Recursion in ABAP

[Former Member]

Hi All,

Is there any specific way by which we can achieve recursion in ABAP programming, or is there only the basic call-within-call structure which should contain an exit criteria?

If there is a specific way to achieve recursion, is there a concept of stack, something like we have in C++?

Please help me to understand this better.

Thanks and Regards,

Vidya.

[kesavadas_thekkillath]

check this recursion program example

Link:https://wiki.sdn.sap.com/wiki/display/Snippets/InverseBOMExplosion

[Former Member]

Thanks for your reply Keshu...I have seen the code and understand it. But in general, can you explain how recusion works in ABAP? Is something like a stack maintained? Can the results of the iterations be used in previous iterations, like it happens in C++?

Thank you all for your replies. I shall try the fibonacci series code and understand how recursion is achieved.

Regards,

Vidya.

Edited by: Vidya D on Sep 8, 2008 9:29 AM

[bpawanchand]

Hi

Check the below subroutine where it is calling the same function and it displays Fibonacci series

FORM fibo  USING   value(p_p_num)
           CHANGING p_w_res.
  DATA :
     w_temp TYPE i,                    " Temporary Variable
     w_no1 TYPE i,                     " Number Variable One
     w_no2 TYPE i,                     " Number Variable TWO
     w_add TYPE i.                     " Stores Sum Of Above 2 Variables

  w_temp = p_p_num.
  IF w_temp EQ 1 OR w_temp EQ 2.
    p_w_res = 1.
  ELSE.
    w_add = 0.
    w_no1 = w_temp - 1.
    w_no2 = w_temp - 2.
    PERFORM fibo USING w_no1 CHANGING p_w_res.
    w_add = w_add + p_w_res.
    PERFORM fibo USING w_no2 CHANGING p_w_res.
    w_add = w_add + p_w_res.
    p_w_res = w_add.
  ENDIF.                               " END IF
ENDFORM.                               " END FORM

Regards

Pavan

[Former Member]

Hi,

ABAP is also a programming language like C++. Here we can write subroutines and loops etc stuff.

Logically, Recursion is a loop kind of thing which runs till some condition is met.

Here also you can write a subroutine and pass the parameters to that subroutine with in a loop and endloop.

With this you can achieve the recursion even in abap also. The way of coding is different.

Hope this gives a clear picture.

Regards,

RSS.

[Former Member]

Hi Vidya,

Check this example for recursion:

http://www.sap-img.com/abap/recursion-with-loop-checking-in-sap.htm

Regards,

Chandra Sekhar

[Former Member]

Recursion can be achieved in ABAP also. Recursion is nothing but to execute a block of code repeatedly until some condition is met.

in ABAP we can use do loop like

do <n> times.

statements.

enddo.

or we can use while statement.

[snijdersSAM]

Hi,

May be a little late, but nevertheless.

-1-

If your recursion is defined within a database table. And the recursive data is found in that table. (think of tree like structures like a BOM).

In that case you might found it easy to use the CONNECT BY clause offered by oracle (embedded SQL) in order to traverse thrue the structure.

-2-

If your data can be represented in XML cannonical form, i would make use of XPATH expressions to traverse thrue those structures. Even when in the ABAP stack. (serialize <-> deserialize).

-3-

If your data can be represented in ABAP-Objects i would propose using linked lists or tree like structures to traverse thrue the structure.

Kind regards

Stef Snijders