应用程序设计：图书管理系统模板（链表+文件）

概述
        主要包括图书的库存信息，每一本书的借阅信息以及每个人的借书信息。
系统功能：
    （1）借阅资料管理（对相关资料进行添加，删除，修改，查询等操做）
    （2）借阅管理（包括借出操做，还书操做）
    （3）读者管理（读者等级：可分为教师，学生。并定义每类读者可借书数量）
    （4）统计分析（当前借阅和相关资料状态。统计分析借阅排行榜，资料状态统计，借阅统计，显示全部至当日到期未还书信息等功能分析）

若是以为链表麻烦的话能够使用（数组+文件）：https://blog.csdn.net/qq_30253757/article/details/85341155

管理员用户名和密码都是admin

#include <iostream>
#include <cstdio>
#include <cstring>
#include <string>
#include <cmath>
#include <cstring>
#include <windows.h>
#include <ctime>
#include <cstdlib>
using namespace std;
typedef struct books //书籍编号————（做者，名称，出版时间，价格）与书籍编号一一对应，不然为新一类书
{                    //数量
    int book_id;
    char author[50], book_name[50];
    int time, count;
    double price;
    struct books *next;
} BOOK, *Pbook;
typedef struct have_been_borrowed //已借出的图书信息，书籍编号，借书编号，借书数量，书名，所借人的帐号名
{
    int book_id;
    int borrowed_book_id;
    int count;
    char book_name[50];
    char student_id[50];
    struct have_been_borrowed *next;
} BORROW, *Pborrow;
typedef struct users //用户信息：用户id，帐户名，密码，所借书的上限
{
    long long int user_id;
    char user_name[50];
    char passwd[50];
    int book_limit;
    int job;
    struct users *next;
} USERS, *Pusers;
Pusers user_now = NULL;
/**************************如下为函数声明**********************************/
void user_error();                                                                          //无用户信息的错误提示
int read_books_information_to_file(Pbook head, Pborrow head2, Pusers head3);                //文件的读取
void welcome();                                                                             //欢迎界面
void null_error();                                                                          //图书库为空的报错信息
void list_borrow(Pborrow head);                                                             //打印已借图书信息
void addbook(struct books *head);                                                           //添加书籍信息
void list(Pbook head);                                                                      //打印全部书籍信息
int search(Pbook head);                                                                     //搜寻书籍信息
int modify(Pbook p);                                                                        //搜寻结束后可进行查找
int del(Pbook before, Pbook will_be_del);                                                   //删除该图书信息
int borrow(Pbook head, Pborrow borrowed);                                                   //借书功能
void return_book_list(Pborrow head, Pbook origin);                                          //还书的列表（便于控制函数的调用）
int return_book(Pborrow head_list, Pbook origin);                                           //还书功能
int return_book_by_student_id(Pborrow head, Pbook origin);                                  //经过学号还书
void add_borrow(Pbook d, Pborrow head, int a, int b, int c, char name[], char book_name[]); //已借的书的添加
void borrowor(Pbook head, Pborrow borrowed);                                                //借书菜单
void del_user(Pusers head);                                                                 //删除用户
int add_users(Pusers head);                                                                 //增长用户
void user_list(Pusers head);                                                                //打印全部用户信息
int user_manage(Pusers head);                                                               //用户管理主列表
int save_books_information_to_file(Pbook head, Pborrow head2, Pusers head3);                //文件的保存
/**************************以上为函数声明**********************************/
/***************************图书基础功能***********************************/
int read_books_information_to_file(Pbook head, Pborrow head2, Pusers head3)
{
    FILE *p = fopen("books_information.dat", "r"), *q = fopen("borrowed_books.dat", "r");
    FILE *u = fopen("users_information.dat", "r");
    if (p == NULL || q == NULL || u == NULL)
    {
        cout << "文件不存在。。。" << endl
             << "已重建相关文件" << endl;
        system("pause");
        system("cls");
        return 1;
    }
    Pbook books_head = head;
    Pborrow borrowed_head = head2;
    Pusers users_head = head3;
    int a, b, k;
    char name[50];
