Tricky Question...?

[santhosh.R gowda]

 
public class Guess{

public static void main(String[] args){




<sometype> x = <somevalue>;


System.out.println(x == x);

}

}

What makes the following code print false ?

[Jesper de Jong]

Well, what do you think? Do you have an idea yourself?

[Rob Spoor]

One hint: <sometype> is a primitive.

[Saifuddin Merchant]

Well I am assuming that in the question I am only allowed to fill in 'sometype' and 'somevalue' and not make any more changes.

Well in which case whatever answer you give me is going to shake my concepts on java. A '==' returning false that's pretty big!

@Rob - We'll with your hint I still don't work this out. If you meant boolean I don't see how it works.

I give up. Is this even really possible

[Henry Wong]

I give up. Is this even really possible

Of course, it's possible. It is a trick question, after all.

And like all trick questions, either you know it or you don't.... but as another hint.... It is related to floating points. And related to how IEEE defines how equality works with floating points.

Henry

[santhosh.R gowda]

i''m not having Idea

[Seetharaman Venkatasamy]

also it is already discussed here and Rob answared this question ... search here

[Saifuddin Merchant]

seetharaman venkatasamy wrote:also it is already discussed here and Rob answared this question ... search here

Exactly what phrase do you want us to search with?
Rob's answered almost every question out here so searching by his name is not a viable option!

@Henry - Point taken - Actually I did think about floating point numbers. I know them all too well.
But to say x == x gives a false -- I cannot think of any possible value of x where this happens? So what could the special value be.

[Seetharaman Venkatasamy]

Sam Mercs wrote:
Exactly what phrase do you want us to search with?

i simply search by "tricky question". Have a look Here

[Joanne Neal]

Sam Mercs wrote:Exactly what phrase do you want us to search with?

floating point equality

[Saifuddin Merchant]

Nan. Interesting to say the least!!!

[Campbell Ritchie]

So you got it. Please don't use thread titles like "tricky question... ?" Look at this FAQ.

Now: I challenge you: prove that such behaviour of NaN is logically correct.

[Saifuddin Merchant]

Campbell Ritchie wrote:So you got it. Please don't use thread titles like "tricky question... ?" Look at this FAQ.

Now: I challenge you: prove that such behaviour of NaN is logically correct.

You mean besides your proof of 2=3?

[Campbell Ritchie]

Oh, you have found it? Yes, beside my proof of 2=3. You could try proving 3=5!

[Saifuddin Merchant]

It was a great question though. Posting one too in the Puzzles Forum