前言


本次课程设计是我第一次独自完成这样一个相对完整的项目,收获很多。但是我更想说一下本次设计中存在的不足。

首先就是在最初设计课程类和学生类时,没有考虑的那么全面,导致出现了很多冗余的接口,和公有私有混着用的情况。其次就是,虽然是用C++写的,却没有把封装体现出来,使用了很多friend友元函数也破坏了类的封装效果。

由于我最开始是在Linux系统上编写的代码,没有装中文包,所以很多注释和输出语句都是用英文写的。后来又转到Windows下的VS环境下编程,也写了一些中文的语句。导致会有中英文混用的情况,可能会影响观感。

在学习这个系统之前,建议先把学生成绩管理系统熟练掌握,掌握最基本的增删改查操作,我在本文中就不再赘述了,把重点放在选课和退选的功能讲解上。

在最后面,我也会把整个项目代码都放出来,大家可以拿去在自己的电脑上运行,应付下作业铁定是没问题的(手动狗头)。


1.系统概述


本系统是学生选课系统,主要是实现大学生的选课需求。进入系统,需要先选择用户(学生或管理员),选择管理员,需要输入对应的密码。选择完身份后,进入主菜单,会出现两个子菜单,学生菜单和课程菜单,选择相应的选项,就会进入相应的菜单,其中0选项是返回上级目录。

进入课程菜单,会看到增删改查相应的操作,还有显示全部课程信息。其中,学生用户没有对课程进行增删改的权利。管理员是超级用户,有所有操作的权利。里面的细节我们在模块的具体实现时再说。

进入学生菜单,也会看到增删改查相关的操作,还有显示全部学生的信息。不同的是,学生菜单中可以进行选课和退选的相关操作。学生用户只有查看信息,选课退选的权利,没有增删改的权利。具体细节也是放在模块中详谈。


2.系统设计


2.1概要设计


在这里插入图片描述


2.2详细设计


2.2.1学生类和课程类模块设计


int flag = 0;                   // default is student

class Course 
{
public:
    friend void Input_course(vector<Course>& cour);
    friend void Delete_course(vector<Course>& cour);
    friend void Modify_course(vector<Course>& cour);
    friend void Lookup_course(vector<Course>& cour);
    friend void Show_course(vector<Course>& cour);
    friend void Add_course(vector<Course>& cour);                                                                       
    friend int Read_course(vector<Course>& cour);
    friend void Write_course(vector<Course>& cour, int n);

    const char* c_id() { return id; }
    const char* c_name() { return name; }
    const bool c_nature() { return nature; }

    Course()
        : id("None")
        , name("None")
        , count(0)
    {}

public:
    char id[20];
    char name[20];
private:
    bool nature;            // 0 indicates elective and 1 indicates compulsory
    int hour;               // class time                                                                             
    int credir;             // credit
public:
    int count;              // count of student 0-60
};

class Student
{
public:
    friend void Input_stu(vector<Student>& stu);
    friend void Delete_stu(vector<Student>& stu);
    friend void Modify_stu(vector<Student>& stu);
    friend void Lookup_stu(vector<Student>& stu);
    friend void Add_stu(vector<Student>& stu);
    friend void Show_stu(vector<Student>& stu);
    friend int Read_stu(vector<Student>& stu);
    friend void Write_stu(vector<Student>& stu, int n);

    friend void Select(vector<Course>& cour, vector<Student>& stu);
    friend void Deselect(vector<Course>& cour, vector<Student>& stu);
public:
    char _id[20];
    char _class[20];
    char _name[20];
    Course _cour_compulsory[2];
    Course _cour_elective[1];
    int _num_compulsory = 0;
    int _num_elective = 0;
};

vector<Course> cour;
vector<Student> stu;

在这个模块中,我设计了两个类来分别存储学生和课程的信息。课程的相关信息包括,课程编号、课程名、课程类型(选修/必修)、学时、学分、以及选课人数。其中规定,每门课选课人数最多不超过60人。还设计了一个构造函数,将课程的编号和课程名都定义为None

学生类中,相关信息包括,学号、班级、姓名、所选择的必修课信息、所选的选修课信息、所选必修课数量、所选选修课数量。其中规定,每名学生所选必修课不超过两门,选修课不超过一门。

在接下来的增删查改操作中,我使用了全局变量cour,和stu这两个动态数组来分别存储课程和学生。其中全局变量flag是一个确定身份状态的变量,默认是0,学生用户。1是超级用户。


2.2.2文件信息读取和录入模块设计


void Write_course(vector<Course>& cour, int n)
{
    fstream myfile;
    myfile.open("course.txt", ios::out | ios::binary);
    if (!myfile)
    {
        cout << "ERROR!course.txt can't open." << endl;
        abort();
    }

    myfile << n << endl << endl;
    for (int i = 0; i < n; i++)
    {
        myfile << cour[i].id << "\t" << cour[i].name << "\t"
            << cour[i].nature << "\t" << cour[i].hour << "\t"
            << cour[i].credir << "\t" << cour[i].count << endl;
    }
    myfile.close();
}

int Read_course(vector<Course>& cour)
{
    cour.clear();                           // clear
    fstream myfile;
    myfile.open("course.txt", ios::in | ios::binary);
    if (!myfile)
    {
        cout << "ERROR!course.txt can't open." << endl;
        abort();
    }

    int n;                                  // count of course
    myfile.seekg(0);
    myfile >> n;

