10週目-タスク1-プログラムの空欄:直線クラス継承点クラス

#include<iostream>
#include<Cmath>
using namespace std;
class Point //      
{
public:
	double x,y;   //         
	Point(){x=0;y=0;}
	Point(double x0, double y0) {x=x0; y=y0;} 
	void PrintP(){cout<<"Point:("<<x<<","<<y<<")";}
};  
class Line: public Point   //           ,                
{
private:
	class Point pt1,pt2;   //       
public:
	Line(Point pts, Point pte);  //    
	double Dx(){return pt2.x-pt1.x;}
	double Dy(){return pt2.y-pt1.y;}
	double Length();//       
	void PrintL();  //              
};

//(1)    ，                        
Line::Line(Point pts, Point pte):Point((pts.x+pte.x)/2,(pts.y+pte.y)/2) {pt1=pts;pt2=pte;} //    ：                 

double Line::Length(){return sqrt(Dx()*Dx()+Dy()*Dy());};//(2)       

void Line::PrintL()
{
	cout<<" 1st ";
	pt1.PrintP();
	cout<<"
 2nd ";
	pt2.PrintP();
	cout<<"
 The middle point of Line: ";
	PrintP();
	cout<<"
 The Length of Line: "<<Length()<<endl; //(3)      
}

int main()
{
	Point ps(-2,5),pe(7,9);
	Line l(ps,pe);
        l.PrintL(); //(4)    l   
        l.PrintP();//(5)    l     ，      ：                  
	system("pause");
	return 0;
}