OJ 期末小测验

#include <iostream>
using namespace std;
class Shape
{
public:
virtual double area() =0;
};
class Rectangle:public Shape
{
public:
    Rectangle (double a,double b):width(a),length(b){}
    virtual double area()
    {
     return width*length;
    }
private:
    double width;
    double length;

};
class Triangle:public Shape
{
   public:
       Triangle (double w,double h):width(w),height(h){}
       virtual  double area()
       {
           return 0.5*width*height;


       }
   private:
    double width;
    double height;

};

int main()

{

    double a,b;

    cin>>a>>b;   //输入矩形的长和宽

    Rectangle r(a,b);//建立Rectangle类对象r, 矩形长a宽b

    Shape *s1=&r;

    cout<<s1->area()<<endl;//输出矩形的面积

    double w,h;

    cin>>w>>h;   //输入矩形的长和宽

    Triangle t(w,h); //建立Triangle类对象t，三角形底边长w高h

    Shape &s2=t;

    cout<<s2.area();//输出三角形面积

    return 0;
}