#include "hdf.h"

#define  FILE_NAME   "General_Vgroups.hdf"

main( )
{
   /************************* Variable declaration **************************/

   intn   status_n;     /* returned status for functions returning an intn  */
   int32  status_32,    /* returned status for functions returning an int32 */
          file_id, vgroup_id;
   int32  lone_vg_number,      /* current lone vgroup number */
          num_of_lones = 0;    /* number of lone vgroups */
   int32 *ref_array;    /* buffer to hold the ref numbers of lone vgroups   */
   char   vgroup_name[VGNAMELENMAX], vgroup_class[VGNAMELENMAX];

   /********************** End of variable declaration **********************/
 
   /*
   * Open the HDF file for reading.
   */
   file_id = Hopen (FILE_NAME, DFACC_READ, 0); 

   /*
   * Initialize the V interface.
   */
   status_n = Vstart (file_id);

   /*
   * Get and print the names and class names of all the lone vgroups.
   * First, call Vlone with num_of_lones set to 0 to get the number of
   * lone vgroups in the file, but not to get their reference numbers.
   */
   num_of_lones = Vlone (file_id, NULL, num_of_lones );

   /*
   * Then, if there are any lone vgroups, 
   */
   if (num_of_lones > 0)
   {
      /*
      * use the num_of_lones returned to allocate sufficient space for the
      * buffer ref_array to hold the reference numbers of all lone vgroups,
      */
      ref_array = (int32 *) malloc(sizeof(int32) * num_of_lones);

      /*
      * and call Vlone again to retrieve the reference numbers into 
      * the buffer ref_array.
      */
      num_of_lones = Vlone (file_id, ref_array, num_of_lones);

      /*
      * Display the name and class of each lone vgroup.
      */
      printf ("Lone vgroups in this file are:\n");
      for (lone_vg_number = 0; lone_vg_number < num_of_lones; 
                                                            lone_vg_number++)
      {
         /*
         * Attach to the current vgroup then get and display its
         * name and class. Note: the current vgroup must be detached before
         * moving to the next.
         */
         vgroup_id = Vattach (file_id, ref_array[lone_vg_number], "r");
         status_32 = Vgetname (vgroup_id, vgroup_name);
         status_32 = Vgetclass (vgroup_id, vgroup_class);
         printf ("   Vgroup name %s and class %s\n", vgroup_name,  
                     vgroup_class); 
         status_32 = Vdetach (vgroup_id);
      } /* for */
   } /* if */

   /*
   * Terminate access to the V interface and close the file.
   */
   status_n = Vend (file_id);
   status_n = Hclose (file_id);

   /*
   * Free the space allocated by this program.
   */
   free (ref_array);
}