Virtual Functions in C++ with Example

By default, C++ matches a function call with the appropriate function definition at compile time. This is termed as static binding.

We can specify the compiler match a function call with the appropriate function definition at run time.

This is known as dynamic binding.

We can declare a function with the keyword virtual if we would like to compiler to use dynamic binding for that specific function.

When a class declares or inherits a virtual function is known as polymorphic class.

Example:

#include<iostream.h>

#include<conio.h>

class A

               {

                              public:

                              virtual void show()

                              {

                                             cout<<”Base Class”;

}

               };

class B : public A

               {

                              public:

                              void show()

                              {

                                             cout<<”Derived Class”;

}

               };

void main()

{

               clrscr();

               A ab;

               B ba;

               A *ptr;

               ptr =&ab;             //Dynamic Typing

               ptr ->show();       // Dynamic Binding

               ptr =&ba;             // Dynamic Typing

               ptr->show();        // Dynamic Binding

               getch();

}

Output:

Base Class

Derived Class