newlib/libc/ctype/isalnum.c

   1 /*
   2 FUNCTION
   3         <<isalnum>>, <<isalnum_l>>---alphanumeric character predicate
   4
   5 INDEX
   6         isalnum
   7 INDEX
   8         isalnum_l
   9
  10 SYNOPSIS
  11         #include <ctype.h>
  12         int isalnum(int <[c]>);
  13
  14         #include <ctype.h>
  15         int isalnum_l(int <[c]>, locale_t <[locale]>);
  16
  17
  18 DESCRIPTION
  19 <<isalnum>> is a macro which classifies singlebyte charset values by table
  20 lookup.  It is a predicate returning non-zero for alphabetic or
  21 numeric ASCII characters, and <<0>> for other arguments.  It is defined
  22 only if <[c]> is representable as an unsigned char or if <[c]> is EOF.
  23
  24 <<isalnum_l>> is like <<isalnum>> 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 isalnum>>' or `<<#undef isalnum_l>>'.
  30
  31 RETURNS
  32 <<isalnum>>,<<isalnum_l>> return non-zero if <[c]> is a letter or a digit.
  33
  34 PORTABILITY
  35 <<isalnum>> is ANSI C.
  36 <<isalnum_l>> is POSIX-1.2008.
  37
  38 No OS subroutines are required.
  39 */
  40
  41 #include <_ansi.h>
  42 #include <ctype.h>
  43
  44 #undef isalnum
  45
  46 int
  47 isalnum (int c)
  48 {
  49         return(__CTYPE_PTR[c+1] & (_U|_L|_N));
  50 }