C# okay with comparing value types to null
c#, null
Solution
This is legal because operator overload resolution has a unique best operator to choose. There is an == operator that takes two nullable ints. The int local is convertible to a nullable int. The null literal is convertible to a nullable int. Therefore this is a legal usage of the == operator, and will always result in false.
Similarly, we also allow you to say "if (x == 12.6)", which will also always be false. The int local is convertible to a double, the literal is convertible to a double, and obviously they will never be equal.
Problem
I ran into this today and have no idea why the C# compiler isn't throwing an error. ``` Int32 x = 1; if (x == null) { Console.WriteLine("What the?"); } ``` I'm confused as to how x could ever possibly be null. Especially since this assignment definitely throws a compiler error: ``` Int32 x = null; ``` Is it possible that x could become null, did Microsoft just decide to not put this check into the compiler, or was it missed completely? Update: After messing with the code to write this article, suddenly the compiler came up with a warning that the expression would never be true. Now I'm really lost. I put the object into a class and now the warning has gone away but left with the question, can a value type end up being null. ``` public class Test { public DateTime ADate = DateTime.Now; public Test () { Test test = new Test(); if (test.ADate == null) { Console.WriteLine("What the?"); } } } ```