帮我用C语言写一个双向链表

好的，我可以回答这个问题。以下是一个简单的双向链表的 C 语言实现：

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

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

struct Node* head = NULL;
struct Node* tail = NULL;

void insertAtBeginning(int data) {
    struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));
    newNode->data = data;
    newNode->prev = NULL;
    newNode->next = head;
    if (head != NULL) {
        head->prev = newNode;
    } else {
        tail = newNode;
    }
    head = newNode;
}

void insertAtEnd(int data) {
    struct Node* newNode = (struct Node*)malloc(sizeof(struct Node));
    newNode->data = data;
    newNode->prev = tail;
    newNode->next = NULL;
    if (tail != NULL) {
        tail->next = newNode;
    } else {
        head = newNode;
    }
    tail = newNode;
}

void delete(int data) {
    struct Node* current = head;
    while (current != NULL) {
        if (current->data == data) {
            if (current == head) {
                head = current->next;
            } else {
                current->prev->next = current->next;
            }
            if (current == tail) {
                tail = current->prev;
            } else {
                current->next->prev = current->prev;
            }
            free(current);
            return;
        }
        current = current->next;
    }
}

void printList() {
    struct Node* current = head;
    while (current != NULL) {
        printf("%d ", current->data);
        current = current->next;
    }
    printf("\n");
}

int main() {
    insertAtBeginning(1);
    insertAtEnd(2);
    insertAtEnd(3);
    insertAtBeginning(4);
    printList();
    delete(2);
    printList();
    return ;
}

这个程序实现了双向链表的基本操作，包括在链表头和尾插入节点，删除指定节点，以及打印链表中的所有节点。