How to compare nullable types?

Question

I have a few places where I need to compare 2 (nullable) values, to see if they\'re the same.

I think there should be something in the framework to support this, but can

Answer 1

Use Compare:

http://msdn.microsoft.com/en-us/library/dxxt7t2a.aspx

Answer 2

C# supports "lifted" operators, so if the type (bool? in this case) is known at compile you should just be able to use:

return x != y;

If you need generics, then EqualityComparer<T>.Default is your friend:

return !EqualityComparer<T>.Default.Equals(x,y);

Note, however, that both of these approaches use the "null == null" approach (contrast to ANSI SQL). If you need "null != null" then you'll have to test that separately:

return x == null || x != y;