Bug #66011 [Csd->Nab]: Wrong serialize of rounded value

Edit report at https://bugs.php.net/bug.php?id=66011&edit=1 ID: 66011 Updated by: nikic@php.net Reported by: proh dot alexey at gmail dot com Summary: Wrong serialize of rounded value -Status: Closed +Status: Not a bug Type: Bug Package: *General Issues PHP Version: Irrelevant Assigned To: maarten Block user comment: N Private report: N Previous Comments: ------------------------------------------------------------------------ [2013-11-01 08:35:01] maarten@php.net Thank you for taking the time to write to us, but this is not a bug. Please double-check the documentation available at http://www.php.net/manual/ and the instructions on how to report a bug at http://bugs.php.net/how-to-report.php See http://3v4l.org/nCNWi for results of your test script and the code by johanntanzer. Behaviour as expected, see the warning at http://php.net/manual/en/language.types.float.php (above link shows different results for 4.3.0 and 4.3.1, which was a major bug and those versions are really ancient) ------------------------------------------------------------------------ [2013-10-31 16:09:36] mail at johanntanzer dot at well that was obvious as you are using strval(), if i do $a = round(1 / 3, 2); var_dump($a, serialize($a)); I get double(0.33) string(22) "d:0.33000000000000002;" on PHP 5.4.6-1ubuntu1.1 (cli) The problem is, i guess, that there is no finite number in the base 2 system that is equal to 0.33, and when you serialize that php takes all the available bits to make it as accurate as possible, so it is serializing the approximation of 0.33 in the base 2 system, which is not equal to 0.33. There is nothing php can do about this since this is just how computers work, but if you know this you could just serialize the strval() version. ------------------------------------------------------------------------ [2013-10-31 16:08:51] nikic@php.net Can't reproduce this either. Don't see how that result could possible happen with the strval() call in there. ------------------------------------------------------------------------ [2013-10-31 15:55:24] mail at johanntanzer dot at Could not reproduce I get string(4) "0.33" string(11) "s:4:"0.33";" as expected ------------------------------------------------------------------------ [2013-10-31 13:19:34] proh dot alexey at gmail dot com Description: ------------ Wrong serialize of rounded value Test script: --------------- $a = strval(round(1 / 3, 2)); var_dump($a, serialize($a)); Expected result: ---------------- float(0.33) string(7) "d:0.33;" Actual result: -------------- float(0.33) string(59) "d:0.330000000000000015543122344752191565930843353271484375;" ------------------------------------------------------------------------ -- Edit this bug report at https://bugs.php.net/bug.php?id=66011&edit=1