ID: 35319
User updated by: ian at euona dot com
Reported By: ian at euona dot com
Status: Bogus
Bug Type: Math related
Operating System: Win XP
PHP Version: 5.0.5
New Comment:
Just because TFM says it is used that way it does not make it less
unintuitive. Math should be the basis of programming languages and if
PHP wants to be taken seriously this issue should be addressed.
STFW
Previous Comments:
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[2005-11-21 23:48:04] [EMAIL PROTECTED]
This is still bogus just for the same reasons as before.
Also, RTFM.
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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
