[TIMOB-14194] TiAPI: Problem with floating point numbers in Titanium

GitHub Issue	n/a
Type	Bug
Priority	Medium
Status	Closed
Resolution	Invalid
Resolution Date	2018-07-11T20:39:45.000+0000
Affected Version/s	Release 3.1.0, Release 3.2.0
Fix Version/s	n/a
Components	iOS
Labels	n/a
Reporter	Calvin Chan
Assignee	Pedro Enrique
Created	2013-06-07T09:13:03.000+0000
Updated	2018-07-11T20:39:45.000+0000

Description

*Problem* The output of floating point values in Titanium differ from browser JavaScript parsers such as [jsbin.com](http://www.jsbin.com/). For example, Ti.API.info(94.1) displays 94.0999999 On jsbin.com the output of alert(94.1) is 94.1 *Note* Since I have to input floating number for some modules, I must use floating number solution. I can't use a string method. I have also tried parseFloat(x.toFixed(1)), Math.round(x*10)/10 etc. The output was the same. *Test case*

var win = Ti.UI.createWindow({
    backgroundColor : "#FFF"
});

for (var i = 0; i < 50; i++)
	Ti.API.info(94.1);

win.open();

*Extended test case*

var win = Ti.UI.createWindow({
	backgroundColor : "#FFF"
});

for (var i = 0; i < 1000; i++)
	Ti.API.info(i + 0.1);
for (var i = 0; i < 1000; i++)
	Ti.API.info(i + 0.2);
for (var i = 0; i < 1000; i++)
	Ti.API.info(i + 0.3);
for (var i = 0; i < 1000; i++)
	Ti.API.info(i + 0.4);
for (var i = 0; i < 1000; i++)
	Ti.API.info(i + 0.5);
for (var i = 0; i < 1000; i++)
	Ti.API.info(i + 0.6);
for (var i = 0; i < 1000; i++)
	Ti.API.info(i + 0.7);
for (var i = 0; i < 1000; i++)
	Ti.API.info(i + 0.8);
for (var i = 0; i < 1000; i++)
	Ti.API.info(i + 0.9);

win.open();

