The array is the most common data structure, present in nearly all programming languages. Using an array in C# involves creating an array object of System.Array type, the abstract base type for all arrays. The Array class provides a set of methods for performing tasks such as sorting and searching that programmers had to build by hand in the past.

An interesting alternative to using arrays in C# is the ArrayList class. An arraylist is an array that grows dynamically as more space is needed. For situations where you can't accurately determine the ultimate size of an array, or where the size of the array will change quite a bit over the lifetime of a program, an arraylist may be a better choice than an array.

In this chapter, we'll quickly touch on the basics of using arrays in C#, then move on to more advanced topics, including copying, cloning, testing for equality and using the static methods of the Array and ArrayList classes.

ARRAY BASICS

Arrays are indexed collections of data. The data can be of either a built-in type or a user-defined type. In fact, it is probably the simplest just to say that array data are objects. Arrays in C# are actually objects themselves because they derive from the System.Array class. Since an array is a declared instance of the System.Array class, you have the use of all the methods and properties of this class when using arrays.