    char author[50];
    double price;
    while (fscanf(p, "%d%s%s%d%lf%d", &a, name, author, &k, &price, &b) != EOF)
    {
        Pbook before = (Pbook)malloc(sizeof(BOOK));
        before->book_id = a;
        strcpy(before->book_name, name);
        strcpy(before->author, author);
        before->count = b;
        before->time = k;
        before->price = price;
        books_head->next = before;
        before->next = NULL;
        books_head = before;
    }
    int c, d, e;
    char borrow_name[50];
    char student_id[50];
    while (fscanf(q, "%d%s%d%d%s", &c, borrow_name, &d, &e, &student_id) != EOF)
    {
        Pborrow after = (Pborrow)malloc(sizeof(BORROW));
        after->book_id = c;
        strcpy(after->book_name, borrow_name);
        after->borrowed_book_id = d;
        after->count = e;
        strcpy(after->student_id, student_id);
        borrowed_head->next = after;
        after->next = NULL;
        borrowed_head = after;
    }
    long long user_id;
    char user_name[50];
    char passwd[50];
    int book_limit;
    int job;
    while (fscanf(u, "%lld%s%s%d%d", &user_id, user_name, passwd, &book_limit,&job) != EOF)
    {
        Pusers english = (Pusers)malloc(sizeof(USERS));
        english->user_id = user_id;
        strcpy(english->user_name, user_name);
        strcpy(english->passwd, passwd);
        english->book_limit = book_limit;
        english->job=job;
        users_head->next = english;
        english->next = NULL;
        users_head = english;
    }
    fclose(p);
    fclose(q);
    fclose(u);
    return 0;
}
int save_books_information_to_file(Pbook head, Pborrow head2, Pusers head3)
{
    system("cls");
	FILE *p = fopen("books_information.dat", "w");
	FILE *bore = fopen("borrowed_books.dat", "w");
    FILE *u = fopen("users_information.dat", "w");
	if (p == NULL )
	{
		cout << "打开文件失败！！！，请重试。。。" << endl;
		return 1;
	}
	if ( bore == NULL)
	{
		cout << "打开文件失败！！！，请重试。。。" << endl;
		return 1;
	}
	if ( u == NULL)
	{
		cout << "打开文件失败！！！，请重试。。。" << endl;
		return 1;
	}
    Pbook q = head->next;
    Pborrow w = head2->next;
    Pusers eng = head3->next;
    cout << "正在写入文件，请稍后。。。" << endl;
    Sleep(1500);
    while (q != NULL)
    {
        fprintf(p, "%d %s %s %d %f %d\n", q->book_id, q->book_name, q->author, q->time, q->price, q->count);
        q = q->next;
    }
    while (w != NULL)
    {
        fprintf(bore, "%d %s %d %d %s\n", w->book_id, w->book_name, w->borrowed_book_id, w->count, w->student_id);
        w = w->next;
    }
    while (eng != NULL)
    {
        fprintf(u, "%lld %s %s %d %d\n", eng->user_id, eng->user_name, eng->passwd, eng->book_limit,eng->job);
        eng = eng->next;
    }
    system("cls");
    cout << "写入完成。请稍后。。。" << endl;
    fclose(p);
    fclose(bore);
	fclose(u);
    return 0;
}
void list_borrow(Pborrow head)
{
    if (head->next == NULL)
    {
        system("cls");
        cout << "数据库无借阅信息" << endl;
        cout << "请按回车退出 。。。" << endl;
        getchar();
        getchar();
        return;
    }
    system("cls");
    for (int i = 0; i < 56; i++)
        printf("*");
    printf("\n");
    printf("* %11s", "借阅编号");
    printf("%11s", "图书编号");
    printf("%10s", "借阅数量");
    printf("%18s   *\n", "借阅者帐号");
    Pborrow p = head->next;
    while (p != NULL)
    {
        printf("* %11d", p->borrowed_book_id);
        printf("%11d", p->book_id);
        printf("%10d", p->count);
        printf("%18s   *\n", p->student_id);
        p = p->next;
    }
    for (int i = 0; i < 56; i++)
        printf("*");
    cout << endl
         << "输入回车继续。。。" << endl;
    getchar();
    getchar();
    system("cls");
}
void addbook(struct books *head)
{
    int id, time, count;
    char name[50], author[50];
    double price;
    struct books *q = head;
    while (1)
    {
        system("cls");
        cout << "请输入书籍编号" << endl;
        cin >> id;
        cout << "请输入书籍名称" << endl;
        scanf("%s", name);
        cout << "请输入做者名字" << endl;
        scanf("%s", author);
        cout << "请输入出版时间" << endl;
        cin >> time;
        cout << "请输入书籍价格" << endl;
        cin >> price;
