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ISDIGIT(3) FreeBSD Library Functions Manual ISDIGIT(3)
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").