The object-oriented programming (OOP) approach facilitated by Think C 4.0 and C++ provides the potential for vast improvements in the MAINTENANCE AND REUSE OF SOURCE CODE. Code maintainability generally depends on how easily the source code can be adapted to changing user requirements. This sort of code reuse differs only in degree from the use of portions of existing source code in entirely new programming efforts.
By encapsulating data with the procedures which act upon the data the programmer can construct "modular" applications, which encourage the reuse of data "objects" (Chapter 4). OOP languages like TC/C++ provide syntactical assistance for such encapsulation. More importantly, they allow the definition of "classes" of objects and the construction of "derived classes". Since even the most modular code often requires customization for reuse in a new programming situation, the ability to easily construct new classes which "inherit" the data structures and functionality of an existing class has great significance.
Applications should be constructed as a collection of interacting objects, each of which represents a data structure and its interface. When an existing class must be
