its contributors
20.\"    may be used to endorse or promote products derived from this software
21.\"    without specific prior written permission.
22.\"
23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
26.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
33.\" SUCH DAMAGE.
34.\"
35.Dd $Mdocdate: September 5 2017 $
36.Dt ISDIGIT 3
37.Os
38.Sh NAME
39.Nm isdigit ,
40.Nm isdigit_l
41.Nd decimal-digit single-byte character test
42.Sh SYNOPSIS
43.In ctype.h
44.Ft int
45.Fn isdigit "int c"
46.Ft int
47.Fn isdigit_l "int c" "locale_t locale"
48.Sh DESCRIPTION
49The
50.Fn isdigit
51and
52.Fn isdigit_l
53functions test for any decimal-digit character.
54The complete list of decimal digits is 0 and 1\(en9, in any locale.
55.Sh RETURN VALUES
56These functions return zero if the character tests false or
57non-zero if the character tests true.
58.Sh ENVIRONMENT
59On systems supporting non-ASCII single-byte character encodings,
60different
61.Fa c
62arguments may correspond to the digits, and the results of
63.Fn isdigit
64may depend on the
65.Ev LC_CTYPE
66.Xr locale 1 .
67.Sh SEE ALSO
68.Xr isalnum 3 ,
69.Xr isalpha 3 ,
70.Xr isascii 3 ,
71.Xr isblank 3 ,
72.Xr iscntrl 3 ,
73.Xr isgraph 3 ,
74.Xr islower 3 ,
75.Xr isprint 3 ,
76.Xr ispunct 3 ,
77.Xr isspace 3 ,
78.Xr isupper 3 ,
79.Xr iswdigit 3 ,
80.Xr isxdigit 3 ,
81.Xr stdio 3 ,
82.Xr toascii 3 ,
83.Xr tolower 3 ,
84.Xr toupper 3 ,
85.Xr ascii 7
86.Sh STANDARDS
87The
88.Fn isdigit
89function conforms to
90.St -ansiC ,
91and
92.Fn isdigit_l
93to
94.St -p1003.1-2008 .
95.Sh HISTORY
96The
97.Fn isdigit
98function first appeared in
99.At v7 ,
100and
101.Fn isdigit_l
102has been available since
103.Ox 6.2 .
104.Sh CAVEATS
105The argument
106.Fa c
107must be
108.Dv EOF
109or representable as an
110.Li unsigned char ;
111otherwise, the result is undefined.
112