C# in Depth

Saying nothingwith nullable typesThis chapter covers■■Motivation for null valuesFramework and runtime support■ Language support in C# 2■Patterns using nullable typesNullity is a concept that has provoked a certain amount of debate over the years. Isa null reference a value, or the absence of a value? Is “nothing” a “something”? Inthis chapter, I’ll try to stay more practical than philosophical. First we’ll look at whythere’s a problem in the first place—why you can’t set a value type variable to nullin C# 1 and what the traditional alternatives have been. After that I’ll introduce youto our knight in shining armor—System.Nullable—before we see how C# 2makes working with nullable types a bit simpler and more compact. Like generics,nullable types sometimes have some uses beyond what you might expect, and we’lllook at a few examples of these at the end of the chapter.So, when is a value not a value? Let’s find out.112Licensed to Rhona Hadida