About array in PlPgsql trigger function

Hello,

In PostgreSQL 8.0.1 (plpgsql), I was trying to use array in the trigger
function.

DECLARE
       clear_id_colValueArr    VARCHAR[100];
BEGIN
       clear_id_colValueArr[1] := NEW.clear_id1;
       clear_id_colValueArr[2] := NEW.clear_id2;
       clear_id_colValueArr[3] := NEW.clear_id3;
....
       clear_id_colValueArr[100] := NEW.clear_id100;
...
END;

I always get NULL for clear_id_colValueArr. Also, I tried to run
raise notice '%', clear_id_colValueArr[0], I got an compile error.

Could someone tell me how to use array in a trigger function please?

Also, is there a way that I can get NEW.ColValues by specifying column
number but not NEW.ColumnName?

Thanks a lot,
Ying