[开发工具]类的组合c++

//例4-4 类的组合 ，线段line类
#include <iostream>
#include <cmath>
using namespace std;
class Point{//Point类的定义
public:
    Point(int xx=0,int yy=0){
        x=xx;
        y=yy;
    }
    Point(Point &p);
    inline int getX(){return x;}
    inline int getY(){return y;}

private:
    int x,y;

};
Point::Point(Point &p) {
    x=p.x;
    y=p.y;
    cout<<"Calling the copy constructor of Point"<<endl;
}
class Line{//Line类的定义
public:
    Line(Point xp1,Point xp2);
    Line(Line &l);
    double getlen(){return len;}
private:
    Point p1,p2;
    double len;
};
Line::Line(Point xp1,Point xp2):p1(xp1),p2(xp2) {
    cout<<"Calling constructor of line "<<endl;
    auto x=static_cast<double>(p1.getX()-p2.getX());
    auto y=static_cast<double>(p1.getY()-p2.getY());
    len = sqrt(x*x+y*y);

}
Line::Line(Line &l):p1(l.p1),p2(l.p2){//组合类的复制构造函数
    cout<<"Calling the copy constructor of Line"<<endl;
    len=l.len;
}
int main()
{
    Point myp1(1,1),myp2(4,5);//建立Point类对象
    Line line(myp1,myp2);
    Line line2=line;
    cout<<"The length of the line is:";
    cout<<line.getlen()<<endl;
    cout<<"The length of the line2 is:";
    cout<<line2.getlen()<<endl;

    return 0;
}