/* Chapter 11 - Program 6 - UNION2.C */
#include <stdio.h>
#define AUTO  1
#define BOAT  2
#define PLANE 3
#define SHIP  4

struct automobile             /* structure for an automobile       */
{
   int tires;
   int fenders;
   int doors;
};


typedef struct                /* structure for a boat or ship      */
{
   int  displacement;
   char length;
} BOATDEF;


struct 
{
   char vehicle;              /* what type of vehicle?             */
   int  weight;               /* gross weight of vehicle           */
   union                      /* type-dependent data               */
   {
      struct automobile car;  /* part 1 of the union               */
      BOATDEF boat;           /* part 2 of the union               */
      struct 
      {
         char engines;
         int wingspan;
      } airplane;             /* part 3 of the union               */
      BOATDEF ship;           /* part 4 of the union               */
   } vehicle_type;
   int  value;                /* value of vehicle in dollars       */
   char owner[32];            /* owners name                       */
} ford, sun_fish, piper_cub;  /* three variable structures         */


int main()
{
       /* define a few of the fields as an illustration            */

   ford.vehicle = AUTO;
   ford.weight = 2742;               /* with a full gas tank       */
   ford.vehicle_type.car.tires = 5;  /* including the spare        */
   ford.vehicle_type.car.doors = 2;

   sun_fish.value = 3742;            /* trailer not included       */
   sun_fish.vehicle_type.boat.length = 20;

   piper_cub.vehicle = PLANE;
   piper_cub.vehicle_type.airplane.wingspan = 27;

   if (ford.vehicle == AUTO)       /* which it is in this case     */
      printf("The ford has %d tires.\n", 
                                      ford.vehicle_type.car.tires);

   if (piper_cub.vehicle == AUTO)  /* which it is not in this case */
      printf("The plane has %d tires.\n",
                                 piper_cub.vehicle_type.car.tires);

   return 0;
}



/* Result of execution

The ford has 5 tires.

*/