Inheritance:

Base class functions and members can be redefined in derived class check it out:

Program:

#include<iostream>

class A

{

protected:

int a,b;

public:

void assign()

{

a=30,b=20;

}

void display()

{

cout<<"\na= "<<" b="<<b;

}

};

class B : public A

{

protected:

int c,d;

public:

void assign()

{

a=40,b=50,c=100,d=200;

}

void display1()

{
cout<<"\na="<<a<<" b="<<b<<" c="<<c<<" d="<<d;

}

};

void main()

{

B deriv;

deriv.assign();

deriv.display1();

A base;

base.assign();

base.display();

}

output:a=40 b=50 c=100 d=200
a=30 b=20