newlib/libc/ctype/islower.c

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