Edit report at http://bugs.php.net/bug.php?id=47304&edit=1
ID: 47304
Comment by: xiaobo dot bob at gmail dot com
Reported by: lennartvdd at mailordersolutions dot nl
Summary: typecast of numeric string to float produces strange
result
Status: Assigned
Type: Bug
Package: Scripting Engine problem
Operating System: win32 only
PHP Version: 5.2.9
Assigned To: pajoye
New Comment:
2010-06-14 09:30:45 BST
I have reproduced this bug, but after changed some setting: change the
"precision" and "serialize_precision" setting in php.ini, and even
changed back, or maybe after i added the printf("%.2f\n",$v2), the echo
$v2 is correctted, but the printf result is always 16.:
finally, i wrote such a script:
for ($i=0; $i<400; $i++)
{
echo $i."-";
printf("%f\n",$i);
}
and found there're 8 number have this bug, they are:
17
19
29
39
170
190
290
390
I'm using windows xp in a virtualbox virtual machine, and a delphi
component named php4delphi, the php version is 5.2.13
Previous Comments:
------------------------------------------------------------------------
[2009-12-23 07:22:24] p dot klein at letsmakesense dot de
I experienced this issue using the number_format() and round()-function.
My example page displays items in a price list and prices like '17' or
'19' (only even numbers) were converted to '16.:' and '18.:'. The weird
thing was that every fourth reload the prices were converted correctly
to '17,00' and '19,00'. The situation improved after I calculated the
floats with BCMath functions. Now three out of four conversions were
correct.
Next thing I tried was to play with the precision setting of php. After
changing the value to '13' the conversion problem disappeared. But even
after changing it back to the default setting the issue hasn't occurred
anymore.
I don't trust the situation. The bug probably still exists, but it's
very hard to reproduce. We didn't have the bug while we used version
5.2.0, but it happened with 5.2.12 and 5.3.1.
----------------
Our system:
Windows Server 2003 R2, Standard Edition, Service Pack 2
Intel Core 2 CPU 6600 @ 2.40 GHz, 3,99 GB RAM
PHP Version 5.2.12
------------------------------------------------------------------------
[2009-09-28 09:58:07] egorich at junik dot lv
Seems that it fixed with rolling back to php 5.2.5 to me.
------------------------------------------------------------------------
[2009-06-22 16:21:28] ciudadsatan at hotmail dot com
The bug in Linux happens with
echo 0.15-0.05;
------------------------------------------------------------------------
[2009-06-22 03:47:55] ang dot chin dot han at gmail dot com
Originally from:
http://www.reddit.com/r/programming/comments/8tqpj/phpwtf_an_annoyance_
will_be_posted_each_day/c0aeg66
In short, in a Ubuntu Hardy 32 bit (64bit unaffected), 5.2.4 (with
Ubuntu patches) a simple
echo 1.0-0.5;
produces "0.0:" instead of "0.1" like in other platforms.
Not sure if it's the same bug as this is casting from float to string.
------------------------------------------------------------------------
[2009-06-08 09:47:15] egorich at junik dot lv
So, any solutions to this?
The problem also arises when i try to convert string to double, like:
$amount = double($amount);
------------------------------------------------------------------------
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