/* p22.c */

/* Managing lists of structures */

#include <malloc.h>
#include <stdlib.h>
#include <stdio.h>

struct sphere_t
{
   struct   sphere_t *next;
   double   center[3];     /* x, y, z */
   double   radius;
};

struct list_t
{
   struct sphere_t *head;
   struct sphere_t *tail;
};

/* Initialize a list structure */

struct list_t *list_init(void)
{

   struct list_t *list;

   list = (struct list_t *)malloc(sizeof(struct list_t));

   list->head = NULL;
   list->tail = NULL;
}

/* Append sphere structure to end of list */

void list_add(
struct list_t   *list,
struct sphere_t *new)
{
   if (list->head == NULL)
   {
      list->head = new;
      list->tail = new;
   }
   else
   {
      list->tail->next = new;
      list->tail = new;
   }
}

/* Allocate a new sphere structure */
/* and read in attributes          */

struct sphere_t *sphere_load(
FILE *in)
{
   double x, y, z;
   double r;
   struct sphere_t *new;

   if (fscanf(in, "%lf %lf %lf %lf", &x, &y, &z, &r) == 4)
   {
       new = malloc(sizeof(struct sphere_t));
       new->center[0] = x;
       new->center[1] = y;
       new->center[2] = z;
       new->radius = r;
       new->next = NULL;
       return(new);
   }
   return(0);
}

void sphere_print(
FILE *where,
struct sphere_t *sphere)
{
   fprintf(where, "Radius =  %6.2lf \n", sphere->radius);
   fprintf(where, "Center = (%6.2lf, %6.2lf, %6.2lf)\n",
                   sphere->center[0], sphere->center[1],
                   sphere->center[2]);
}



main()
{
   double x, y, z;
   double r;
   struct sphere_t *sphere;
   struct list_t   *list;

/* Allocate and initialize the list structure */

   list = list_init();

/* Load sphere descriptions until end of file */

   while (sphere = sphere_load(stdin))
   {
      list_add(list, sphere);
   }

/* Print the sphere descriptions */

   sphere = list->head;
   while (sphere)
   {
      sphere_print(stderr, sphere);
      sphere = sphere->next;
   }
}