David Casillas David Casillas - 1 month ago 9
PHP Question

Error using $_SERVER in a variable variable (PHP)

I was trying to get the name of a superglobal variable through a GET parameter. I was told to pass only

_VAR_NAME
(without the
$
) in the get request, so in the program I have to access it through a variable variable:
$$_GET['parameter_name']
.

Everything went fine except with
$_SERVER
. To try what was wrong I just did a small php script to test what was happening. Here is the code:

<?php
// ¡¡ This does not work !!
$nombre = "_SERVER";
$var = $$nombre;
print_r($var);
// This works
$nombre = "_GET";
$var = $$nombre;
print_r($var);
?>


Is there any reason for the
_SERVER
version not working?
I get the following error:


Notice: Undefined variable:
_SERVER
in ...

Answer

You can try the alternative syntax:

$var = $GLOBALS["_SERVER"];
print_r($var);

This is functionally equivalent to $$varvar.

One more critical thing to check is if $_SERVER itself is there. (If not, place an empty count($_SERVER); expression at the start of your script.)

It can be absent if variables_order= was modified in the php.ini (though it should really just show up as empty array in recent PHP versions.)