32-bit vs 64-bit division different

[woodworks]

Trying to write a decimal to base-32 converter and ran into a strange problem.

 

If I run this code:

 

<?php
$result = 657911351231 / 32;
echo $result;
?>

 

On a 32-bit machine the output is: 20559729725.969

 

On a 64-bit machine the output is: 20559729726

 

What gives? Why is the 32-bit system producing a more accurate result?

 

How do I force PHP to return the more accurate result on the 64-bit machine?

 

Thanks.

[xyph]

Returns 20559729725.969 on 64-bit Win7.

 

 

[Zane]

same here..

[woodworks]

Thanks for the responses. It must be something with older software/OS. The problem is occurring on an Ubuntu 8.0.4.4 LTS, 64-bit, server install. The problem does not occur on an Ubuntu 10.04.3 LTS, 64-bit, server installation.

[Alex]

You could always use BCMath.

[woodworks]

Turns out the bug has nothing to do with 32-bit vs 64-bit. It's a bug that was addressed in PHP 5.3. The system I am running it on is an old Ubuntu 8.04 server which has PHP 5.2 installed. Also, the bug is just a formatting issue caused by the conversion from float to string. Using printf to format the output instead of a simple echo will force PHP 5.2 to display the correct value.