1.\" Copyright (c) 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" the American National Standards Committee X3, on Information 6.\" Processing Systems. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)isdigit.3 8.1 (Berkeley) 6/4/93 33.\" $FreeBSD$ 34.\" 35.Dd May 4, 2007 36.Dt ISDIGIT 3 37.Os 38.Sh NAME 39.Nm isdigit, isnumber 40.Nd decimal-digit character test 41.Sh LIBRARY 42.Lb libc 43.Sh SYNOPSIS 44.In ctype.h 45.Ft int 46.Fn isdigit "int c" 47.Ft int 48.Fn isnumber "int c" 49.Ft int 50.Fn isdigit_l "int c" "locale_t loc" 51.Ft int 52.Fn isnumber_l "int c" "locale_t loc" 53.Sh DESCRIPTION 54The 55.Fn isdigit 56function tests for a decimal digit character. 57Regardless of locale, this includes the following characters only: 58.Bl -column \&``0''______ \&``0''______ \&``0''______ \&``0''______ \&``0''______ 59.It "\&``0''" Ta "``1''" Ta "``2''" Ta "``3''" Ta "``4''" 60.It "\&``5''" Ta "``6''" Ta "``7''" Ta "``8''" Ta "``9''" 61.El 62.Pp 63The 64.Fn isnumber 65function behaves similarly to 66.Fn isdigit , 67but may recognize additional characters, depending on the current locale 68setting. 69.Pp 70The value of the argument must be representable as an 71.Vt "unsigned char" 72or the value of 73.Dv EOF . 74.Pp 75The _l-suffixed versions take an explicit locale argument, whereas the 76non-suffixed versions use the current global or per-thread locale. 77.Sh RETURN VALUES 78The 79.Fn isdigit 80and 81.Fn isnumber 82functions return zero if the character tests false and 83return non-zero if the character tests true. 84.Sh COMPATIBILITY 85The 86.Bx 4.4 87extension of accepting arguments outside of the range of the 88.Vt "unsigned char" 89type in locales with large character sets is considered obsolete 90and may not be supported in future releases. 91The 92.Fn iswdigit 93function should be used instead. 94.Sh SEE ALSO 95.Xr ctype 3 , 96.Xr iswdigit 3 , 97.Xr multibyte 3 , 98.Xr xlocale 3 , 99.Xr ascii 7 100.Sh STANDARDS 101The 102.Fn isdigit 103function conforms to 104.St -isoC . 105The 106.Fn isdigit_l 107function conforms to 108.St -p1003.1-2008 . 109.Sh HISTORY 110The 111.Fn isnumber 112function appeared in 113.Bx 4.4 . 114