1.编写链表，链表里面随便搞点数据，使用 fprintf 将链表中所有的数据，保存到文件中，使用 fscanf 读取文件中的数据，写入链表中

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

// 定义链表节点结构体
struct ListNode {
    int data;
    struct ListNode* next;
};

// 链表操作函数
struct ListNode* createList() {
    struct ListNode* head = NULL;
    struct ListNode* curr = NULL;

    // 插入节点到链表
    int num;
    printf("请输入链表数据（以 0 结束）：\n");
    scanf("%d", &num);

    while (num!= 0) {
        struct ListNode* newNode = (struct ListNode*)malloc(sizeof(struct ListNode));
        newNode->data = num;
        newNode->next = NULL;

        if (head == NULL) {
            head = newNode;
        } else {
            curr->next = newNode;
        }
        curr = newNode;
        scanf("%d", &num);
    }

    return head;
}

// 将链表数据保存到文件
void saveListToFile(struct ListNode* head, const char* filename) {
    FILE* file = fopen(filename, "w");
    if (file == NULL) {
        printf("无法打开文件!\n");
        return;
    }

    struct ListNode* curr = head;
    while (curr!= NULL) {
        fprintf(file, "%d\n", curr->data);
        curr = curr->next;
    }

    fclose(file);
    printf("链表数据已成功保存到文件!\n");
}

// 从文件中读取数据并写入链表
struct ListNode* readListFromFile(const char* filename) {
    FILE* file = fopen(filename, "r");
    if (file == NULL) {
        printf("无法打开文件!\n");
        return NULL;
    }

    struct ListNode* head = NULL;
    struct ListNode* curr = NULL;
    int data;

    // 从文件中读取数据并插入链表
    while (fscanf(file, "%d", &data) == 1) {
        struct ListNode* newNode = (struct ListNode*)malloc(sizeof(struct ListNode));
        newNode->data = data;
        newNode->next = NULL;

        if (head == NULL) {
            head = newNode;
        } else {
            curr->next = newNode;
        }
        curr = newNode;
    }

    fclose(file);
    return head;
}

int main() {
    struct ListNode* list = createList();

    // 保存链表数据到文件
    saveListToFile(list, "list_data.txt");

    struct ListNode* newList = readListFromFile("list_data.txt");

    // 遍历链表并打印数据
    if (newList!= NULL) {
        struct ListNode* curr = newList;
        while (curr!= NULL) {
            printf("%d ", curr->data);
            curr = curr->next;
        }
        printf("\n");
    } else {
        printf("从文件中读取数据失败!\n");
    }

    return 0;
}