        cout << "请输入书籍数量" << endl;
        cin >> count;
        while (q->next != NULL)
        {
            if (id == q->next->book_id && strcmp(name, q->next->book_name) == 0 && strcmp(author, q->next->author) == 0)
            {
                if (time == q->next->time && price == q->next->price)
                {
                    q->next->count += count;
                    system("cls");
                    cout << "图书添加成功。。。" << endl;
                    Sleep(1000);
                    system("cls");
                    break;
                }
            }
            q = q->next;
        }
        if (q->next == NULL)
        {
            struct books *p;
            p = (struct books *)malloc(sizeof(struct books));
            q->next = p;
            p->next = NULL;
            p->book_id = id;
            p->count = count;
            p->price = price;
            p->time = time;
            strcpy(p->book_name, name);
            strcpy(p->author, author);
            cout << "图书添加成功。。。" << endl;
            Sleep(1000);
        }
        system("cls");
        int in;
        cout << "是否要继续？" << endl
             << "*****************" << endl
             << "*    1.继续     *" << endl
             << "*    0.结束     *" << endl
             << "*****************" << endl;
        cin >> in;
        if (in == 0)
            return;
    }
}
void null_error()
{
    system("cls");
    cout << "数据库无图书信息，请先添加图书信息" << endl;
    cout << "请按回车退出搜索。。。" << endl;
	system("pause");
}
void list(Pbook head)
{
    if (head->next == NULL)
    {
		null_error();
        return;
    }
    system("cls");
    for (int i = 0; i < 70; i++)
        printf("*");
    printf("\n");
    printf("* %8s", "图书编号");
    printf("%14s", "图书名称");
    printf("%10s", "做者");
    printf("%14s", "时间");
    printf("%10s", "价格");
    printf("%10s *\n", "数量");
    Pbook p = head->next;
    while (p != NULL)
    {
        printf("* %8d", p->book_id);
        printf("%14s", p->book_name);
        printf("%10s", p->author);
        printf("%14d", p->time);
        printf("%10.2f", p->price);
        printf("%10d *\n", p->count);
        p = p->next;
    }
    for (int i = 0; i < 70; i++)
        printf("*");
    cout << endl
         << "输入回车继续。。。" << endl;
	system("pause");
    system("cls");
}
/*************************图书查找，修改，删除功能区*******************************/
int search(Pbook head)
{
    int want_to_search, flag;
    while (1)
    {
        Pbook p = head->next, before = head;
        flag = 0;
        if (head->next == NULL)
        {
			null_error();
            return 0;
        }
        system("cls");
        cout << "请输入要搜索的图书编号：";
        cin >> want_to_search;
        system("cls");
        cout << "正在寻找，请稍后。。。";
        while (p != NULL)
        {
            if (p->book_id == want_to_search)
            {
                system("cls");
                flag = 1;
                break;
            }
            before = p;
            p = p->next;
        }
        if (flag == 0)
        {
            system("cls");
            cout << "未查找到相应图书信息\n";
            cout << "接下来要作什么？" << endl
                 << "\t1.继续查找" << endl
                 << "\t0.结束" << endl;
            int in;
            cin >> in;
            if (in == 1)
                continue;
            else
                return 0;
        }
        else
        {
            int in;
            system("cls");
            cout << "已找到相关图书，接下来要作什么？" << endl;
            while (1)
            {
                int flag1 = 0;
                cout << "******************************" << endl;
                cout << "*    1.打印相关图书信息      *" << endl;
                cout << "*    2.对相关图书进行修改    *" << endl;
                cout << "*    3.删除该图书信息        *" << endl;
                cout << "*    4.继续查找              *" << endl;
                cout << "*    0.退出                  *" << endl;
                cout << "******************************" << endl;
                cin >> in;
                switch (in)
                {
                case 1:
                    system("cls");
                    for (int i = 0; i < 70; i++)
                        printf("*");
                    printf("\n* %8s", "图书编号");
                    printf("%14s", "图书名称");
                    printf("%10s", "做者");
                    printf("%14s", "时间");
                    printf("%10s", "价格");
                    printf("%10s *\n", "数量");
                    printf("* %8d", p->book_id);
                    printf("%14s", p->book_name);
                    printf("%10s", p->author);
                    printf("%14d", p->time);
                    printf("%10.2f", p->price);
                    printf("%10d *\n", p->count);
                    for (int i = 0; i < 70; i++)
                        printf("*");
                    cout << endl
                         << "输入以回车继续。。。";
                    getchar();
                    getchar();
                    system("cls");
                    flag = 0;
                    break;
                case 2:
                    if (modify(p) == 1)
                    {
                        flag1 = 1;
                        break;
                    }
                    else
                    {
                        flag1 = 0;
                        break;
                    }
                case 3:
                    if (del(before, p) == 1)
                    {
                        return 1;
                    }
                    else
                    {
                        return 0;
                    }
                case 4:
                    flag1 = 1;
                    break;
                case 0:
                    return 0;
                }
                if (flag1 == 1)
                    break;
                else
                {
                    system("cls");
                    cout << "还须要作什么？" << endl;
                    continue;
                }
            }
        }
    }
}
int del(Pbook before, Pbook will_be_del)
{
    before->next = will_be_del->next;
    free(will_be_del);
    system("cls");
    cout << "该图书信息已被删除" << endl
         << "你还须要作什么？" << endl;
    while (1)
    {
        cout << "**********************" << endl
             << "*    1.继续搜索       *" << endl
             << "*    0.退出搜索       *" << endl
             << "**********************" << endl;
        int in;
        cin >> in;
        if (in == 1)
        {
            return 1;
        }
        else if (in == 0)
            return 0;
        else
        {
            cout << "输入错误，请从新选择" << endl;
            continue;
        }
    }
}
int modify(Pbook p)
{
    system("cls");
    cout << "您须要作什么？" << endl;
    int in;
    while (1)
    {
        cout << "*************************" << endl;
        cout << "*     1.修改图书名称    *" << endl;
        cout << "*     2.修改做者        *" << endl;
        cout << "*     3.修改出版时间    *" << endl;
        cout << "*     4.修改价格        *" << endl;
        cout << "*     5.修改数量        *" << endl;
        cout << "*     6.回到上一目录    *" << endl;
        cout << "*     0.退出            *" << endl;
        cout << "*************************" << endl;
        cin >> in;
        system("cls");
        switch (in)
        {
        case 1:
            cout << "原有的图书名称为：" << p->book_name << endl
                 << "请键入修改后的名称:";
            scanf("%s", p->book_name);
            break;
        case 2:
            cout << "原有的做者为：" << p->author << endl
                 << "请键入修改后的做者：";
            scanf("%s", p->author);
            break;
        case 3:
            cout << "原有的出版时间为：" << p->time << endl;
            cout << "请键入修改后的时间：";
            cin >> p->time;
            break;
        case 4:
            cout << "原有的价格为：" << p->price << endl;
            cout << "请键入修改后的价格：";
            cin >> p->price;
            break;
        case 5:
            cout << "原有的数量为：" << p->count << endl;
            cout << "请键入修改后的数量：";
            cin >> p->count;
            break;
        case 6:
            return 0;
            break;
        case 0:
            return 1;
            break;
        }
        system("cls");
        cout << "信息修改为功，按回车继续。。。" << endl;
