C# in Depth, Second Edition

Chapter 4. Saying nothing with nullable types

This chapter covers

• Motivation for null values
• Framework and runtime support
• Language support in C# 2
• Patterns using nullable types

Nullity is a concept that has provoked debate over the years. Is a null reference a value, or the absence of a value? Is “nothing” a “something”? Should languages support the concept of nullity at all, or should it be represented in other patterns? In this chapter, I’ll try to stay more practical than philosophical. First we’ll look at why there’s a problem at all—why you can’t set a value type variable to null in C# 1 and what the traditional alternatives have been. After that, I’ll introduce you to our knight in shining armor—System.Nullable<T>—before we see how ...