Inheritance program

[mgarrard14]

I need help with program. I am new to inheritance and am having trouble figuring out what to do.

Goal
• Application of Inheritance and virtual functions
Points
Description
In this lab, you have to implement the following class hierarchy using Inheritance.
Shape
Circle Polygon
Sphere
Rectangle Square
Cube
You have to define one class for each shape. And, use public inheritance when deriving from base
classes. Each shape should contain following attributes and member functions.
Circle
int r;
void area();
void perimeter();
void volume();
Sphere
int r;
void area();
void perimeter();
void volume();
Rectangle
int length, width;
void area();
void perimeter();
void volume();
Square
int length;
void area();
void perimeter();
void volume();
Cube
int length;
void area();
void perimeter();
void volume();
Functions area(), perimeter(), and volume() are inherited from Shape class. You have to
declare them as virtual functions. Since classes Shape and Polygon are conceptual, you have
to define them as abstract classes (remember pure virtual functions). All others should be
concrete classes i.e., all classes should inherit these functions from its base class and override.
Certain functions are not defined for certain shapes. For example, volume is not defined for
Circle and, hence, print a warning message in the overridden function. Something like following:
void Circle::volume ( void ) {
cout << "Volume is not defined for circle." << endl;
}
Along with these functions, you should have proper constructors to construct the objects of each
class. Please note that, you can only create objects of concrete classes. You should use
appropriate formulae to calculate the area, perimeter and volume. You can take the value of Π
to be 3.14. All methods should print appropriate messages. For example, “Area of circle is 31.0”
etc.
At this point, we have all the classes set up and now we want to test by creating some
dummy shapes and by calculating the area etc. Most importantly, we want to check the
functionality of virtual functions. To do so, we always invoke the member functions using a
pointer to Shape class i.e., Shape *. You can check using pointer to Polygon also i.e., Polygon *.
Sample Test Program
main ( ) {
Shape *ptr;
Circle c ( 5 );
Rectangle r ( 5, 10 );
ptr = &c;
ptr->perimeter();
ptr = &r;
ptr->area();
ptr->volume();
} // main
Sample Output:
Perimeter of circle = 31.4
Area of rectangle = 50
Volume is not defined for rectangle.
I will be testing your program with more extensive programs than the given sample program.
Hence, you should create your test programs and test whether each virtual method is
printing appropriate messages.
More Information
Remember that new operator allocates memory on Heap and returns the
pointer. Hence the value returned by new operator would be a pointer
value. So doing following is an error:
Circle X = new Circle () ; // X is just an object not a pointer.
You should do one of the following:
Circle *px = new Circle ();
or
Circle x ();
Of course, with px, you should access the variable using arrow operator.
Something like px->x, px->y, and px->r.
And, this is assuming that there exists a default constructor for
Circle. If you have constructor Circle( int ) then, you should
create object like this:
Circle x ( 3 );
Circle *px = new Circle ( 3 );
I hope everyone is familiar with calling base class constructors from
derived class constructor. Just to make sure, here is an example.
class Figure {
public:
Figure (int xx, int yy) {
x = xx;
y = yy;
}
protected:
int x;
int y;
};
class Rectangle : public Figure {
public:
/* Call Constructor of Figure first and then construct this
* object
*/
Rectangle (int xx, int yy, int ll, int hh) : Figure(xx, yy) {
length = ll;
height = hh;
}
protected:
int length;
int height;
};

[firedraco]

Read: http://www.cplusplus.com/doc/tutorial/inheritance/#inheritance