// oop.cpp : Defines the entry point for the console application.
//

#include <iostream>
using namespace std;

class A {
protected:
	int a;
public:
	int x;
	A(int b) {
		x = 1;
		cout << "Parent Constructor : " << endl;
		a = b;}
	virtual void show () {x = 1; cout << "Parent: "; cout << a << endl;}
	//class with pure virtual function is abstract and can't be instantiated
	//virtual void show()=0; //pure virtual function
	void myfun() { cout << "Parent My Function";}
};


class B : public A{
private:
	int a;
	int b;
public:
	int x;
	B(int a, int b);
	void show(){x = 0; cout << "Child: "; cout << a << endl;}
	//friend function can access all members of the class inside which it is defined
	friend void f();
	void myfun(){cout << "Child My Function";}
};

B::B(int a, int b):A(b) {
	x = 0;
	this->a = a;
	this->b = b;
}

void f() {
	B b(1, 1);
	b.b = 10;
	cout << "Friend" << endl;
	cout << "Value of b is " << b.b << endl;
}

int main()
{
	B b(1, 2);
	f();
	A *a;
	//example of polymorphism
	a = &b;
	a->show();
	//if the parent function is not defined as virtual
	//every call to the function will call parent version
	a->myfun();
	cout << a->x << endl; //member variables of parents are always accessed.
	A c(2);
	a = &c;
	a->myfun();
	a->show();
	cout << a->x <<endl;
	return 0;
}