Controlling Access to Class Members

In the previous section, I designed class Cylinder that binds together its data members and member functions in a syntactic unit. This syntax repairs two problems with using global functions for object-oriented programming.

First, using global functions for access to data does not force the indication that data and operations belong together. Hence, it is possible to tear apart the functions that belong together and spread them throughout different places in the source code (making the code more difficult for the maintainer to understand and modify). Second, global function names are global. To avoid potential name conflicts, programmers have to coordinate their activities even when parts of the program they are working on are not immediately related. The class syntax clearly indicates that data and functions belong together. The class scope eliminates the potential for function name conflicts.