C++ OO Pointers in Polymorphism

Pointers are often used in C++ to achieve polymorphism. When a function is declared as virtual, it enables dynamic binding, which means that the appropriate function to call is determined at runtime based on the type of the object pointed to by the pointer.

In other words, when a pointer of the base class type points to an object of the derived class, and the function is called using the pointer, the function in the derived class is executed rather than the function in the base class. This is an important aspect of polymorphism in C++, and it allows for the creation of flexible and extensible code. 

#include <iostream>

using namespace std;

class Prim{
    public:
        virtual void printing() {}
};

class Sec : public Prim{
    public:
        void printing() {
            cout << "I am From Sec Cls" << endl;
        }
};

class Third : public Prim {
    public:
        void printing() {
            cout << "I am from Third Cls" << endl;
        }
};

int main() {

    Sec Object;
    Sec *Ptr1 = &Object;

    Ptr1->printing();

    Third Object_2;
    Third *Ptr2 = &Object_2;

    Ptr2->printing();

    return 0;
}

This C++ code defines three classes: Prim, Sec, and Third. The Prim class has a virtual function printing() defined. The Sec and Third classes inherit from Prim and override the printing() function.

In the main() function, an object of the Sec class is created and a pointer Ptr1 of type Sec is initialized to point to the Object object. The Ptr1->printing() statement calls the printing() function on the object pointed to by Ptr1. Since the printing() function is virtual and has been overridden in the Sec class, the printing() function in the Sec class is called and the output is "I am From Sec Cls".

Then, an object of the Third class is created and a pointer Ptr2 of type Third is initialized to point to the Object_2 object. The Ptr2->printing() statement calls the printing() function on the object pointed to by Ptr2. Again, since the printing() function is virtual and has been overridden in the Third class, the printing() function in the Third class is called and the output is "I am from Third Cls".