Get No of Days in given Date Range

DATA: LV_DATE LIKE P0001-BEGDA VALUE '20090401',
LV_DAT LIKE P0001-BEGDA VALUE '20090601',
F_DAYS LIKE P0347-SCRDD.


CALL FUNCTION 'HR_HK_DIFF_BT_2_DATES'
EXPORTING
DATE1 = LV_DAT
DATE2 = LV_DATE
OUTPUT_FORMAT = '02'
IMPORTING
DAYS = F_DAYS
EXCEPTIONS
INVALID_DATES_SPECIFIED = 1
OTHERS = 2.

WRITE : / F_DAYS.

Link for Date Calculations

http://wiki.sdn.sap.com/wiki/display/ABAP/Function+Module+related+on+Date+calculations