SunshinePHP Developer Conference 2015

$GLOBALS

(PHP 4, PHP 5)

$GLOBALSグローバルスコープで使用可能なすべての変数への参照

説明

スクリプトのグローバルスコープに現在定義されているすべての変数への参照を含む連想配列です。 変数名が配列のキーとなります。

例1 $GLOBALS の例

<?php
function test() {
    
$foo "local variable";

    echo 
'$foo in global scope: ' $GLOBALS["foo"] . "\n";
    echo 
'$foo in current scope: ' $foo "\n";
}

$foo "Example content";
test();
?>

上の例の出力は、 たとえば以下のようになります。

$foo in global scope: Example content
$foo in current scope: local variable

注意

注意:

これは 'スーパーグローバル' あるいは自動グローバル変数と呼ばれるものです。 スクリプト全体を通してすべてのスコープで使用することができます。 関数やメソッドの内部で使用する場合にも global $variable; とする必要はありません。

注意: 変数の可用性

他のスーパーグローバル とは異なり、$GLOBALS は PHP で常に使用可能です。

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User Contributed Notes 5 notes

up
11
therandshow at gmail dot com
3 years ago
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.
up
5
mstraczkowski at gmail dot com
1 year 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";
up
-12
bkilinc at deyta dot net
1 year ago
I prefer accessing globals through static function calls. Source code looks better; I use glb::get('myglobalvar') instead of $GLOBALS['myglobalvar']. This gives me full control over global access, which can be the source of problems in practice.

class glb
{
    static public function set($name, $value)
    {
        $GLOBALS[$name] = $value;
    }

    static public function get($name)
    {
        return $GLOBALS[$name];
    }

}

$myglobalvar = 'Hello, World !';

function myfunction()
{
    $val = glb::get('myglobalvar');
    echo "$val\n";
    glb::set('myglobalvar', 'hi, again :)');
    $val = glb::get('myglobalvar');
    echo "$val\n";
}

myfunction();
up
-18
ravenswd at yahoo dot com
6 years ago
Keep in mind that $GLOBALS is, itself, a global variable. So code like this won't work:

<?php
   
print '$GLOBALS = ' . var_export($GLOBALS, true) . "\n";
?>

This results in the error message: "Nesting level too deep - recursive dependency?"
up
-37
Gratcy
2 years ago
this is technique that i always did for configuration file..

<?php
$conf
['conf']['foo'] = 'this is foo';
$conf['conf']['bar'] = 'this is bar';

function
foobar() {
    global
$conf;
   
var_dump($conf);
}

foobar();

/*
result is..

array
  'conf' =>
    array
      'foo' => string 'this is foo' (length=11)
      'bar' => string 'this is bar' (length=11)

*/
?>
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