isdigit(3)

NAME

isdigit, isnumber - decimal-digit character test

LIBRARY

Standard C Library (libc, -lc)

SYNOPSIS

#include <ctype.h>
int
isdigit(int c);
int
isnumber(int c);

DESCRIPTION

The isdigit() function tests for a decimal digit character.

Regardless
of locale, this includes the following characters only:

``0'' ``1'' ``2'' ``3''

``4''
``5'' ``6'' ``7'' ``8''

``9''

The isnumber() function behaves similarly to isdigit(), but

may recognize
additional characters, depending on the current locale set

ting.

For single C chars locales (see multibyte(3)) the value of

the argument
is representable as an unsigned char or the value of EOF.

RETURN VALUES

The isdigit() and isnumber() functions return zero if the

character tests
false and returns non-zero if the character tests true.

COMPATIBILITY

The 4.4BSD extension of accepting arguments outside of the

range of the
unsigned char type in locales with large character sets is

considered
obsolete and may not be supported in future releases. The

iswdigit()
function should be used instead.

SEE ALSO

ctype(3), iswdigit(3), multibyte(3), ascii(7)

STANDARDS

The isdigit() function conforms to ISO/IEC 9899:1990 (``ISO

C89'').

HISTORY

The isnumber() function appeared in 4.4BSD.

BSD August 21, 2004

BSD