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.\" 3. 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 , 40.Nm isnumber 41.Nd decimal-digit character test 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In ctype.h 46.Ft int 47.Fn isdigit "int c" 48.Ft int 49.Fn isnumber "int c" 50.Ft int 51.Fn isdigit_l "int c" "locale_t loc" 52.Ft int 53.Fn isnumber_l "int c" "locale_t loc" 54.Sh DESCRIPTION 55The 56.Fn isdigit 57function tests for a decimal digit character. 58Regardless of locale, this includes the following characters only: 59.Bl -column \&``0''______ \&``0''______ \&``0''______ \&``0''______ \&``0''______ 60.It "\&``0''" Ta "``1''" Ta "``2''" Ta "``3''" Ta "``4''" 61.It "\&``5''" Ta "``6''" Ta "``7''" Ta "``8''" Ta "``9''" 62.El 63.Pp 64The 65.Fn isnumber 66function behaves similarly to 67.Fn isdigit , 68but may recognize additional characters, depending on the current locale 69setting. 70.Pp 71The value of the argument must be representable as an 72.Vt "unsigned char" 73or the value of 74.Dv EOF . 75.Pp 76The _l-suffixed versions take an explicit locale argument, whereas the 77non-suffixed versions use the current global or per-thread locale. 78.Sh RETURN VALUES 79The 80.Fn isdigit 81and 82.Fn isnumber 83functions return zero if the character tests false and 84return non-zero if the character tests true. 85.Sh COMPATIBILITY 86The 87.Bx 4.4 88extension of accepting arguments outside of the range of the 89.Vt "unsigned char" 90type in locales with large character sets is considered obsolete 91and may not be supported in future releases. 92The 93.Fn iswdigit 94function should be used instead. 95.Sh SEE ALSO 96.Xr ctype 3 , 97.Xr iswdigit 3 , 98.Xr multibyte 3 , 99.Xr xlocale 3 , 100.Xr ascii 7 101.Sh STANDARDS 102The 103.Fn isdigit 104function conforms to 105.St -isoC . 106The 107.Fn isdigit_l 108function conforms to 109.St -p1003.1-2008 . 110.Sh HISTORY 111The 112.Fn isnumber 113function appeared in 114.Bx 4.4 . 115