newlib/libc/ctype/isdigit.c

   1 /*
   2 FUNCTION
   3         <<isdigit>>, <<isdigit_l>>---decimal digit predicate
   4
   5 INDEX
   6         isdigit
   7
   8 INDEX
   9         isdigit_l
  10
  11 SYNOPSIS
  12         #include <ctype.h>
  13         int isdigit(int <[c]>);
  14
  15         #include <ctype.h>
  16         int isdigit_l(int <[c]>, locale_t <[locale]>);
  17
  18 DESCRIPTION
  19 <<isdigit>> is a macro which classifies singlebyte charset values by table
  20 lookup.  It is a predicate returning non-zero for decimal digits, and 0 for
  21 other characters.  It is defined only if <[c]> is representable as an
  22 unsigned char or if <[c]> is EOF.
  23
  24 <<isdigit_l>> is like <<isdigit>> but performs the check based on the
  25 locale specified by the locale object locale.  If <[locale]> is
  26 LC_GLOBAL_LOCALE or not a valid locale object, the behaviour is undefined.
  27
  28 You can use a compiled subroutine instead of the macro definition by
  29 undefining the macro using `<<#undef isdigit>>' or `<<#undef isdigit_l>>'.
  30
  31 RETURNS
  32 <<isdigit>>, <<isdigit_l>> return non-zero if <[c]> is a decimal digit
  33 (<<0>>--<<9>>).
  34
  35 PORTABILITY
  36 <<isdigit>> is ANSI C.
  37 <<isdigit_l>> is POSIX-1.2008.
  38
  39 No supporting OS subroutines are required.
  40 */
  41
  42 #include <_ansi.h>
  43 #include <ctype.h>
  44
  45
  46 #undef isdigit
  47 int
  48 isdigit (int c)
  49 {
  50         return(__CTYPE_PTR[c+1] & _N);
  51 }