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Bug #44405 Math calculation problem with 1.19 - 1
Submitted: 2008-03-11 11:04 UTC Modified: 2008-03-11 11:25 UTC
From: thbley at gmail dot com Assigned:
Status: Not a bug Package: *General Issues
PHP Version: 5.2.5 OS: WinVista
Private report: No CVE-ID: None
View Developer Edit
 [2008-03-11 11:04 UTC] thbley at gmail dot com 
Description:
------------
There seems to be a problem with the numeric calculation:

if ( (1.19 - 1) == 0.19 ) {
	echo "@@";
}

The expression "(1.19 - 1) == 0.19" does not evaluate to true.

My environments (problem exists on both platforms):
WinVista: PHP 5.25
Debian: 5.2.0-8+etch10

Reproduce code:
---------------
if ( (1.19 - 1) == 0.19 ) {
	echo "@@";
}


Expected result:
----------------
output: @@

Actual result:
--------------
output: <nothing>

Patches

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 [2008-03-11 11:25 UTC] pajoye@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
 
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