Omitting function arguments in PHP -

i have function saves every user log looks

<?php function create_log($action=null, $outcome, $message)   {     require 'dbc.php';     include 'get_ip.php';     $ip = get_ip_address();     $datetime = date('m-d-y h:i:s a', time());     $query = "insert tbllogs (logorigin, logaction, loguser, logdate, logoutcome, logmessage) values (:origin, :action, :user, :dt, :outcome, :message)";     $stmt  = $dbc->prepare($query);     $stmt->bindparam(':origin', $ip);     $stmt->bindparam(':action', $action);     $stmt->bindparam(':user', $_session['id']);     $stmt->bindparam(':dt', $datetime);     $stmt->bindparam(':outcome', $outcome);     $stmt->bindparam(':message', $message);     $stmt->execute();   } 

and when call doing this:

create_log('log in', 'failed', '');  

my problem is, $message parameter used whenever need only. should call create_log('log in', 'failed', '');or can call this? create_log('log in', 'failed');? if so, how?

you specify default values parameters:

function create_log($action = '', $outcome = '', $message = '') 

this way, if call create_log without 1 of parameters, assigned value in function's definition ('' parameters in above example).