Polymorphism

In OOP, we can use same name for methods and attributes in different classes; the methods or attributes are invoked based on the object type; e.g. in Listing 14.7, 
the method ‘scarySound’ is used for class ‘Animal’ and ‘Bird’ at Lines 8 and 15 respectively. Then object of these classes are created at Line 26-27. Finally,
method ‘scarySound’ is invoked at Lines 29-30; here Line 29 is the object of class Animal, therefore method of that class is invoked and corresponding message is printed. 
Similarly, Line 30 invokes the ‘scaryMethod’ of class Bird and corresponding line is printed.


// PolymorphismEx.cpp

#include <iostream>
using namespace std;

class Animal{
public:
    void scarySound(){
        cout << "Animals are running away due to scary sound." << endl;
    }
};

class Bird{
public:
    void scarySound(){
        cout << "Birds are flying away due to scary sound." << endl;
    }
};

// empty class
class Insect{
};

int main(){
    Animal a;
    Bird b;
    Insect i;

    a.scarySound();
    b.scarySound();

    return 0;
}

/* Outputs
Animals are running away due to scary sound.
Birds are flying away due to scary sound.
*/