		system("pause");
        system("cls");
        cout << "您还须要作什么？" << endl;
    }
}
/************************************借阅功能区**************************************************/
void borrowor(Pbook head, Pborrow borrowed)
{
    system("cls");
    if (head->next == NULL)
    {
		null_error();
        return;
    }
    int in;
    cout << "您要作什么" << endl;
    while (1)
    {
        cout << "***************************" << endl
             << "*       1.借阅图书       *" << endl
             << "*       2.归还图书       *" << endl
             << "*       0.退出           *" << endl
             << "***************************" << endl;
        cin >> in;
        int tsl;
        switch (in)
        {
        case 1:
            tsl = borrow(head, borrowed);
            while (tsl != 0)
            {
                tsl = borrow(head, borrowed);
            }
            break;
        case 2:
            return_book_list(borrowed, head);
            break;
        case 0:
            return;
        }
        system("cls");
        cout << "您还须要作什么？" << endl;
    }
}
int borrow(Pbook head, Pborrow borrowed)
{
    system("cls");
    cout << "请输入搜寻根据" << endl;
    cout << "*************************" << endl
         << "*       1.图书编号	*" << endl
         << "*       2.图书名称      *" << endl
         << "*       3.图书做者      *" << endl
         << "*       0.退出          *" << endl
         << "*************************" << endl;
    int in;
    cin >> in;
    system("cls");
    int want_to_find_num;
    char want_to_find_name[50];
    char want_to_find_author[50];
    switch (in)
    {
    case 1:
        cout << "请输入图书编号：";
        cin >> want_to_find_num;
        break;
    case 2:
        cout << "请输入图书名称：";
        cin >> want_to_find_name;
        break;
    case 3:
        cout << "请输入图书做者：";
        cin >> want_to_find_author;
        break;
    case 0:
        return 0;
    }
    Pbook p = head->next;
    int flag2 = 0;
    while (p != NULL)
    {
        switch (in)
        {
        case 1:
            if (want_to_find_num == p->book_id)
                flag2 = 1;
            break;
        case 2:
            if (strcmp(want_to_find_name, p->book_name) == 0)
                flag2 = 1;
            break;
        case 3:
            if (strcmp(want_to_find_author, p->author) == 0)
                flag2 = 1;
            break;
        }
        if (flag2 == 1)
            break;
        p = p->next;
    }
    if (flag2 == 0)
    {
        system("cls");
        cout << "未找到相关图书，是否借阅其它图书？" << endl;
        cout << "********************" << endl
             << "*      1.继续      *" << endl
             << "*      0.结束	    *" << endl
             << "********************" << endl;
        int intwice;
        cin >> intwice;
        if (intwice == 1)
            return 1;
        else
            return 0;
    }
    else
    {
        system("cls");
        if (p->count == 0)
        {
            cout << "该图书暂时缺货" << endl
                 << "****************" << endl
                 << "*  1.继续借阅  *" << endl
                 << "*  0.退出      *" << endl
                 << "****************" << endl;
            int in;
            cin >> in;
            if (in == 1)
                return 1;
            else
                return 0;
        }
        cout << "已找到该图书，";
        while (1)
        {
            cout << "目前此书还有" << p->count << "本" << endl
                 << "你如今还能够借阅" << user_now->book_limit << "本书" << endl
                 << "请输入借阅数量（输入0为取消借阅）：" << endl;
            int borrow_count;
            cin >> borrow_count;
            system("cls");
            if (borrow_count > p->count)
            {
                cout << "没这么多书！！！" << endl
                     << "************************" << endl
                     << "*     1.输入其余数量   *" << endl
                     << "*     2.借阅其余图书   *" << endl
                     << "*     0.取消借阅       *" << endl
                     << "************************" << endl;
                int choose_book;
                cin >> choose_book;
                if (choose_book == 2)
