genstructs/tailq.c

   1 /* compile with:
   2    gcc tailq.c -o tailq -Wall -W -Wextra -ansi -pedantic */
   3
   4 #include <stdio.h>
   5 #include <stdlib.h>
   6 #include <string.h>
   7 #include <sys/queue.h>
   8
   9 TAILQ_HEAD(tailhead, entry) head;
  10
  11 struct entry {
  12     TAILQ_ENTRY(entry) entries;
  13     const char *str;
  14 } *np, *n;
  15
  16 int main(void)
  17 {
  18     const char *str[] = { "this", "is", "a", "double", "linked", "tailq" };
  19     unsigned int i;
  20
  21     /* Initialize list */
  22     TAILQ_INIT(&head);
  23
  24     /* Populate list with str[] items */
  25     for (i = 0; i < sizeof str / sizeof *str; i++) {
  26         if ((n = malloc(sizeof(struct entry))) == NULL) {
  27             perror("malloc");
  28            goto CLEANUP_AND_EXIT;
  29         }
  30         n->str = str[i];
  31
  32         TAILQ_INSERT_TAIL(&head, n, entries);
  33     }
  34
  35     /* Traverse list forward */
  36     TAILQ_FOREACH(np, &head, entries)
  37         printf("%s %s", np->str,
  38                TAILQ_NEXT(np, entries) != NULL ?
  39                "-> " : "\n");
  40
  41     /* Traverse list in reverse order */
  42     TAILQ_FOREACH_REVERSE(np, &head, tailhead, entries)
  43         printf("%s %s", np->str,
  44                TAILQ_PREV(np, tailhead, entries) != NULL ?
  45                "-> " : "\n");
  46
  47  CLEANUP_AND_EXIT:;
  48     /* Delete all elements */
  49     while (TAILQ_FIRST(&head) != NULL) {
  50         np = TAILQ_FIRST(&head);
  51         TAILQ_REMOVE(&head, TAILQ_FIRST(&head), entries);
  52         free(np);
  53     }
  54
  55     return EXIT_SUCCESS;
  56 }