Bug #52892 [Opn->Bgs]: Casting/rounding problem

Edit report at http://bugs.php.net/bug.php?id=52892&edit=1 ID: 52892 Updated by: rasmus@php.net Reported by: vahe at spir dot me Summary: Casting/rounding problem -Status: Open +Status: Bogus Type: Bug Package: *Math Functions Operating System: Debian GNU/Linux 5.0.5 (lenny) PHP Version: Irrelevant 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: ------------------------------------------------------------------------ [2010-09-20 13:25:34] vahe at spir dot me Description: ------------ After adding 10 times 0.1 and casting it into int or flooring it return value is 0 instead of 1. Test script: --------------- $a = 0.1+0.1+0.1+0.1+0.1+0.1+0.1+0.1+0.1+0.1; print $a; // 1 print round($a); // 1 print (int)$a; // 0 instead of 1 print floor($a); // 0 instead of 1 var_dump($a); // float(1) ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/bug.php?id=52892&edit=1