genstructs/tailq.c

   1 /*
   2  * Compile with:
   3  * gcc tailq.c -o tailq -Wall -W -Wextra -ansi -pedantic
   4  */
   5
   6 #include <stdio.h>
   7 #include <stdlib.h>
   8 #include <string.h>
   9 #include <sys/queue.h>
  10
  11 TAILQ_HEAD(tailhead, entry) head;
  12
  13 struct entry {
  14     TAILQ_ENTRY(entry) entries;
  15     const char *str;
  16 } *np, *n;
  17
  18 int main(void)
  19 {
  20     const char *str[] = { "this", "is", "a", "double", "linked", "tailq" };
  21     unsigned int i;
  22
  23     /* Initialize list */
  24     TAILQ_INIT(&head);
  25
  26     /* Populate list with str[] items */
  27     for (i = 0; i < sizeof str / sizeof *str; i++) {
  28         if ((n = malloc(sizeof(struct entry))) == NULL) {
  29             perror("malloc()");
  30            goto CLEANUP_AND_EXIT;
  31         }
  32         n->str = str[i];
  33
  34         TAILQ_INSERT_TAIL(&head, n, entries);
  35     }
  36
  37     /* Traverse list forward */
  38     TAILQ_FOREACH(np, &head, entries)
  39         printf("%s %s", np->str,
  40                TAILQ_NEXT(np, entries) != NULL ?
  41                "-> " : "\n");
  42
  43     /* Traverse list in reverse order */
  44     TAILQ_FOREACH_REVERSE(np, &head, tailhead, entries)
  45         printf("%s %s", np->str,
  46                TAILQ_PREV(np, tailhead, entries) != NULL ?
  47                "-> " : "\n");
  48
  49  CLEANUP_AND_EXIT:;
  50     /* Delete all elements */
  51     while (TAILQ_FIRST(&head) != NULL) {
  52         np = TAILQ_FIRST(&head);
  53         TAILQ_REMOVE(&head, TAILQ_FIRST(&head), entries);
  54         free(np);
  55     }
  56
  57     return EXIT_SUCCESS;
  58 }