As of PHP 5.4 $GLOBALS is now initialized just-in-time. This means there now is an advantage to not use the $GLOBALS variable as you can avoid the overhead of initializing it. How much of an advantage that is I'm not sure, but I've never liked $GLOBALS much anyways.
$GLOBALS
(PHP 4, PHP 5, PHP 7, PHP 8)
$GLOBALS — Référence toutes les variables disponibles dans un contexte global
Description
Un tableau associatif contenant les références sur toutes les variables globales actuellement définies dans le contexte d'exécution global du script. Les noms des variables sont les index du tableau.
Exemples
Exemple #1 Exemple avec $GLOBALS
<?php
function test() {
$foo = "variable locale";
echo '$foo dans le contexte global : ' . $GLOBALS["foo"] . "\n";
echo '$foo dans le contexte courant : ' . $foo . "\n";
}
$foo = "Exemple de contenu";
test();
?>
Résultat de l'exemple ci-dessus est similaire à :
$foo dans le contexte global : Exemple de contenu $foo dans le contexte courant : variable locale
Notes
Note:
Ceci est une 'superglobale', ou variable globale automatique. Cela signifie simplement que cette variable est disponible dans tous les contextes du script. Il n'est pas nécessaire de faire global $variable; pour y accéder dans les fonctions ou les méthodes.
Note: Disponibilité des variables
Contrairement à toutes les autres superglobales, $GLOBALS a toujours été disponible en PHP.
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User Contributed Notes 4 notes
therandshow at gmail dot com ¶
12 years ago
mstraczkowski at gmail dot com ¶
10 years ago
Watch out when you are trying to set $GLOBALS to the local variable.
Even without reference operator "&" your variable seems to be referenced to the $GLOBALS
You can test this behaviour using below code
<?php
/**
* Result:
* POST: B, Variable: C
* GLOBALS: C, Variable: C
*/
// Testing $_POST
$_POST['A'] = 'B';
$nonReferencedPostVar = $_POST;
$nonReferencedPostVar['A'] = 'C';
echo 'POST: '.$_POST['A'].', Variable: '.$nonReferencedPostVar['A']."\n\n";
// Testing Globals
$GLOBALS['A'] = 'B';
$nonReferencedGlobalsVar = $GLOBALS;
$nonReferencedGlobalsVar['A'] = 'C';
echo 'GLOBALS: '.$GLOBALS['A'].', Variable: '.$nonReferencedGlobalsVar['A']."\n\n";
vittorio.zamparella at famous googlemail ¶
7 years ago
I finally found information about superglobals not being found in $GLOBALS:
https://bugs.php.net/bug.php?id=65223&edit=2
-------------------------------------
[2013-07-09 12:00 UTC] johannes @php.net
[...]super-globals (aka. auto globals) are not added to symbol tables by default for performance reasons unless the parser sees need. i.e.
<?php
$_SERVER;
print_r($GLOBALS);
?>
will list it. You can also control this using auto_gloals_jit in php.ini: http://www.php.net/manual/en/ini.core.php#ini.auto-globals-jit
-------------------------------------
http://www.php.net/manual/en/language.variables.variable.php
-------------------------------------
Warning
Please note that variable variables cannot be used with PHP's Superglobal arrays within functions or class methods. The variable $this is also a special variable that cannot be referenced dynamically.
-------------------------------------
stevenjeffries at gmail dot com ¶
8 years ago
I ran into the case where I needed to know if my script was in the global scope or not.
You can use $GLOBALS to figure out which case that is:
<?php // file foo.php
$some_unique_prefix_foo = "ok";
if (isset($GLOBALS["some_unique_prefix_foo"])) {
echo "Foo is in global scope.\n";
} else {
echo "Foo is NOT in global scope.\n";
}
unset($some_unique_prefix_foo);
// Inside another file.
function test() {
include "foo.php";
}
test();
?>
Outputs:
Foo is in global scope.
Foo is NOT in global scope.
