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Bug #64742 float(1) casts to int as 0
Submitted: 2013-04-30 14:37 UTC Modified: 2013-04-30 14:40 UTC
From: bondo dot the dot clown at gmail dot com Assigned:
Status: Not a bug Package: Math related
PHP Version: Irrelevant OS: linux
Private report: No CVE-ID: None
View Developer Edit
 [2013-04-30 14:37 UTC] bondo dot the dot clown at gmail dot com 
Description:
------------
code speaks for himself

php --version
  PHP 5.4.6-1ubuntu1.2 (cli) (built: Mar 11 2013 14:57:54) 
  Copyright (c) 1997-2012 The PHP Group
  Zend Engine v2.4.0, Copyright (c) 1998-2012 Zend Technologies
    with XCache v2.0.0, Copyright (c) 2005-2012, by mOo
    with Xdebug v2.2.1, Copyright (c) 2002-2012, by Derick Rethans



Test script:
---------------
echo (int)(8.95 - 7.95);

Expected result:
----------------
1

Actual result:
--------------
0

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 [2013-04-30 14:40 UTC] johannes@php.net
-Status: Open +Status: Not a bug
 [2013-04-30 14:40 UTC] johannes@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.

8.95 - 7.95 is not exactly 1 (int) rounds down.

$ php -d precision=99 -r 'echo 8.95 - 7.95;'
0.99999999999999911182158029987476766109466552734375
 
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