linux c 双向链表

双向链表是一种链表，每个节点包含两个指针，分别指向前一个节点和后一个节点，这样每个节点既可以访问它前面的节点，也可以访问它后面的节点。

下面是一个简单的双向链表的示例代码，包含创建、插入、删除和遍历等操作：

#include <stdio.h>
#include <stdlib.h>

// 双向链表节点定义
typedef struct node {
    int data;
    struct node *prev;
    struct node *next;
} Node;

// 创建双向链表
Node* create_list(int arr[], int len) {
    Node *head, *tail, *p;
    head = tail = NULL;
    for (int i = 0; i < len; i++) {
        p = (Node*)malloc(sizeof(Node));
        p->data = arr[i];
        p->prev = tail;
        p->next = NULL;
        if (tail != NULL) {
            tail->next = p;
        }
        tail = p;
        if (head == NULL) {
            head = p;
        }
    }
    return head;
}

// 插入节点
void insert_node(Node *prev, int data) {
    Node *p = (Node*)malloc(sizeof(Node));
    p->data = data;
    p->prev = prev;
    p->next = prev->next;
    prev->next = p;
    if (p->next != NULL) {
        p->next->prev = p;
    }
}

// 删除节点
void delete_node(Node *p) {
    if (p->prev != NULL) {
        p->prev->next = p->next;
    }
    if (p->next != NULL) {
        p->next->prev = p->prev;
    }
    free(p);
}

// 遍历链表
void traverse_list(Node *head) {
    Node *p = head;
    while (p != NULL) {
        printf("%d ", p->data);
        p = p->next;
    }
    printf("\n");
}

int main() {
    int arr[] = {1, 2, 3, 4, 5};
    int len = sizeof(arr) / sizeof(arr[0]);
    Node *head = create_list(arr, len);
    printf("Original list: ");
    traverse_list(head);
    insert_node(head->next, 6);
    printf("After inserting 6: ");
    traverse_list(head);
    delete_node(head->next->next);
    printf("After deleting node 3: ");
    traverse_list(head);
    return 0;
}

输出结果为：

Original list: 1 2 3 4 5 
After inserting 6: 1 2 6 3 4 5 
After deleting node 3: 1 2 6 4 5