C++ Program to illustrates the use of Virtual base class

The word polymorphism means having many forms. Typically, polymorphism occurs when there is a hierarchy of classes and they are related by inheritance.

C++ polymorphism means that a call to a member function will cause a different function to be executed depending on the type of object that invokes the function.

Virtual Function : :

A virtual function is a function in a base class that is declared using the keyword virtual. Defining in a base class a virtual function, with another version in a derived class, signals to the compiler that we don’t want static linkage for this function.

Below is the source code for C++ Program to illustrates the use of Virtual base class which is successfully compiled and run on Windows System to produce desired output as shown below :

SOURCE CODE : :

/*  C++ Program to illustrates the use of Virtual base class  */

#include<iostream>
using namespace std;
// This program illustrates the use of the virtual base clas
class B  // Base class
{
                protected:
                        int base_data ;
                public:
                        void get_b_data(int b)
                        {
                                cout << "\n\n Accessing the data from the base class B------------>" ;
                                base_data = b ;
                        }
                        void display_b_data(void)
                        {
                                cout << "\n base_data = " << base_data ;
                        }
};
class D1 : virtual public B  // First virtual base class.
{                                        // This class is derived from the class B.
                protected:
                        int der1_data ;
                public:
                        void get_d1_data(int d1)
                        {
                                cout << "\n\n Accessing the data from the derived class D1---------->" ;
                                der1_data = d1 ;
                        }
                        void display_d1_data(void)
                        {
                                cout << "\n der1_data = " << der1_data ;
                        }
};

class D2 : virtual public B // Second virtual base class.
{                                       // This class is also derived from the class B.
                protected:
                        int der2_data ;
                public:
                        void get_d2_data(int d2)
                        {
                                cout << "\n\n Accessing the data from the derived class D2---------->" ;
                                der2_data = d2 ;
                        }
                        void display_d2_data(void)
                        {
                                cout << "\n der2_data = " << der2_data ;
                        }
};
class D3 : public D1, public D2 // This class inherits the properties of the
{                                                   // classes B, D1 and D2.
                public:
                        int der3_data ;
                public:
                        void get_d3_data(int d3)
                        {
                                cout << "\n\n Accessing the data from the derived class D3---------->" ;
                                der3_data = d3 ;
                        }
                        void display_d3_data(void)
                        {
                                cout << "\n der3_data = " << der3_data ;
                        }
};

int main()
{
        D3 der3 ;  // Object of the class D3.
        der3.get_b_data(7);    // Accessing the member functions of the base class B.
        der3.display_b_data( ) ;
        der3.get_d1_data(8) ; // Accessing the member functions of the class D1.
        der3.display_d1_data( );
        der3.get_d2_data(18) ; // Accessing the member functions of the class D2.
        der3.display_d2_data( );
        der3.get_d3_data(15); // Accessing the member functions from its own class D3.
        der3.display_d3_data( );
return 0;
}

OUTPUT : :

/*  C++ Program to illustrates the use of Virtual base class  */

 Accessing the data from the base class B------------>
 base_data = 7

 Accessing the data from the derived class D1---------->
 der1_data = 8

 Accessing the data from the derived class D2---------->
 der2_data = 18

 Accessing the data from the derived class D3---------->
 der3_data = 15

Process returned 0

Above is the source code and output for C++ Program to illustrates the use of Virtual base class which is successfully compiled and run on Windows System to produce desired output.