Can a valid H5 object have hid_t = 0 ?

Hdf-forum archives
1

I am writing C++ code that interfaces with the HDF5 C API. Specifically, I
am using a unique_ptr with a custom deleter to manage objects through their
hid_t references. Does the HDF5 library ever return a zero hid_t as a
reference to a valid HDF5 object, or can hid_t=0 be used as a sort of "null
pointer"?

Thank you,
John Jumper

2

Hi John,

···

On Sep 16, 2014, at 2:34 AM, John Jumper <jspm.jumper@gmail.com> wrote:

I am writing C++ code that interfaces with the HDF5 C API. Specifically, I am using a unique_ptr with a custom deleter to manage objects through their hid_t references. Does the HDF5 library ever return a zero hid_t as a reference to a valid HDF5 object, or can hid_t=0 be used as a sort of "null pointer”?

This question is frequently received by our Helpdesk. Please see the answer to its variation http://www.hdfgroup.org/hdf5-quest.html#gzero

While 0 is a valid value for an HDF5 identifier, an HDF5 C function that returns an object identifier, when succeeds, never uses 0 as a return value for the object identifier, i.e., an identifier of a valid HDF5 object (file, group, dataset, attribute and datatype) will have a positive value.

The HDF folks, please correct me, if I am wrong!

Elena

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Elena Pourmal The HDF Group http://hdfgroup.org
1800 So. Oak St., Suite 203, Champaign IL 61820
217.531.6112
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Thank you,
John Jumper
_______________________________________________
Hdf-forum is for HDF software users discussion.
Hdf-forum@lists.hdfgroup.org
http://mail.lists.hdfgroup.org/mailman/listinfo/hdf-forum_lists.hdfgroup.org
Twitter: https://twitter.com/hdf5