Bug #52872 [Opn->Bgs]: Basic math operation returns incorrect result

Edit report at http://bugs.php.net/bug.php?id=52872&edit=1 ID: 52872 Updated by: rasmus@php.net Reported by: ndesbarats at gmail dot com Summary: Basic math operation returns incorrect result -Status: Open +Status: Bogus Type: Bug Package: Scripting Engine problem Operating System: Windows 7 PHP Version: 5.3.3 Block user comment: N New Comment: Floating point values have a limited precision. Hence a value might not have the same string representation after any processing. That also includes writing a floating point value in your script and directly printing it without any mathematical operations. If you would like to know more about "floats" and what IEEE 754 is, read this: http://docs.sun.com/source/806-3568/ncg_goldberg.html Thank you for your interest in PHP. . Previous Comments: ------------------------------------------------------------------------ [2010-09-17 16:43:27] ndesbarats at gmail dot com Description: ------------ See test script below. Test script: --------------- <?php $num = 123456.123456; echo 'remainder: '.($num - (integer)$num).'<br />'; // remainder should be 0.123456 // instead, I get a remainder of 0.12345600000117 (!!!!!!!) ?> Expected result: ---------------- // remainder should be 0.123456 Actual result: -------------- // instead, I get a remainder of 0.12345600000117 (!!!!!!!) ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/bug.php?id=52872&edit=1