Aim: To implement a program to find area of rectangle, surface area of box and volume of box using virtual functions.

Code:                      

class rect

{

            double l,b;

            public:

                        virtual void getdata();

                        virtual void area();

};

void rect::getdata()

{

            cout<<"Enter the length and breadth of rectangle:\n";

            cin>>l>>b;

}

void rect::area()

{

            cout<<"Area of rectangle = "<

}

class box:public rect

{

            double l,b,h;

            public:

                        void getdata();

                        void area();

                        void volume();

};

void box::getdata()

{

            cout<<"\nEnter the length, breadth and height of the box:\n";

            cin>>l>>b>>h;

}

void box::area()

{

            cout<<"Surface area of the box = "<<2*(l*b+b*h+l*h)<<" sq. units\n";

}

void box::volume()

{

            cout<<"Volume of the box = "<

}

void main()

{

            rect r,*ptr;

            box b;

            clrscr();

            ptr=&r;

            ptr->getdata();

            ptr->area();

            ptr=&b;

            ptr->getdata();

            ptr->area();

            ((box *)ptr)->volume();

            getch();

}

Output:

Enter the length and breadth of rectangle:

10

15

Area of rectangle = 150 sq. units

Enter the length, breadth and height of the box:

5

12

6

Surface area of the box = 324 sq. units

Volume of the box = 360 cu. units