ISDIGIT(3)

NAME
isdigit, isdigit_l, isnumber, isnumber_l - decimal-digit character test

LIBRARY
libc

SYNOPSIS
#include <ctype.h>
int
isdigit(int c);
int
isnumber(int c);
int
isdigit_l(int c, locale_t locale);
#include <xlocale.h>
int
isnumber_l(int c, locale_t locale);

DESCRIPTION
The isdigit() and isdigit_l() functions test 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() and isnumber_l() functions behave similarly to isdigit() and isdigit_l(), but may recognize additional characters, depending on the current locale setting.

The value of the argument must be representable as an unsigned char or the value of EOF.

The _l-suffixed versions take an explicit locale argument, whereas the non-suffixed versions use the current global or per-thread locale.

RETURN VALUES
The isdigit(), isdigit_l(), isnumber(), and isnumber_l() functions return zero if the character tests false and return 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(), iswdigit_l(), iswnumber(), and iswnumber_l() functions should be used instead.

SEE ALSO
ctype(3), ctype_l(3), iswdigit(3), iswdigit_l(3), multibyte(3), xlocale(3), ascii(7)

STANDARDS
The isdigit() function conforms to isoC. The isdigit_l() function conforms to p1003.1-2008.

HISTORY
The isnumber() function appeared in 4.4BSD.