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Chapter 5

Programming in the Large II: Objects and Classes

Whereas a subroutine represents a single task, an object can encapsulate both data (in the form of instance variables) and a number of different tasks or "behaviors" related to that data (in the form of instance methods). Therefore objects provide another, more sophisticated type of structure that can be used to help manage the complexity of large programs.

The first four sections of this chapter introduce the basic things you need to know to work with objects and to define simple classes. The remaining sections cover more advanced topics; you might not understand them fully the first time through. In particular, Section 5.5 covers the most central ideas of object-oriented programming: inheritance and polymorphism. However, in this textbook, we will generally use these ideas in a limited form, by creating independent classes and building on existing classes rather than by designing entire hierarchies of classes from scratch.

Contents of Chapter 5:

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