Edit report at http://bugs.php.net/bug.php?id=52315&edit=1
ID: 52315 Updated by: ahar...@php.net Reported by: wisent at yandex dot ru Summary: Error in type convert after specific round() operation -Status: Open +Status: Bogus Type: Bug Package: Math related Operating System: Ubuntu 8.04 PHP Version: 5.2.13 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: ------------------------------------------------------------------------ [2010-07-12 14:40:58] wisent at yandex dot ru Description: ------------ First I perform specific round() operation. Then I convert the number from float to integer. The result is wrong, the number differs by 1 from what it should be. The problem appears not for every number. Test script: --------------- // this works bad: $sum = '4926.11'; $sum = round($sum, 2) * 100; var_dump($sum); // float(492611) $sum = (integer) $sum; var_dump($sum); // int(492610) // the same round() operation, the other number, works good $sum = '426.11'; $sum = round($sum, 2) * 100; var_dump($sum); // float(42611) $sum = (integer) $sum; var_dump($sum); // int(42611) // the first numbers, the other round() operation, works good $sum = '4926.11'; $sum = round($sum * 100); var_dump($sum); // float(492611) $sum = (integer) $sum; var_dump($sum); // int(492611) ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/bug.php?id=52315&edit=1
