、编写三个函数，实现 （1）遍历一个双向链表 （2）插入一个节点 （3）删除一个节点

好的，这是一个关于编程的问题，让我来回答。

1. 遍历双向链表的函数实现：

void traverseList(Node* head) {
    Node* curr = head;
    while (curr != NULL) {
        // 处理当前节点
        curr = curr->next;
    }
}

2. 插入节点的函数实现：

void insertNode(Node* head, Node* newNode, int index) {
    if (head == NULL) {
        head = newNode;
        return;
    }

    Node* curr = head;
    int i = 0;
    while (curr != NULL && i < index - 1) {
        curr = curr->next;
        i++;
    }

    if (curr == NULL) {
        return;
    }

    newNode->next = curr->next;
    newNode->prev = curr;
    curr->next = newNode;
    if (newNode->next != NULL) {
        newNode->next->prev = newNode;
    }
}

3. 删除节点的函数实现：

void deleteNode(Node* head, int index) {
    if (head == NULL) {
        return;
    }

    Node* curr = head;
    int i = 0;
    while (curr != NULL && i < index - 1) {
        curr = curr->next;
        i++;
    }

    if (curr == NULL || curr->next == NULL) {
        return;
    }

    Node* temp = curr->next;
    curr->next = temp->next;
    if (temp->next != NULL) {
        temp->next->prev = curr;
    }
    free(temp);
}

希望我的回答能够帮助到您！