#35656 [Opn->Bgs]: Strange behaviour when multiplying floats with one multiplicator being 0
ID: 35656
Updated by: sniper@php.net
Reported By: php at lipfi dot ch
-Status: Open
+Status: Bogus
Bug Type: Scripting Engine problem
Operating System: Gentoo Linux 2005.1
PHP Version: 5.1.1
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Previous Comments:
------------------------------------------------------------------------
[2005-12-13 11:00:33] php at lipfi dot ch
Description:
------------
When multiplying two float values, one being 0, one being negative,
it's possible to either get 0 or -0 (!) as a result depending on the
operands order.
This is IMHO not how math is supposed to work.
Additionally, I'm seing discrepancies between the variables value and
what var_dump() things it contains. The problem is very simple to
reproduce
Reproduce code:
---------------
<?php
$v = 0*-0.02;
var_dump($v);
echo "$v\n";
$v = floatval($v);
echo "$v\n\n";
$v = -0.02*0;
var_dump($v);
echo "$v\n";
?>
Expected result:
----------------
float(0)
0
0
float(0)
0
Actual result:
--------------
float(0)
-0
-0
float(0)
0
(the -0 obviously being the problem here)
------------------------------------------------------------------------
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Thread (4 messages)