ABAP/4   ОКМ   ДМ   экономическая информатика   4GL   Теория и практика обработки информации

Компьютерный язык ABAP/4 - ключевые слова

DATA

Variants

1. DATA f.
2. DATA f(len).
3. DATA: BEGIN OF rec,
...
END OF rec.
4. DATA: BEGIN OF itab OCCURS n,
...
END OF itab.
5. DATA: BEGIN OF COMMON PART c,
...
END OF COMMON PART.

Effect

Defines global and local variables. Variables allow you to address declared data objects . They always have a particular data type. Data types and data objects are important components of the ABAP/4 type concept .

Variant 1

DATA f.

Additions




1. ... TYPE typ
2. ... LIKE f1
3. ... TYPE typ OCCURS n
4. ... LIKE f1 OCCURS n
5. ... TYPE LINE OF itabtyp
6. ... LIKE LINE OF itab
7. ... VALUE lit
8. ... DECIMALS n
9. ... WITH HEADER LINE

Effect

Creates the internal field f in its standard length. If you do not specify the type (using the addition TYPE ), a field of type C is assumed.

The field f can be up to 30 characters long. You can use any characters you like except the special characters '(' , ')' , '+' , '-' , ',' and ':' . Numeric characters are allowed but the field name may not consist of numbers alone.

SPACE is a reserved word and therefore cannot be used. Also, the field name cannot be the same as one of the additional parameters of the introductory key word (e.g. PERFORM SUB USING CHANGING. ).

Recommendations for field names:
Always use a letter as the first character.
Use the underscore to join together words which are part of the same name (e.g. NEW_PRODUCT ). The hyphen should not be used here, since it is reserved for the names of field string components (see below).

Addition 1

... TYPE typ.

Effect

Creates a field f of the type typ . You can use either one of the predefined types listed below or one of your own types which you define with TYPES .
The standard length ( SL ) of the field depends on the type.
TypeDescriptionSLInitial value
CText (character) 1Blank
NNumeric text 1'00...0'
DDate (YYYYMMDD) 8'00000000'
TTime (HHMMSS) 6'000000'
XHexadecimal 1X'00'
IWhole number (integer) 40
PPacked number 80
FFloating point no. 8'0.0'

Example

DATA NUMBER TYPE I.

Creates the field NUMBER as type I . You can also use it in the program, particularly if you want to assign number values and perform calculations.

Notes



Addition 2

... LIKE f1

Effect

Creates the field f with the same field attributes as the field F1 which is already known. Any data objects are valid (fields, parameters, structures, ...) as long as types have been assigned.

f1 can be any Dictionary reference.

Example

DATA TABLE_INDEX LIKE SY-TABIX.

The field TABLE_INDEX now has the same attributes as SY-TABIX (the index for internal tables).

Note

This addition is often useful, since the ABAP/4 runtime system performs type changes on fields automatically. Any unnecessary and/or unwanted conversions are thus avoided.

Addition 3

... TYPE typ OCCURS n

Effect

Defines an internal table without header line. Such a table consists of any number of table lines with the type typ .
To fill and edit this table, you can use statements like APPEND , READ TABLE , LOOP and SORT .
The OCCURS parameter n defines how many tables lines are created initially. If necessary, you can increase the size later. Otherwise, the OCCURS parameter is of no significance, apart from the exception that applies with APPEND SORTED BY .

Example

TYPES: BEGIN OF LINE_TYPE, NAME(20) TYPE C, AGE TYPE I, END OF LINE_TYPE. DATA: PERSONS TYPE LINE_TYPE OCCURS 20, PERSONS_WA TYPE LINE_TYPE. PERSONS_WA-NAME = 'Michael'. PERSONS_WA-AGE = 25. APPEND PERSONS_WA TO PERSONS. PERSONS_WA-NAME = 'Gabriela' PERSONS_WA-AGE = 22. APPEND PERSONS_WA TO PERSONS. The internal table PERSONS now consists of two table entries.

Note

Access to table entries not in main memory takes much longer. On the other hand, there is not enough space in main memory to hold such large tables because the roll area is resticted (see above).

Addition 4

... LIKE f1 OCCURS n

Effect

Defines an internal table without header line. Such a table consists of any number of table lines with the structure as specified by the data object f1 . Processing is the same as for addition 3.

Example

DATA: BEGIN OF PERSON, NAME(20), AGE TYPE I, END OF PERSON. DATA: PERSONS LIKE PERSON OCCURS 20. PERSON-NAME = 'Michael'. PERSON-AGE = 25. APPEND PERSON TO PERSONS. PERSON-NAME = 'Gabriela' PERSON-AGE = 22. APPEND PERSON TO PERSONS. The internal table PERSONS now consists of two table entries.

Addition 5

... TYPE LINE OF itabtype

Effect

The specified type itabtyp must be an internal table type. This operation creates a data object with the same line type as the table type specified.

Example

TYPES TAB_TYP TYPE I OCCURS 10. DATA TAB_WA TYPE LINE OF TAB_TYP.
The data object TAB_WA now has the same attributes as a line of the table type TAB_TYP and thus the type I .

Addition 6

... LIKE LINE OF itab

Effect

The data object tab must be an internal table with or without a header line. This operation creates a data object with the same line type as the table specified.

Example

DATA TAB TYP TYPE I OCCURS 10. DATA TAB_WA TYPE LINE OF TAB.

The data object TAB_WA now has the same attributes as a line of the table TAB and thus the type I .

