I can't seem to figure out why the CS50x gradebook says that my find code is wrong but when I check the exact same code using check50, I get all smileys.

I did everything as per instructed. I uploaded my pset3.zip file. Fifteen.c was graded fine. But something seems to be wrong with the grading of my find.c or helpers.c. They say that it doesn't find 42 in the various scenarios given when it should, but I still get marks for the tasks when the code is not expected to find 42.

I did a manual test using my codes and the scenarios given and they work fine. Even tested it with check50 and it says it's fine with the following message.

jharvard@appliance (~/pset3/find): check50 2014/x/pset3/find helpers.c
:) helpers.c exists
:) helpers.c compiles
:) finds 42 in {42,43,44}
:) finds 42 in {41,42,43}
:) finds 42 in {40,41,42}
:) finds 42 in {41,42,43,44}
:) finds 42 in {40,41,42,43}
:) finds 42 in {39,40,41,42}
:) doesn't find 42 in {39,40,41}

Anyone else with the same problem? Anyone who can offer any assistance? Would be greatly appreciated!

  • 2
    If you're sure that everything is correct, you may drop Robert Bowden a note at rob@cs.harvard.edu!
    – kzidane
    Aug 3, 2014 at 14:02
  • @Kareem Will do! Thanks so much for your extremely prompt response! Absolutely loving this course by the way! ;) Aug 3, 2014 at 14:51
  • 1
    @Jonathan did you ever figure out what was wrong? If so, sharing your answer could be very helpful for other students with the same problem. On this site, answering your own questions is encouraged.
    – Air
    Aug 22, 2014 at 19:13
  • 1
    As a mild suggestion, did you run update50 before check50? Your appliance may be out of date and in need of an update.
    – Shironecko
    Sep 3, 2014 at 0:17
  • I had a similar issue, where check50 got it all right, but as a control, I did manual testing ie take the control they give you for "./generate 50 1000 | ./find 2008" and try to use find to get another number from the sequence generated. In my case I used the number generated right after '2008' which was '34195' or something like that, and it would never find it, then it turned out that I was never sorting the numbers correctly. I always do a manual test, as check50 won't help me with real-world situations. Nov 25, 2014 at 22:56

2 Answers 2


If you're sure that everything is correct, you may drop Rob Bowden a note at rob@cs.harvard.edu!

Please mark this as best answer to take this question out of the unanswered list. Thank you Kareem.


I know this was posted a long time ago, but for anyone who is new here, I've had the same problem. Are you sure that when you submit it, the gradebook says find.c and nothing else? If it says something else, you have two options:

  1. You could delete all the other saves and then re-download the program. Then you could submit it. This would solve your issue.


  1. You could go back to your first download (if it passed check50) and then submit that.

If it says find.c and you are confident that your code is correct, you could send edx a note or follow @i_am_david's answer. Again, I know this was posted a long, long time ago, but for anyone who's new, I hope this answer helps.

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