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ABAP Keyword Documentation →  ABAP - Reference →  Processing External Data →  ABAP File Interface →  Statements for the ABAP File Interface →  OPEN DATASET 

OPEN DATASET - position

Short Reference

Other versions: 7.31 | 7.40 | 7.54

Syntax


... AT POSITION pos ... .

Effect

This addition sets the file pointer at the position specified in pos. pos expects a numerical data object. Numbers with a value greater than the value range of the data type i can also be entered.

The position is specified in bytes; the start of the file corresponds to position 0. If pos contains the value -1, the position is at the end of the file. For all other negative values, the behavior is undefined.

Note the following special cases:

  • If the file is opened for reading and the value of pos is greater than the length of the file, the file pointer is positioned outside the file. Unless the position is changed, no data can be read. If write changes are made to a file opened for reads by a non- Unicode program, the file is padded with hexadecimal 0 from the end of the file to the specified position, and the write change is made after this position.

  • If the file is opened for writing, the next time writing takes place, the file is filled with hexadecimal 0 from the start of the file to the specified position, and the new content is written after that.

  • If the file is opened for appending, the position specification is ignored and the file pointer remains positioned at the end of the file.

  • If the file is opened for changing, and the value of pos is greater than the length of the file, the next time the file is written in, it is filled with hexadecimal 0 from the end of the file to the specified position, and the new content is written after that.

    • The addition POSITION cannot be specified if one of the additions FILTER or BYTE-ORDER MARK is specified at the same time.


    Notes

    • For file sizes larger than 2 GB, a position pos of the data type i is not sufficient for positioning in the whole file, and p or decfloat must be used instead.
    • The positioning can be overwritten by the statement SET DATASET. In particular, for positioning the file pointer at the end of the file, SET DATASET should be used instead of entering the value -1 in pos.
    • Free position specifications are more suitable for binary files than for text files. In the case of text files, positions depend on the character format, end-of-line marking, and a possible byte order mark (BOM) in UTF-8 files.