calling a cfc through a udf

case 1: user-defined function alone

<cffunction name="getNameFromId">
    <cfargument name="id" default="1">
    <cfset var selectedUser = "">
    <cfset user = arrayNew(1)>
    <cfset user[1] = "John">
    <cfset user[2] = "Steve">
    <cfset user[3] = "Joe">
    <cfset user[4] = "Bob">
    <cfset selectedUser = user[arguments.id]>
    <cfreturn selectedUser>
</cffunction>

<cfoutput>#getNameFromId(3)#</cfoutput>

case 2: (a) content of CFM page userName.cfm

<cfset userObject = createobject("component", "User")>
<cfoutput>#userObject.getNameFromId(2)#</cfoutput>

<!--- Alternative, using cfinvoke --->
<!---
<cfinvoke component="User" method="getNameFromId" returnVariable="userName">
    <cfinvokeargument name="id" value="2">
</cfinvoke>
<cfoutput>#userName#</cfoutput>
--->

(b) The user-defined function is in a component saved as User.cfc in the same directory as the page userName.cfm

<cfcomponent displayname="User">
<cffunction name="getNameFromId">
    <cfargument name="id" default="1">
    <cfset var selectedUser = "">
    <cfset user = arrayNew(1)>
    <cfset user[1] = "John">
    <cfset user[2] = "Steve">
    <cfset user[3] = "Joe">
    <cfset user[4] = "Bob">
    <cfset selectedUser = user[arguments.id]>
    <cfreturn selectedUser>
</cffunction>
</cfcomponent>

Thank you for the response, but is there a sample that i can look at that would show me how to call a cfc through a udf? I've been searching around but haven't been able to find one.

The most efficient way of doing it is to run one query that gets all the names for you list of uids.

If you data is as simple as an ID and a Name, a simple structure or array would surfice.

I.E.

<cfset myStruct = { 
     1='John',
     2='Steve',
     3='Joe',
     4='Bob'
}>

<cfoutput>#myStruct[3]#</cfoutput>

But, if your data is more complex.  Yes you can access a CFC from within a UDF just like any place else in your CFML.