Problem related to field-Symbol?

Question

HI All,
I am writting the below coding, Please tell me whether the Field Symbol will act as a table or not as I want to append a lot of data to field symbol. Please tell me is there any problem in the code.
LOOP AT lt_vepoequi_keys into ls_vepoequi_keys.
        READ TABLE lt_vekp ASSIGNING <ls_vekp_str> with key
          matnr = ls_vepoequi_keys-matnr.
        IF sy-subrc = 0.
          <ls_vekp_str>-stoff = ls_vepoequi_keys-stoff.
          <ls_vekp_str>-sonum = ls_vepoequi_keys-sonum.
          <ls_vekp_str>-lagkl = ls_vepoequi_keys-lagkl.
          <ls_vekp_str>-lagkt = ls_vepoequi_keys-lagkt.
endif.
endloop.

Answer 1

Hi Abhinav,
you have internal table (say it_employee) with fields name,age,senior_category.
now when you loop this internal table you will need workarea.
loop at it_employee into wa_employee.
                  if wa_employee-age > 60.
                        wa_employee-senior_category = 'YES'.
                  else.
                          wa_employee-senior_category = 'NO'.
                  endif.
                          modify it_employee from wa_employee. 
                 endloop.
now one use of Field-symbols is : when internal table is huge and when you loop with workarea and modify internal table each time, it takes time. So if we use Field-symbols performance would increase.
loop at it_employee assigning into <fs_employee>.
                  if <fs_employee>-age > 60.
                        <fs_employee>-senior_category = 'YES'.
                  else.
                          <fs_employee>-senior_category = 'NO'.
                  endif.
            endloop.
Now  you see in the above code, i have not used modify statement because when i loop internal table, the field symbol points directly to the memory of internal table.
So during loop if i assign any value to the field symbol then it directly changes the internal table value, so there wont be any need to use modify statement.
Hope you are clear with this example....
Regards
Sajid