First knowledge of opencv4.x --- image template matching

Image template matching knowledge ：

// Image template matching 
#include <stdio.h>
#include <iostream>
#include <string>
#include <opencv2\opencv.hpp>
using namespace std;
using namespace cv;
int main()
{
    
	Mat img = imread("person2.jpeg");
	Mat temp = imread("person2_temp.jpeg");
	Mat result;
	matchTemplate(img, temp, result, TM_CCOEFF_NORMED);
	Point max_index, min_index;
	// Match the result at the mark of the original image 
	double min_value, max_value;
	minMaxLoc(result, &min_value, &max_value, &min_index, &max_index);// Be careful result The element position in is consistent with the element position in the top left corner of the matched part of the original image 
	rectangle(img, Rect(max_index.x, max_index.y, temp.cols, temp.rows), Scalar(255, 255, 255), 2);
	namedWindow("result", WINDOW_NORMAL);
	namedWindow("temp", WINDOW_NORMAL);
	namedWindow("img", WINDOW_NORMAL);
	imshow("result", result);
	imshow("temp", temp);
	imshow("img", img);
	waitKey(0);
	return 0;
}