From:             haochen at pristineprinting dot com
Operating system: CentOS 5.3
PHP version:      5.2.11
PHP Bug Type:     Math related
Bug description:  Looks like overlow

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 bug report at http://bugs.php.net/?id=49947&edit=1
-- 
Try a snapshot (PHP 5.2):            
http://bugs.php.net/fix.php?id=49947&r=trysnapshot52
Try a snapshot (PHP 5.3):            
http://bugs.php.net/fix.php?id=49947&r=trysnapshot53
Try a snapshot (PHP 6.0):            
http://bugs.php.net/fix.php?id=49947&r=trysnapshot60
Fixed in SVN:                        
http://bugs.php.net/fix.php?id=49947&r=fixed
Fixed in SVN and need be documented: 
http://bugs.php.net/fix.php?id=49947&r=needdocs
Fixed in release:                    
http://bugs.php.net/fix.php?id=49947&r=alreadyfixed
Need backtrace:                      
http://bugs.php.net/fix.php?id=49947&r=needtrace
Need Reproduce Script:               
http://bugs.php.net/fix.php?id=49947&r=needscript
Try newer version:                   
http://bugs.php.net/fix.php?id=49947&r=oldversion
Not developer issue:                 
http://bugs.php.net/fix.php?id=49947&r=support
Expected behavior:                   
http://bugs.php.net/fix.php?id=49947&r=notwrong
Not enough info:                     
http://bugs.php.net/fix.php?id=49947&r=notenoughinfo
Submitted twice:                     
http://bugs.php.net/fix.php?id=49947&r=submittedtwice
register_globals:                    
http://bugs.php.net/fix.php?id=49947&r=globals
PHP 4 support discontinued:          http://bugs.php.net/fix.php?id=49947&r=php4
Daylight Savings:                    http://bugs.php.net/fix.php?id=49947&r=dst
IIS Stability:                       
http://bugs.php.net/fix.php?id=49947&r=isapi
Install GNU Sed:                     
http://bugs.php.net/fix.php?id=49947&r=gnused
Floating point limitations:          
http://bugs.php.net/fix.php?id=49947&r=float
No Zend Extensions:                  
http://bugs.php.net/fix.php?id=49947&r=nozend
MySQL Configuration Error:           
http://bugs.php.net/fix.php?id=49947&r=mysqlcfg

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