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Bug #44204 intval makes very big mistakes
Submitted: 2008-02-21 17:22 UTC Modified: 2008-02-21 21:21 UTC
Votes:1
Avg. Score:5.0 ± 0.0
Reproduced:1 of 1 (100.0%)
Same Version:0 (0.0%)
Same OS:1 (100.0%)
From: bugs at kathaus dot nl Assigned:
Status: Not a bug Package: Variables related
PHP Version: 5.2.5 OS: Linux
Private report: No CVE-ID: None
View Developer Edit
 [2008-02-21 17:22 UTC] bugs at kathaus dot nl 
Description:
------------
see a page I created to show this bug:

http://www.budgetdedicated.com/phpbug.php




Reproduce code:
---------------
for quick reproduction:

$v=18.82;
$v=$v*100;
$v=intval($v);
echo $v."\n"; // 1820 = OK

$v=18.81;
$v=$v*100;
$v=intval($v);
echo $v."\n"; // 1800 = BAD

Expected result:
----------------
intval (18.81*100) == 1881


Actual result:
--------------
1880

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 [2008-02-21 21:12 UTC] crrodriguez at suse dot de 
Floating point values have a limited precision. Hence a value might 
not have the same string representation after any processing. That also
includes writing a floating point value in your script and directly 
printing it without any mathematical operations.

If you would like to know more about "floats" and what IEEE
754 is, read this:
http://docs.sun.com/source/806-3568/ncg_goldberg.html
 
Thank you for your interest in PHP.
 [2008-02-21 21:21 UTC] derick@php.net 
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