Variable name as a string

Could someone tell me how to get the name of a variable as a string. This would be useful in form submission with multiple check-boxes to match against database records. At the moment I use ${"var".$ID[$x]} or someting like that to go through all the possible matches, but it would be quicker to explode the name of a checkbox like a string like cb_1 to match to record 1 etc. There is some reason I do not use the value of the check box, but I can't remember it now! John