Problem reading data from nested internal table.

Question

Hi,
Below is my code;
*********SAP Code********
TYPES: BEGIN OF v54a0_scdd,
         fknum  LIKE vfkk-fknum,
         change LIKE vfkkd-updkz,
         x      TYPE v54a0_scd,
         y      TYPE v54a0_scd,
         tvtf   LIKE tvtf,
       END OF v54a0_scdd.
SCD table for dialog
TYPES: v54a0_scdd_tab TYPE v54a0_scdd OCCURS 1.
*********SAP Code********
*Custom declaration*****
data: wa_freight_costs type v54a0_scdd_tab.
data: it_freight_costs type v54a0_scdd_tab occurs 0.
*****Here data is getting appended to it_freight_costs. P_frieght_costs is coming from standard program.
     move p_freight_costs TO wa_FREIGHT_COSTS.
     append wa_freight_costs to it_freight_costs.
     clear wa_freight_costs.
***Now the problem is here. I am not able to read the data from the nested internal table x-item.
if i use <fs_f_costs> to move data from it_freight_costs in the outer loop, i get a syntax error; <i> "the line type of the table it_freight_costs is not compatible with field symbol type <fs_f_costs>" </i>
     FIELD-SYMBOLS: <fs_f_costs> type line of v54a0_scdd_tab.
      LOOP AT it_freight_costs assigning <fs_f_costs>.
          LOOP AT <fs_f_costs>-x-item ASSIGNING <fs_freight_item>.        
              <b> I want to read <fs_freight_item>-vfkp-netwr.</b> 
         ENDLOOP.
Can anyone guide me?

Answer 1

A quick look at how I would do this. Note I haven't checked if this compiles just done a quick brain-dump.
  DATA: lr_f_costs TYPE REF TO v54a0_scdd_tab,
        lr_f_cost TYPE REF TO v54a0_scdd.
  LOOP AT it_freight_costs REFERENCE INTO lr_f_costs.
    LOOP AT lr_f_costs->* REFERENCE INTO lr_f_cost.
    ENDLOOP.
  ENDLOOP.
As you can see I personally prefer pointers to field symbols - I don't believe there is any performance differences and because of my background in other languages pointers make more sense to me.
Cheers
Graham Robbo