1 #include <string.h> 2 3 #define N 256 4 5 size_t 6 strcspn(const char *s, const char *b) 7 { 8 char map[N], *os; 9 10 memset(map, 0, N); 11 for(;;) { 12 map[*(unsigned char*)b] = 1; 13 if(*b++ == 0) 14 break; 15 } 16 os = s; 17 while(map[*(unsigned char*)s++] == 0) 18 ; 19 return s - os - 1; 20 } 21