fid = H5F.open('example.h5');
gid = H5G.open(fid,'/g3');
dset_id = H5D.open(fid,'/g4/world');
[~,objs] = H5F.get_obj_ids(fid,'H5F_OBJ_ALL',3);
for j = 1:numel(objs)
    name = H5I.get_name(objs(j));
    fprintf('object ''%s'':  ==> ',name);
    type = H5I.get_type(objs(j));
    switch(type)
        case H5ML.get_constant_value('H5I_FILE')
            fprintf('FILE identifier.\n');
        case H5ML.get_constant_value('H5I_GROUP')
            fprintf('GROUP identifier.\n');
        case H5ML.get_constant_value('H5I_DATASET')
            fprintf('DATASET identifier.\n');
        otherwise
            fprintf('unknown identifier type.\n');
    end
end
H5G.close(gid);
H5F.close(fid);