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Former Member

Is it safe to have nested loops on the same internal table?

Posted on Nov 13, 2003 at 05:52 PM 140 Views

Hello experts,

I am wondering that whether the follow code is legal/safe:

CLEAR old_key.

LOOP AT itab INTO itab_wa.

IF itab_wa-key <> old_key.

old_key = itab_wa-key.

LOOP AT itab INTO itab_wa1 WHERE key = old_key.

* do some processing here.

ENDLOOP.

ENDIF.

ENDLOOP.

Thanks and best regards.

zj

ABAP Development SAP NetWeaver Enterprise Search

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Former Member

Posted on Nov 14, 2003 at 02:59 PM

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If the code is unclear then the maintenance of the code will be expensive, and lead to errors.
Try:
SORT ITAB BY key.
CLEAR old_key
LOOP AT itab INTO itab_wa.
IF itab_wa-key <> old_key.
old_key = itab_wa-key.
* Do first time through processing.
ENDIF.
Do some processing here.
ENDLOOP.
If you do not have any need for first time through process then you do not need 'old_key'.
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3 Comments
- Former Member Former Member
  
  Nov 20, 2003 at 05:53 PM
  
  Me too, I think the code is okay. It could be better as Matthew mentioned.
  But there is one good advice when using the variable sy-tabix:
  save it as soon as possible!
  Code:
  CLEAR old_key.
  LOOP AT itab INTO itab_wa.
  outer_sy_tabix = sy-tabix. " save sy-tabix
  IF itab_wa-key <> old_key.
  old_key = itab_wa-key.
  LOOP AT itab INTO itab_wa1 WHERE key = old_key.
  * do some processing here.
  ENDLOOP.
  ENDIF.
  process outer sy-tabix
  if outer_sy_tabix = 1.
  ....
  endif.
  ENDLOOP.
  If you're doing things in a LOOP, for example another loop or a perform or other things, and you have to use sy-tabix in the lower part of the loop, always save it!
  The same is to do with other system variables as sy-index or sy-subrc in similar cases.
  KInd Regards Axel Kiltz
  
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