To Modify a field value with field symbols

Question

we had a requirement like we are getting in a floating point value in a field of an IDoc segment like 12.327- .Here if we see that the negative sign is after the floating point value and if we try to insert this into a database then it will throw out an error.Before inserting the value we need to covert the incoming value in the form -12.327.
I used the field symbols inorder to get the values and to change them.
But iam not able to modify the internal table from the new value.
Here is my sample code.
DATA: IT_MBEW TYPE TABLE OF MBEW,
      WA_MBEW TYPE MBEW,
      IT_DFIES TYPE TABLE OF DFIES,
      WA_DFIES TYPE DFIES,
      IT_DD03L TYPE TABLE OF DD03L,
      WA_DD03L TYPE DD03L,
      L_FIELD TYPE VALUE,
      WA_VALUE TYPE mbew,
      L_MBEW TYPE DDOBJNAME VALUE 'MBEW'.
FIELD-SYMBOLS: <FS1> TYPE ANY.
FIELD-SYMBOLS: <FS3> TYPE ANY.
FIELD-SYMBOLS: <FS2> TYPE ANY.
SELECT * INTO CORRESPONDING FIELDS OF TABLE IT_MBEW
  FROM MBEW  WHERE MATNR = '000000000000100110'.
LOOP AT IT_MBEW INTO WA_MBEW.
  WA_MBEW-SALK3 = - 354471.
  MODIFY IT_MBEW FROM WA_MBEW.
ENDLOOP.
To call the FM inorder to get the fieldnames for MBEW table
CALL FUNCTION 'DDIF_FIELDINFO_GET'
  EXPORTING
    TABNAME              = L_MBEW
    FIELDNAME            = ' '
   LANGU                = SY-LANGU
    LFIELDNAME           = ' '
   ALL_TYPES            = ' '
    GROUP_NAMES          = ' '
    UCLEN                =
  IMPORTING
    X030L_WA             =
    DDOBJTYPE            =
    DFIES_WA             =
    LINES_DESCR          =
TABLES
   DFIES_TAB            = IT_DFIES
    FIXED_VALUES         =
EXCEPTIONS
   NOT_FOUND            = 1
   INTERNAL_ERROR       = 2
   OTHERS               = 3
IF SY-SUBRC <> 0.
MESSAGE ID SY-MSGID TYPE SY-MSGTY NUMBER SY-MSGNO
        WITH SY-MSGV1 SY-MSGV2 SY-MSGV3 SY-MSGV4.
ENDIF.
SELECT TABNAME FIELDNAME DATATYPE POSITION INTO CORRESPONDING FIELDS OF TABLE
         IT_DD03L FROM DD03L
         WHERE TABNAME = 'MBEW'
         AND   DATATYPE = 'CURR'
         ORDER BY POSITION ASCENDING.
*LOOP AT IT_MBEW INTO WA_MBEW.
LOOP AT IT_MBEW assigning <fs1>.
ASSIGN WA_MBEW TO <FS1>.
do.
  LOOP AT IT_DD03L INTO WA_DD03L.
    READ TABLE IT_DFIES INTO WA_DFIES WITH  KEY FIELDNAME = WA_DD03L-FIELDNAME
                                      DATATYPE = WA_DD03L-DATATYPE.
    IF SY-SUBRC = 0.
      ASSIGN WA_DFIES-FIELDNAME TO <FS2>.
      ASSIGN COMPONENT SY-TABIX OF STRUCTURE <FS1> TO <FS3>.
      MOVE <FS3> TO L_FIELD.
      CONDENSE L_FIELD.
      CALL FUNCTION 'CLOI_PUT_SIGN_IN_FRONT'
        CHANGING
          VALUE = L_FIELD.
      IF SY-SUBRC = 0.
        ASSIGN L_FIELD TO <FS3>.
                MODIFY ITMBEW INDEX SY-TABIX FROM <FS3>._    
ENDIF.
    ENDIF.
  ENDLOOP.
*enddo.
ENDLOOP.
The Modify statement is not working.....Plesae help me in this regard.
Thanks
Srinivas

Answer 1

Hello.
When you write,
LOOP AT it_mbew ASSIGNING <fs1>.
ENDLOOP.
you don't need to use statements:
ASSIGN WA_MBEW TO <FS1>
nor
MODIFY it_mbew
after that.
If you just write:
LOOP AT it_mbew ASSIGNING <fs1>.
  <fs1>-field1 = 'A'.
  <fs1>-field2 = 'B'.
ENDLOOP.
all records of it_mbew will have field1 = 'A' and field2 = 'B'.
The point is, statement LOOP assigning <fs1> will make the field symbol to became a pointer to the records of the internal table. So, if you change the field symbol, you are changing the internal table already.
Regards.
Valter Oliveira.