Method Overriding

Method overriding means a derived class provides its own version of a base-class method with the same name and compatible signature.

Overriding is used when the derived class needs specialized behavior.

Basic Example

#include <iostream>
using namespace std;

class Animal {
public:
    void sound() const {
        cout << "Animal sound" << endl;
    }
};

class Dog : public Animal {
public:
    void sound() const {
        cout << "Bark" << endl;
    }
};

int main() {
    Dog dog;
    dog.sound();

    return 0;
}

Output:

Bark

Overriding With Virtual Function

For runtime polymorphism, the base function should be virtual.

#include <iostream>
using namespace std;

class Shape {
public:
    virtual void draw() const {
        cout << "Drawing shape" << endl;
    }
};

class Circle : public Shape {
public:
    void draw() const override {
        cout << "Drawing circle" << endl;
    }
};

int main() {
    Circle circle;
    Shape* shape = &circle;

    shape->draw();

    return 0;
}

Output:

Drawing circle

Overriding vs Overloading

Why Use override

The override keyword asks the compiler to check that the function really overrides a virtual base function.

If the signature is wrong, the compiler reports an error.

That protects you from accidental bugs.

Viva Answer

Method overriding occurs when a derived class defines its own version of a base-class method with the same signature. If the base method is virtual and called through a base pointer or reference, C++ uses runtime polymorphism to call the derived version.

Quick Check

1. What must match for overriding?
2. Why should base functions be marked virtual for runtime polymorphism?
3. What does override help the compiler check?