Derive business days

CREATE OR REPLACE FUNCTION F_BUSINESS_DAYS
(V_START_DATE IN DATE, V_END_DATE IN DATE)
RETURN NUMBER IS DAY_COUNT NUMBER := 0;
CURR_DATE DATE;
BEGIN -- loop through and update
CURR_DATE := V_START_DATE;
WHILE CURR_DATE <= V_END_DATE
LOOP
IF TO_CHAR(CURR_DATE,'DY') NOT IN ('SAT','SUN')
THEN DAY_COUNT := DAY_COUNT + 1;
END IF;
CURR_DATE := CURR_DATE + 1;
END LOOP;
RETURN DAY_COUNT;
END F_BUSINESS_DAYS;