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Bug #42418 Strange behaviour of modulus function
Submitted: 2007-08-24 19:45 UTC Modified: 2007-08-27 05:56 UTC
From: onyjgyjz at trashmail dot net Assigned:
Status: Not a bug Package: Math related
PHP Version: 5.2.3 OS: WinXP
Private report: No CVE-ID: None
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 [2007-08-24 19:45 UTC] onyjgyjz at trashmail dot net 
Description:
------------
Somehow the modulus operator does not behave as expected on some special numbers.(maybe integer overflow or something like that?)

Php-version i used:
PHP 5.2.3 (cli) (built: May 31 2007 09:37:22)
Copyright (c) 1997-2007 The PHP Group
Zend Engine v2.2.0, Copyright (c) 1998-2007 Zend Technologies

Reproduce code:
---------------
$a=11213214321;
echo $a % 2;

Expected result:
----------------
Output of: 1

Actual result:
--------------
Output of: -1

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 [2007-08-26 16:49 UTC] iliaa@php.net 
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

11213214321 overflows an integer and is converted into a negative 
number. The modulus operation is then performed on a negative value, 
hence the -1 return value.
 [2007-08-27 05:56 UTC] onyjgyjz at trashmail dot net 
Shouldn't it return an error, if an integer was overflowed?
(like this "Division through Zero" error)
 
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