Question

I’m just interested in people’s opinions. When using nullable types in C# what is the best practice way to test for null:

bool isNull = (i == null); 

or

bool isNull = !i.HasValue; 

Also when assigning to a non-null type is this:

long? i = 1; long j = (long)i; 

better than:

long? i = 1; long j = i.Value; 

Answer 1

Use the forms that were specially implemented for you by the C# team. If anyone objects, tell them Anders said it was okay.

What I’m saying, flippantly, is that a lot of work went into integrating nullable types into c# to give you a good programming experience.

Note that in terms of performance, both forms compile down to the same IL, ie:

int? i = 1; bool isINull = i == null; int j = (int)i; 

Ends up like this after the C# compiler has got to it:

int? i = 1; bool isINull = !i.HasValue; int j = i.Value;