newlib/libc/string/strspn.c

   1 /*
   2 FUNCTION
   3         <<strspn>>---find initial match
   4
   5 INDEX
   6         strspn
   7
   8 SYNOPSIS
   9         #include <string.h>
  10         size_t strspn(const char *<[s1]>, const char *<[s2]>);
  11
  12 DESCRIPTION
  13         This function computes the length of the initial segment of
  14         the string pointed to by <[s1]> which consists entirely of
  15         characters from the string pointed to by <[s2]> (excluding the
  16         terminating null character).
  17
  18 RETURNS
  19         <<strspn>> returns the length of the segment found.
  20
  21 PORTABILITY
  22 <<strspn>> is ANSI C.
  23
  24 <<strspn>> requires no supporting OS subroutines.
  25
  26 QUICKREF
  27         strspn ansi pure
  28 */
  29
  30 #include <string.h>
  31
  32 size_t
  33 strspn (const char *s1,
  34         const char *s2)
  35 {
  36   const char *s = s1;
  37   const char *c;
  38
  39   while (*s1)
  40     {
  41       for (c = s2; *c; c++)
  42         {
  43           if (*s1 == *c)
  44             goto found;
  45         }
  46       if (*c == '\0')
  47         break;
  48 found:
  49       s1++;
  50     }
  51
  52   return s1 - s;
  53 }