3-7 类的友元函数的应用

Problem Description

通过本题目的练习可以掌握类的友元函数的定义和用法

要求设计一个点类Point，它具有两个double型的数据成员x，y。为该类设计构造函数。并为其添加一个友元函数用于计算并输出两点间的距离；再添加一个输出成员函数用于输出点的信息。

 

 

并编写主函数，实现以下的输入输出内容。

Input

4个double型的数，中间用一个空格间隔。

Output

输出数据共3行，前两行用于显示要求距离的两个点的信息，第三行显示两点的距离。

Example Input

5 6 2 3

Example Output

The first point is the coordinate:X=5,Y=6The second point is the coordinate:X=2,Y=3The distance between the two points is:4.24264

#include <iostream>#include <math.h>using namespace std;class Point{public:    Point();    void setPoint();    void showPoint();    friend void Distance(Point &p1, Point &p2);private:    double x, y;};Point::Point(){    x = 0;    y = 0;}void Point::setPoint(){    cin >> x >> y;}void Point::showPoint(){    cout << "X=" << x <<',' << "Y=" <<y << endl;}void Distance(Point &p1, Point &p2){    double a = p1.x - p2.x;    double b = p1.y - p2.y;    double c = sqrt(a*a+b*b);    cout << c << endl;}int main(){    Point p1, p2;    p1.setPoint();    p2.setPoint();    cout << "The first point is the coordinate:";    p1.showPoint();    cout << "The second point is the coordinate:";    p2.showPoint();    cout << "The distance between the two points is:";    Distance(p1, p2);    return 0;}