ID: 49947 Updated by: johan...@php.net Reported By: haochen at pristineprinting dot com -Status: Open +Status: Bogus Bug Type: Math related Operating System: CentOS 5.3 PHP Version: 5.2.11 New Comment:
Thank you for taking the time to write to us, but this is not a bug. Please double-check the documentation available at http://www.php.net/manual/ and the instructions on how to report a bug at http://bugs.php.net/how-to-report.php pow(2,100)+2 will be converted to a float, and floats aren't precise. Previous Comments: ------------------------------------------------------------------------ [2009-10-21 17:29:36] haochen at pristineprinting dot com Description: ------------ It looks like overflow when I do plus 1. But when I do tims 2, it looks correct. Strange! I guess times and division move left or right for binery number(...1011101...). Plus and minus functions maybe have bugs? I don't know my code is wrong or it is a bug. Server is Centos 5.3+PHP 5.2.11+Apache = Web Server I just put this code into public_html And client is WinXP+SP3+IE7. IE open the php. Wrong result. Thanks a lot. Reproduce code: --------------- <?php $x=2; $p=100; $y=pow($x,$p); $a=number_format($y); $b=$y+2; $c=$y*2; $r=number_format($a); $rr=number_format($b); echo "pow($x,$p) = $a <br><br>"; echo "pow($x,$p)+2 = $r <br><br>"; echo "pow($x,$p)*2 = $rr <br><br>"; ?> Expected result: ---------------- pow(2,100) = 1,267,650,600,228,229,401,496,703,205,376 pow(2,100)+2 = 1,267,650,600,228,229,401,496,703,205,378 pow(2,100)*2 = 2,535,301,200,456,458,802,993,406,410,752 Actual result: -------------- pow(2,100) = 1,267,650,600,228,229,401,496,703,205,376 pow(2,100)+2 = 1,267,650,600,228,229,401,496,703,205,376 pow(2,100)*2 = 2,535,301,200,456,458,802,993,406,410,752 ------------------------------------------------------------------------ -- Edit this bug report at http://bugs.php.net/?id=49947&edit=1
