3-7 类的友元函数的应用

3-7 类的友元函数的应用

Time Limit: 1000MS Memory Limit: 65536KB

Submit Statistic

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

Hint

Author

#include <iostream>#include <cmath>using namespace std;class Point{private:    double x;    double y;public:    Point(double a = 0, double b = 0)                   //构造函数    {        x = a;        y = b;    }    void showpoint1()                                   //输出点一坐标    {        cout << "The first point is the coordinate:X=" << x << ",Y=" << y << endl;    }    void showpoint2()                                   //输出点二坐标    {        cout << "The second point is the coordinate:X=" << x << ",Y=" << y << endl;    }    friend void showdis(Point &, Point &);              //友元};void showdis(Point & p1, Point & p2){    double dis = sqrt((p1.x - p2.x) * (p1.x - p2.x) + (p1.y - p2.y) * (p1.y - p2.y));    cout << "The distance between the two points is:" << dis << endl;}int main(){    double x1, x2, y1, y2;    cin >> x1 >> y1 >> x2 >> y2;    Point p1(x1, y1);    Point p2(x2, y2);    p1.showpoint1();    p2.showpoint2();    showdis(p1, p2);    return 0;}