折半查找

#include<stdio.h>
#include<stdlib>

int BinarySearch(int arr[],int size,int toFind){
	int left=0;
	int right = size - 1;//最后一个元素的下标；
	while(left<=right){
	int mid=(left+right)/2;
	if(arr[mid] > toFind){
		right = mid - 1;
		}else if(arr[mid] < toFind){
			left = mid + 1;
		}else{
			return mid;}
	}
	return -1;
}

int main(){
int arr[4] = {1,2,3,4};
int size = sizeof(arr)/sizeof(arr[0]);
int ret = BinarySearch(arr, size, 1);
}