C/C++中组合详解及其作用介绍 C

概述
案例
总结

概述组合 (Composition) 指在一个类中另一类的对象作为数据成员.

文章图片

案例在平面上两点连成一条直线, 求直线的长度和直线中点的坐标.
要求:

基类: Dot
派生类: Line (同时组合)
派生类 Line 从基类 Dot 继承的 Dot 数据, 存放直线的中点坐标
Line 类再增加两个 Dot 对象, 分别存放两个端点的坐标

Dot 类:

#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: " << x << endl; cout << "y: " << y << endl; }; }; #endif //PROJECT5_DOT_H

Line 类:

#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: (" << d1.x << ", " << d1.y << ")" << endl; cout << "dot2: (" << d2.x << ", " << d2.y << ")" << endl; }}; #endif //PROJECT5_LINE_H

main:

#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; }

【C/C++中组合详解及其作用介绍】输出结果: