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Bug #80144 if you go to do the sum is 0, but php returns 3.3306690738755E-15. Why?
Submitted: 2020-09-24 08:43 UTC Modified: 2020-09-24 08:49 UTC
From: daniel dot maoloni at gmail dot com Assigned: cmb (profile)
Status: Not a bug Package: *Math Functions
PHP Version: 7.4.10 OS: Windows 10 Pro - XAMMP
Private report: No CVE-ID: None
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 [2020-09-24 08:43 UTC] daniel dot maoloni at gmail dot com 
Description:
------------
$a=33.460000;
$b=-34.870000;
$c=1.410000;

echo $a+$b+$c;

result PHP : 3.3306690738755E-15

if you go to do the sum is 0, but php returns 3.3306690738755E-15. Why?

thank you


Test script:
---------------
$a=33.460000;
$b=-34.870000;
$c=1.410000;

echo $a+$b+$c;

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 [2020-09-24 08:49 UTC] cmb@php.net
-Status: Open +Status: Not a bug -Assigned To: +Assigned To: cmb
 [2020-09-24 08:49 UTC] cmb@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.
 
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