How to find error message comming in oracle API's

After the calling of API give the following
IF (fnd_msg_pub.count_msg > 0)THEN
FOR i IN 1..fnd_msg_pub.count_msg
LOOP

fnd_msg_pub.get
( p_msg_index => i,
p_encoded => 'F',
p_data => x_msg_data,
p_msg_index_out => X_msg_count
);

DBMS_OUTPUT.PUT_LINE('API ERROR: ' || x_msg_data);
END LOOP;
dbms_output.put_line(x_jtf_note_id ||'--'|| x_return_status ||'--'|| X_msg_count ||'--'|| x_msg_data);
ELSE
DBMS_OUTPUT.PUT_LINE('Updated sr : ' || to_char(ChildIncId));
End if;