SQL & PL/SQL

Hi guys
I have a small issue i n the function i am writing...
i have to write a function which evalutes the numeric value also the nulls
if my data column has number in it then this is TRUE in my case
while others are false
but when i am writing this m getting error as function returend no values.

CREATE OR REPLACE FUNCTION IS_NUMERIC( str IN VARCHAR2 )
RETURN NUMBER
IS
NUM NUMBER;
BEGIN
NUM := TO_NUMBER(str);
IF NUM is not null then
RETURN 0;
END IF;
EXCEPTION
WHEN OTHERS THEN
RETURN 1;
END;

thanks

Edited by: user10647455 on Dec 3, 2008 1:59 PM