Virtual Functions Programs:I II III

#include<iostream.h>
class Base
{
public:
int b;
void show()
{
cout<<"\n Hello I m in Base";
}
};

class Derv:public Base
{
public:
int d;
void show()
{
cout<<"\n Hello I m in Derv";
}
}  ;


int main()
{
Base B, *bptr;
Derv D,*dptr;

//CASE I
bptr=&B;
bptr->show(); // In Base

//CASE II
bptr=&D;
bptr->show(); // In Base

//CASE III
//dptr=&B; //Not OK, cant convert

//CASE IV
dptr=&D;
dptr->show();           //In Derv

}

==============================

#include<iostream.h>

class Base

{

public:

int b;

void show()

{

cout<<"\n Hello I m in Base show";

}

virtual void disp()

{

cout<<"\n Hello I m in Base disp";

}

virtual void display()

{

cout<<"\n Hello I m in Base display";

}

};

class Derv:public Base

{

public:

int d;

void show()

{

cout<<"\n Hello I m in Derv show";

}

void disp()

{

cout<<"\n Hello I m in Derv disp";

}

}  ;

int main()

{

Base B, *bptr;

Derv D,*dptr;

B.show();        //Base

B.disp();       // Base

B.display();    //Base

D.show();        //Derv

D.disp();       //Derv

D.display();    //Base

bptr=&B;

bptr->show(); // In Base

bptr->disp(); // In Base //////********

bptr->display();  // In Base

bptr=&D;

bptr->show(); // In Base

bptr->disp(); // In Derv   ////////*********

bptr->display(); // In Base

//////*****This is run time polymorphism

}

=================

#include<iostream.h>

class Figure

{

public:

virtual void showarea(){};

};

class Tri:public Figure

{

public:

void showarea()

{

cout<<"\n Hello I m in Triangle";

}

}  ;

class Rect:public Figure

{

public:

void showarea()

{

cout<<"\n Hello I m in Rectangle";

}

}  ;

class Square:public Figure

{

public:

void showarea()

{

cout<<"\n Hello I m in Square";

}

}  ;

int main()

{

Figure *fptr[3];

Tri T;

Rect R;

Square S;

fptr[0]=&T;

fptr[1]=&R;

fptr[2]=&S;

for(int i=0;i<3;i++)

{

fptr[i]->showarea();

}

}