Use variable in offset and length in table expression component?

Question

I am trying to see if there is a way to do the following

IF line_exists( company_accounts2[ saknr+0(2) = wa_company_accounts-saknr+0(wa_account_levels-num_of_digits) ] ).

  ENDIF.

But the number 2 in saknr+0(2) with a parameter and specifically with the one that exists in the other side of equality (wa_account_levels-num_of_digits). Is there any way to do it with another way? Because if I replace the 2 with the wa_account_levels-num_of_digits I am getting the error "The length specification "WA_ACCOUNT_LEVELS-NUM_OF_DIGITS" is not numeric."
Thanks in advance

PS. What is not working and this is what I am asking below the above code is the following code:

IF line_exists( tab[ matnr+0(ls_mara-num_of_digits) = ls_mara-matnr+0(ls_mara-num_of_digits) ] ).

THIS CODE IS NOT WORKING.

Answer 1

Pass the left side of the equality as a text variable between parentheses, which contains the name of the variable and its offset:

  DATA(lv_text) = |saknr+({ wa_account_levels-num_of_digits })|.

  IF line_exists( company_accounts2[ (lv_text) = wa_company_accounts-saknr+0(wa_account_levels-num_of_digits) ] ).
    CONTINUE.
  ELSE.
    "make the APPEND
  ENDIF.

Answer 2

It works perfectly, for what you wanna achieve your wa_account_levels-num_of_digits should have primitive type i (INT1, INT2, INT4, INT8 in database).

Here is the working MARA sample

SELECT * UP TO 5 ROWS
FROM mara
INTO TABLE @DATA(tab).

READ TABLE tab INTO DATA(ls_mara) INDEX 1.

IF line_exists( tab[ matnr+0(2) = ls_mara-matnr+0(ls_mara-stfak) ] ).

ENDIF.

UPDATE: dynamic specification of the table components for read access is not possible:

If the data type of the components is character-like and flat, an offset/length +off(len) can be appended to the name of the component (as in substring access) to access subareas of the component. Only directly specified numbers or constants can be specified for off and len.