Week 10 - task 1- fill in the blank: line class inherits point class

【 subject 】 In the next section of the class definition , The functions to be filled in are provided by the annotation contents

The procedure after filling in the blanks is as follows ：

Log in and copy

#include<iostream>
#include<Cmath>
using namespace std;
class Point // Define the coordinate point class 
{
public:
	double x,y;   // The abscissa and ordinate of the point 
	Point(){x=0;y=0;}
	Point(double x0, double y0) {x=x0; y=y0;} 
	void PrintP(){cout<<"Point:("<<x<<","<<y<<")";}
};  
class Line: public Point // Use coordinate point class to define line class ,  The data member of its base class represents the midpoint of the line 
{
private:
	class Point pt1,pt2;   // The two ends of a line 
public:
	Line(Point pts, Point pte);  // Constructors 
	double Dx(){return pt2.x-pt1.x;}
	double Dy(){return pt2.y-pt1.y;}
	double Length();// Calculate the length of the line 
	void PrintL();  // Output the two ends of the line and the length of the line 
};

//(1) Constructors , Respectively initialize the corresponding endpoint and the midpoint described by the base class attribute with parameters 
Line::Line(Point pts, Point pte):Point((pts.x+pte.x)/2,(pts.y+pte.y)/2) {pt1=pts;pt2=pte;} // Problem solving instruction ： The key here is to give a pair of parameters during the initialization of its base class 

double Line::Length(){return sqrt(Dx()*Dx()+Dy()*Dy());};//(2) Calculate the length of the line 

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

int main()
{
	Point ps(-2,5),pe(7,9);
	Line l(ps,pe);
        l.PrintL(); //(4) Output line l Information about 
        l.PrintP();//(5) Output line l The information in the middle , Here again ： An object of a derived class calls a member function provided by its base class 
	system("pause");
	return 0;
}

      

       
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