The HDF_OPEN function opens or creates an HDF file for reading and/or writing.

Note that any combination of the READ, WRITE and CREATE keywords is valid.

Syntax


Result = HDF_OPEN( Filename [, /ALL] [, /CREATE] [, NUM_DD=value] [, /RDWR] [, /READ] [, /WRITE] )

Return Value


If successful, a non-zero file handle (a longword integer) is returned. Longword -1 is returned on failure.

Arguments


Filename

A scalar string containing the name of the file to be opened.

Keywords


ALL

Set this keyword to create a new HDF file with read and write access. Setting this keyword is equivalent to:

HDF_OPEN(filename, /READ, /WRITE, /CREATE)

CREATE

Set this keyword to create a new HDF file.

NUM_DD

Use this keyword to override the machine default for the number of data descriptors to be allocated per DD block. For example:

H = HDF_OPEN('foo.hdf',/CREATE,/WRITE, NUM_DD=100)

RDWR

Set this keyword to open file with both read and write access. Setting this keyword is equivalent to:

HDF_OPEN(filename, /READ, /WRITE)

READ

Set this keyword to open the file with read access.

WRITE

Set this keyword to open the file with write access.

Version History


Pre 4.0

Introduced