lists with pointer // abstract classes

#include<iostream>
#include<list>
using namespace std;
class Shape
{
public:
	Shape(int a,int b):x(a),y(b) {}
	virtual void display()=0;
	virtual void printArea()=0;
protected:
	int x;
	int y;
};

class Square:public Shape
{
public:
	Square(int a):Shape(a,a) {}
	void display()
	{
		cout<<"x: "<<x<<endl;
		cout<<"y: "<<y<<endl;
	}
	void printArea()
	{
		cout<<"area: "<<x*x<<endl;
	}
};
class Rectangle:public Shape
{
public:
	Rectangle(int a,int b):Shape(a,b) {}
	void display()
	{
		cout<<"x: "<<x<<endl;
		cout<<"y: "<<y<<endl;
	}
	void printArea()
	{
		cout<<"area: "<<x*y<<endl;
	}
};
class Circle:public Shape
{
public:
	Circle(int a,int b):Shape(a,b) {}
	void display()
	{
		cout<<"center: "<<x<<endl;
		cout<<"radius: "<<y<<endl;
	}
	void printArea()
	{
		cout<<"area: "<<y*y*3<<endl;
	}
};

#################################

#include"shape.h"
#include<iostream>

using namespace std;

int main()
{
	list<Shape *> myList;
	list<Shape *>::iterator myIterator;
	myList.push_back(new Square(4));
	myList.push_back(new Rectangle(5,3));
	myList.push_back(new Circle(2,1));

	for(myIterator=myList.begin(); myIterator!=myList.end(); myIterator++)
		{
			(*myIterator)->display();
			(*myIterator)->printArea();
		}
	myList.pop_front();

	for(myIterator=myList.begin(); myIterator!=myList.end(); myIterator++)
		{
			(*myIterator)->display();
			(*myIterator)->printArea();
		}
	system("pause");
	return 0;
}