These files can be accessed through fstring.h , fstring.cpp and fstgproj.cpp . Revised versions of both case study 3 systems were loaded on Nov. 15, 2000. If you plan to use FString for other purposes you should be sure to download its new version. For the Interface Again for this case study, the two problems are unrelated. The base class is now Shape.
Shape is an abstract class since it has member functions which are pure virtual.
Hence, a variable of class Shape can not be created. However, Shape does serve a useful function as the base class since with dynamic binding it provides the base functions for Area and Volume because Point has neither and Circle has no Volume. The use of dynamic binding is illustrated by two functions which take the base class Shape as either a pointer or reference. To see that the proper calls are being made you should run this case you self and examine the calls being made. The header, source code and test code can be found as ptcircylpoly.h , ptcircylpoly.cpp and ptcircylpolytest.cpp , respectively.