PHP: Detecting references in $GLOBALS

Question

I have a simple way to detect references in an array (For debugging purposes)

First I clone the array with array_values and then I alter the clone and look for changes in the original. If it's changed that element is a reference.

Short example:

<?php

$a = [
    'a' => 'b',
    2 => 3,
];

$b = ['wow'];

$a['ref'] = &$b;

function getrefs($array) {
    $marker = uniqid();
    $copy = array_values($array);
    $i = 0;
    $return = [];
    foreach ($array as $key => &$val) {
        $stash = $val;
        $copy[$i] = $marker;
        if ($val === $marker) {
            $val = $stash;
            $return[] = $key;
        }
        $i++;
    }
    return $return;
}

var_dump($a);
var_dump(getrefs($a));

The problem is that when I try to use this on $GLOBALS it's not working, and I can't figure out why. Everything in $GLOBALS should be a reference by all rights.

Is $GLOBALS just so strange that it's the only array where array_values won't correctly copy references?

You didn't show your attempt with $GLOBALS. Did you try $GLOBALS['GLOBALS']? — AbraCadaver
– AbraCadaver, Commented Mar 29, 2017 at 18:03

Richard Tyler Miles · Accepted Answer · 2017-03-29 18:03:24Z

1

It's a possibility that you're not accounting for recursion. The built-in PHP function:

var_dump($GLOBALS);

Will have the following output

array(7) {
   ["_GET"]=>
      array(0) {
   }
   ["_POST"]=>
      array(0) {
   }
   ["_COOKIE"]=>
      array(1) {
      ["PHPSESSID"]=>
      string(26) "od602et6qcfj6pa3pkjtl8go57"
   }
   ["_FILES"]=>
      array(0) {
   }
   ["GLOBALS"]=>
      *RECURSION*
   ["_SESSION"]=>
      &array(0) {
   }
}

answered Mar 29, 2017 at 18:03

Richard Tyler Miles

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1 Comment

J V Over a year ago

Nope that's not it. $GLOBALS for some reason is referenced every time it's assigned except when passed through array_values (IE: $a = $GLOBALS;$a['test'] = 1234; will result in $GLOBALS['test'] === 1234, but with array_values it looks like every last reference is broken somehow)

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