$GLOBALS

$GLOBALS — 引用全局作用域中可用的全部变量

说明

一个包含了全部变量的全局组合数组。变量的名字就是数组的键。

范例

Example #1 $GLOBALS 范例

  <?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 ();
 ?>

以上例程的输出类似于：

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

注释

Note:

“Superglobal”也称为自动化的全局变量。这就表示其在脚本的所有作用域中都是可用的。不需要在函数或方法中用 global $variable; 来访问它。

Note: 变量可用性

与所有其他超全局变量不同， $GLOBALS 在PHP中总是可用的。

用户评论:

[#1] stevenjeffries at gmail dot com [2015-11-19 09:55:18]

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.

[#2] mstraczkowski at gmail dot com [2013-06-11 17:58:28]

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

// 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";

[#3] bkilinc at deyta dot net [2013-04-05 09:21:05]

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();

[#4] Gratcy [2012-05-13 19:03:50]

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(); ?>

[#5] therandshow at gmail dot com [2011-06-29 06:32:33]

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.

[#6] ravenswd at yahoo dot com [2008-08-12 13:02:23]

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?"