二分查找

需要在在长度为n的数组中，查找target，并且输出其在数组中的下标。
（前置条件：数组已排序）
若数组未排序，则可以放入容器中（如：vector），进行sort

#include<iostream>using namespace std;static int index = 0;static int mid;void binarySearch(int a[],int len,int target,bool &found){    int start = 0, last = len -1;    while ( (start < last) && !found)    {       mid = (start+last+1)/2;        if (target < a[mid])            last = mid -1;        else if (target > a[mid])            start = mid + 1;        else            found = true;    }    index = mid;}int main(){    int target;    cin >> target;    int n;    cin >> n;    int arr[n];    for (int i = 0; i < n; i++)        cin >> arr[i];    bool  found = false;    binarySearch(arr,n,target,found);    cout << found << " " << index << " " << arr[index];    return 0;}