11.3-点类派生直线类

/*
*Copyright (c) 2013 ,烟台大学计算机学院
*All rights reserved.
*作者：张凤宁
*完成日期：2014年5月27
*版本号：v1.0
*问题描述：
*样例输入：
*样例输出：
*问题分析：用简单的方法，学会活学活用
*/
#include<iostream>
#include<Cmath>
using namespace std;
class Point //定义坐标点类
{
public:
    Point():x(0),y(0) {};
    Point(double x0, double y0):x(x0), y(y0) {};
    double getX()
    {
        return x;
    }
    double getY()
    {
        return y;
    }
    void PrintPoint(); //输出点的信息
protected:
    double x,y;   //点的横坐标和纵坐标
};
void Point::PrintPoint()
{
    cout<<"Point: ("<<x<<","<<y<<")";    //输出点
}
class Line: public Point   //利用坐标点类定义直线类, 其基类的数据成员表示直线的中点
{
public:
    Line(Point pts, Point pte); //构造函数，用初始化直线的两个端点及由基类数据成员描述的中点
    double Length();    //计算并返回直线的长度
    void PrintLine();   //输出直线的两个端点和直线长度
private:
    class Point pts,pte;   //直线的两个端点，从Point类继承的数据成员表示直线的中点
};
Line::Line(Point pt1, Point pt2):Point((pt1.getX()+pt2.getX())/2,(pt1.getY()+pt2.getY())/2)
{
    pts=pt1;
    pte=pt2;
}
double Line::Length()
{
    return sqrt((pte.getX()-pts.getX())*(pte.getX()-pts.getX())+(pte.getY()-pts.getY())*(pte.getY()-pts.getY()));
}
void Line::PrintLine()
{
    cout<<"1st Point:";
    pts.PrintPoint();
    cout<<endl;
    cout<<"2nd Point:";
    pte.PrintPoint();
    cout<<endl;
    cout<<"The Length of Line:"<<Length()<<endl;
}
int main()
{
    Point ps(-2,5),pe(7,9);
    Line l(ps,pe);
    cout<<"About the Line: "<<endl;
    l.PrintLine();  //输出直线l的信息：两端点及长度
    cout<<"The middle point of Line is: ";
    l.PrintPoint(); //输出直线l中点的信息
    return 0;
}
<span style="font-family:Arial;BACKGROUND-COLOR: #ffffff">运行结果：</span>

<img src="https://img-blog.youkuaiyun.com/20140527134621437?watermark/2/text/aHR0cDovL2Jsb2cuY3Nkbi5uZXQvdTAxMjM2OTc1Mg==/font/5a6L5L2T/fontsize/400/fill/I0JBQkFCMA==/dissolve/70/gravity/Center" alt="" />