#35656 [NEW]: Strange behaviour when multiplying floats with one multiplicator being 0
From: php at lipfi dot ch
Operating system: Gentoo Linux 2005.1
PHP version: 5.1.1
PHP Bug Type: Scripting Engine problem
Bug description: Strange behaviour when multiplying floats with one multiplicator being 0
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)
--
Edit bug report at http://bugs.php.net/?id=35656&edit=1
--
Try a CVS snapshot (PHP 4.4): http://bugs.php.net/fix.php?id=35656&r=trysnapshot44
Try a CVS snapshot (PHP 5.1): http://bugs.php.net/fix.php?id=35656&r=trysnapshot51
Try a CVS snapshot (PHP 6.0): http://bugs.php.net/fix.php?id=35656&r=trysnapshot60
Fixed in CVS: http://bugs.php.net/fix.php?id=35656&r=fixedcvs
Fixed in release: http://bugs.php.net/fix.php?id=35656&r=alreadyfixed
Need backtrace: http://bugs.php.net/fix.php?id=35656&r=needtrace
Need Reproduce Script: http://bugs.php.net/fix.php?id=35656&r=needscript
Try newer version: http://bugs.php.net/fix.php?id=35656&r=oldversion
Not developer issue: http://bugs.php.net/fix.php?id=35656&r=support
Expected behavior: http://bugs.php.net/fix.php?id=35656&r=notwrong
Not enough info: http://bugs.php.net/fix.php?id=35656&r=notenoughinfo
Submitted twice: http://bugs.php.net/fix.php?id=35656&r=submittedtwice
register_globals: http://bugs.php.net/fix.php?id=35656&r=globals
PHP 3 support discontinued: http://bugs.php.net/fix.php?id=35656&r=php3
Daylight Savings: http://bugs.php.net/fix.php?id=35656&r=dst
IIS Stability: http://bugs.php.net/fix.php?id=35656&r=isapi
Install GNU Sed: http://bugs.php.net/fix.php?id=35656&r=gnused
Floating point limitations: http://bugs.php.net/fix.php?id=35656&r=float
No Zend Extensions: http://bugs.php.net/fix.php?id=35656&r=nozend
MySQL Configuration Error: http://bugs.php.net/fix.php?id=35656&r=mysqlcfg
Thread (4 messages)
- php at lipfi dot ch