#include <iostream>
using namespace std;

class Base {
public:
    virtual void show() {
        cout << "This is Base class show() function" << endl;
    }
};

class Derived : public Base {
public:
    void show() {
        cout << "This is Derived class show() function" << endl;
    }
};

int main() {
    Base *bptr;        // Base class pointer
    Derived dobj;      // Derived class object

    bptr = &dobj;      // Base pointer pointing to derived object

    // Calling virtual function
    bptr->show();

    return 0;
}

Documentation

Output

This is Derived class show() function

----------------------------------------------------------------------------------------------------------

✔ Pointer to base class
✔ Pointer to derived class
✔ Virtual function usage
✔ Runtime polymorphism

Key Concept

A base class pointer can point to a derived class object
If the function is declared virtual, the derived class function is called at runtime

Explanation

virtual keyword ensures dynamic binding
Function call is resolved at runtime
Even though pointer is of Base type, Derived function is executed
This concept is called Runtime Polymorphism
Virtual functions are accessed using base class pointers