C++求图形面积（完整版各种输入错误情况校验）

#include<iostream>
using namespace std;
const double p = 3.14159;
class shape
{
public:
virtual double area() = 0;    //声明纯虚函数
virtual void shapeName() = 0;
};
class Circle:public shape         //类继承
{
public:
Circle(double r)
{
radius = r;
}

double area()
{
        return p*radius*radius;
}
void shapeName()
{
cout<<"Circle:"<<endl;
}
~Circle(){};
private:
double radius;
};
class Square:public shape

{
public:
Square(double s)
{
size = s;
}
~Square(){};
double area()
{
        return size*size;
}
void shapeName()
{
cout<<"Square:"<<endl;
}
private:
double size;
};
class Circle_Zhu:public shape
{
public:
Circle_Zhu(double r,double h)
{
radius = r;
height = h;
}
~Circle_Zhu(){};                     //析构函数清理内存空间
double area()
{
        return p*radius*radius*height;