What are major and essential feature that make program object oriented. If a base and derived class each include a member function with same name, which member function will be called by an object of a derived class and why? Explain with example.

 The major and essential features that make a program object-oriented are:

1. Encapsulation: The ability to hide the implementation details of a class from outside users and provide a well-defined interface for interaction with the class.
2. Inheritance: The ability to create new classes that are derived from existing classes and inherit their properties and behavior.
3. Polymorphism: The ability to define different behaviors for the same function or method depending on the context in which it is called.
4. Abstraction: The ability to define and use abstract data types that can be manipulated without knowing their underlying implementation details.

Now, if a base and derived class each include a member function with the same name, the member function of the derived class will be called by an object of a derived class. this is because the derived class overrides the member function of the base class with its own implementation. 

Here's an example to illustrate this:

#include <iostream>

using namespace std;

class Shape {

    public:

        virtual void draw() {

            cout << "Drawing a shape" << endl;

        }

};

class Rectangle : public Shape {

    public:

        void draw() {

            cout << "Drawing a rectangle" << endl;

        }

};

int main() {

    Shape* s = new Rectangle();

    s->draw();

    delete s;

    return 0;

}

In this example, we define a base class "Shape" with a virtual member function 'draw()', which prints a message indicating that a shape is being drawn. We then define a derived class 'Rectangle' that overrides the 'draw()' function to print a message indicating that a rectangle is being drawn.

In the 'main()' function, we create a pointer 's' of the 'Shape*' and assign it to a new "Rectangle" object. We then call the 'draw()' function on the pointer 's'. Since 's' is a pointer to a 'Shape' object, but it points to a 'Rectangle' object, the 'draw()' function of the 'Rectangle' class is called. This is because the 'Rectangle' class overrides the 'draw()' function of the 'Shape' class with its own implementation,