Animal.h

#include <iostream>
#include <string>
using namespace std;

class Animal
{
private:
	string animal;
public:
	Animal(){}
	Animal(string animal)
	{
		this->animal = animal;
	}

	void move()
	{
		cout<<"\n\tEvery animal moves.";
	}

};

Dog.h

#include <iostream>
#include <string>
#include "Animal.h"
using namespace std;

class Dog:public Animal
{
private:
	string dog
;
public:
	Dog(string dog):Animal()
	{
		this->dog=dog;
	}
	void move()
	{
		cout<<"\n\tDog moves running.\n";
	}
};

Main.cpp

#include <iostream>
#include <string>
#include "Dog.h"
using namespace std;

int main()
{
	Animal anyAnimal("Jery");
	Dog myDog("Tom");
	Animal &anyAnimalRef = anyAnimal;
	Dog &myDogRef = myDog;

	cout<<"\nCalling function move() for objects";
	anyAnimal.move();
	myDog.move();

	cout<<"\nCalling function move() with references";
	anyAnimalRef.move();
	myDogRef.move();

	cout<<"\nCalling function move() with the changed reference";
	anyAnimalRef = myDog;
	anyAnimalRef.move();

	cout<<"\n\n Calling function move() with base-class reference to derived-class object";
	Animal &anyAnimalRef2 = myDog;
	anyAnimalRef2.move();
	cout<<endl;

	cout<<endl;
	system ("pause");
	return 0;
}