- var_dump: documentation ( source)
- spl_object_hash: documentation ( source)
<?php
$h1 = spl_object_hash(new stdClass); // the obj is destroyed just after the call, since it has no refs
$h2 = spl_object_hash(new stdClass); // when the second obj is constructed, the first is destroyed already, so it could happen that the second one get the same memory address internally
var_dump($h1 === $h2);