C++ Polymorphism

Polymorphism

Polymorphism means "many forms", and it occurs when we have many classes that are related to each other by inheritance.

Like we specified in the previous chapter; Inheritance lets us inherit attributes and methods from another class. Polymorphism uses those methods to perform different tasks. This allows us to perform a single action in different ways.

For example, think of a base class called Animal that has a method called animalSound(). Derived classes of Animals could be Pigs, Cats, Dogs, Birds - And they also have their own implementation of an animal sound (the pig oinks, and the cat meows, etc.):

Example

// Base class
class Animal {
public:
    void animalSound() {
    cout << "The animal makes a sound \n" ;
}
};

// Derived class
class Pig : public Animal {
public:
    void animalSound() {
    cout << "The pig says: wee wee \n" ;
}
};

// Derived class
class Dog : public Animal {
public:
    void animalSound() {
    cout << "The dog says: bow wow \n" ;
}
};

Remember from the Inheritance chapter that we use the : symbol to inherit from a class.

Now we can create Pig and Dog objects and override the animalSound() method:

Example

// Base class
class Animal {
public:
    void animalSound() {
    cout << "The animal makes a sound \n" ;
}
};

// Derived class
class Pig : public Animal {
public:
    void animalSound() {
    cout << "The pig says: wee wee \n" ;
   }
};

// Derived class
class Dog : public Animal {
public:
    void animalSound() {
    cout << "The dog says: bow wow \n" ;
}
};

int main() {
Animal myAnimal;
Pig myPig;
Dog myDog;

myAnimal.animalSound();
myPig.animalSound();
myDog.animalSound();
return 0;
}

Try it Yourself »