Why can't you use null as a key for a Dictionary?

Question

Apparently, you cannot use a null for a key, even if your key is a nullable type.

This code:

var nullableBoolLabels = new System.Collect         


        

Answer 1

Not using null is part of the contract according to the MSDN page: http://msdn.microsoft.com/en-us/library/k7z0zy8k.aspx

I guess the reason is that having null as valid value will just complicate the code for no reason.