C++ Program For Virtual Function

Program 1

// Program for Virtual Function
#include<iostream>
#include<string.h>
#define clrscr() system("cls")
using namespace std;
class Base   // Abstract class
{
    public:
    void virtual display()=0;   
};
class Derived:public Base
{
    public:
    void display()
    {
        cout<<"\n display method of derived class";
    }
};
class Derived1:public Base
{
    public:
    void display()
    {
        cout<<"\n display method of derived  1 class";
    }
};

int main()
{
    clrscr();
    Base *p;
    Derived D;
    p=&D;
    p->display();

    // Derived D,*p;  // Both object and pointer of derived class;
    // p=&D;
    // p->display();
    // Base B,*p; // Both object and pointer of base class;
    // p=&B;
    // p->display();

    return 0;
}

Program 2

// Program for Virtual Function
#include<iostream>
#include<string.h>
#define clrscr() system("cls")
using namespace std;
class Button   //Abstract Class
{
    public:
    void virtual click()=0;
    void virtual dbclick()=0;
};
class Color:public Button  //Programmer 1
{
    public:
    void click()
    {
        cout<<"\nNow color is red........ click";
    }
  void dbclick()
  {
     cout<<"\nNow color is blue.......double click";
  }
    
};
class Image:public Button //Programmer 2
{
   public:
    void click()
    {
           cout<<"\nThis is My Click Image.....";  
    }
  void dbclick()
    {
           cout<<"\nThis is My  duble Click Image.....";
    }
};
int main()
{
    clrscr();
    Button *p;    // Reference Object
    Color C;
    p=&C;
    p->click();
    p->dbclick();
}