Multiple checkboxes

Hello, I'm trying to get the values from a form post with multiple checkboxes checked . Here is what I have, if ($row = mysql_fetch_array($result)); do { <input type=checkbox name=class_id[] value=$row[class_id]> $row[name] }while ($row = mysql_fetch_array($result)); and when submitted if ($class_id) { foreach($class_id as $varName) print "Variable: $varName\n"; } All I get from this is Invalid argument supplied for foreach(). From what I could find doing a google search was to create an array using class_id[] and the above foreach(). Thanks in advance for any help! Mike