NAME
isdigit, isnumber,
isdigit_l, isnumber_l
— decimal-digit character
test
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include
<ctype.h>
int
isdigit(int
c);
int
isnumber(int
c);
int
isdigit_l(int
c, locale_t
loc);
int
isnumber_l(int
c, locale_t
loc);
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() or
iswdigit_l() function 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
ISO/IEC 9899:1990 (“ISO C90”).
The isdigit_l() function conforms to
IEEE Std 1003.1-2008 (“POSIX.1”).
HISTORY
The isnumber() function appeared in
4.4BSD.