freebsd-dev/lib/libc/locale/isdigit.3

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.\"     @(#)isdigit.3	8.1 (Berkeley) 6/4/93
.\" $FreeBSD$
.\"
.Dd October 6, 2002
.Dt ISDIGIT 3
.Os
.Sh NAME
.Nm isdigit, isnumber
.Nd decimal-digit character test
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In ctype.h
.Ft int
.Fn isdigit "int c"
.Ft int
.Fn isnumber "int c"
.Sh DESCRIPTION
The
.Fn isdigit
function tests for any decimal-digit character.
For any locale,
this includes the following characters only:
.Pp
.Bl -column \&``0''______ \&``0''______ \&``0''______ \&``0''______ \&``0''______
.It "\&``0''\t``1''\t``2''\t``3''\t``4''"
.It "\&``5''\t``6''\t``7''\t``8''\t``9''"
.El
.Pp
For single C
.Va char Ns s
locales (see
.Xr multibyte 3 )
the value of the argument is
representable as an
.Li unsigned char
or the value of
.Dv EOF .
.Sh RETURN VALUES
The
.Fn isdigit
function returns zero if the character tests false and
returns non-zero if the character tests true.
.Sh COMPATIBILITY
Although
.Fn isdigit
accepts arguments outside of the range of the
.Vt "unsigned char"
type in locales with large character sets,
this is a
.Bx 4.4
extension and the
.Fn iswdigit
function should be used instead for maximum portability.
.Sh SEE ALSO
.Xr ctype 3 ,
.Xr iswdigit 3 ,
.Xr multibyte 3 ,
.Xr ascii 7
.Sh STANDARDS
The
.Fn isdigit
function conforms to
.St -isoC .