C++ Program to define an Abstract Class in Polymorphism

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 define an Abstract Class in Polymorphism which is successfully compiled and run on Windows System to produce desired output as shown below :

SOURCE CODE : :

/*  C++ Program to define an Abstract Class in Polymorphism  */

#include<iostream>
#include <string.h>
using namespace std;

class Card // An abstract class
{
        protected:
                char recipient[20];
        public:
                virtual void greeting()=0; // A pure virtual function
} ;
class Holiday : public Card
{
        public:
                Holiday( char r[ ] )
                {
                        strcpy(recipient,  r) ;
                }
                void greeting() // implementation of function in sub class
                {
                        cout <<  "Dear "  <<  recipient  << endl  ;                           cout <<  "Season's Greetings!\n\n" ;
                }
} ;

class Birthday : public Card
{
        private:
                int age;
        public:
                Birthday ( char r[ ], int years )
                {
                        strcpy(recipient, r);
                        age = years;
                }
                void greeting()  // Implementation of function in sub class
                {
                        cout << "Dear " << recipient << ",\n" ;
                        cout << "Happy "  << age  << "th" << " Birthday\n\n";
                }
} ;

class Holi : public Card
{
        private:
                int colors;
        public:
                Holi( char r[ ], int c )
                {
                        strcpy(recipient, r) ;
                        colors    = c;
                 }
                void greeting()  // Implementation of function in subclass
                {
                        cout << "Dear "  << recipient << ",\n";
                        cout << " Happy holi and lots of colors for you\n";
                        for ( int j=0; j < colors; j++ )
                                cout << "*";
                        cout << "\n\n" ;
                }
} ;


int main ()
{
                Holiday   hol ( "Codez" );
                hol.greeting();
                Birthday  bd( "CodezClub", 21 );
                bd.greeting();
                Holi holi( "Max", 7 );
                holi.greeting();
return 0;
}

OUTPUT : :

/*  C++ Program to define an Abstract Class in Polymorphism  */

Dear Codez
Season's Greetings!

Dear CodezClub,
Happy 21th Birthday

Dear Max,
 Happy holi and lots of colors for you
*******

Process returned 0

Above is the source code and output for C++ Program to define an Abstract Class in Polymorphism which is successfully compiled and run on Windows System to produce desired output.