Convert varchar to sdo_geometry

Question

I have a table of linestrings - all coordinates have precision, which I want to remove.
I am trying to do it in PL/SQL as below, but since the new geometry with the rounded coordinates is a varchar, I keep getting the error:
PL/SQL: ORA-00932: inconsistent datatypes: expected UDT got CHAR
Has anyone got any ideas how I can round the coordinates within the varray, without having to take them out and put them back in?
SET SERVEROUT ON size 200000
     DECLARE
     i          number := 1;
     k          mdsys.sdo_geometry;
     geom          varchar2(32767);
     BEGIN
     SELECT     GEOMETRY
     into     k
     FROM     TABLE
     WHERE     id = &id;
          geom := 'MDSYS.SDO_GEOMETRY(2002, NULL, NULL, MDSYS.SDO_ELEM_INFO_ARRAY(1, 2, 1), MDSYS.SDO_ORDINATE_ARRAY(';
          while i < k.sdo_ordinates.count LOOP
               geom := geom || round(k.sdo_ordinates(i)) || ',';
               i := i + 1;
          end loop;
          geom := geom || round(k.sdo_ordinates(i)) || ')' ;
          dbms_output.put_line(geom);
          UPDATE     TABLE
          SET     GEOMETRY = geom
          WHERE     id = &id;
     END;
/

Answer 1

Got it working after the original post. Just didn't realise that sdo_ordinates behaves the same as any other varray collection.
In the end I used it as a trigger.
create or replace trigger tr_ins_geom
before insert on <table> for each row
     DECLARE
     i          number := 0;
     geom          mdsys.sdo_geometry := :new.geometry;
     point_x          number := round(:new.geometry.sdo_point.x);     
     point_y          number := round(:new.geometry.sdo_point.y);     
     new_point     mdsys.sdo_geometry;
     BEGIN
     if (point_x is null and point_y is null) then     
          for i in 1..geom.sdo_ordinates.count LOOP
               geom.sdo_ordinates(i) := round(geom.sdo_ordinates(i));
          end loop;
          :new.GEOMETRY := geom;
     else
          new_point := MDSYS.SDO_GEOMETRY(2001, NULL, MDSYS.SDO_POINT_TYPE(point_x, point_y, NULL), NULL, NULL);
          :new.GEOMETRY := new_point;
     end if;
end;
/