Introduction

Throughout the previous chapters, you have used variables that refer to a single value, such as the string and double system types, system class instances, and your own class instances. .NET has a variety of data structures that can be used to store multiple values. These structures are generally referred to as collections. This chapter builds on this concept by introducing collection types from the System.Collections.Generic namespace.

You can create variables that can store multiple object references using collection types. Such collections include lists that resize to accommodate the number of elements and dictionaries that offer access to the elements using a unique key as an identifier. For example, you may need to store a list of international dialing codes using the codes as unique identifiers. In this case, you need to be certain that the same dialing code is not added to the collection twice.

These collections are instantiated like any other classes and...