Why does c# allow this? ( null checking to int)

Question

Possible Duplicate:
C# okay with comparing value types to null

Why does C# allow :

class MyClass
{
    public int MyInt;
}

static void Main(string[] args)
{
    MyClass m = new MyClass();
    if (m.MyInt == null) // <------------- ?
        Console.Write("......");
}

Resharper says "expression is always false" - which is obviously - true since MyInt is int and not int?

But how C# allow this to compile? The property will always be there and its type is int!

What are you trying to achieve through testing if MyInt is null ? — Eregrith, Sep 06 '12 at 07:47
@Schaliasos MyInt can't hold null . so your example is not the same — Royi Namir, Sep 06 '12 at 07:49
Why not? It'd be silly if the equality operator wouldn't accept certain operands. — Will Vousden, Sep 06 '12 at 07:49
study of declaration and initialization int will solve your problem — Gyan Chandra Srivastava, Sep 06 '12 at 07:49
There isn't a reason it wouldn't compile, however it may get removed since it is meaningless. You could check the asm to see if it was removed. — Garrett Fogerlie, Sep 06 '12 at 07:50
@RoyiNamir And `true` can never be `false`; it's exactly the same. — Will Vousden, Sep 06 '12 at 07:50
study of declaration and initialization int will solve your problem — Gyan Chandra Srivastava, Sep 06 '12 at 07:50
Eric Lippert already answered that, I think (http://stackoverflow.com/questions/1972262/c-sharp-okay-with-comparing-value-types-to-null) — wasyl, Sep 06 '12 at 07:51
i still wonder if int a=null; this leads to an error but if if(class.name==null) no error at compile time ...there is issue with the framework or something elase — Pranay Rana, Sep 06 '12 at 07:52
Just as an aside, in release mode this provably unreachable code is not actually compiled into the final IL. This will only feature in debug (or non-optimised). — Adam Houldsworth, Sep 06 '12 at 08:03

score -1 · Accepted Answer · answered Sep 06 '12 at 07:52

-1

I think, this is simply for the same reason why would compile

if(false)
   Console.WriteLine("never get here");

Something that would never execute.

Worth mantioning that, yes you don't get error, but you get a warning on this.

answered Sep 06 '12 at 07:52

Tigran

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@downvoter: reason or downvoting for hobby? – Tigran Sep 06 '12 at 07:54
2

There are many people who love to downvote without explanation – Snake Eyes Sep 06 '12 at 07:57
2

I downvoted because I didn't believe it to be an answer to the question. It would have been more appropriate as a comment. – Nick Sep 06 '12 at 10:24
But `Console.Write(1 / 0);` does not compile. – Oybek Jun 16 '13 at 19:14
@downvoter: care to explain ? – Tigran Nov 22 '13 at 13:49

Why does c# allow this? ( null checking to int)

1 Answers1