3-7 类的友元函数的应用

Time Limit: 1000MSMemory Limit: 65536KB

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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

代码如下：

#include<iostream>#include<cmath>using namespace std;class Point{public:    Point (double x=0,double y=0) :x(x),y(y){};    int getX()    {        return x;    }    int getY()    {        return y;    }    void showpoint1()    {        cout<<"The first point is the coordinate:"<<"X="<<x<<","<<"Y="<<y<<endl;    }    void showpoint2()    {        cout<<"The second point is the coordinate:"<<"X="<<x<<","<<"Y="<<y<<endl;    }    friend double dist(Point &p1,Point &p2);private:    double x,y;};double dist(Point &p1,Point &p2){    double x=p1.x-p2.x;    double y=p1.y-p2.y;    return static_cast<double>(sqrt(x*x+y*y));}int main(){    double a,b,c,d;    cin>>a>>b>>c>>d;    Point Dis1(a,b);    Point Dis2(c,d);    Dis1.showpoint1();    Dis2.showpoint2();    cout<<"The distance between the two points is:"<<dist(Dis1,Dis2)<<endl;    return 0;}