IN: File dataspace selection identifier; H5S_ALL if the selection is the current extent of the dataset (See NOTE below)
hsize_t * nchunks
IN/OUT: Number of chunks in the selection
H5D_GET_NUM_CHUNKS retrieves the number of chunks nchunks in a set of selected elements specified by fspace_id for a dataset specified by the identifier dset_id. If fspace_id is H5S_ALL, the function will retrieve the total number of chunks stored for the dataset.
NOTE: Please be aware that in the HDF5-1.10.5 release, the file space identifier does not (yet) support non-trivial selections. The implementation also does not currently support the H5S_ALL macro. As a workaround, get the dataspace for the dataset (H5D_GET_SPACE), select all elements in the dataspace (H5S_SELECT_ALL) and pass that in for fspace_id.
Returns a non-negative value if successful. Otherwise returns a negative value.