Addition 7

... VALUE lit

Effect

The initial value of the field f is the literal lit instead of that defined in the table above. You can also specify a constant or even use IS INITIAL . In the latter case, the field is preset to the type-specific initial value. This form is particularly important in connection with the CONSTANTS statement which always requires you to use the addition VALUES .

Example

DATA NUMBER TYPE I VALUE 123, FLAG VALUE 'X', TABLE_INDEX LIKE SY-TABIX VALUE 45.
When created, the field NUMBER of type I contains 123 rather than the expected initial value of 0. The newly created field FLAG of type C (length 1) contains 'X' , while TABLE_INDEX contains 45, since the system field SY-TABIX is a numeric field.

Addition 8

... DECIMALS n

Effect

Only makes sense with field type P . When you perform calculations and on output, the field has n decimal decimal places, where n is a number between 0 and 14.

In the case of newly generated programs, you normally activate fixed point arithmetic in the attributes. If it is not set, the DECIMALS specification is taken into account on output, but not when performing calculations. This means that the programmer must take care of any decimal point calculations by multiplying or dividing by powers of ten. (see COMPUTE )
Fixed point arithmetic should always be active when you are performing calculations, since this enables intermediate results (for division) to be calculated as accurately as possible (in this case, to 31 decimal places).
To decide whether you should use the fixed point type P or the floating point type F , see "ABAP/4 number types ".

Addition 9

... WITH HEADER LINE

Effect

You can only use this addition with table types. When you specify WITH HEADER LINE , you create a header line with the same name type as a table line in addition to the table. With non-table operations (e.g. MOVE ), the name f refers to this header line. With table operations (e.g. APPEND ,
the name f refers to the table or the table and header line. The notation f[] always denotes the table. The result of this expression is a table without a header line and can be used as such.

Example

DATA: BEGIN OF PERSON_TYPE, NAME(20), AGE TYPE I, END OF PERSON_TYPE. DATA: PERSONS LIKE PERSON_TYPE OCCURS 20 WITH HEADER LINE. PERSON-NAME = 'Michael'. PERSON-AGE = 25. APPEND PERSONS. PERSON-NAME = 'Gabriela' PERSON-AGE = 22. APPEND PERSONS. * Delete header line CLEAR PERSONS. * Delete table CLEAR PERSONS[].

Variant 2

DATA f(len).

Additions



As for variant 1

Effect

Creates the field f in the length len .

You can use this variant only for fields of type C , N , P and X . Any other field types must have their standard lengths (see table under effect of variant 1).

The lengths allowed depend on the field type:
TypeAllowed lengths
C1 - 65535
N1 - 65535
P1 - 16
X1 - 65535

Note

Each byte can contain (one character or) two decimal or hexadecimal digits. Since one place in type P fields is reserved for the sign, a type P field of length 3 can contain 5 digits, whereas a type X field of length 3 can hold 6 digits. Both have an output length of 6.

Variant 3

DATA: BEGIN OF rec,
...
END OF rec.

Effect

Defines the field string rec which groups together all the fields defined for the field string rec between " BEGIN OF REC " and " END OF rec ". Each field carries the prefix " rec- ". Field strings can be nested to any depth. See Data objects .
When a field string needs the same fields as an already defined field string in addition to its own fields, you can include these fields in the field string with INCLUDE STRUCTURE . If no additional fields are needed, it is better to use LIKE .

Example

DATA: BEGIN OF PERSON, NAME(20) VALUE 'May', AGE TYPE I, END OF PERSON. PERSON-AGE = 35.
The field PERSON-NAME now contains the contents "May".
DATA: BEGIN OF PERSON1, FIRSTNAME(20) VALUE 'Michael'. INCLUDE STRUCTURE PERSON. DATA END OF PERSON1.

Notes




Variant 4

DATA: BEGIN OF itab OCCURS n,
...
END OF itab.

Additions



... VALID BETWEEN f1 AND f2

Effect

Defines the internal table itab .

An internal table includes a header line, which is a field string containing the fields defined between " BEGIN OF itab OCCURS n " and " END OF itab " (see variant 3), and any number of table lines with the same structure as the header line.

To fill and edit an internal table, you use various statements such as APPEND , LOOP and SORT .

The OCCURS parameter n determines how many table lines are held in main storage (the roll area). If you also generate table entries, these are rolled out either to a main storage buffer or to disk (the paging area).

Example

DATA: BEGIN OF PERSONS OCCURS 20, NAME(20), AGE TYPE I, END OF PERSONS. PERSONS-NAME = 'Michael'. PERSONS-AGE = 25. APPEND PERSONS. PERSONS-NAME = 'Gabriela'. PERSONS-AGE = 22. APPEND PERSONS.

The internal table now consists of two table entries.

PERSONS also includes the header line (work area) through which all operations on the actual table pass.

Note

Access to table entries not in main storage is considerably slower. Also, main storage cannot hold large tables in their entirety, since the size of the roll area is restricted (see above).

Addition

... VALID BETWEEN f1 AND f2

Effect

Can appear only after " END OF itab ".

The sub-fields f1 and f2 of the internal table itab must have the line-related validity range (see PROVIDE ).

Variant 5

DATA: BEGIN OF COMMON PART c,
.....
END OF COMMON PART.

Effect

Defines one or more common data areas in programs linked by external PERFORM calls. If only one common data area exists, you can omit the name c . There may be just one unnamed COMMON area or one or more named COMMON areas. You assign named COMMON areas to each other by name. The structure of data areas must always be the same for both the calling and the called program (otherwise, the program terminates with an error message at runtime).




Index
© SAP AG 1996
ABAP/4   ОКМ   ДМ   экономическая информатика   4GL   Теория и практика обработки информации

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