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Bug #34246 Dividing number by half over and over eventually returns 0
Submitted: 2005-08-25 11:41 UTC Modified: 2005-08-25 11:48 UTC
From: platinumsupreme at aol dot com Assigned:
Status: Not a bug Package: Math related
PHP Version: 4.4.0 OS: Windows XP
Private report: No CVE-ID: None
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 [2005-08-25 11:41 UTC] platinumsupreme at aol dot com
Description:
------------
There is a problem out there that states that if you take a number and keep dividing it by half you should never reach zero. But apparently in PHP that is not the case..

 

Reproduce code:
---------------
<?php
$number = 50;
echo "Starting Number: $number<br>";

while($number > 0){
$number = $number / 2;
echo "Number: $number<br>";
}
?>

Expected result:
----------------
It should just go on for a ridiculous amount of time until it memory leaks...

Actual result:
--------------
It ends up at 0.

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 [2005-08-25 11:48 UTC] derick@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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