Taking number form string

The below code will fecth the number in a string:

CREATE OR REPLACE FUNCTION GET_NUMBER_FROM_STRING(STR1 VARCHAR2) RETURN NUMBER

IS
lv_num number(20);
BEGIN
SELECT TO_NUMBER(TRIM(TRANSLATE(LOWER(STR1),'abcdefghijklmnopqrstuvwxyz/-+',' '))) INTO lv_num FROM dual;
RETURN(lv_num);
EXCEPTION
WHEN OTHERS THEN
RETURN(-1);
END;


e.g
select GET_NUMBER_FROM_STRING('AD223445') from dual;