виртуальные функции

#include "stdafx.h"
#include <iostream>
using namespace std;
class Shape 
{
public:
    virtual void Area() = 0;
    virtual void Print() = 0;     
};
class tr:public Shape
{
    protected:
    double s;
public:
    virtual void Area (double _st1, double _st2)
    {
        s=_st1*_st2*0.5;
    }
    virtual void Print()
    {
        cout<<"S tr = "<<s;
    }
};
class kv:public Shape
{
    double s1;
public:
    virtual void Area (double _st3,double _st4)
    {
        s1=_st3*_st4;
    }
    virtual void Print()
    {
        cout<<"S kB= "<<s1;
    }
};
int _tmain(int argc, _TCHAR* argv[])
{
    Shape *p[4];int type;
    double x;
    double y;
 
    for(int i = 0; i < 3; i++)
    {
        cin>>type;
        switch(type)
        {
        case 1: cin>>x,y;
            p[i]= new tr(x,y);
            break;
    case 2: cin>>x,y;
            p[i]=new kv(x,y);
            break;
        }
    }
    for(int i = 0; i < 3; i++)
    {
        p[i]->Print();
    }
    return 0;
}

#include <iostream>
#include <string>
 
class Shape
{
public:
    explicit Shape(std::string const& name_) : name(name_){}
    virtual size_t Area() const = 0;
    virtual void Print() const = 0;
protected:
    std::string name;
};
 
class Square : public Shape
{
public:
    explicit Square(size_t width_ = 1, std::string const& name_ = "Square") : Shape(name_), width(width_){}
    size_t Area() const
    {
        return width * width;
    }
    void Print() const
    {
        std::cout << name << '\n' << width << '\n' << "area is " << Area() << std::endl;
    }
protected:
    size_t width;
};
 
class Rectangle : public Square
{
public:
    explicit Rectangle(size_t height_ = 1, size_t width_ = 1, std::string const& name_ = "Rectangle") : Square(width_, name_), height(height_){}
    size_t Area() const
    {
        return height * width;
    }
    void Print() const
    {
        std::cout << name << '\n' << height << '\n' << width << '\n' << "area is " << Area() << std::endl;
    }
private:
    size_t height;
};
 
int main()
{
    size_t const size(2);
    Shape* arr[size] = {0};
    arr[0] = new Square(3, "Square1");
    arr[1] = new Rectangle(2, 4, "Rectangle1");
    for(size_t i = 0; i < size; ++i)
    {
        if(arr[i])
            arr[i]->Print();
        std::cout << std::endl;
        delete arr[i];
        arr[i] = 0;
    }
    return 0;
}