2676-3-7 类的友元函数的应用

3-7 类的友元函数的应用

#include <bits/stdc++.h>using namespace std;class Point{private:    double x, y;public:    Point(double x = 0, double y = 0);    void Output(const char *name);    friend void Distance(Point &, Point &);};Point::Point(double x, double y){    this->x = x;    this->y = y;}void Point::Output(const char *name){    /*不能用printf 会限制输出精度*/    cout << "The "<< name << " point is the coordinate:X="<< x << ",Y=" << y << endl;}void Distance(Point& t1, Point& t2){    double a, b;    a = t1.x - t2.x;    b = t1.y - t2.y;    cout << "The distance between the two points is:" <<sqrt(pow(a,2) + pow(b,2)) << endl;}int main(){    double x1, y1, x2, y2;    cin >> x1 >> y1 >> x2 >> y2;    Point t1(x1, y1), t2(x2, y2);    t1.Output("first");    t2.Output("second");    Distance(t1, t2);    return 0;}