用C++实现二分查找算法，用于在已排序的数组中查找目标值的位置，代码输出为？

int binarySearch(const std::vector& arr, int target) {

int left = 0;

int right = arr.size() - 1;

while (left <= right) {

int mid = left + (right - left) / 2;

if (arr[mid] == target)

return mid;

else if (arr[mid] < target)

left = mid + 1;

else

right = mid - 1;

}

return -1;}

int main(){

vector v = {2,4,6,8,10,13,15};

cout << binarySearch(v,8) << " ";

cout << binarySearch(v,5) << endl;}