c语言双向循环链表基本操作,请用代码展示

以下是 C 语言双向循环链表的基本操作代码：

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

struct Node {
    int data;
    struct Node* prev;
    struct Node* next;
};

struct Node* head = NULL;

// 在链表末尾插入节点
void insert(int data) {
    struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));
    newNode->data = data;
    newNode->prev = NULL;
    newNode->next = NULL;

    if (head == NULL) {
        head = newNode;
        head->prev = head;
        head->next = head;
    } else {
        struct Node* lastNode = head->prev;
        lastNode->next = newNode;
        newNode->prev = lastNode;
        newNode->next = head;
        head->prev = newNode;
    }
}

// 在链表中删除节点
void delete(int data) {
    if (head == NULL) {
        printf("链表为空，无法删除节点！\n");
        return;
    }

    struct Node* currentNode = head;
    while (currentNode->data != data) {
        currentNode = currentNode->next;
        if (currentNode == head) {
            printf("链表中没有该节点！\n");
            return;
        }
    }

    if (currentNode == head) {
        head = head->next;
    }

    struct Node* prevNode = currentNode->prev;
    struct Node* nextNode = currentNode->next;
    prevNode->next = nextNode;
    nextNode->prev = prevNode;

    free(currentNode);
}

// 在链表中查找节点
void search(int data) {
    if (head == NULL) {
        printf("链表为空，无法查找节点！\n");
        return;
    }

    struct Node* currentNode = head;
    while (currentNode->data != data) {
        currentNode = currentNode->next;
        if (currentNode == head) {
            printf("链表中没有该节点！\n");
            return;
        }
    }

    printf("链表中存在节点 %d\n", data);
}

// 打印链表中的所有节点
void print() {
    if (head == NULL) {
        printf("链表为空，无法打印节点！\n");
        return;
    }

    struct Node* currentNode = head;
    do {
        printf("%d ", currentNode->data);
        currentNode = currentNode->next;
    } while (currentNode != head);
    printf("\n");
}

int main() {
    insert(1);
    insert(2);
    insert(3);
    insert(4);
    insert(5);

    print(); // 输出：1 2 3 4 5

    delete(3);

    print(); // 输出：1 2 4 5

    search(4); // 输出：链表中存在节点 4

    return 0;
}

以上代码实现了双向循环链表的基本操作，包括在链表末尾插入节点、在链表中删除节点、在链表中查找节点以及打印链表中的所有节点。