*Log - Unusual Titanium values*

[INFO] :   64.09999999999999
[INFO] :   65.09999999999999
[INFO] :   66.09999999999999
[INFO] :   67.09999999999999
[INFO] :   68.09999999999999
[INFO] :   69.09999999999999
...
[INFO] :   70.09999999999999
[INFO] :   71.09999999999999
[INFO] :   72.09999999999999
[INFO] :   73.09999999999999
[INFO] :   74.09999999999999
[INFO] :   75.09999999999999
[INFO] :   76.09999999999999
[INFO] :   77.09999999999999
[INFO] :   78.09999999999999
[INFO] :   79.09999999999999
[INFO] :   80.09999999999999
[INFO] :   81.09999999999999
[INFO] :   82.09999999999999
[INFO] :   83.09999999999999
[INFO] :   84.09999999999999
[INFO] :   85.09999999999999
[INFO] :   86.09999999999999
[INFO] :   87.09999999999999
[INFO] :   88.09999999999999
[INFO] :   89.09999999999999
[INFO] :   90.09999999999999
[INFO] :   91.09999999999999
[INFO] :   92.09999999999999
[INFO] :   93.09999999999999
[INFO] :   94.09999999999999
[INFO] :   95.09999999999999
[INFO] :   96.09999999999999
[INFO] :   97.09999999999999
[INFO] :   98.09999999999999
[INFO] :   99.09999999999999
...
[INFO] :   8.199999999999999
[INFO] :   9.199999999999999
...
[INFO] :   8.300000000000001
[INFO] :   9.300000000000001
...
[INFO] :   64.40000000000001
[INFO] :   65.40000000000001
[INFO] :   66.40000000000001
[INFO] :   67.40000000000001
[INFO] :   68.40000000000001
[INFO] :   69.40000000000001
[INFO] :   70.40000000000001
[INFO] :   71.40000000000001
[INFO] :   72.40000000000001
[INFO] :   73.40000000000001
[INFO] :   74.40000000000001
[INFO] :   75.40000000000001
[INFO] :   76.40000000000001
[INFO] :   77.40000000000001
[INFO] :   78.40000000000001
[INFO] :   79.40000000000001
[INFO] :   80.40000000000001
[INFO] :   81.40000000000001
[INFO] :   82.40000000000001
[INFO] :   83.40000000000001
[INFO] :   84.40000000000001
[INFO] :   85.40000000000001
[INFO] :   86.40000000000001
[INFO] :   87.40000000000001
[INFO] :   88.40000000000001
[INFO] :   89.40000000000001
[INFO] :   90.40000000000001
[INFO] :   91.40000000000001
[INFO] :   92.40000000000001
[INFO] :   93.40000000000001
[INFO] :   94.40000000000001
[INFO] :   95.40000000000001
[INFO] :   96.40000000000001
[INFO] :   97.40000000000001
[INFO] :   98.40000000000001
[INFO] :   99.40000000000001
...
[INFO] :   64.59999999999999
[INFO] :   65.59999999999999
[INFO] :   66.59999999999999
[INFO] :   67.59999999999999
[INFO] :   68.59999999999999
[INFO] :   69.59999999999999
[INFO] :   70.59999999999999
[INFO] :   71.59999999999999
[INFO] :   72.59999999999999
[INFO] :   73.59999999999999
[INFO] :   74.59999999999999
[INFO] :   75.59999999999999
[INFO] :   76.59999999999999
[INFO] :   77.59999999999999
[INFO] :   78.59999999999999
[INFO] :   79.59999999999999
[INFO] :   80.59999999999999
[INFO] :   81.59999999999999
[INFO] :   82.59999999999999
[INFO] :   83.59999999999999
[INFO] :   84.59999999999999
[INFO] :   85.59999999999999
[INFO] :   86.59999999999999
[INFO] :   87.59999999999999
[INFO] :   88.59999999999999
[INFO] :   89.59999999999999
[INFO] :   90.59999999999999
[INFO] :   91.59999999999999
[INFO] :   92.59999999999999
[INFO] :   93.59999999999999
[INFO] :   94.59999999999999
[INFO] :   95.59999999999999
[INFO] :   96.59999999999999
[INFO] :   97.59999999999999
[INFO] :   98.59999999999999
[INFO] :   99.59999999999999
...
[INFO] :   8.800000000000001
[INFO] :   9.800000000000001
...
[INFO] :   64.90000000000001
[INFO] :   65.90000000000001
[INFO] :   66.90000000000001
[INFO] :   67.90000000000001
[INFO] :   68.90000000000001
[INFO] :   69.90000000000001
[INFO] :   70.90000000000001
[INFO] :   71.90000000000001
[INFO] :   72.90000000000001
[INFO] :   73.90000000000001
[INFO] :   74.90000000000001
[INFO] :   75.90000000000001
[INFO] :   76.90000000000001
[INFO] :   77.90000000000001
[INFO] :   78.90000000000001
[INFO] :   79.90000000000001
[INFO] :   80.90000000000001
[INFO] :   81.90000000000001
[INFO] :   82.90000000000001
[INFO] :   83.90000000000001
[INFO] :   84.90000000000001
[INFO] :   85.90000000000001
[INFO] :   86.90000000000001
[INFO] :   87.90000000000001
[INFO] :   88.90000000000001
[INFO] :   89.90000000000001
[INFO] :   90.90000000000001
[INFO] :   91.90000000000001
[INFO] :   92.90000000000001
[INFO] :   93.90000000000001
[INFO] :   94.90000000000001
[INFO] :   95.90000000000001
[INFO] :   96.90000000000001
[INFO] :   97.90000000000001
[INFO] :   98.90000000000001
[INFO] :   99.90000000000001

Attachments

File	Date	Size
螢幕快照 2013-06-07 下午05.11.43.png	2013-06-07T09:13:03.000+0000	64672
螢幕快照 2013-06-07 下午06.19.37.png	2013-06-07T10:20:39.000+0000	24811

Comments

Daniel Sefton 2013-06-12

Tested and confirmed with iOS 6 simulator, Ti SDK 3.1 GA and 3.2 CI.
Carter Lathrop 2013-06-12
Calvin Chan 2013-06-13

Yes, it only in iOS, and I have fixed it by modifying the module. Detail:http://stackoverflow.com/questions/16981033/bug-of-using-floating-number-in-titanium-sdk Thanks all.
Stephen Feather 2013-11-20

Calvin, Have you submitted a PR for your fix?
Christopher Williams 2018-07-11

Marking as Invalid an closing. This is just how floating point numbers work. If you need to represent dollar amounts or specific decimal values, then you need to handle that in a different way. The linked stack overflow post and answer go directly to that. There are libraries intended to handle precisely this use case: - https://github.com/dtrebbien/BigDecimal.js - https://github.com/MikeMcl/decimal.js/ - http://mathjs.org/docs/datatypes/bignumbers.html It's possible that someday this support will make it into a future JS spec, as V8 has just added BigInts: https://developers.google.com/web/updates/2018/05/bigint

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