list_for_each_entry含义以及示例

`list_for_each_entry` 是 Linux 内核中用于遍历双向链表的宏，它可以在链表中遍历每个节点，并且可以访问每个节点的成员。

它的语法如下：

list_for_each_entry(pos, head, member)

其中，`pos` 是遍历链表时当前节点的指针，`head` 是链表头指针，`member` 是链表节点中指向下一个节点的成员指针。

下面是一个示例：

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

struct student {
    char name[20];
    int age;
    struct list_head list;
};

int main()
{
    struct student *stu1, *stu2, *stu3;
    struct student *pos;
    struct list_head *head;
    int i;

    // 初始化链表头
    head = (struct list_head *)malloc(sizeof(struct list_head));
    INIT_LIST_HEAD(head);

    // 添加节点到链表
    stu1 = (struct student *)malloc(sizeof(struct student));
    strcpy(stu1->name, "Tom");
    stu1->age = 18;
    list_add_tail(&stu1->list, head);

    stu2 = (struct student *)malloc(sizeof(struct student));
    strcpy(stu2->name, "Jerry");
    stu2->age = 20;
    list_add_tail(&stu2->list, head);

    stu3 = (struct student *)malloc(sizeof(struct student));
    strcpy(stu3->name, "Mike");
    stu3->age = 22;
    list_add_tail(&stu3->list, head);

    // 遍历链表
    printf("遍历链表:\n");
    list_for_each_entry(pos, head, list) {
        printf("name: %s, age: %d\n", pos->name, pos->age);
    }

    // 释放节点
    list_for_each_entry(pos, head, list) {
        list_del(&pos->list);
        free(pos);
    }

    // 释放链表头
    free(head);

    return 0;
}

输出结果：

遍历链表:
name: Tom, age: 18
name: Jerry, age: 20
name: Mike, age: 22