ABAP-数据引用详解编程语言

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*& Report  ZRICO_TEST3 
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report zrico_test3. 
 
data:ztb type string, 
     zfd type string. 
data:gt_tab like table of mara with header line. 
 
start-of-selection. 
  ztb = 'MARA'. 
  zfd = 'MATNR'. 
 
  field-symbols:<zs> type mara, 
                <zl> type any, 
                <z1> type any. 
  data:dref type ref to data. 
 
  create data dref type (ztb). 
  assign dref->* to <zs>. 
 
  assign component zfd of structure <zs> to <zl>. 
 
  types:begin of t_struct,            "*定義一個結構* 
          col1 type i, 
          col2 type i, 
        end of t_struct. 
  data: dref1 type ref to data,       "*定義兩個數據引用* 
        dref2 type ref to data. 
  field-symbols: <fs1> type t_struct, "*定義兩個字段符號* 
                 <fs2> type i. 
  create data dref1 type t_struct.    "*利用數據引用，動態創建對象* 
  assign dref1->* to <fs1>.           "*因為數據引用只是地址，不能直接操作使用，需要把它分配給字段符號* 
  <fs1>-col1 = 1.                     "*賦值給組件字段* 
  <fs1>-col2 = 2. 
  dref2 = dref1.                      "*把一個數據引用賦值給另一個數據引用* 
  assign dref2->* to <fs1>.           "*爲了要輸出，需要把數據應用分配給字段符號* 
  write: / 'DREF2',<fs1>-col1, <fs1>-col2. "*可以直接輸出了* 
  assign dref2->* to <fs2> casting.   "*把結構變量分配給整形字段符號，因此要進行隱式數據類型轉換* 
  write / <fs2>.                      "*輸出<FS2>字段符號變量內容* 
  get reference of <fs1>-col2 into dref2. "*取得變量的數據應用，給DREF2* 
  assign dref2->* to <fs2>.           "*分配變量給字段符號<FS2>* 
  write / <fs2>.