一，设计模式简介

强调了抽象的概念，而不是分而治之，上代码

#include <iostream>
#include <vector>

class Shape
{
public:
    virtual void draw() = 0;
    virtual ~Shape() {}
};

class Point : public Shape
{
public:
    Point()
    {

    }
    ~Point()
    {

    }
    virtual void draw()
    {
        std::cout << "use Point" << std::endl;
    }
};

class Line : public Shape 
{
public:
    Line()
    {
 
    }
    ~Line()
    {

    }

    virtual void draw()
    {
        std::cout << "use line" << std::endl;
    }
};

class Rect : public Shape
{
public:

    Rect()
    {

    }
    ~Rect()
    {

    }

    virtual void draw()
    {
        std::cout << "use Rect" << std::endl;
    }

};

int main()
{
    Shape* ptShape = new Point; 
    Shape* lineShape = new Line;
    Shape* rectShape = new Rect;

    std::vector<Shape*> shapeVector; //这里Shape要用指针,多态性
    shapeVector.push_back(ptShape);
    shapeVector.push_back(lineShape);
    shapeVector.push_back(rectShape);
    for (auto& theShape : shapeVector)  //针对各种形状，各负其责
    {
        theShape->draw();
    }

    
    delete ptShape;
    ptShape = nullptr;
    delete lineShape;
    lineShape = nullptr;
    delete rectShape;
    rectShape = nullptr;

    return 0;
}

 

打印结果是:

use Point
use line
use Rect

 

这里用了抽象类，

如果分而治之，则会需要3个数组，分别判断具体属于哪个类，是点，圆还是线，再调用相应类的方法。如果再添加，还需要再加数组，1万个种类的图形则需要1万种数组

本文地址：https://blog.csdn.net/directx3d_beginner/article/details/107570052