Concept of virtual functions in C++

 

In C++, a virtual function is a member function of a class that can be overridden in derived classes. Virtual functions are used in the context of polymorphism, which allows objects of different classes to be treated as objects of a common base class. This enables dynamic binding, meaning that the appropriate function to call is determined at runtime based on the actual derived class of the object.

Here's an example:

cpp
#include <iostream>
using namespace std;

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

class Square : public Shape {
public:
    void draw() override {
        cout << "Drawing a square" << endl;
    }
};

int main() {
    Shape* shape1 = new Circle();
    Shape* shape2 = new Square();

    shape1->draw(); // Calls Circle's draw
    shape2->draw(); // Calls Square's draw

    delete shape1;
    delete shape2;

    return 0;
}

In this example, the draw function is declared as virtual in the base class Shape, and it is overridden in the derived classes Circle and Square. When we call draw on a base class pointer that points to a derived class object, the appropriate overridden function is called at runtime.