I really had a good laugh at this.
Did you know, that PHP as a $GLOBALS global variable containing all global veriables as array? Well, if not, now you do. In consequence this means that there are essentially two way to to access global variables: Just take a look at the folling example
<?php
$a = "This is a";
$GLOBALS['b'] = "This is b";
var_dump($GLOBALS['a']);
var_dump($b);
?>which results in
string(9) "This is a"
string(9) "This is b"
So far so good. Now here’s the fun part $GLOBALS, being a global variable, contains itself. Well, at least this is quite consequent, though it offers the posibility to do something like this:
<?php
$a = "This is a";
$GLOBALS['b'] = "This is b";
$GLOBALS['GLOBALS']['c'] = "This is c";
var_dump($GLOBALS['a']);
var_dump($GLOBALS['GLOBALS']['b']);
var_dump($c);
?>and of course you get
string(9) "This is a"
string(9) "This is b"
string(9) "This is c"
Also - with the help of references - you can redefine $GLOBALS to anything you like. Lets mess with this a bit more seriously:
<?php
$a = &$GLOBALS;
$a['b'] = "This is b";
$a['a']['c'] = "This is c";
$a['a'] = "This is a";
var_dump($a);
var_dump($b);
var_dump($c);
?>just has the same result as above. I do not even want to imagine what else you could do with this.
Instead I just want to conclude, by correcting myself: $GLOBALS is not only a “global” variable, actually it is a “superglobal” variable, which essentially means that it is implicitly available in any scope without declaration.
Yep, PHP actually has this kind of concept, you can read it all by yourself in the PHP Manual.