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ISDIGIT(3)               BSD Library Functions Manual               ISDIGIT(3)

     isdigit, isnumber -- decimal-digit character test

     Standard C Library (libc, -lc)

     #include <ctype.h>

     isdigit(int c);

     isnumber(int c);

     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 isdigit() and isnumber() functions return zero if the character tests false and return non-zero if
     the character tests true.

     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.

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

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

     The isnumber() function appeared in 4.4BSD.

BSD                               May 4, 2007                              BSD

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