- var_dump: documentation ( source)
<?php
${0xFF} = 'Hello Peter'; // $GLOBALS['255']
${2 + 2} = 'Hello Peter'; // $GLOBALS['4']
${'_SESSION'} = 'test'; // $GLOBALS['Hello Peter']
${'_SERVER'} = 'test'; // $GLOBALS['Hello Peter']
var_dump($GLOBALS, $_SESSION);