$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?"