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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.

     For single C chars locales (see multibyte(3)), the value of the argument is 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                             August 21, 2004                            BSD