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SDsetexternalfile/sfsextf

intn SDsetexternalfile(int32 sds_id, char *filename, int32 offset)
sds_id

IN:

Dataset identifier returned from SDselect

filename

IN:

Name of the external file

offset

IN:

Byte count from the beginning of the external file to where the data starts

Purpose

Stores data in an external file.

Return value

Returns SUCCEED (or 0) if successful and FAIL (or -1) otherwise.

Description

SDsetexternalfile allows users to move the data values for a dataset into an external data file. Only the dataset values can be stored externally, all other data must stay in the original file.

Data can only be moved once for any given dataset and it is the user's responsibility to make sure the external data file is kept with the "original" file. The offset parameter is the number of bytes from the beginning of the external file to where the external data begins. This routine can only be called on HDF post-version 3.2 files (i.e. calling on a netCDF file that was opened with the multi-file interface will fail)

If the SDS specified by sds_id already exists, its data will be moved to the external file and the connection between the tag and the data in the primary file will be broken, effectively making that data inaccessible to the interface routines. However, the data itself must be explicitly deleted by the hdfpack command-line utility, as SDsetexternalfile doesn't do this.

See the Reference Manual entries for HXsetcreatedir and HXsetdir for more information on the options available for accessing external files.

FORTRAN

integer function sfsextf(sds_id, file_name, offset)

integer sds_id, offset

character* (*) file_name



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HDF User's Reference Manual, Draft 06/09/97, NCSA HDF Development Group.