Program Of Pure Virtual Function In C++

#include< iostream.h>

#include< conio.h>

class abc

{

protected :

int a,b;

public:

void take()

{ 

cout<< "\nEnter two 'int' values::";

cin>>a>>b;

} 

virtual void display()=0; 

}; 

class xyz:public abc

{

public:

void display()

{

cout<< "\nSum for 1st derived class="<< a+b;

}

};

class mn:public abc

{

public:

void display()

{

cout<< "\nSum for 2nd derived class:"<< a+b;

}

};

void main()

{

clrscr();

xyz ob;

mn ob1;

abc *ptr;

ptr=&ob;

cout<< "\nFor object of 1st derived class."<< endl;

ptr->take();

ptr->display();

cout<< "\nFor object of 2nd derived class."<< endl;

ptr=&ob1;

ptr->take();

ptr->display();

getch();

}

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Pure  Virtual Function

In object-oriented programming, a  virtual method is a function or method whose behaviour can be overridden within an inheriting class by a function with the same signature. This concept is a very important part of the polymorphism portion of object-oriented programming (OOP).

by:---http://en.wikipedia.org/wiki/Virtual_function