Quick Question about Variables

I have a form with checkboxes and they have a name of "associate_<id>". How can I call these variables (or other ideas of getting ID numbers from check boxes)? In PERL i know you can use ${"associate_".$id} but I cant seem to find the equivalent for PHP. I could then get a list of id's and check if each one is "on". I think this would be the easiest, but maybe someone else has another idea. Thanks in advanced, Matthew Walkup mwalkup@morningstarstudios.net