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Bug #52016 cast a float variable rounds the value
Submitted: 2010-06-07 16:43 UTC Modified: 2010-06-07 16:47 UTC
From: nbourdial at x-prime dot com Assigned:
Status: Not a bug Package: Scripting Engine problem
PHP Version: 5.2.13 OS: Linux 2.6.26-2-686
Private report: No CVE-ID: None
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From: nbourdial at x-prime dot com
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 [2010-06-07 16:43 UTC] nbourdial at x-prime dot com 
Description:
------------
Hi,

when I cast a float variable to int, the final value is not correct for some values.

Test script:
---------------
var_dump((int)("37.91"*100));


Expected result:
----------------
int(3791)

Actual result:
--------------
int(3790)

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 [2010-06-07 16:47 UTC] degeberg@php.net
-Status: Open +Status: Bogus
 [2010-06-07 16:47 UTC] degeberg@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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