ID: 35319
Updated by: [EMAIL PROTECTED]
Reported By: ian at euona dot com
-Status: Open
+Status: Bogus
Bug Type: Math related
Operating System: Win XP
PHP Version: 5.0.5
New Comment:
This is still bogus just for the same reasons as before.
Also, RTFM.
Previous Comments:
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[2005-11-21 22:12:19] ian at euona dot com
Description:
------------
This is the same problem as stated in reports 20365 and 29822. This is
indeed not bogus, PHP, C and Javascript are NOT producing the
mathematical correct result. Per definition modulus arithmetics create
a ring structure containing the values [0,1,...,(n-1)]. THERE ARE NO
NEGATIVE NUMBERS! The current behavior is not intuitive and basically
incorrect. An integer typecast is not the same as floor.
This is a big problem when shifting table fields (e.g. weekdays). Take
a look at spreadsheet software.
//This is the way % should behave
function math_mod($a,$n){$n=abs($n);if($n===0){return NULL;}return
$a-$n*floor($a/$n);}
//this function emulates ($a%$n)
function php_mod($a,$n){return $a-$n*(int)($a/$n);}
Reproduce code:
---------------
echo -5%7 , ' ', fmod(-5,7),' ', 1%0,' ', 3%-2;
Expected result:
----------------
2 2 NULL 1
Actual result:
--------------
-5 -5 NULL 1
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Edit this bug report at http://bugs.php.net/?id=35319&edit=1
