hid_t    file_id, fapl_id;
hid_t    dataset_id, dapl_id;
unsigned counter;

/* Create a copy of the file access property list */
fapl_id = H5Pcreate(H5P_FILE_ACCESS);

/* Set up the object flush property values */
/* flush_cb: callback function to invoke when an object flushes (see below) */
/* counter: user data to pass along to the callback function */
H5Pset_object_flush_cb(fapl_id, flush_cb, &counter);

/* Open the file */
file_id = H5Fopen(FILE, H5F_ACC_RDWR, H5P_DEFAULT);

/* Create a group */
gid = H5Gcreate2(fid, “group”, H5P_DEFAULT, H5P_DEFAULT_H5P_DEFAULT);

/* Open a dataset */
dataset_id = H5Dopen2(file_id, DATASET, H5P_DEFAULT);

/* The flush will invoke flush_cb() with counter */
H5Dflush(dataset_id);
/* counter will be equal to 1 */

/* ... */

/* The flush will invoke flush_cb() with counter */
H5Gflush(gid);
/* counter will be equal to 2 */

/* ... */

/* The callback function for object flush property */
static herr_t
flush_cb(hid_t obj_id, void *_udata)
{
    unsigned *flush_ct = (unsigned *)_udata;
    ++(*flush_ct);
    return 0;
}