The following code shows the existing definition for the Person class, displayed in a nullable enabled context. You should see the warning in the constructor that takes firstName and lastName arguments, but does not set the MiddleName property.
On this page, you're going to modify the Person class in different ways to remove the warning. Farther down this page, you see the code that uses the Person class. Different changes to the Person class will generate different warnings in those later samples.
Think about your design intent. Should MiddleName always be non-null? Or does it better reflect your design for MiddleName to be null for some people? You can either initialize the MiddleName property, or change string to string? in the declaration:
public string? MiddleName { get; set; }After you've made that change, look at the two code snippets that follow. Once the environment analyzes your code, you'll see warnings. Examine each and adjust the code to fix the warnings. Start with the GetLengthOfMiddleName method:
If needed, fix the code that calls it:
One possible solution for GetLengthOfName would be the following code:
private static int GetLengthOfMiddleName(Person p)
{
string? middleName = p.MiddleName;
return middleName?.Length ?? 0;
}You can let the may be null type flow among declarations. You can use the ?. operator to safely dereference a may be null variable, combined with the ?? operator to provide a default value.
Nullable reference types enable you to declare your intent around reference types: some should never be null, while for others null indicates a missing value. By declaring your intent, the compiler can help you enforce that intent.