C语言减半算法

C语言折半算法
#include <stdio.h>#define LEN 8int a[LEN] = { 1, 2, 2, 2, 5, 6, 8, 9 };int binarysearch(int number){int mid, start = 0, end = LEN - 1;while (start <= end) {mid = (start + end) / 2;if (a[mid] < number)start = mid + 1;else if (a[mid] > number)end = mid - 1;elsereturn mid;}return -1;}int main(void){printf("%d\n", binarysearch(5));return 0;}