Hi,
Please try below logic,
REPORT ZPRG_DATE_DIFF.
TYPES : BEGIN OF ty_data,
rollno TYPE char10,
begda TYPE d,
endda TYPE d,
END OF ty_data.
DATA : lv_frmdate TYPE d VALUE '20150101',
lv_enddate TYPE d VALUE '20150131',
lv_date TYPE d.
DATA : lt_data TYPE table of ty_data,
ls_data TYPE ty_data.
DATA : lv_diff TYPE i.
lv_diff = lv_enddate - lv_frmdate.
lv_date = lv_frmdate.
DO lv_diff TIMES.
ls_data-begda = lv_date.
ls_data-endda = lv_date.
ls_data-rollno = '5126'.
APPEND ls_data to lt_data.
lv_date = lv_date + 1.
ENDDO.
Regards,
Vishal