1.標頭檔案

/*
 * list.h - Linked list implementation. Part of the Linux-NTFS project.
 *
 * Copyright (c) 2000-2002 Anton Altaparmakov and others
 *
 * This program/include file is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as published
 * by
 
 the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program/include file is distributed in the hope that it will be
 * useful, but WITHOUT ANY WARRANTY; without even the implied warranty
 * of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 

 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program (in the main directory of the Linux-NTFS
 * distribution in the file COPYING); if not, write to the Free Software
 * Foundation,Inc., 59 Temple Place, Suite 330
 
, Boston, MA  02111-1307  USA
 */

#ifndef _NTFS_LIST_H
#define _NTFS_LIST_H

/**
 * struct list_head - Simple doubly linked list implementation.
 *
 * Copied from Linux kernel 2.4.2-ac18 into Linux-NTFS (with minor
 * modifications). - AIA
 *
 * Some of the internal functions ("__xxx") are useful when
 * manipulating whole lists rather than single entries, as
 * sometimes we already know the next/prev entries and we can
 * generate better code by using them directly rather than
 * using the generic single-entry routines.
 */
struct list_head {
    struct list_head *next, *prev;
};

#define LIST_HEAD_INIT(name) { &(name), &(name) }

#define LIST_HEAD(name) \
    struct list_head name = LIST_HEAD_INIT(name)

#define INIT_LIST_HEAD(ptr) do { \
    (ptr)->next = (ptr); (ptr)->prev = (ptr); \
} while (0)

/**
 * __list_add - Insert a new entry between two known consecutive entries.
 * @new:
 * @prev:
 * @next:
 *
 * This is only for internal list manipulation where we know the prev/next
 * entries already!
 */
static __inline__ void __list_add(struct list_head * new,
        struct list_head * prev, struct list_head * next)
{
    next->prev = new;
    new->next = next;
    new->prev = prev;
    prev->next = new;
}

/**
 * list_add - add a new entry
 * @new:    new entry to be added
 * @head:   list head to add it after
 *
 * Insert a new entry after the specified head.
 * This is good for implementing stacks.
 */
static __inline__ void list_add(struct list_head *new, struct list_head *head)
{
    __list_add(new, head, head->next);
}

/**
 * list_add_tail - add a new entry
 * @new:    new entry to be added
 * @head:   list head to add it before
 *
 * Insert a new entry before the specified head.
 * This is useful for implementing queues.
 */
static __inline__ void list_add_tail(struct list_head *new, struct list_head *head)
{
    __list_add(new, head->prev, head);
}

/**
 * __list_del -
 * @prev:
 * @next:
 *
 * Delete a list entry by making the prev/next entries point to each other.
 *
 * This is only for internal list manipulation where we know the prev/next
 * entries already!
 */
static __inline__ void __list_del(struct list_head * prev,
        struct list_head * next)
{
    next->prev = prev;
    prev->next = next;
}

/**
 * list_del - deletes entry from list.
 * @entry:  the element to delete from the list.
 *
 * Note: list_empty on entry does not return true after this, the entry is in
 * an undefined state.
 */
static __inline__ void list_del(struct list_head *entry)
{
    __list_del(entry->prev, entry->next);
}

/**
 * list_del_init - deletes entry from list and reinitialize it.
 * @entry:  the element to delete from the list.
 */
static __inline__ void list_del_init(struct list_head *entry)
{
    __list_del(entry->prev, entry->next);
    INIT_LIST_HEAD(entry);
}

/**
 * list_empty - tests whether a list is empty
 * @head:   the list to test.
 */
static __inline__ int list_empty(struct list_head *head)
{
    return head->next == head;
}

/**
 * list_splice - join two lists
 * @list:   the new list to add.
 * @head:   the place to add it in the first list.
 */
static __inline__ void list_splice(struct list_head *list,
        struct list_head *head)
{
    struct list_head *first = list->next;

    if (first != list) {
        struct list_head *last = list->prev;
        struct list_head *at = head->next;

        first->prev = head;
        head->next = first;

        last->next = at;
        at->prev = last;
    }
}

/**
 * list_entry - get the struct for this entry
 * @ptr:    the &struct list_head pointer.
 * @type:   the type of the struct this is embedded in.
 * @member: the name of the list_struct within the struct.
 */
#define list_entry(ptr, type, member) \
    ((type *)((char *)(ptr)-(unsigned long)(&((type *)0)->member)))

/**
 * list_for_each - iterate over a list
 * @pos:    the &struct list_head to use as a loop counter.
 * @head:   the head for your list.
 */
#define list_for_each(pos, head) \
    for (pos = (head)->next; pos != (head); pos = pos->next)

/**
 * list_for_each_safe   -   iterate over a list safe against removal of list entry
 * @pos:    the &struct list_head to use as a loop counter.
 * @n:      another &struct list_head to use as temporary storage
 * @head:   the head for your list.
 */
#define list_for_each_safe(pos, n, head) \
    for (pos = (head)->next, n = pos->next; pos != (head); \
        pos = n, n = pos->next)

#endif /* defined _NTFS_LIST_H */

2.測試程式碼

 #include <stdio.h>
#include "list.h"

struct person
{
    int age;
    int weight;
    struct list_head list;
};

void person_test()
{
    struct person *tmp;
    struct list_head *pos, *n;
    int age_i, weight_j;

    // 定義並初始化一個連結串列頭
    struct list_head person_head;
    INIT_LIST_HEAD(&person_head);
    weight_j = 35;
    for(age_i = 10; age_i < 40; age_i += 5)
    {
        weight_j += 5;
        tmp =(struct person*)malloc(sizeof(struct person));
        tmp->age = age_i;
        tmp->weight = weight_j;

        // 把這個節點連結到連結串列後面
        // 這裡因為每次的節點都是加在person_head的後面，所以先加進來的節點就在連結串列裡的最後面
        // 列印的時候看到的順序就是先加進來的就在最後面列印
        list_add(&(tmp->list), &(person_head));

    }

    // 下面把這個連結串列中各個節點的值打印出來
    printf("\n");
    printf("=========== print the list ===============\n");
    list_for_each(pos, &person_head)
    {
        // 這裡我們用list_entry來取得pos所在的結構的指標
        tmp = list_entry(pos, struct person, list);
        printf("age:%d,  weight: %d \n", tmp->age, tmp->weight);
    }
    printf("\n");

    // 下面刪除一個節點中，age為20的節點
    printf("========== print list after delete a node which age is 20 ==========\n");
    list_for_each_safe(pos, n, &person_head)
    {
        tmp = list_entry(pos, struct person, list);
        if(tmp->age == 20)
        {
            list_del_init(pos);
            free(tmp);
        }

    }

    list_for_each(pos, &person_head)
    {
        tmp = list_entry(pos, struct person, list);
        printf("age:%d,  weight: %d \n", tmp->age, tmp->weight);
    }

    list_for_each_safe(pos, n, &person_head)
    {
        tmp = list_entry(pos, struct person, list);
        list_del_init(pos);
        free(tmp);
    }
    // 釋放資源
}

int main(int argc, char* argv[])
{   
    person_test();
    return 0;
}