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Bug #44803 round()
Submitted: 2008-04-22 23:41 UTC Modified: 2008-04-23 01:00 UTC
From: oguzhanozbay at yahoo dot com Assigned:
Status: Not a bug Package: Unknown/Other Function
PHP Version: 5.2.5 OS: ýss isapi & apache 2.2
Private report: No CVE-ID: None
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 [2008-04-22 23:41 UTC] oguzhanozbay at yahoo dot com 
Description:
------------
How can it be!

Reproduce code:
---------------
echo round(60000000*10.5);

output 6.3E+8 !!!

echo round(60000000*(10.5));

output 6.3E+8 !!!

echo round(60000000*(10.5),2);

output 6.3E+8 !!!

echo round(70000000*(10.5));

output 7.35E+8 !!!

echo round(70000000*(11.5),2);

output 805000000 => true

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 [2008-04-23 00:47 UTC] felipe@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.
 [2008-04-23 01:00 UTC] oguzhanozbay at yahoo dot com 
; The number of significant digits displayed in floating point numbers.
precision    =  14

This my php.ini precision config.

I make it 30 (and resart server) but nothing changed.

same server, same config ->

echo 60000000*(10.5);

output 6.3E+8

echo 6000000000000*10;

output 60000000000000

How can "60000000*(10.5)" need much precision than "6000000000000*10"?
 
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