How to control an infinite loop in recursion

[former_member254358]

Hi,

I have a BOM in which there are infinite loops, it means that a material can contains itself in the following level or in a deeper level.

For example,

(1, 2), (1, 3), (2, 4), (4, 1)

I have seen how recursive works in abap but I don't know how to control infinite loops.

Can anybody help me?

Thanks in advance.

Regards.

[former_member254358]

Hi,

I have a BOM in which there are infinite loops, it means that a material can contains itself in the following level or in a deeper level.

For example,

(1, 2), (1, 3), (2, 4), (4, 1)

I have seen how recursive works in abap but I don't know how to control infinite loops.

Can anybody help me?

Thanks in advance.

Regards.

[Former Member]

Hi David

You should give us more details, I mean how you think to arrange your LOOP

Max

[former_member254358]

Hi Max,

I'll try to explain in more detail what I'm looking for.

The loop shoul stop when:

1. I find a raw material (my raw materials begin with m or s)

2. I find a material which hasn't components

3. I find a material that is in the origin of the loop. For example, if I want the list of material of 1 (in the example) the loop shoul stop in the material 4 because it coints the 1 component.

[Former Member]

Perhaps something like this could work:

DATA: BEGIN OF w_bom,
         matnr LIKE mast-matnr,
         werks LIKE mast-werks,
         stlnr LIKE mast-stlnr,
         items LIKE STANDARD TABLE OF stpo,
       END   OF w_bom.


 DATA: t_bom LIKE STANDARD TABLE OF w_bom.

 PARAMETERS: p_matnr LIKE mast-matnr,
             p_werks LIKE mast-werks.


 PERFORM get_bom USING p_matnr p_werks.

FORM get_bom  USING    p1_matnr
                        p1_werks.
   DATA: l_mast TYPE mast.
   DATA: l_stpo TYPE stpo.

 * Check if BOM material was loaded
   READ TABLE t_bom TRANSPORTING NO FIELDS WITH KEY matnr = p1_matnr
                                                    werks = p1_werks.
   CHECK sy-subrc <> 0.
 * Check no raw material
   CHECK p1_matnr(1) <> 'M' AND p1_matnr <> 'S'.
 * Check BOM
   SELECT * INTO l_mast
     FROM mast
       WHERE matnr = p1_matnr
         AND werks = p1_werks.
   ENDSELECT.
   CHECK sy-subrc = 0.
   CLEAR w_bom.
   FREE w_bom-items.
 *
   w_bom-matnr = l_mast-matnr.
   w_bom-werks = l_mast-werks.
   w_bom-stlnr = l_mast-stlnr.
   SELECT * INTO TABLE w_bom-items
     FROM stpo
        WHERE stlty = 'M'
          AND stlnr = l_mast-stlnr.
   CHECK sy-subrc = 0.
   APPEND w_bom TO t_bom.
 * Check next level
   LOOP AT w_bom-items INTO l_stpo.
     PERFORM get_bom USING l_stpo-idnrk l_mast-werks.
   ENDLOOP.
 ENDFORM.       

The routine GET_BOM should call itself until the conditions to stop the search are satisfied, I can't try this code but you can try it or something like that.

[former_member254358]

Thanks Max for the example. I'll try the example with my BOM.

I haven't still run the example but, looking the code what I don't see is, where do you control the if the current material had appeared before in the loop?

I will use one of my materials with infinite loop to see what happens.

Thanks again.

[Former Member]

* Check if BOM material was loaded
   READ TABLE t_bom TRANSPORTING NO FIELDS 
          WITH KEY matnr =p1_matnr
                             werks = p1_werks.
   CHECK sy-subrc <> 0.

The main table T_BOM (or something like that) is to store the bom unread

If the current material is a bom read in previous level, the search will be stopped else continue

  w_bom-matnr = l_mast-matnr.
   w_bom-werks = l_mast-werks.
   w_bom-stlnr = l_mast-stlnr.
   SELECT * INTO TABLE w_bom-items
     FROM stpo
        WHERE stlty = 'M'
          AND stlnr = l_mast-stlnr.
   CHECK sy-subrc = 0.
   APPEND w_bom TO t_bom.

I mean it needs a support where to store the results of previous levels

Ma

[rosenberg_eitan]

Hi,

Looks like chemical industry.

Try this:

Create internal table of matnr lets call it it_comp_1 .

Logic:

loop on root materials

for each:

- Clear it_comp_1 .

- Add the root matnr to it_comp_1 .

- When you traverse the tree fill check if the it_comp_1 contain the component if yes return without  going any deeper.

- if not add the component to it_comp_1 and go deeper.

For your knowledge there are standard functions that can be used,

Do a google using search operators :   site:scn.sap.com bom explosion functions

We use this: CS_BOM_EXPL_MAT_V2

Regards.

[former_member254358]

Thanks Eitan, the process it clear.

Regards.