Why does casting a null to a primitive(ie: int) in .net 2.0 throw a null ref exception and not a invalid cast exception?

Question

I was going through some code and came across a scenario where my combobox has not been initialized yet. This is in .NET 2.0 and in the following code, this.cbRegion.Select

Answer 1

It has to do with Boxing and unboxing. It is trying to pull an int out of the box (unbox), but the object is null, so you get a null reference exception before it ever gets the change to cast.