/* Batorder.c */
/* Example of a circularly-linked list. */

/* include files */
#include <stdio.h>
#include <string.h>
#define NAME_LENGTH 20

/* global structure, variables, and constants */

  struct batter_node         /* node for linked list */
    {
     char batter_name[NAME_LENGTH];
     struct batter_node *next;      /* link to next node */
    };

  struct batter_node *first;
  struct batter_node *current_batter;   /* pointer to current batter */

/* function prototypes */
int get_batter_name(char *);
void add_node(char *);
void do_rotation();
void delete_list();

/* beginning of main function */
int main()
{
 char name[NAME_LENGTH];

 if(get_batter_name(name))   /* prompt user for data for the node */
   {
     first = (struct batter_node *)malloc(sizeof(struct batter_node)); /* initialize list head */
     strcpy(first->batter_name, name);
     first->next = first;       /* initialize next node pointer to first */
     current_batter = first;

     while(get_batter_name(name))
      {
       add_node(name);
      }
     do_rotation();  /* display the counties and populations */
     delete_list();   /* free the memory used by the linked list */
   }
 return 0;
}

/* Function that gets data from user. */
int get_batter_name(char *name)
 {
  int keep_data = 1;

  printf("\nEnter batter name (Press Enter alone to stop): ");
  fgets(name,NAME_LENGTH, stdin);
  if(name[0] == '\n')
   {
    keep_data = 0;
   }
  name[strlen(name) - 1] = '\0'; /* overwrite \n with \0 */
  return(keep_data);
 }

/* Function that adds a node to the end of the linked list. */
void add_node(char *name)
{
  struct batter_node *new_rec_ptr; /* Declare temporary pointer for the new node. */

  new_rec_ptr = (struct batter_node *)malloc(sizeof(struct batter_node)); /* Allocate memory for a new node and */
				 /* initialize pointer to point to it. */

  strcpy(new_rec_ptr->batter_name, name);
  new_rec_ptr->next = first;  /* Set next node pointer of new node to first */

  current_batter->next = new_rec_ptr; /* Place new node in list */
  current_batter = new_rec_ptr;
}

/* Function that displays entire linked list. */
void do_rotation()
{
 char user_input[3]; /* char, \n, \0 */

 current_batter = first;   /* Move current_batter to first */
 do
  {
   printf("\nThe next batter is %s.\n", current_batter->batter_name);
   printf("\nPress Enter for next batter or Q and Enter to quit: ");
   fgets(user_input, 3, stdin);
   current_batter = current_batter->next;
  } while((user_input[0] != 'Q') && (user_input[0] != 'q'));
}

/* Function that frees the memory used by the linked list. */
void delete_list()
{
 struct batter_node *temp_ptr;  /* pointer used for temporary storage */

 current_batter = first;  /* Move current_ptr to head of the list. */

 do    /* Traverse list until the end is reached. */
  {
   temp_ptr = current_batter->next;   /* Set temporary pointer to point */
				   /* to the remainder of the list. */
   free( current_batter);   /* Delete current */
   current_batter = temp_ptr;
  } while(temp_ptr != first);
}