Whats the use of Nullable.GetUnderlyingType, if typeof(int?) is an Int32?

Question

why is typeof int? an Int32

int? x = 1;
Console.WriteLine(x.GetType().Name);

If it is okay then what\'s the use of

Answer 1

Mainly its for dealing with a generic method:: e.g.

public static void SomeMethod(T argument)
{
     if(Nullable.GetUnderlyingType(typeof(T) != null)
     {
             /* special case for nullable code go here */
     }
     else
     {
            /* Do something else T isn't nullable */
     }
}

It's important to know this, as certain things that are very cheap can be wildly expensive on nullable's. For instance, if(argument == null) is normally super cheap, but when done in a generic method on a Nullable is forced to box the argument to get a null reference. Your best bet is to use EqualityComparer.Default which will slow everything else down, but makes nullable's not suffer.