OPEN DATASET - position
Short Reference
ABAP Syntax ... AT POSITION pos ... .
What does it do? 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.
Latest 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.
Documentation extract taken from SAP system, � Copyright SAP AG. All rights reserved