Learning C# 3.0

Using Arrays

An array is a collection of objects, all of the same type (all ints, all strings, and so on). Arrays are also indexed, meaning that the language provides a way for you to say “Get me the third item in the array.” Indexing also means that the items in the array are stored in a specific order, which further means that you can loop through the contents of the array in order. That process is called iteration, and we’ll show you how to do it in a minute. Arrays are a standard feature of almost all modern languages, and C# provides built-in syntax for declaring and using arrays.

Arrays are a bit tricky to visualize at first—a bunch of objects occupying the space of a single object. To picture a basic array (also called a one-dimensional array—you’ll see why it’s called that shortly), imagine a series of mailboxes, all lined up one after the other, as shown in Figure 10-1. Each mailbox can hold exactly one object in C#. Each mailbox also has a number (an address in the real world; an index in C#), so you can identify which item is in which box. Unlike real-world mailboxes, though, all the mailboxes must hold the same kind of object; you declare the type of object that the mailboxes will hold when you declare the array.

Figure 10-1. An array of five integers. Each “mailbox” is one item in the array, which has its own address (the index), and can hold exactly one object.

The important ...