#include<iostream>
using namespace std;
const double PI=3.1415926;
class Shape
{
public:
virtual double Area()=0;
};
class Triangle:public Shape
{
private:
double d,h;
public:
Triangle(double di,double gao)
{
d=di;
h=gao;
}
double Area()
{
cout<<"三角形面积为：";
return d*h*1/2;
}
};
class Circle:public Shape
{
private:
double r;
public:
Circle(double radius)
{
r=radius;
}
double Area()
{
cout<<"圆面积为：";
return PI*r*r;
}
};
class Ractangle:public Shape
{
private:
double a,b;
public:
Ractangle(double chang,double kuang)
{
a=chang;
b=kuang;
}
double Area()
{
cout<<"矩形面积为：";
return a*b;
}
};
void main()
{
Shape *p;
double a,b;
cout<<"请输入三角形底边和高：";
cin>>a>>b;
Triangle t(a,b);
p=&t;
cout<<p->Area()<<endl<<endl;
cout<<"请输入圆的半径：";
cin>>a;
Circle c(a);
p=&c;
cout<<p->Area()<<endl<<endl;
cout<<"请输入矩形两边长：";
cin>>a>>b;
Ractangle r(a,b);
p=&r;
cout<<p->Area()<<endl<<endl;
}。