FUNCTION reverseString RETURNS CHARACTER (
   INPUT i_c AS CHARACTER
):

   DEFINE VARIABLE cresult AS CHARACTER   NO-UNDO.
   DEFINE VARIABLE ii      AS INTEGER     NO-UNDO.

   DO ii = LENGTH( i_c ) TO 1 BY -1:
      cresult = cresult + SUBSTRING( i_c, ii, 1 ).
   END.
   RETURN cresult.

END FUNCTION.

MESSAGE reverseString( "asdf" ) VIEW-AS ALERT-BOX.