c++多态虚函数代码

#include <iostream>
using namespace std;

class Shape
{
protected:
    int width, height;

public:
    Shape(int a = 0, int b = 0)
    {
        width = a;
        height = b;
    }
    // 这个函数的作用  好像是让函数是虚函数 虚函数--这里写的不一定是具体执行的 还要看后面有没有重构内容
    virtual int area()
    {
        cout << "Parent class area :" << endl;
        return 0;
    }
};
class Rectangle : public Shape
{
public:
    Rectangle(int a = 0, int b = 0) : Shape(a, b) {}
    int area()
    {
        cout << "Rectangle class area :" << endl;
        return (width * height);
    }
};
class Triangle : public Shape
{
public:
    Triangle(int a = 0, int b = 0) : Shape(a, b) {}
    int area()
    {
        cout << "Triangle class area :" << endl;
        return (width * height / 2);
    }
};
// 程序的主函数
int main()
{
    Shape *shape;
    Rectangle rec(10, 7);
    Triangle tri(10, 5);

    // 存储矩形的地址
    shape = &rec;
    // 调用矩形的求面积函数 area
    shape->area();

    // 存储三角形的地址
    shape = &tri;
    // 调用三角形的求面积函数 area
    shape->area();

    cout << "============分隔符====" << endl;
    rec.area();
    tri.area();

    return 0;
}