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Bug #65420 Comparison with double values wrong
Submitted: 2013-08-08 08:52 UTC Modified: 2013-08-08 10:44 UTC
From: g dot karagyozov at gmail dot com Assigned:
Status: Not a bug Package: Apache related
PHP Version: 5.5.1 OS: OSX
Private report: No CVE-ID: None
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 [2013-08-08 08:52 UTC] g dot karagyozov at gmail dot com 
Description:
------------
Comparison with some double values is not correct.

Test script:
---------------
var_dump(1.8 > (1.9 - 0.1));
var_dump(1.1 > (1.2 - 0.1));

Expected result:
----------------
false expected

Actual result:
--------------
true returned

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 [2013-08-08 10:44 UTC] rasmus@php.net
-Status: Open +Status: Not a bug
 [2013-08-08 10:44 UTC] rasmus@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://www.floating-point-gui.de/

Thank you for your interest in PHP.

.
 
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