#33030 [Opn->Bgs]: Floating point subtraction : incorrect precision

ID: 33030 Updated by: tony2001@php.net Reported By: justandy at lagparty dot org -Status: Open +Status: Bogus Bug Type: Math related Operating System: XP PHP Version: 5CVS-2005-05-13 (dev) 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: ------------------------------------------------------------------------ [2005-05-13 22:59:13] justandy at lagparty dot org Description: ------------ PHP 5.0.0 (cli) (built: Jul 13 2004 21:39:58) Copyright (c) 1997-2004 The PHP Group Zend Engine v2.0.0, Copyright (c) 1998-2004 Zend Technologies // Subtraction for floating point numbers is incorrect. I searched the existing bug reports and could not find anything similar. Running the same version on LINUX reports the correct value. Reproduce code: --------------- <? //CORRECT: 0.03 echo 1.06 - 1.03; //WRONG : 0.029999999999999 echo 6.06 - 6.03; ?> Expected result: ---------------- 0.03 Actual result: -------------- 0.029999999999999 ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=33030&edit=1