                    return 1;
                else if (choose_book == 0)
                    return 0;
                else
                {
                    system("cls");
                    continue;
                }
            }
            else
            {
                p->count -= borrow_count;
                user_now->book_limit -= borrow_count;
                add_borrow(p, borrowed, p->book_id, p->book_id * 10000 + p->count, borrow_count, user_now->user_name, p->book_name);
                cout << "借阅成功，请按时归还。" << endl
                     << "输入回车以继续。。。";
                getchar();
                return 0;
            }
            system("cls");
        }
    }
    return 0;
}
void add_borrow(Pbook d, Pborrow head, int a, int b, int c, char name[], char book_name[])
{
    Pborrow p = head;
    while (p->next != NULL)
        p = p->next;
    Pborrow q = (Pborrow)malloc(sizeof(BORROW));
    q->book_id = a;
    strcpy(q->book_name, book_name);
    q->borrowed_book_id = b;
    q->count = c;
    strcpy(q->student_id, name);
    p->next = q;
    q->next = NULL;
    cout << "请记录您的借书编号：" << b << endl;
    cout << "请按下回车继续。。。";
    getchar();
    getchar();
    system("cls");
    return;
}
void return_book_list(Pborrow head, Pbook origin)
{
    system("cls");
    cout << "请选择：" << endl
         << "**************************" << endl
         << "*     1.经过学号还书      *" << endl
         << "*     2.经过编号还书      *" << endl
         << "*     0.退出             *" << endl
         << "**************************" << endl;
    int in;
    cin >> in;
    system("cls");
    if (in == 1)
    {
        return_book_by_student_id(head, origin);
    }
    else if (in == 2)
    {
        return_book(head, origin);
    }
    else
        return;
}
int return_book_by_student_id(Pborrow head, Pbook origin)
{
    system("cls");
    char student_id[50];
    int flag = 0;
    cout << "请输入您的账号：";
    cin >> student_id;
    system("cls");
    Pborrow p = head->next;
    while (p != NULL)
    {
        if (strcmp(p->student_id, student_id) == 0)
        {
            if (flag == 0)
            {
                flag = 1;
                cout << "****************************************************************" << endl
                     << "*  借书编号      书籍名称      借书数量        借书者学号      *" << endl;
            }
            printf("*%10d", p->borrowed_book_id);
            printf("%14s", p->book_name);
            printf("%14d", p->count);
            printf("%18s      *\n", p->student_id);
        }
        p = p->next;
    }
    if (flag == 1)
    {
        cout << "****************************************************************" << endl;
        return_book(head, origin);
        return 0;
    }
    else
    {
        system("cls");
        cout << "您没有借过书" << endl
             << "按下回车继续。。。" << endl;
        getchar();
        getchar();
        system("cls");
        return 0;
    }
}
int return_book(Pborrow head_list, Pbook origin)
{
    int return_id;
    cout << "请输入您的借书编号以还书（输入0取消还书）：";
    cin >> return_id;
    if (return_id == 0)
    {
        system("cls");
        cout << "取消成功" << endl;
        system("pause");
        return 0;
    }
    int flag = 0;
    Pborrow p = head_list->next, before = head_list;
    while (p != NULL)
    {
        if (p->borrowed_book_id == return_id)
        {
            flag = 1;
            break;
        }
        before = p;
        p = p->next;
    }
    system("cls");
    if (flag == 0)
    {
        cout << "借书编号有误，请从新输入" << endl;
        cout << "按下回车继续";
        getchar();
        getchar();
        system("cls");
        return 1;
    }
    else
    {
        origin->count += p->count;
        user_now->book_limit += p->count;
        before->next = p->next;
        free(p);
        cout << "归还成功。。。";
        Sleep(2000);
        system("cls");
    }
    return 0;
}
int fix_passwd_by_oneself()
{
    system("cls");
    while (1)
    {
        cout << "请输入修改后的密码：";
        char passwd_now[50], again[50];
        cin >> passwd_now;
        cout << "请再次输入密码：";
        cin >> again;
