CLR via C#, Fourth Edition

Chapter 19. Nullable Value Types

In this chapter:

C#’s Support for Nullable Value Types

C#’s Null-Coalescing Operator

The CLR Has Special Support for Nullable Value Types

As you know, a variable of a value type can never be null; it always contains the value type’s value itself. In fact, this is why they call these types value types. Unfortunately, there are some scenarios in which this is a problem. For example, when designing a database, it’s possible to define a column’s data type to be a 32-bit integer that would map to the Int32 data type of the Framework Class Library (FCL). But a column in a database can indicate that the value is nullable. That is, it is OK to have no value in the row’s column. Working with database data by using the Microsoft ...