C++组合(Composition)的介绍与实例

#ifndef PROJECT5_DOT_H
#define PROJECT5_DOT_H

#include 
using namespace std;

class Dot {
public:
    double x, y;
    Dot(double a, double b) : x(a), y(b) {};
    void show() {
        cout <<"x: " <

#ifndef PROJECT5_LINE_H
#define PROJECT5_LINE_H

#include "Dot.h"

class Line : public Dot {
private:
    Dot d1;
    Dot d2;
public:
    Line(const Dot &d1, const Dot &d2) : Dot(0, 0), d1(d1), d2(d2) {
        x = (d1.x + d2.x) / 2;
        y = (d1.y + d2.y) / 2;
    }

    void show(){
        Dot::show();
        cout <<"dot1: (" <

#include 
#include "Dot.h"
#include "Line.h"
using namespace std;

int main() {
    double a, b;
    cout <<"Input Dot1: \n";
    cin >> a >> b;
    Dot dot1(a,b);
    cout <<"Input Dot2: \n";
    cin >> a >> b ;
    Dot dot2(a,b);
    Line l1(dot1, dot2);
    l1.show();

    return 0;
}