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- #include <string.h>
- /* Return pointer to first occurrence of s2 in s1, NULL if none */
- char
- *strstr(const char *s1, const char *s2)
- {
- char *p, *pa, *pb;
- int c0, c;
- c0 = *s2;
- if(c0 == 0)
- return s1;
- s2++;
- for(p=strchr(s1, c0); p; p=strchr(p+1, c0)) {
- pa = p;
- for(pb=s2;; pb++) {
- c = *pb;
- if(c == 0)
- return p;
- if(c != *++pa)
- break;
- }
- }
- return 0;
- }
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