Freecodecamp: Exact Change Problem Issue
Challenge Name
https://www.freecodecamp.com/challenges/exact-change
Issue Description
I had problem with this problem due to inaccurate calculations while working with "0.01" value. Sometimes returning value of calculation had wrong value after 7 or 8 decimal places (for example 1.01 - 0.01 = 0.999999996).
Did anyone else had similar problem?
I managed to solve it but still took me a lot of time to do it due to this issue that shouldn't happen... Anyone have any idea why it is so. My opinion is that it is due to way that js saves integer and float values...
Browser Information
- Browser Name, Version: Google Chrome, 52.0.2743.82 (64-bit)
- Operating System: Linux Ubuntu 16.04
- Mobile, Desktop, or Tablet: Laptop
Your Code
Screenshot
FatKoala
All 5 comments
Hi, @FatKoala. You can read all about floating point arithmetic (and good ways to handle it) here and other places online.
And a fun fact: JavaScript doesn't make a type distinction between floats and integers. 1 and 1.00000 are the same number in JS (though this isn't strictly the cause of the floating point precision errors you experienced).
It might be worthwhile to include a resource about floating point arithmetic (though not necessarily the one I linked to above) in the Helpful Links of this challenge as it is probably the first one which requires users to understand the precision issues it raises.
cc @FreeCodeCamp/issue-moderators for feedback on adding such a link (and which link to add)
BKinahan
on 4 Aug 2016
Yeah this is a very interesting topic and should be broached IMHO.
In JavaScript there is just on numeric Data type that is number and it's usually a 64 bit floating point (considering how Browsers (JS Engines to be precise) are implementing them).
Let's tag this as Help wanted for some one in the community to link up a good resource. I'll try and look up as well, but yeah it's better if it comes from someone who perhaps is a Language expert.
raisedadead
on 4 Aug 2016
Thanks for the link, it was helpful... got really frustrated about problem while I was coding... now it has sense... I agree that it should be linked somewhere or explained earlier that those things happen...
FatKoala
on 4 Aug 2016
I poked around a bit and @BKinahan's link seems to be at least as good if not better than most and seems to be a straight-forward site. I vote we use his link. I'm happy to do the PR unless someone else wants to.
dhcodes
on 10 Aug 2016
@dhcodes please go ahead, :wink:
raisedadead
on 10 Aug 2016
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Most helpful comment
Hi, @FatKoala. You can read all about floating point arithmetic (and good ways to handle it) here and other places online.
And a fun fact: JavaScript doesn't make a type distinction between floats and integers.
1and1.00000are the same number in JS (though this isn't strictly the cause of the floating point precision errors you experienced).It might be worthwhile to include a resource about floating point arithmetic (though not necessarily the one I linked to above) in the Helpful Links of this challenge as it is probably the first one which requires users to understand the precision issues it raises.
cc @FreeCodeCamp/issue-moderators for feedback on adding such a link (and which link to add)