22.5. Identifying Class Attributes

In Section 22.4, we began the first stage of an object-oriented design (OOD) for our ATM system—analyzing the requirements document and identifying the classes needed to implement the system. We listed the nouns and noun phrases in the requirements document and identified a separate class for each one that plays a significant role in the ATM system. We then modeled the classes and their relationships in a UML class diagram (Fig. 22.10).

Classes have attributes (data) and operations (behaviors). Class attributes are implemented in C++ programs as data members, and class operations are implemented as member functions. In this section, we determine many of the attributes needed in the ATM system. In Section 22.6, we examine how these attributes represent an object’s state. In Section 22.7, we determine class operations.