十一周 项目三 点类

#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){};    void PrintPoint(); //输出点的信息    double getx()    {        return x;    }    double gety()    {        return y;    }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};double Line::Length(){    return sqrt(pow((pts.getx()-pte.getx()),2)+pow((pts.gety()-pte.gety()),2));}void Line::PrintLine(){    cout<<"1st ("<<pts.getx()<<","<<pts.gety()<<")"<<endl;    cout<<"2nd ("<<pte.getx()<<","<<pte.gety()<<")"<<endl;    cout<<"长度："<<Length()<<endl;}Line::Line(Point ps, Point pe):Point((ps.getx()+pe.getx())/2,(ps.gety()+pe.gety())/2){    pts=ps;    pte=pe;//这一段不是太懂}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: "<<endl;    l.PrintPoint(); //输出直线l中点的信息    return 0;}