ISDIGIT(3)             FreeBSD Library Functions Manual             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);

     int
     isdigit_l(int c, locale_t loc);

     int
     isnumber_l(int c, locale_t loc);

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 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() and isnumber() 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()
     function should be used instead.

SEE ALSO
     ctype(3), iswdigit(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.

FreeBSD 13.1-RELEASE-p6           May 4, 2007          FreeBSD 13.1-RELEASE-p6