list.h链表使用

- 日理万妓 2022-05-14 00:17 163阅读 0赞

# 1.头文件 #

/*
     * 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.测试代码 #

#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;
    
        // 定义并初始化一个链表头
        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;
    
            // 把这个节点链接到链表后面
            // 这里因为每次的节点都是加在person_head的后面，所以先加进来的节点就在链表里的最后面
            // 打印的时候看到的顺序就是先加进来的就在最后面打印
            list_add(&(tmp->list), &(person_head));
    
        }
    
        // 下面把这个链表中各个节点的值打印出来
        printf("\n");
        printf("=========== print the list ===============\n");
        list_for_each(pos, &person_head)
        {
            // 这里我们用list_entry来取得pos所在的结构的指针
            tmp = list_entry(pos, struct person, list);
            printf("age:%d, weight: %d \n", tmp->age, tmp->weight);
        }
        printf("\n");
    
        // 下面删除一个节点中，age为20的节点
        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);
        }
        // 释放资源
    }
    
    int main(int argc, char* argv[])
    {   
        person_test();
        return 0;
    }