二分法查找

#include <stdio.h>#include <stdlib.h>#define MAX_LENGTH_INSERT_SORT 7/***二分法查找*/int binary_search(int a[],int lo,int hi,int key){    int mid=lo+(hi-lo)/2;    if(key<a[mid]) return binary_search(a,lo,mid-1,key);    else if(key>a[mid]) return binary_search(a,mid+1,hi,key);    else return mid;}int main(){    int b[9]={1,2,3,4,5,6,7,8,9};    printf("%d",binary_search(b,0,8,3));    return 0;}