Hey guys. This is an assignment I've been given by my professor for a C++ course. The assignment description is below:

Create a class ThreeDShape that has a default constructor and pure virtual functions double getSurfaceArea(), double getVolume() and void print(). Function getSurfaceArea() should compute and return the surface area of a three dimensional shape. Function getVolume() should compute and return the volume of a three dimensional shape. Function print() should displays the values of all member variables, the surface area and the volume. The class should also declare a public static constant of type double, PI, with a value of 3.14159265358979. The code for this class and the derived classes should be place in namespace ThreeDimensionalShapes.

Create a derived class of ThreeDShape named Sphere which has the following:
• Private member variable radius.
• A one-parameter constructor that sets the radius. The radius must be greater than 0.
• Appropriate accessor and mutator functions for the radius.
• Implementations of the pure virtual functions inherited form class ThreeDShape.

Create a second class derived from ThreeDShape named Cylinder which has the following:
• Private member variables for the radius and the height of the cylinder.
• A two-parameter constructor that sets the height and the radius of the cylinder. Both the radius and the height must be greater than 0.
• Appropriate accessor and mutator functions for the member variables.
• Implementations of the virtual functions inherited from class ThreeDShape.

Formulas for computing the surface areas and volumes are given below:
Surface Area Volume
Cylinder 2*PI * r * (r + h) PI * pow(r,2) * h where r is radius ; h is height
Sphere: 4* PI*pow(r,2) 4.0/3.0* PI * pow(r, 3) where r is radius

Write a driver program that creates a sphere and a cylinder and then calls the print() function to display information about them. Each class that you create should be separated into an interface (header) file and an implementation file.

// END of description

The parts I don't understand how to code are the virtual functions. Also how would I place the classes in a new namespace called ThreeDimensionalShapes? The other thing I am not clear on is what is meant by "Each class that you create should be separated into an interface (header) file and an implementation file." Would the implementation file be a standard .cpp file? What then should go into the header file? Any help would be very much appreciated!

Excellent, I will read up on the virtual functions and thank you for the info on what should go in a header file.

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