CFLib.org – Common Function Library Project

Description:
ListSwap(list, A, B) will swap the list element at position A and the list element at position B and return a new list with the swapped elements. If either position is not a valid element in the string, the original list is returned. The fourth (optional) argument to the UDF is the delimiter definition for the list (default is ",").

Return Values:
Returns a string.

Example:

<cfset list = "a,bb,ccc,dddd,eeeee,ffffff,ggggggg,hhhhhhh,iiiiiiiii,kkkkkkkkkk">
<cfoutput>
original list = #list#<br>
swap positions 3 and 4 = #listswap(list, 3, 4)#
</cfoutput>

Parameters:

Full UDF Source:

/**
 * Swaps two elements in a list.
 * 
 * @param list      The list to modify. (Required)
 * @param positionA      The first position to swap. (Required)
 * @param positionB      The second position to swap. (Required)
 * @param delims      The delimiter to use. Defaults to a comma. (Optional)
 * @return Returns a string. 
 * @author Rob Baxter (rob@microjuris.com) 
 * @version 1, June 21, 2002 
 */
function ListSwap(list, PositionA, PositionB)
{
    var elementA = "";
    var elementB = "";
    var Delims = ",";

    if (ArrayLen(Arguments) gt 3)
        Delims = Arguments[4];
            
    if (PositionA gt ListLen(list) Or PositionB gt ListLen(list) Or PositionA lt 1 or PositionB lt 1)
        return list;    
    
    elementA = ListGetAt(list, PositionA, Delims);
    elementB = ListGetAt(list, PositionB, Delims);
    
    //do the swap
    list = ListSetAt(list, PositionA, elementB, Delims);
    list = ListSetAt(list, PositionB, elementA, Delims); 

    return list;
}