ISDIGIT(3)               BSD 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);

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.

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

STANDARDS
     The isdigit() function conforms to ISO/IEC 9899:1990 (``ISO C90'').

HISTORY
     The isnumber() function appeared in 4.4BSD.

BSD                               May 4, 2007                              BSD