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SDstart/sfstart
int32 SDstart(char *
filename
, int32
access_mode
)
filename
IN:
Name of the HDF file
access_mode
IN:
The SDS access mode in effect during the current session
Purpose
Opens the HDF file and initializes the SD interface.
Return value
Returns an
sd_id
if successful and FAIL (or -1) otherwise.
Description
This routine opens a file and returns an
sd_id
. This routine must be called for each file before any other SD calls can be made on that file. The
access_mode
parameter is one of the following:
DFACC_READ - Open existing file for read-only access. If the file doesn't exist, specifying this mode will result in an error condition.
DFACC_WRITE - Open existing file for read and write access. If the file doesn't exist, specifying this mode will result in an error condition.
DFACC_CREATE - Create a new file with read and write access. If the file does exist, the contents of this file will be deleted before any new writes occur (the file contents will be replaced).
The file can be any one of the following:an XDR-based netCDF file, "old-style" DFSD file or a "new-style" SD file.
If
access_mode
is set to DFACC_CREATE "new-style" SD files will be created. If
access_mode
is set to DFACC_RDONLY, the specified file will not be created if it doesn't exist.
The type of identifier returned by
SDstart
is currently not the same as the identifier returned by
Hopen
. As a result,
sd_id
s are not understood by other HDF interfaces and
h_id
s are not recognized by the SD interface.
To mix SD calls and other HDF library calls, use
SDstart
and
Hopen
on the same file.
SDstart
must precede all SD calls, and
Hopen
must proceed all other HDF function calls. To terminate access to the file, use both
SDend
and
Hclose
to dispose of the
sd_id
and the
h_id
.
FORTRAN
integer function sfstart(filename, access_mode)
character* (*) filename
integer access_mode
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hdfhelp@ncsa.uiuc.edu
HDF User's Reference Manual, Draft 06/09/97, NCSA HDF Development Group.