+972 52-548-6969
ChallengeWhat does this code do?
time to read 1 min | 55 words
Without compiling this, can you answer me whatever this piece of code will compile? And if so, what does it do?
var dummyVariable1 = 1; var dummyVariable2 = 3; var a = dummyVariable1
+-+-+-+-+ + + + + + +-+-+-+-+-+
dummyVariable2;
Oh, and I want to hear reasons, too.
More posts in "Challenge" series:
- (01 Jul 2024) Efficient snapshotable state
- (13 Oct 2023) Fastest node selection metastable error state–answer
- (12 Oct 2023) Fastest node selection metastable error state
- (19 Sep 2023) Spot the bug
- (04 Jan 2023) what does this code print?
- (14 Dec 2022) What does this code print?
- (01 Jul 2022) Find the stack smash bug… – answer
- (30 Jun 2022) Find the stack smash bug…
- (03 Jun 2022) Spot the data corruption
- (06 May 2022) Spot the optimization–solution
- (05 May 2022) Spot the optimization
- (06 Apr 2022) Why is this code broken?
- (16 Dec 2021) Find the slow down–answer
- (15 Dec 2021) Find the slow down
- (03 Nov 2021) The code review bug that gives me nightmares–The fix
- (02 Nov 2021) The code review bug that gives me nightmares–the issue
- (01 Nov 2021) The code review bug that gives me nightmares
- (16 Jun 2021) Detecting livelihood in a distributed cluster
- (21 Apr 2020) Generate matching shard id–answer
- (20 Apr 2020) Generate matching shard id
- (02 Jan 2020) Spot the bug in the stream
- (28 Sep 2018) The loop that leaks–Answer
- (27 Sep 2018) The loop that leaks
- (03 Apr 2018) The invisible concurrency bug–Answer
- (02 Apr 2018) The invisible concurrency bug
- (31 Jan 2018) Find the bug in the fix–answer
- (30 Jan 2018) Find the bug in the fix
- (19 Jan 2017) What does this code do?
- (26 Jul 2016) The race condition in the TCP stack, answer
- (25 Jul 2016) The race condition in the TCP stack
- (28 Apr 2015) What is the meaning of this change?
- (26 Sep 2013) Spot the bug
- (27 May 2013) The problem of locking down tasks…
- (17 Oct 2011) Minimum number of round trips
- (23 Aug 2011) Recent Comments with Future Posts
- (02 Aug 2011) Modifying execution approaches
- (29 Apr 2011) Stop the leaks
- (23 Dec 2010) This code should never hit production
- (17 Dec 2010) Your own ThreadLocal
- (03 Dec 2010) Querying relative information with RavenDB
- (29 Jun 2010) Find the bug
- (23 Jun 2010) Dynamically dynamic
- (28 Apr 2010) What killed the application?
- (19 Mar 2010) What does this code do?
- (04 Mar 2010) Robust enumeration over external code
- (16 Feb 2010) Premature optimization, and all of that…
- (12 Feb 2010) Efficient querying
- (10 Feb 2010) Find the resource leak
- (21 Oct 2009) Can you spot the bug?
- (18 Oct 2009) Why is this wrong?
- (17 Oct 2009) Write the check in comment
- (15 Sep 2009) NH Prof Exporting Reports
- (02 Sep 2009) The lazy loaded inheritance many to one association OR/M conundrum
- (01 Sep 2009) Why isn’t select broken?
- (06 Aug 2009) Find the bug fixes
- (26 May 2009) Find the bug
- (14 May 2009) multi threaded test failure
- (11 May 2009) The regex that doesn’t match
- (24 Mar 2009) probability based selection
- (13 Mar 2009) C# Rewriting
- (18 Feb 2009) write a self extracting program
- (04 Sep 2008) Don't stop with the first DSL abstraction
- (02 Aug 2008) What is the problem?
- (28 Jul 2008) What does this code do?
- (26 Jul 2008) Find the bug fix
- (05 Jul 2008) Find the deadlock
- (03 Jul 2008) Find the bug
- (02 Jul 2008) What is wrong with this code
- (05 Jun 2008) why did the tests fail?
- (27 May 2008) Striving for better syntax
- (13 Apr 2008) calling generics without the generic type
- (12 Apr 2008) The directory tree
- (24 Mar 2008) Find the version
- (21 Jan 2008) Strongly typing weakly typed code
- (28 Jun 2007) Windsor Null Object Dependency Facility
Comments
First I thought I will compile but after I look at the MSDN it said "Variables declared by using var cannot be used in the initialization expression" so the last line probably throw an error.
I had to cheat and fire up the compiler :-\ (feel free to delete this if I'm spoiling the surprise). I guessed no as I didn't realise that + could be a unary operator.
You end up with dummyVariable1 + (expr), where expression consists of alternating the sign of dummyVariable2 using the unary forms of + and -. It ends up as dummyVariable1 + (-dummyVariable2), or -2.
I don't want to think about how you came up with this :-S :-)
One for the old pen and paper.. It should boil down to 1 + -3 as there are nine negative operators in the expression, the positive operators can be reduced which should make it equivalent to dummyVariable1 + -(-(-(-( -(-(-(-(-(dummyVariable2))))) )))) if I got all the brackets in there correctly or more simply 1 + ---------3 == 1 + -3 = -2. So yes it should have no problem compiling :)
I don't know, and don't care. There should be laws against code like this.
LOL! Why is that Thomas?
@Dave - "Without compiling this..."
So amazing that you could run this and come up with the answer.
@Sammy - Because it's not readable... at all :) But that's not the point to this post anyway.
I suspect it does compile, but I don't care. This code causes any one reading such code to become homicidal and begin searching for the masochist who wrote such code. The reason? My God, if you have to ask .... :-P
@JC,
I wasn't trying to amaze. I can't help my lack of innate intelligence, hence I resorted to cheating :)
The reason for my comment was that my "without compiling this..." guess was dead wrong. I thought I'd cover the "giving reasons" part of the challenge instead :) .
I could have just omitted to mention I compiled it, but wanted to illustrate one key way someone could get the problem wrong. Sorry if I spoiled it for you :-\
@JC, you're quite right though -- it was a silly thing to do. Note to self: think before pressing submit. Consider my intraweb pass revoked :)
I've had questions like this on interviews and always feel like saying "if anybody in my team wrote code like this, I'd tell them not to", there's no point ...
@Dave - no prob, I just felt like being rude that day :)
Comment preview