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queue.3: stailq: Complete example 

Signed-off-by: Alejandro Colomar <colomar.6.4.3@gmail.com>
Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
This commit is contained in:
Alejandro Colomar 2020-10-17 12:16:17 +02:00 committed by Michael Kerrisk
parent 7a737de2e1
commit 740656b855
1 changed files with 64 additions and 53 deletions
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117
man3/queue.3
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@ -721,59 +721,9 @@ from the tail queue.
.\" .Fa head1
.\" and
.\" .Fa head2 .
.Ss Singly-linked tail queue example
.Bd -literal
STAILQ_HEAD(stailhead, entry) head =
STAILQ_HEAD_INITIALIZER(head);
struct stailhead *headp; /* Singly-linked tail queue head. */
struct entry {
...
STAILQ_ENTRY(entry) entries; /* Tail queue. */
...
} *n1, *n2, *n3, *np;
STAILQ_INIT(&head); /* Initialize the queue. */
n1 = malloc(sizeof(struct entry)); /* Insert at the head. */
STAILQ_INSERT_HEAD(&head, n1, entries);
n1 = malloc(sizeof(struct entry)); /* Insert at the tail. */
STAILQ_INSERT_TAIL(&head, n1, entries);
n2 = malloc(sizeof(struct entry)); /* Insert after. */
STAILQ_INSERT_AFTER(&head, n1, n2, entries);
/* Deletion. */
STAILQ_REMOVE(&head, n2, entry, entries);
free(n2);
/* Deletion from the head. */
n3 = STAILQ_FIRST(&head);
STAILQ_REMOVE_HEAD(&head, entries);
free(n3);
/* Forward traversal. */
STAILQ_FOREACH(np, &head, entries)
np\-> ...
.\" /* Safe forward traversal. */
.\"STAILQ_FOREACH_SAFE(np, &head, entries, np_temp) {
.\" np\->do_stuff();
.\" ...
.\" STAILQ_REMOVE(&head, np, entry, entries);
.\" free(np);
.\"}
/* TailQ Deletion. */
while (!STAILQ_EMPTY(&head)) {
n1 = STAILQ_FIRST(&head);
STAILQ_REMOVE_HEAD(&head, entries);
free(n1);
}
/* Faster TailQ Deletion. */
n1 = STAILQ_FIRST(&head);
while (n1 != NULL) {
n2 = STAILQ_NEXT(n1, entries);
free(n1);
n1 = n2;
}
STAILQ_INIT(&head);
.Ed
.Pp
See the EXAMPLES section below for an example program
using a singly-linked tail queue.
.Ss Lists
A list is headed by a structure defined by the
.Nm LIST_HEAD
@ -1328,6 +1278,67 @@ main(void)
exit(EXIT_SUCCESS);
}
.Ed
.Ss Singly-linked tail queue example
.Bd -literal
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/queue.h>
struct entry {
int data;
STAILQ_ENTRY(entry) entries; /* Singly-linked tail queue. */
};
STAILQ_HEAD(stailhead, entry);
int
main(void)
{
struct entry *n1, *n2, *n3, *np;
struct stailhead head; /* Singly-linked tail queue
head. */
STAILQ_INIT(&head); /* Initialize the queue. */
n1 = malloc(sizeof(struct entry)); /* Insert at the head. */
STAILQ_INSERT_HEAD(&head, n1, entries);
n1 = malloc(sizeof(struct entry)); /* Insert at the tail. */
STAILQ_INSERT_TAIL(&head, n1, entries);
n2 = malloc(sizeof(struct entry)); /* Insert after. */
STAILQ_INSERT_AFTER(&head, n1, n2, entries);
STAILQ_REMOVE(&head, n2, entry, entries);/* Deletion. */
free(n2);
n3 = STAILQ_FIRST(&head);
STAILQ_REMOVE_HEAD(&head, entries); /* Deletion from the head. */
free(n3);
n1 = STAILQ_FIRST(&head);
n1->data = 0;
for (int i = 1; i < 5; i++) {
n1 = malloc(sizeof(struct entry));
STAILQ_INSERT_HEAD(&head, n1, entries);
n1->data = i;
}
/* Forward traversal. */
STAILQ_FOREACH(np, &head, entries)
printf("%i\en", np->data);
/* TailQ Deletion. */
n1 = STAILQ_FIRST(&head);
while (n1 != NULL) {
n2 = STAILQ_NEXT(n1, entries);
free(n1);
n1 = n2;
}
STAILQ_INIT(&head);
exit(EXIT_SUCCESS);
}
.Ed
.Ss List example
.Bd -literal
#include <stddef.h>