        if (strcmp(passwd_now, again) == 0)
        {
            strcpy(user_now->passwd, passwd_now);
            cout << "密码修改为功。。。" << endl;
            system("pause");
            return 0;
        }
        else
        {
            cout << "两次输入密码不一致。。。" << endl;
            system("pause");
        }
    }
}
/*****************************************用户管理***********************************************/
char administrator[50] = "admin";
char admin_passwd[50] = "admin";
int user_judge(Pusers head)
{
    system("cls");
    char user_id[50];
    cout << "请输入您的帐号：";
    cin >> user_id;
    if (strcmp(administrator, user_id) == 0)
    {
        cout << "请输入密码：";
        char passwd[50];
        cin >> passwd;
        if (strcmp(passwd, admin_passwd) == 0)
            return 2; //权限为2，即最高权限————管理员
    }
    Pusers p = head->next;
    while (p != NULL)
    {
        if (strcmp(p->user_name, user_id) == 0)
        {
            char passwd[50];
            cout << "请输入密码：";
            cin >> passwd;
            int count_limit = 3;
            while (count_limit--)
            {
                if (strcmp(passwd, p->passwd) == 0)
                {
                    user_now = p;
                    return 1;
                } //权限为1，为用户权限
            }
            return 0; //权限为0，即未登陆，没有权限
        }
        p = p->next;
    }
    cout << "暂未收录该用户信息，请联系管理员。。。" << endl;
    system("pause");
    return 0;
}
void user_error()
{
    system("cls");
    cout << "暂未收录任何用户信息" << endl;
    system("pause");
}
void del_user(Pusers head)
{
    if (head->next == NULL)
    {
        user_error();
        return;
    }
    cout << "请输入要注销用户编号：";
    long long id;
    cin >> id;
    Pusers p = head;
    while (p->next != NULL)
    {
        if (id == p->user_id)
        {
            break;
        }
        p = p->next;
    }
    if (p->next == NULL)
    {
        cout << "该用户不存在。。。" << endl;
        system("pause");
        return;
    }
    p->next = p->next->next;
    free(p->next);
    cout << "用户删除成功。。。" << endl;
    system("pause");
    return;
}
int add_users(Pusers head)
{
    system("cls");
    Pusers p = head;
    while (p->next != NULL)
    {
        p = p->next;
    }
    while (1)
    {
		system("cls");
        Pusers q = (Pusers)malloc(sizeof(USERS));
        p->next = q;
        q->next = NULL;
        char idid[50];
        int flag = 1;
        while (flag)
        {
            cout << "请输入用户编号(编号为数字)：";
            cin >> idid;
            q->user_id=0;
            long long ten=1;
            for (int i = strlen(idid)-1; i >=0 ; i--)
            {
                if (idid[i] >= '0' && idid[i] <= '9')
                {
                    q->user_id +=( idid[i] - '0')*ten;
                    flag = 0;
                    ten*=10;
                }
                else
                {
                    flag = 1;
                    break;
                }
            }
            if (flag == 1)
            {
                system("cls");
                cout << "编号为数字！！！" << endl;
                cout << "编号为数字！！！" << endl;
                cout << "编号为数字！！！" << endl;
                system("pause");
                system("cls");
            }
        }
		flag = 1;
		while (flag)
		{
			cout << "请输入帐号：";
			scanf("%s", q->user_name);
			if (strcmp(q->user_name, "admin") == 0)
			{
				cout << "帐号不能为admin" << endl;
				system("pause")
			}
			Pusers chongfu = head->next;
			while (chongfu != NULL)
			{
				if (strcmp(q->user_name, chongfu->user_name) == 0)
				{
					break;
				}
			}
			if (chongfu == NULL)
			{
				flag = 0;
			}
			else
			{
				cout << "用户名已存在" << endl;
				system("pause");
				system("cls");
			}
		}
        cout << "请输入密码：";
        scanf("%s", q->passwd);
        cout << "用户身份：" << endl
             << "1.学生" << endl
             << "2.老师" << endl;
        int job;
        cin >> job;
        q->book_limit = job * 10;
        q->job=job;
		p->next = q;
        p = p->next;
        system("cls");
        cout << "添加成功。。。" << endl;
        system("pause");
        system("cls");
        cout << "是否继续添加？" << endl
