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ISDIGIT(3)		     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 cur-
     rent 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 obso-
     lete  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  is-
     digit_l() function conforms to IEEE Std 1003.1-2008 ("POSIX.1").

HISTORY
     The isnumber() function appeared in 4.4BSD.

FreeBSD ports 15.quarterly	December 19, 2022		      ISDIGIT(3)

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