CHAPTER 4 CLASSES: THE BASICS

Creating Variables and Instances of a Class

The class declaration is just the blueprint from which instances of the class are created. Once a class is declared, you can create instances of the class.

•Classes are reference types, which, as you will remember from the previous chapter, means that they require memory both for the reference to the data and for the actual data.

•The reference to the data is stored in a variable of the class type. So, to create an instance of the class, you need to start by declaring a variable of the class type. If the variable isn’t initialized, its value is undefined.

Figure 4-2 illustrates how to define the variable to hold the reference. At the top of the code on the left is a declaration for class Dealer. Below that is a declaration for class Program, which contains method Main. Main declares variable theDealer of type Dealer. Since the variable is uninitialized, its value is undefined, as shown on the right in the figure.

Figure 4-2. Allocating memory for the reference of a class variable

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