A virtual function is a member function that is declared within the base class and redefined by a derived class. It is declared by the keyword virtual.
You will understand more clearly after the example.
#include<iostream.h>
#include<conio.h>
class A
{
public:
virtual void show()
{
cout << "A show called" << endl;
}
};
class B:public A
{
public:
void show()
{
cout << "B show called" << endl;
}
};
void main()
{
A a1,*ptr;
clrscr();
ptr=&a1;
ptr->show();
B b1;
ptr=&b1;
ptr->show();
getch();
}
Output:
A show called
B show called
If you do not write virtual keyword in the base class then output will be
A show called
A show called