写一份代码c++，将文件中的数据读取出来并存储到链表中，包括1打开文件，2 读取文件 3 关闭文件 和将链表中的数据存储到文件中1打开文件，2 读取文件 3 关闭文件

以下是c++代码实现：

#include <iostream>
#include <fstream>
using namespace std;

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

void readFile(Node*& head, const string& filename) {
    ifstream file(filename);
    if (file.is_open()) {
        int value;
        while (file >> value) {
            Node* newNode = new Node;
            newNode->data = value;
            newNode->next = nullptr;
            if (head == nullptr) {
                head = newNode;
            }
            else {
                Node* current = head;
                while (current->next != nullptr) {
                    current = current->next;
                }
                current->next = newNode;
            }
        }
        file.close();
        cout << "File read successfully!" << endl;
    }
    else {
        cout << "Error opening file!" << endl;
    }
}

void writeFile(Node* head, const string& filename) {
    ofstream file(filename);
    if (file.is_open()) {
        Node* current = head;
        while (current != nullptr) {
            file << current->data << endl;
            current = current->next;
        }
        file.close();
        cout << "File written successfully!" << endl;
    }
    else {
        cout << "Error opening file!" << endl;
    }
}

void printList(Node* head) {
    Node* current = head;
    while (current != nullptr) {
        cout << current->data << " ";
        current = current->next;
    }
    cout << endl;
}

int main() {
    Node* head = nullptr;
    const string filename = "data.txt";
    // read file
    readFile(head, filename);
    // print list
    cout << "Data in linked list: ";
    printList(head);
    // write file
    writeFile(head, "output.txt");
    // deallocate memory
    Node* current = head;
    while (current != nullptr) {
        Node* temp = current;
        current = current->next;
        delete temp;
    }
    return 0;
}

这段代码实现了将文件中的数据读取出来并存储到链表中，以及将链表中的数据存储到文件中的功能。其中，`readFile`函数负责读取文件，`writeFile`函数负责写入文件，`printList`函数负责打印链表中的数据。需要注意的是，在读取完文件后，需要手动释放链表内存，避免内存泄漏。