OPEN DATASET - mode - ABAP Keyword Documentation

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OPEN DATASET - mode

Quick Reference

Syntax

... {BINARY MODE}
  | {TEXT MODE encoding [linefeed]}
  | {LEGACY BINARY MODE [ endian][ CODE PAGE cp]}
  | {LEGACY TEXT MODE [ endian] [ CODE PAGE cp] [ linefeed]} ...

Alternatives:

1. ... BINARY MODE

2. ... TEXT MODE

3. ... LEGACY BINARY MODE

4. ... LEGACY TEXT MODE

Effect

These mandatory additions define whether the file is handled as a binary file or as a text file. By specifying LEGACY, files can be written in the format that is expected by a non- Unicode system, and files that have been created by a non-Unicode-system can be read. The byte order or the code page must be specified explicitly.

Alternative 1

... BINARY MODE

Effect

The addition IN BINARY MODE opens the file as a binary file. When writing to a binary file, the binary content of a data object is passed in unchanged form to the file. When reading from a binary file, the binary content of the file is passed in unchanged form to a data object.

Alternative 2

... TEXT MODE

Effect

The addition IN TEXT MODE opens the file as a text file. Only the content of character-like data objects can be passed to text files and read from text files.

The addition ENCODING defines how the characters are represented in the text file. When writing to a text file, the content of a data object is converted to the representation entered after ENCODING, and passed to the file. If the data type is character-like and flat, any trailing blanks are cut off. In the data type string, trailing blanks are not cut off.

The end-of-line selection of the relevant platform is applied to the passed data by default. When reading from a text file, the content of the file is read until the next end-of-line selection, converted from the format specified after ENCODING into the current character format, and passed to a data object. The end-of-line selection used is controlled using the addition linefeed.

Alternative 3

... LEGACY BINARY MODE

Effect

Opening a legacy file. The addition IN LEGACY BINARY MODE opens the file as a legacy binary file, where endian can be used to specify the byte order and CODE PAGE can be used to specify the code page that handle the content of the file.

Note

When a flat character-like field is written to the legacy binary files, the number of bytes written to the file is the same as the number of characters in the source field. The field content can be influenced by this when writing texts in Eastern Asian languages. It is therefore best to only write texts opened without the addition LEGACY to text files.

Alternative 4

... LEGACY TEXT MODE

Effect

Opening a legacy file. The addition IN LEGACY TEXT MODE opens the file as a legacy text file, where (in legacy binary files) endian can be used to specify the byte order and CODE PAGE can be used to specify the code page that handle the content of the file. The syntax and semantics of {BIG|LITTLE} ENDIAN and CODE PAGE cp are the same as in legacy binary files. The syntax and meaning of linefeed are the same as for regular text files.

In contrast to legacy binary files, the trailing blanks are cut off when writing character-like flat data objects to a legacy text file. Also, as in the case of a text file, an end-of-line selection is appended to the passed data by default. Unlike the text files opened by the addition IN TEXT MODE, there is no check on whether the data objects used in writing or reading are character-like. Also, the LENGTH additions of the statements READ DATASET and TRANSFER are used for counting. In legacy text files these additions count in bytes, and an text files they count in the units of a character represented in the memory.

Notes

As is the case with legacy binary files, it is possible to access text files written in non-Unicode systems as legacy text files. In this case, the content is converted accordingly.
When writing to a flat character-like field in legacy text files, the maximum number of bytes that can be written to the file is the maximum number of characters in the source field. The field content can be influenced by this when writing texts in Eastern Asian languages. It is therefore best to only write texts opened without the addition LEGACY to text files.

Example

A file test.dat is created as a text file, then filled with data, changed, and read. Since each TRANSFER statement appends an end-of-line selection to the written content, the content of the file is double-lined after the change. The first line contains "12ABCD". The second line contains "890". The character "7" was overwritten by the end-of-line selection of the first line.

DATA: file   TYPE string VALUE `test.dat`,
      result TYPE string.

DATA output TYPE TABLE OF string WITH EMPTY KEY.

OPEN DATASET file FOR OUTPUT IN TEXT MODE
                             ENCODING DEFAULT
                             WITH SMART LINEFEED.
TRANSFER `1234567890` TO file.
CLOSE DATASET file.

OPEN DATASET file FOR UPDATE IN TEXT MODE
                             ENCODING DEFAULT
                             WITH SMART LINEFEED
                             AT POSITION 2.
TRANSFER `ABCD` TO file.
CLOSE DATASET file.

OPEN DATASET file FOR INPUT IN TEXT MODE
                            ENCODING DEFAULT
                            WITH SMART LINEFEED.
WHILE sy-subrc = 0.
  READ DATASET file INTO result.
  APPEND result TO output.
ENDWHILE.
CLOSE DATASET file.

cl_demo_output=>display_data( output ).

Continue
OPEN DATASET - encoding
OPEN DATASET - WITH LINEFEED
OPEN DATASET - endian
OPEN DATASET - CODE PAGE