missing/strstr.c

   1 /* public domain rewrite of strstr(3) */
   2
   3 #include "ruby/missing.h"
   4
   5 size_t strlen(const char*);
   6
   7 char *
   8 strstr(const char *haystack, const char *needle)
   9 {
  10     const char *hend;
  11     const char *a, *b;
  12
  13     if (*needle == 0) return (char *)haystack;
  14     hend = haystack + strlen(haystack) - strlen(needle) + 1;
  15     while (haystack < hend) {
  16         if (*haystack == *needle) {
  17             a = haystack;
  18             b = needle;
  19             for (;;) {
  20                 if (*b == 0) return (char *)haystack;
  21                 if (*a++ != *b++) {
  22                     break;
  23                 }
  24             }
  25         }
  26         haystack++;
  27     }
  28     return 0;
  29 }