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Bug #49377 number_format and decimal numbers
Submitted: 2009-08-26 16:12 UTC Modified: 2009-08-26 16:26 UTC
From: matt at mx-dev dot net Assigned:
Status: Not a bug Package: Math related
PHP Version: 5.2.10 OS: Windows
Private report: No CVE-ID: None
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From: matt at mx-dev dot net
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 [2009-08-26 16:12 UTC] matt at mx-dev dot net 
Description:
------------
I've encountered a bug using the number_format function with a high decimal value. Actually, an approximative number appear randomly if the decimal number is greater than 30.

I think that the bug can be reproduced being a little bit sticky. I succeeded to reproduce this bug with the following code :
number_format(25, 49, ',', ' ');

Reproduce code:
---------------
echo number_format(15, 50, ',', ' ');

Expected result:
----------------
15,00000000000000000000000000000000000000000000000000

Actual result:
--------------
14,99999999999999822364316059974953532218933105468750

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 [2009-08-26 16:26 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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