// 创建一个基类 Shape，其中包含一个纯虚函数 draw() ，用于绘制形状。从 Shape 派生出 Rectangle 类和 Circle 类，分别实现不同形状的绘制方法
#include <iostream>
#include <cstring>
#include <cstdlib>

using namespace std;

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

class Rectangle : public Shape
{
public:
    void draw()
    {
        cout << "Rectangle" << endl;
    }
};

class Circle : public Shape
{
public:
    void draw()
    {
        cout << "Circle" << endl;
    }
};

int main()
{
    Shape *p = new Rectangle;
    p->draw();
    p = new Circle;
    p->draw();
    return 0;
}