ABAP DESCRIBE语句

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DESCRIBE. 17

DESCRIBE FIELD.. 17

TYPE typ. 17

LENGTH ilen. 19

DECIMALS dec. 19

OUTPUT-LENGTH olen. 19

HELP-ID hlp. 20

EDIT MASK mask. 20

DESCRIBE TABLE. 21

DESCRIBE DISTANCE

DESCRIBE

可参考反射RTTS

DESCRIBE FIELD

DESCRIBE FIELD dobj
  [TYPE typ [COMPONENTScom]]
  [LENGTHilen IN {BYTE|CHARACTER} MODE]
  [DECIMALSdec]
  [OUTPUT-LENGTH olen]
  [HELP-ID hlp]
  [EDIT MASK mask].

TYPE typ

以下是不同类型的dobj返回的类型ID列表，ID大小写敏感：

COMPONENTS选项是对结构的字段数进行统计，如果有内嵌的结构，则只算直接（最高级别的）内嵌的结构，且只算做１个。

DATA: BEGIN OF struc1,
        comp1 TYPE c LENGTH 1,
        comp2 TYPE string,
        BEGIN OF struc2,
          comp1 TYPE c LENGTH 1,
          comp2 TYPE i,
        END OF struc2,
      END OF struc1,
      typ1  TYPE c LENGTH 1,
      comp1 TYPE i,
      typ2  TYPE c LENGTH 1,
      comp2 TYPE i.

DESCRIBE FIELD: struc1        TYPE typ1 COMPONENTS comp1,
                struc1-struc2 TYPE typ2 COMPONENTS comp2.
WRITE:/ typ1,comp1,/ typ2,comp2.

DESCRIBE FIELD: struc1        TYPE typ1,
                struc1-struc2 TYPE typ2.
WRITE:/ typ1,/ typ2.

v          3

u          2

v

u

LENGTH ilen

当使用IN CHARACTER MODE选项时，dobj必须是flat and character-like，针对deep data types的dobj，你只能使用IN BYTE MODE，并且此情况下返回的长度为引用所占长度（在SAP系统中每个reference的长度固定为8 bytes）

对于固定长度类型的dobj，是在创建这个变量时就已决定。如果字符串类型，则不会计算尾部空格，此时可以使用预置函数strlen来测定

DATA: text  TYPE c LENGTH 1,
      blen  TYPE i,
      clen  TYPE i,
      bytes TYPE i.

DESCRIBE FIELD text LENGTH blen IN BYTE MODE.
DESCRIBE FIELD text LENGTH clen IN CHARACTER MODE.
bytes = blen / clen.
WRITE:/ blen,clen,bytes.

2           1           2

DECIMALS dec

dobj的小数位

DATA: p  TYPE p LENGTH 8 DECIMALS 4,
      i  TYPE i.
DESCRIBE FIELD p DECIMALS i.
WRITE:/ i.

4

OUTPUT-LENGTH olen

测试dobj屏幕输出宽度，对于那些固定长度数据类型，输出宽度都是已经预置好的，对于strings，则为0

Numeric Data Types

注：上面表中的s类型显示宽度只有5位，不中以显示符号；i显示宽度为11,可以显示符号

Character-like data types

Byte-Like Data Types

DATA: date1 TYPE d,
      date2 TYPE sy-datum,
      olen1 TYPE i,
      olen2 TYPE i.

DESCRIBE FIELD date1 OUTPUT-LENGTH olen1.
DESCRIBE FIELD date2 OUTPUT-LENGTH olen2.

WRITE: / date1,date2,/ olen1,olen2.

00000000 00.00.0000

8          10

HELP-ID hlp

DATA: carrid TYPE spfli-carrid,
      hlp    TYPE string,
      struc  TYPE dfies-tabname,
      comp   TYPE dfies-fieldname.
DESCRIBE FIELD carrid HELP-ID hlp.
SPLIT hlp AT ‘-‘ INTO struc comp.
WRITE:/ hlp, / struc,/ comp.
CALL FUNCTION ‘F4IF_FIELD_VALUE_REQUEST‘
  EXPORTING
    tabname   = struc
    fieldname = comp.

EDIT MASK mask

If a conversion routine is assigned to the data object dobj by referring to a domain in ABAP Dictionary, two equals signs "==" precede the name of the conversion routine and the result is assigned to the data object mask.

DATA: time    TYPE s_fltime,
      seconds TYPE i,
      msk     TYPE string.

DESCRIBE FIELD time EDIT MASK msk.
WRITE msk.
seconds = 333.
WRITE / seconds USING EDIT MASK msk.

==SDURA

5:33

DESCRIBE TABLE

DESCRIBE TABLE itab [KIND knd] [LINES lin] [OCCURS n].

不同的选项使你能够判断表类型、行数、初始化大小。另外，系统字段sy-tfill 和 sy-tleng 保存着表行数量和以字节计的表行长度。注：为了更详细的关于内表的信息，应用RTTS的方法代替语句describe table。没有指定一个附加项，语句describe table 只设置系统字段sy-tfill 和sy-tleng的值。

a)         KIND knd

标识为T 时代表标准表，为S时代表排序表，为H时代表哈希表。这些值在类型组SYDES中已被定义成常量sydes_kind-standed ，sydes_kind-sorted，sydes_kind-hashed。

b)         LINES lin  内表表行数量

注：在版本6.10中，内表表行的当前数量也可以用内建函数lines来判断

c)         OCCURS n

在内表用选项initial size 或者老式的选项ocurs创建期间决定内表所需要的初始化内存大小

FORM sort_descending CHANGING itab TYPE ANY TABLE.
  DATA tabkind TYPE c LENGTH 1.
  DESCRIBE TABLE itab KIND tabkind.
  IF tabkind = sydes_kind-standard OR
     tabkind = sydes_kind-hashed.
    SORT itab DESCENDING.
  ELSEIF tabkind = sydes_kind-sorted.
    MESSAGE ‘...‘ TYPE ‘E‘.
  ELSE.
    MESSAGE ‘...‘ TYPE ‘E‘.
  ENDIF.
ENDFORM.

DESCRIBE DISTANCE

DESCRIBE DISTANCE BETWEEN dobj1 AND dobj2 INTO dst
                          IN {BYTE|CHARACTER} MODE.

dobj1 and dobj2两个变量地址起始位置的距离

DATA: BEGIN OF struc,
        comp1 TYPE i,
        comp2 TYPE x LENGTH 1,
        comp3 TYPE c LENGTH 4 VALUE ‘Hey‘,
        comp4 TYPE c LENGTH 4 VALUE ‘you!‘,
        comp5 TYPE x,
      END OF struc.
DATA: off TYPE i,
      len TYPE i,
      len2 TYPE i.

FIELD-SYMBOLS: <hex>    TYPE x,
               <result> TYPE c.

DESCRIBE DISTANCE BETWEEN:
         struc       AND struc-comp3 INTO off IN BYTE MODE,
         struc-comp3 AND struc-comp5 INTO len IN BYTE MODE,
         struc       AND struc-comp1 INTO len2 IN BYTE MODE.

ASSIGN: struc TO <hex> CASTING,
        <hex>+off(len) TO <result> CASTING.

WRITE: / ‘Offset off is‘, off,
       / ‘Length len is‘, len,
       / ‘<result> points to‘, <result>,
       / len2.

Offset off is          6

Length len is         16

<result> points toHey you!

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