1 #include <lib9.h> 2 3 /* 4 * Return pointer to first occurrence of s2 in s1, 5 * 0 if none 6 */ 7 char* 8 strstr(char *s1, char *s2) 9 { 10 char *p; 11 int f, n; 12 13 f = s2[0]; 14 if(f == 0) 15 return s1; 16 n = strlen(s2); 17 for(p=strchr(s1, f); p; p=strchr(p+1, f)) 18 if(strncmp(p, s2, n) == 0) 19 return p; 20 return 0; 21 } 22