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.Sh DESCRIPTION 50The 51.Fn isdigit 52function tests for a decimal digit character. 53Regardless of locale, this includes the following characters only: 54.Pp 55.Bl -column \&``0''______ \&``0''______ \&``0''______ \&``0''______ \&``0''______ 56.It "\&``0''\t``1''\t``2''\t``3''\t``4''" 57.It "\&``5''\t``6''\t``7''\t``8''\t``9''" 58.El 59.Pp 60The 61.Fn isnumber 62function behaves similarly to 63.Fn isdigit , 64but may recognize additional characters, depending on the current locale 65setting. 66.Pp 67The value of the argument must be representable as an 68.Vt "unsigned char" 69or the value of 70.Dv EOF . 71.Sh RETURN VALUES 72The 73.Fn isdigit 74and 75.Fn isnumber 76functions return zero if the character tests false and 77return non-zero if the character tests true. 78.Sh COMPATIBILITY 79The 80.Bx 4.4 81extension of accepting arguments outside of the range of the 82.Vt "unsigned char" 83type in locales with large character sets is considered obsolete 84and may not be supported in future releases. 85The 86.Fn iswdigit 87function should be used instead. 88.Sh SEE ALSO 89.Xr ctype 3 , 90.Xr iswdigit 3 , 91.Xr multibyte 3 , 92.Xr ascii 7 93.Sh STANDARDS 94The 95.Fn isdigit 96function conforms to 97.St -isoC . 98.Sh HISTORY 99The 100.Fn isnumber 101function appeared in 102.Bx 4.4 . 103