Working with null values

You have seen how reference types are different from value types in how they are stored in memory, and how to store primitive values like numbers in struct variables. But what if a variable does not yet have a value? How can we indicate that? C# has the concept of a null value, which can be used to indicate that a variable has not been set.

Making a value type nullable

By default, value types like int and DateTime must always have a value, hence their name. Sometimes, for example, when reading values stored in a database that allows empty, missing, or null values, it is convenient to allow a value type to be null. We call this a nullable value type.

You can enable this by adding a question mark as a suffix to the type when declaring a variable.

Let’s see an example:

1. Use your preferred coding tool to add a new Console App/console project named NullHandling to the Chapter06 workspace/solution.
   • In Visual Studio Code...