C++: A Dialog Programming with the C++ Standard Library

User-defined Data Types

In C++, a user-defined variable is called an object. Each object has a type, just like variables of native types (short, char, etc.). For example, if we define a class called StockItem (as we will do in this chapter), then an object can be of type StockItem, just as a native variable can be of type short. However, an additional step is required when we want to use user-defined types. Since the compiler has no intrinsic knowledge of these types, we have to tell it exactly what they are and how they work. We do this by defining a class, which specifies both the data contained in the user-defined variable and what operations can be performed on these data.

Here's how Susan reacted upon her first encounter with this idea. ...