How to check which events are set on the oracle database ?

I came across the situation where i was not able to find that which events have been set on database. I had set the 10035 event to capture the hard parse failures on the database. But when i check for the value for event parameter, i got nothing.

SQL> show parameter event

NAME                                 TYPE        VALUE
------------------------------------ ----------- ------------------------------
event                                string

Then i search on the internet related to this and i found the below PL/SQL block. By using this PL/SQL block we can check which events are set on the oracle database.

SET SERVEROUTPUT ON
DECLARE
    l_level NUMBER;
BEGIN
    FOR l_event IN 10000..10999
    LOOP
        dbms_system.read_ev (l_event,l_level);
        IF l_level > 0 THEN
            dbms_output.put_line ('Event '||TO_CHAR (l_event)||' is set at level '||TO_CHAR (l_level));
        END IF;
    END LOOP;
END;

When i execute this block, I got list of the event which are set on the database.

SQL>
SET SERVEROUTPUT ON
SQL> DECLARE
    l_level NUMBER;
BEGIN
    FOR l_event IN 10000..10999
    LOOP
SQL          dbms_system.read_ev (l_event,l_level);
  7          IF l_level > 0 THEN
  8              dbms_output.put_line ('Event '||TO_CHAR (l_event)||' is set at level '||TO_CHAR (l_level));
  9          END IF;
 10      END LOOP;
 11  END;
 12  /
Event 10035 is set at level 1

PL/SQL procedure successfully completed.
How to check which events are set on the oracle database ?