void *bsearch(const void *key, const void *base, size_t num, size_t size, int(*cmp)(const void *key, const void *elt)) { size_t start = 0, end = num; int result; while (start < end) { size_t mid = start + (end - start) / 2; result = cmp(key, base + mid * size); if (result < 0) end = mid; else if (result > 0) start = mid + 1; else return (void *)base + mid * size; } return NULL; }