VIRTUAL FUNCTION :-
Virtual Function is a function that is declared within a base class and redefined in the derived class. Virtual functions are declared by preceding the class declaration with a keyword "virtual". When a virtual function is declared C++ decides to execute a function based on the type of object pointed by the base pointer and not on the type of pointer.
Example:
#include <iostream.h>
#include<conio.h>
#include<stdio.h>
class BB
{
public:
void show() { cout << " BASE BASE\n" ; }
virtual void print() { cout << "base base\n"; }
};
class DD : public BB
{
public:
void show() { cout << "DERIVED DERIVED\n"; }
void print() { cout << "derived derived\n"; }
};
int main()
{
BB B;
DD D;
BB *ptr;
cout << "ptr points to base class\n" ;
ptr = &B;
ptr->show();
ptr->print();
cout << "ptr points derived class\n";
ptr = &D;
ptr->show();
ptr->print();
getch();
return 0;
}
OUTPUT:
ptr points to base class
BASE BASE
base base
ptr points derived class
BASE BASE
derived derived
