The ?? operator returns the left-hand operand if it is not null, or else it returns the right operand.
int? i = null; int count = i ?? 0;
The value that count is set to is 0. The ?? operator is short hand for:
int? i = null; int count = i.HasValue ? i.Value : 0;
int? i = null; int count = 0; if (i.HasValue) count = i.Value;
The Understanding C# series at Coder Journal will be an on going project to help the readers to better understand the C# programming language that doesn't get covered except at the more advanced levels.