Summary

In this module, you learned how to enable nullable context and act on build warnings/errors to avoid NullReferenceException. You began by defining nullability in C#. You learned that all reference types can be null and that Nullable<T> enables value types to also be assigned null.

Utilizing a nullable-enabled context, you identified code where null might have been errantly dereferenced. After reevaluating the code, you expressed your intent and adjusted the desired behavior of the code using various C# operators. You learned about the null-forgiving (!), null-coalescing (??), and null-conditional (?.) operators.

There are many possible ways to handle nullability within C#. In a nullable-enabled context, the C# compiler helps you have a better understanding of how your expressed intent flows through.

Additional resources

• Nullable reference types
• Nullable value types (C# reference)
• Learn techniques to resolve nullable warnings
• Update a codebase with nullable reference types to improve null diagnostic warnings
• ?. and ?[] (null-conditional) operators
• ?? and ??= operators (C# reference)
• ! (null-forgiving) operator (C# reference)