Bug #52324 [Dup]: bad result when adding two floats

Edit report at http://bugs.php.net/bug.php?id=52324&edit=1 ID: 52324 User updated by: brunog at micro-examples dot com Reported by: brunog at micro-examples dot com Summary: bad result when adding two floats Status: Duplicate Type: Bug Package: *General Issues Operating System: ubuntu PHP Version: 5.2.14RC2 New Comment: yes the issues you mention are connected to mine since there are only a few operations in my source code example, and not billions as in others, maybe it will be easier to track the bug to me, lunar phase is a stranger to this problem but I can check again in a few days if you like :)) I believe it is a conjonction between floating point internal representation and float to str routine that causes problem I have this problem on CODERO and 1AND1 dedicated servers that come with ubuntu, so I think many other users may be impacted too a workaround in my case would be to multiply operands by 100 and to divide result by 100 it seems that this issues goes back and forth depending on multiple criteria, and may come again at any time thank you Previous Comments: ------------------------------------------------------------------------ [2010-07-13 04:52:25] aharvey@php.net Actually, the colon is part of the output here: we have a rare bug that seems to be platform, architecture, compiler and optimisation level dependent. (It may also involve the phase of the moon, but we can't be absolutely sure -- I've never been able to reproduce it, and I've tried pretty hard.) Other bugs discussing this issue include bug #47716, bug #49764 and bug #51396. ------------------------------------------------------------------------ [2010-07-13 01:35:03] brunog at micro-examples dot com strangely it works fine on an older php version PHP Version => 5.1.6 gives 0.1 as expected ------------------------------------------------------------------------ [2010-07-13 01:16:39] rasmus@php.net It doesn't show 0.0 on any PHP version I have access to. No idea about your 5.2.4. That's from 3 years ago. I don't have anything that old on any of my machines. ------------------------------------------------------------------------ [2010-07-13 01:10:58] brunog at micro-examples dot com maybe, but 0.0: is not a correct value at all as an add result, whatever floating point accuracy is 0.09 + 0.02 gives 0.11 as expected, neither 0.109999999999 nor 0.:: ------------------------------------------------------------------------ [2010-07-13 01:04:36] rasmus@php.net That is the "correct" value according to how computers store floating point values. If you want it accurate to 2 decimal places, round() it to 2 decimal places. Read the big red warning box here: http://php.net/manual/en/language.types.float.php ------------------------------------------------------------------------ The remainder of the comments for this report are too long. To view the rest of the comments, please view the bug report online at http://bugs.php.net/bug.php?id=52324 -- Edit this bug report at http://bugs.php.net/bug.php?id=52324&edit=1