Chapter 15, Problem 5PP

Consider a graphics system that has classes for various figures—rectangles, squares, triangles, circles, and so on. For example, a rectangle might have data members for height, width, and center point, while a square and circle might have only a center point and an edge length orradius, respectively. In a well-designed system, these would be derived from a common class, Figure. You are to implement such a system. The class Figure is the base class. You should add only Rectangle and Triangle classes derived from Figure. Each class has stubs for member functions erase and draw. Each of these member functions outputs amessage telling what function has been called and what the class of the calling object is. Since these are just stubs, they do nothing more than output this message. The member function center calls the erase and draw functions to erase and redraw the figure at the center. Since you have only stubs for erase and draw, center will not do any “cantering” but will call the member functions erase and draw. Also add an output message in the member function center that announces that center is being called. The member functions should take no arguments.

There are three parts to this project:

a. Write the class definitions using no virtual functions. Compile andtest.

b. Make the base class member functions virtual. Compile and test.

c. Explain the difference in results.

For a real example, you would have to replace the definition of each of these member functions with code to do the actual drawing. You will be asked to do this in Programming Project 6.s

Use the following main function for all testing:

//This program tests Programming Project 5. #include <iostream> #include "figure.h" #include "rectangle.h" #include "triangle.h" using std::cout; int main( ) { Triangle tri; tri.draw( ); cout<< "\nDerived class Triangle object calling center( ).\n"; tri.center( ); //Calls draw and center Rectangle rect; rect.draw( ); cout<< "\nDerived class Rectangle object calling center().\n"; rect.center( ); //Calls draw and center return 0; }