             << "1.是" << endl
             << "0.否" << endl;
        cin >> job;
        system("cls");
        if (job == 0)
        {
            return 0;
        }
    }
}
void user_list(Pusers head)
{
    system("cls");
    if (head->next == NULL)
    {
        user_error();
        return;
    }
    Pusers p = head->next;
    printf("%10s%16s%16s\n", "用户编号", "用户名", "身份");
    while (p != NULL)
    {
        char job[50];
        if (p->job == 1)
        {
            strcpy(job, "学生");
        }
        else
            strcpy(job, "老师");
        printf("%10d", p->user_id);
        printf("%16s", p->user_name);
        printf("%16s\n", job);
        p = p->next;
    }
    system("pause");
    system("cls");
}
int user_manage(Pusers head)
{
    system("cls");
    cout << "1.增长用户" << endl
         << "2.注销用户" << endl
         << "3.全部用户" << endl
         << "0.退出" << endl;
    cout << "请选择：";
    int in;
    cin >> in;
    switch (in)
    {
    case 1:
        add_users(head);
        break;
    case 2:
        del_user(head);
        break;
    case 3:
        user_list(head);
        break;
    case 0:
        return 0;
    }
}
/*****************************************主函数区***********************************************/
void welcome(int root)
{
    if (root == 1)
    {
        cout << "1.全部图书" << endl
             << "2.借还图书" << endl
             << "3.更改密码" << endl
             << "0.退出" << endl;
    }
    else if (root == 2)
    {
        cout << "1.增长图书" << endl
             << "2.全部图书" << endl
             << "3.搜索图书" << endl
             << "4.用户管理" << endl
             << "5.查看全部已借图书" << endl
             << "0.退出" << endl;
    }
    printf("请输入相应序号：");
}

int main()
{
    int n;
    BOOK headd;
    BORROW borrowedd;
    Pbook head = &headd;
    Pborrow borrowed = &borrowedd;
    USERS user_head;
    Pusers puser = &user_head;
    headd.next = NULL;
    borrowedd.next = NULL;
    user_head.next = NULL;
    read_books_information_to_file(head, borrowed, puser);
    int root = user_judge(puser);
    system("cls");
    while (root == 0)
    {
        cout << "\t1.继续登录" << endl
             << "\t0.退出" << endl;
        cout << "\t请选择：";
        int in;
        cin >> in;
        if (in == 0)
        {
            cout << "感谢使用。。。" << endl;
            Sleep(1000);
            return 0;
        }
        else
        {
            root = user_judge(puser);
        }
    }
    welcome(root);
    int ffllaagg;
    if (root == 1) //普通用户选项
    {
        while (cin >> n)
        {
            if (n == 0)
            {
                system("cls");
                // cout << "感谢您的使用." << endl;
                break;
                ;
            }
            switch (n)
            {
            case 1:
                list(head);
                break;
            case 2:
                borrowor(head, borrowed);
                break;
            case 3:
                fix_passwd_by_oneself();
                break;
            }
            system("cls");
            cout << "你还要作什么：" << endl;
            welcome(root);
        }
    }
    else if (root == 2)
    {
        while (cin >> n)
        {
            if (n == 0)
            {
                system("cls");
                // cout << "感谢您的使用." << endl;
                break;
                ;
            }
            switch (n)
            {
            case 1:
                addbook(head);
                break;
            case 2:
                list(head);
                break;
            case 3:
                ffllaagg = search(head);
                while (ffllaagg)
                {
                    ffllaagg = search(head);
                }
                break;
            case 4:
                user_manage(puser);
                break;
            case 5:
                list_borrow(borrowed);
                break;
            }
            system("cls");
            cout << "您还须要作什么" << endl;
            welcome(root);
        }
    }
    system("cls");
    save_books_information_to_file(head, borrowed, puser);
    system("pause");
    return 0;
}