CSA_attribute_reference	name = CSA_ENTRY_ATTR_END_DATE; 
char			buffer[80]; 
time_t			endtime; 
CSA_entry_handle	new_entry;  

for (i = 0; i < num_entries; i++) {
     /* get the end time of the appointment */
     stat = csa_read_entry_attributes(cal, entries[i], 0, &name,
          &num_attributes, &entry_attrs, NULL);
     if (stat == CSA_SUCCESS) {
  /* change the end time to be one hour later */
  from_iso8601_time(entry_attrs[0].value->item.date_time_value, &endtime);
  endtime += 60*60 /* number of second in an hour */
  to_iso8601_time(endtime, buffer);

   attrs[0].name = CSA_ENTRY_ATTR_END_DATE;
  attrs[0].value = &attr_val[i];
  attrs[0].attribute_extensions = NULL;
  attr_val[0].type = CSA_VALUE_DATE_TIME;
  attr_val[0].item.date_time_value = buffer;
   stat = csa_update_entry_attributes(cal, entries[0], CSA_SCOPE_ALL,
         CSA_FALSE, 1, attrs, &new_entry,
         NULL); 	if (stat == CSA_SUCCESS) {
      csa_free(new_entry);
  } else {
      /* handle error */
  }
   csa_free(entry_attrs);
      } else {
      /* handle error */ 
    }
}