Working with Null Values
Learn about nullable value types in C#, declared with the question mark, and manage them with Nullable <T>.
We'll cover the following...
We have seen how reference types differ 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. We can enable this by adding a question mark as a suffix to the type when declaring a variable. Let’s see an example:
Step 1: Use your preferred coding tool to add a new Console App or console project named NullHandling to the Chapter06 workspace or solution.
In Visual Studio Code, select
NullHandlingas the activeOmniSharpproject.In Visual Studio 2022, set
NullHandling...