Why does .ToString() on a null string cause a null error, when .ToString() works fine on a nullable int with null value?

Question

selectedItem has two fields:

• int? _cost
• string _serialNumber

In this example, _cost

Answer 1

The Nullable is actually a struct exposing two properties: HasValue and Value. If you do this you will get your error:

int? i = null;
i.Value.ToString()

In order to check whether or not your int? has a value you can access i.HasValue