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

struct list {
    char *str;
    struct list *prev;
    struct list *next;
};

int
main (void)
{
    unsigned int i;
    struct list *start, *end, *current, *tmp;

    start = NULL;

    for (i = 0; i < 10; i++)
      {
        struct list *entry;

        entry = malloc (sizeof (struct list));
        entry->str = malloc (strlen ("hello-N") + 1);
        sprintf (entry->str, "hello-%d", i);

        if (!start)
          {
            start = current = entry;
            start->prev = NULL;
          }
        else
          {
            tmp = current;
            current->next = entry;
            current = current->next;
            current->prev = tmp;
          }
      }

    current->next = NULL;

    end = current;

    for (current = start; current; current = current->next)
      puts (current->str);

    for (current = end; current; current = current->prev)
      puts (current->str);

    for (current = start; current; current = tmp)
      {
        tmp = current->next;
        free (current->str);
        free (current);
      }

    exit (EXIT_SUCCESS);
}