/* Chapter 12 - Program 1 - DYNLIST.C */
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

struct animal 
{
   char name[25];
   char breed[25];
   int  age;
} *pet1, *pet2, *pet3;


int main()
{
   pet1 = (struct animal *)malloc(sizeof(struct animal));
   /* It is an error to fail to check the allocation, see text. */
   /* We will check for proper allocation in the next program.  */

   strcpy(pet1->name, "General");
   strcpy(pet1->breed, "Mixed Breed");
   pet1->age = 1;

   pet2 = pet1;   /* pet2 now points to the above data structure */

   pet1 = (struct animal *)malloc(sizeof(struct animal));
   strcpy(pet1->name, "Frank");
   strcpy(pet1->breed, "Labrador Retriever");
   pet1->age = 3;

   pet3 = (struct animal *)malloc(sizeof(struct animal));
   strcpy(pet3->name, "Krystal");
   strcpy(pet3->breed, "German Shepherd");
   pet3->age = 4;

       /* now print out the data described above */

   printf("%s is a %s, and is %d years old.\n", 
                                 pet1->name, pet1->breed, pet1->age);

   printf("%s is a %s, and is %d years old.\n",
                                 pet2->name, pet2->breed, pet2->age);

   printf("%s is a %s, and is %d years old.\n", 
                                 pet3->name, pet3->breed, pet3->age);

   pet1 = pet3;      /* pet1 now points to the same structure that */
                     /*   pet3 points to                           */
   free(pet3);       /* this frees up one structure                */
   free(pet2);       /* this frees up one more structure           */
/* free(pet1);        this cannot be done, see explanation in text */

   return 0;
}



/* Result of execution

Frank is a Laborador Retriever, and is 3 years old.
General is a Mixed Breed, and is 1 years old.
Krystal is a German Shepherd, and is 4 years old.

*/