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

Hint

Author

 黄晶晶

#include<iostream>
#include<cmath>
using namespace std;
class Point
{
public:
    Point(double xx = 0, double yy = 0);
    void display();
    void display1();
    friend double dist(Point &p1, Point &p2);//非成员函数
private:
    double x, y;
};
Point :: Point(double xx, double yy)
{
    x = xx;
    y = yy;
}
void Point :: display()
{
    cout<<"The first point is the coordinate:X="<<x<<","<<"Y="<<y<<endl;
}
void Point :: display1()
{
    cout<<"The second point is the coordinate:X="<<x<<","<<"Y="<<y<<endl;
}
double dist(Point &p1, Point &p2)
{
    double x = p1.x - p2.x;
    double y = p1.y - p2.y;
    return (sqrt(x * x + y * y));
}
int main()
{
    double x1, x2, y1, y2;
    cin>>x1>>y1>>x2>>y2;
    Point myp1(x1, y1), myp2(x2, y2);
    myp1.display();
    myp2.display1();
    cout<<"The distance between the two points is:"<<dist(myp1, myp2)<<endl;
    return 0;
}