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Bug #75184 A $GLOBAL variable is magically modified
Submitted: 2017-09-11 09:57 UTC Modified: 2017-09-11 10:08 UTC
From: hdfou at yahoo dot fr Assigned:
Status: Not a bug Package: Scripting Engine problem
PHP Version: 7.0.23 OS: windows 10
Private report: No CVE-ID: None
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From: hdfou at yahoo dot fr
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 [2017-09-11 09:57 UTC] hdfou at yahoo dot fr 
Description:
------------
A $GLOBALS value is updated and should not be updated.

Test script:
---------------
$GLOBALS['availableLanguages'] = array(
 'fr' => array( 'n' => 'Français' ) , 
 'en' => array( 'n' => 'English' ) 
);

$GLOBALS['lang']='fr';

echo 'At the biginning, $GLOBALS[\'lang\']=' . $GLOBALS['lang'] . '<br />' ;

foreach( $GLOBALS['availableLanguages'] as $lang => $value){
 echo '$lang=' . $lang . '<br />';
}

// nowhere $GLOBALS['lang'] has been changed by the script but at the end
// $GLOBALS['lang'] = "en" instead of "fr".

echo '<br />$GLOBALS[\'lang\']="' . $GLOBALS['lang'] . '" ' . ($GLOBALS['lang']=='en' ? '<b style="color:red;">THIS SHOULD BE "fr"</b>' : '<b style="color:green;">OK</b>' ) ;
exit();

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 [2017-09-11 10:08 UTC] kelunik@php.net
-Status: Open +Status: Not a bug
 [2017-09-11 10:08 UTC] kelunik@php.net 
You're in the global scope with your "foreach".

foreach( $GLOBALS['availableLanguages'] as $lang => $value){

That modifies the global $lang.

I'd recommend to not use $GLOBALS.
 [2017-09-11 10:15 UTC] spam2 at rhsoft dot net 
i second not to use $GLOBALS at all, especially in code whcih runs in the global scope because it's just a useless additional OPCODE and in many cases harder for a IDE to do sane autocompletion

within function just do "global $varname" which is one OPCODE instead one for each usage and so no difference if it's used only once and faster when used multiple times

in the sample of the bugreporter $GLOBALS can be completly removed and then you see $lang is used before and within the loop and it's only not obvious because of the inconsistent usage auf $GLOBALS['lang'] and $lang which are both the same var in the same scope
 
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