H5: General Library Functions

The C Interfaces:

H5open H5close

H5get_libversion H5check_version

H5garbage_collect H5dont_atexit

The FORTRAN90 Interfaces:
In general, each FORTRAN90 subroutine performs exactly the same task as the corresponding C function. The links below go to the C function descriptions, which serve as general descriptions for both. A button, under Non-C API(s) at the end of the C function description, opens an external browser window displaying the FORTRAN90-specific information. You will probably want to adjust the size and location of this external window so that both browser windows are visible and to facilitate moving easily between them.

h5open_f

h5close_f

Name: H5open

Signature:

herr_t H5open(void)

Purpose:

Initializes the HDF5 library.

Description:

H5open initialize the library. This function is normally called automatically, but if you find that an HDF5 library function is failing inexplicably, try calling this function first.

Parameters:

None.

Returns:

Returns a non-negative value if successful; otherwise returns a negative value.

Non-C API(s):

Name: H5close

Signature:

herr_t H5close(void)

Purpose:

Flushes all data to disk, closes file identifiers, and cleans up memory.

Description:

H5close flushes all data to disk, closes all file identifiers, and cleans up all memory used by the library. This function is generally called when the application calls exit, but may be called earlier in event of an emergency shutdown or out of desire to free all resources used by the HDF5 library.

Parameters:

None.

Returns:

Returns a non-negative value if successful; otherwise returns a negative value.

Non-C API(s):

Name: H5garbage_collect

Signature:

herr_t H5garbage_collect(void)

Purpose:

Garbage collects on all free-lists of all types.

Description:

H5garbage_collect walks through all the garbage collection routines of the library, freeing any unused memory.

It is not required that H5garbage_collect be called at any particular time; it is only necessary in certain situations where the application has performed actions that cause the library to allocate many objects. The application should call H5garbage_collect if it eventually releases those objects and wants to reduce the memory used by the library from the peak usage required.

The library automatically garbage collects all the free lists when the application ends.

Parameters:

None.

Returns:

Returns a non-negative value if successful; otherwise returns a negative value.

Name: H5dont_atexit

Signature:

herr_t H5dont_atexit(void)

Purpose:

Instructs library not to install atexit cleanup routine.

Description:

H5dont_atexit indicates to the library that an atexit() cleanup routine should not be installed. The major purpose for this is in situations where the library is dynamically linked into an application and is un-linked from the application before exit() gets called. In those situations, a routine installed with atexit() would jump to a routine which was no longer in memory, causing errors.

In order to be effective, this routine must be called before any other HDF function calls, and must be called each time the library is loaded/linked into the application (the first time and after it's been un-loaded).

Parameters:

None.

Returns:

Returns a non-negative value if successful; otherwise returns a negative value.

Name: H5get_libversion

Signature:

herr_t H5get_libversion(unsigned *majnum, unsigned *minnum, unsigned *relnum )

Purpose:

Returns the HDF library release number.

Description:

H5get_libversion retrieves the major, minor, and release numbers of the version of the HDF library which is linked to the application.

Parameters:

unsigned *majnum

OUT: The major version of the library.

unsigned *minnum

OUT: The minor version of the library.

unsigned *relnum

OUT: The release number of the library.

Returns:

Returns a non-negative value if successful; otherwise returns a negative value.

Name: H5check_version

Signature:

herr_t H5check_version(unsigned majnum, unsigned minnum, unsigned relnum )

Purpose:

Description:

H5check_version verifies that the arguments match the version numbers compiled into the library. This function is intended to be called by the user to verify that the version of the header files compiled into the application matches the version of the HDF5 library being used.

Due to the risks of data corruption or segmentation faults, H5check_version causes the application to abort if the version numbers do not match.

If the version numbers of the library do not match the version numbers in the header files being checked, the library calls the standard C function abort().

Parameters:

unsigned majnum

IN: The major version of the library.

unsigned minnum

IN: The minor version of the library.

unsigned relnum

IN: The release number of the library.

Returns:

Returns a non-negative value if successful. Upon failure, this function causes the application to abort.