dynamic name

Hi,
I have the form is displayed with several text boxes.  The checkbox is displayed beside each field which has it own ID.  If i check three checkboxes then hit next, i'd like to see it passed three diffrent IDs' passed to next.cfm page.  Can someone please help how to pass value with dynamic name?

<!---form.cfm--->
<cfform name="update" method="post" action="next">
    <cfloop query="q_cat">
    ......
    <cfinput type="checkbox" id="cat" name="update_#id#" value="#id#">
    <cfinput type="submit" name="next" value="Next">
    </cfloop>
</cfform>

<!---next.cfm--->
  <cfoutput>
  #evaluate("update.#id#")#
  </cfoutput>

thank you