Nullability

Enable nullable awareness

Modern projects enable nullable reference types so the compiler warns about possible nulls.

string title = "C#";
string? maybeMissing = null;
Console.WriteLine(title);

Check before use

Test for null or use the null-conditional operator.

int? length = maybeMissing?.Length;
Console.WriteLine(length ?? 0);

Null-forgiving operator

The ! operator tells the compiler you are sure. Prefer real checks when possible.

// only when you truly know it is not null
// Console.WriteLine(maybeMissing!.Length);

Null habits

• Annotate intentional nulls with ?
• Return empty collections instead of null when practical
• Use ArgumentNullException.ThrowIfNull at API boundaries
• Treat warnings as errors in serious projects