使用结构体和指针存储线性表结构，实现线性表的以 下操作：求链表节点总数、添加新节点、输出所有节点、任意位置插入新节点、删除节 点、查找节点。

在使用结构体和指针来存储线性表时，首先定义一个结构体表示链表节点，通常包含数据域和指向下一个节点的指针。以下是实现基本操作的步骤：

1. **定义链表节点结构** (Node.h):

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

2. **初始化操作** - 求节点总数:

int countNodes(Node* head) {
    int count = 0;
    if (head != nullptr) {
        while (head) {
            count++;
            head = head->next;
        }
    }
    return count;
}

3. **添加新节点** - 使用`push_back`方法(例如在C++里)：

void addNode(int value, Node*& head) {
    Node* newNode = new Node{value, nullptr};
    if (head == nullptr) {
        head = newNode;
    } else {
        Node* current = head;
        while (current->next != nullptr) {
            current = current->next;
        }
        current->next = newNode;
    }
}

4. **输出所有节点**:

void printList(Node* head) {
    if (head != nullptr) {
        Node* temp = head;
        while (temp) {
            std::cout << temp->data << " ";
            temp = temp->next;
        }
        std::cout << "\n";
    }
}

5. **任意位置插入新节点**:

void insertAtPosition(int value, int position, Node*& head) {
    Node* newNode = new Node{value, nullptr};
    if (position <= 0) {
        newNode->next = head;
        head = newNode;
    } else {
        Node* current = head;
        for (int i = 1; i < position && current != nullptr; ++i) {
            current = current->next;
        }
        if (current != nullptr) {
            newNode->next = current->next;
            current->next = newNode;
        }
    }
}

6. **删除节点** - 删除指定值的节点:

void removeNode(int value, Node*& head) {
    if (head != nullptr) {
        if (head->data == value) {
            Node* temp = head;
            head = head->next;
            delete temp;
            return;
        }
        Node* current = head;
        while (current->next != nullptr && current->next->data != value) {
            current = current->next;
        }
        if (current->next != nullptr) {
            Node* toDelete = current->next;
            current->next = current->next->next;
            delete toDelete;
        }
    }
}

7. **查找节点** - 查找特定值的节点:

Node* findNode(int value, Node* head) {
    Node* current = head;
    while (current != nullptr) {
        if (current->data == value) {
            return current;
        }
        current = current->next;
    }
    return nullptr;
}