newlib/libc/string/strcspn.c

   1 /*
   2 FUNCTION
   3         <<strcspn>>---count characters not in string
   4
   5 INDEX
   6         strcspn
   7
   8 SYNOPSIS
   9         size_t strcspn(const char *<[s1]>, const char *<[s2]>);
  10
  11 DESCRIPTION
  12         This function computes the length of the initial part of
  13         the string pointed to by <[s1]> which consists entirely of
  14         characters <[NOT]> from the string pointed to by <[s2]>
  15         (excluding the terminating null character).
  16
  17 RETURNS
  18         <<strcspn>> returns the length of the substring found.
  19
  20 PORTABILITY
  21 <<strcspn>> is ANSI C.
  22
  23 <<strcspn>> requires no supporting OS subroutines.
  24  */
  25
  26 #include <string.h>
  27
  28 size_t
  29 strcspn (const char *s1,
  30         const char *s2)
  31 {
  32   const char *s = s1;
  33   const char *c;
  34
  35   while (*s1)
  36     {
  37       for (c = s2; *c; c++)
  38         {
  39           if (*s1 == *c)
  40             goto end;
  41         }
  42       s1++;
  43     }
  44 end:
  45   return s1 - s;
  46 }