Bug #69517 [NEW]: round() does something weird on result of pow()

From: leafface at gmail dot com Operating system: Mac OS X PHP version: 5.5.24 Package: Unknown/Other Function Bug Type: Bug Bug description:round() does something weird on result of pow() Description: ------------ round() acts weird in some cases when pow() theoretically returns a round number. The bug doesn't occur if precision for round() is set and is greater than 14. (Sorry, I actually have PHP 5.5.14, but it's pretty unlikely this has been resolved since.) Test script: --------------- <pre> <? $n = pow(8, 2/3); echo ($n == round($n) ? 'true' : 'false'). "\n". ($n == round($n, 14) ? 'true' : 'false'). "\n". ($n == round($n, 15) ? 'true' : 'false'); Expected result: ---------------- true true true Actual result: -------------- false false true -- Edit bug report at https://bugs.php.net/bug.php?id=69517&edit=1 -- Try a snapshot (PHP 5.4): https://bugs.php.net/fix.php?id=69517&r=trysnapshot54 Try a snapshot (PHP 5.5): https://bugs.php.net/fix.php?id=69517&r=trysnapshot55 Try a snapshot (trunk): https://bugs.php.net/fix.php?id=69517&r=trysnapshottrunk Fixed in SVN: https://bugs.php.net/fix.php?id=69517&r=fixed Fixed in release: https://bugs.php.net/fix.php?id=69517&r=alreadyfixed Need backtrace: https://bugs.php.net/fix.php?id=69517&r=needtrace Need Reproduce Script: https://bugs.php.net/fix.php?id=69517&r=needscript Try newer version: https://bugs.php.net/fix.php?id=69517&r=oldversion Not developer issue: https://bugs.php.net/fix.php?id=69517&r=support Expected behavior: https://bugs.php.net/fix.php?id=69517&r=notwrong Not enough info: https://bugs.php.net/fix.php?id=69517&r=notenoughinfo Submitted twice: https://bugs.php.net/fix.php?id=69517&r=submittedtwice register_globals: https://bugs.php.net/fix.php?id=69517&r=globals PHP 4 support discontinued: https://bugs.php.net/fix.php?id=69517&r=php4 Daylight Savings: https://bugs.php.net/fix.php?id=69517&r=dst IIS Stability: https://bugs.php.net/fix.php?id=69517&r=isapi Install GNU Sed: https://bugs.php.net/fix.php?id=69517&r=gnused Floating point limitations: https://bugs.php.net/fix.php?id=69517&r=float No Zend Extensions: https://bugs.php.net/fix.php?id=69517&r=nozend MySQL Configuration Error: https://bugs.php.net/fix.php?id=69517&r=mysqlcfg