The following script :

<? 
  switch ($argc) {  }
?>

produces :

20:17 [webase3:p3] titi:~/html% php temp.phtml
Content-Type: text/html

temp.phtml:  Freeing 0x080EDFF8 (4 bytes), allocated in zend_hash.c on line 185<br>
temp.phtml:  Freeing 0x080EDFA8 (40 bytes), allocated in zend_hash.c on line 175<br>

Note that $argc is not randomly chosen : you must use a variable that has been defined, either by the CGI, of with the GET or POST methods. With a plain variable ($foobar) it doesn't show up.