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Bug #37938 String to Integer conversion problem
Submitted: 2006-06-27 20:27 UTC Modified: 2006-06-27 20:40 UTC
From: fprado at pmovil dot com dot br Assigned:
Status: Not a bug Package: Variables related
PHP Version: 5.1.4 OS: Fedora Core release 3 (Heidelber
Private report: No CVE-ID: None
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From: fprado at pmovil dot com dot br
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 [2006-06-27 20:27 UTC] fprado at pmovil dot com dot br
Description:
------------
When I multiply 2.30 by 100 and then try to typecast the result as a integer, I get the result 229.

Reproduce code:
---------------
<?php
echo "2.30"*100;
echo "\n";
echo (int)("2.30"*100);
echo "\n";
echo "2.99"*100;
echo "\n";
echo (int)("2.99"*100);
echo "\n";
echo "2.50"*100;
echo "\n";
echo (int)("2.50"*100);
echo "\n";
echo "2.55"*100;
echo "\n";
echo (int)("2.55"*100);
echo "\n";
echo (int)("230");
?>


Expected result:
----------------
230
230
299
299
250
250
255
255
230

Actual result:
--------------
230
229
299
299
250
250
255
254
230

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 [2006-06-27 20:40 UTC] tony2001@php.net
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.


 
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