    Course temp;
    for (int i = 0; i < n; i++)
    {
        myfile >> temp.id >> temp.name >> temp.nature
            >> temp.hour >> temp.credir >> temp.count;
        cour.push_back(temp);           // push_back
    }

    myfile.close();
    return n;
}

// 学生数据的文件操作
void Write_stu(vector<Student>& stu, int n)
{
    fstream myfile;
    myfile.open("student.txt", ios::out | ios::binary);
    if (!myfile)
    {
        cout << "ERROR! student.txt can't open!" << endl;
        abort();
    }

    myfile << n << endl << endl;
    for (int i = 0; i < n; i++)
    {
        myfile << stu[i]._id << "\t" << stu[i]._class << "\t"
            << stu[i]._name << "\t" 
            << stu[i]._cour_compulsory[0].c_id()   << "\t"
            << stu[i]._cour_compulsory[0].c_name() << "\t"
            << stu[i]._cour_compulsory[1].c_id()   << "\t"
            << stu[i]._cour_compulsory[1].c_name() << "\t"
            << stu[i]._cour_elective[0].c_id()     << "\t"
            << stu[i]._cour_elective[0].c_name()   << "\t"
            << stu[i]._num_compulsory << "\t" << stu[i]._num_elective << endl;
    }

    myfile.close();
}

int Read_stu(vector<Student>& stu)
{
    stu.clear();                            // clear
    fstream myfile;
    myfile.open("student.txt", ios::in | ios::binary);
    if (!myfile)
    {
        cout << "ERROR! student.txt can't open!" << endl;
        abort();
    }

    int n;
    myfile.seekg(0);
    myfile >> n;

    Student temp;

    for (int i = 0; i < n; i++)
    {
        myfile >> temp._id >> temp._class
            >> temp._name
            >> temp._cour_compulsory[0].id
            >> temp._cour_compulsory[0].name
            >> temp._cour_compulsory[1].id
            >> temp._cour_compulsory[1].name
            >> temp._cour_elective[0].id
            >> temp._cour_elective[0].name
            >> temp._num_compulsory >> temp._num_elective;
        stu.push_back(temp);            // push_back
    }

    myfile.close();
    return n;
}

这里,我利用了两个文件,一个course.txt来存放课程信息,一个student.txt来存放学生信息。写入文件的第一个数据一定是课程,学生的数量。在调用Write函数要传一个数量进入。

需要注意,在向文件中写入学生的信息时,我并没有将学生成员变量中,_cour_compulsory_cour_elective数组中的信息全部写入,只是写入的学生所选课程的编号和课程名。


2.2.3增删改查模块设计


void Input_course(vector<Course>& cour)
{
    system("cls");
    cour.clear();
    int i = 0;
    char sign = '0';
    Course temp;

    cout << "=============== Please input the massage ===============" << endl;
    while (sign != 'n' && sign != 'N')
    {
    loop:
        cout << "ID: ";
        cin >> temp.id;

        int c = 0;
        while (c < i)
        {
            c++;
            if (!strcmp(temp.id, cour[i - c].id))
            {
                cout << "ID repeat, please input again." << endl;
                goto loop;
            }
        }

        cout << "name of course: ";
        cin >> temp.name;
        cout << "elective or compilsory(0 or 1): ";
        cin >> temp.nature;
        cout << "class hour: ";
        cin >> temp.hour;
        cout << "credir: ";
        cin >> temp.credir;
        temp.count = 0;                 // the default is 0

        cour.push_back(temp);           // push_back

        cout << "whether continue(y or n): ";
        cin >> sign;
        i++;
    }

    Write_course(cour, i);                  // save
}

void Delete_course(vector<Course>& cour)
{
    system("cls");
    int n = Read_course(cour);
    int i = 0;
    char id[20];
    cout << "=============== Delete the message of course ===============" << endl;
    cout << "please input the ID of course which you want to delete: ";
    cin >> id;
    while (i < n && strcmp(id, cour[i].id))
        i++;

    if (i == n)
    {
        cout << "no fount." << endl;
        system("pause");
        return;
    }
    else
    {
        if (cour[i].count)
        {
            cout << "所选人数不为零,请联系所有学生退课后,再修改课程信息。" << endl;
            system("pause");
            return;
        }
    }

    for (int j = i; j < n - 1; j++)
        swap(cour[j], cour[j + 1]);

    // save
    char sign;
    cout << "whether delete(y or n): ";
    cin >> sign;
    if (sign != 'n' && sign != 'N')
    {
        cour.erase(cour.end() - 1);
        Write_course(cour, n - 1);
        cout << "=============== Delete succeed ===============" << endl;
    }
}

void Modify_course(vector<Course>& cour)
{
    system("cls");
    int n = Read_course(cour);                      // count of course
    char id[20];
    int i = 0;

    cout << "=============== Modify course ===============" << endl;
    cout << "input the ID of course you want to modify: ";
    cin >> id;
    while ( i < n && strcmp(id, cour[i].id))        // i < n 要提前判断
        i++;

    if (i == n)
    {
        cout << "no found." << endl;
        system("pause");
        return;
    }
    else
    {
        if (cour[i].count)
        {
            cout << "所选人数不为零,请联系所有学生退课后,再修改课程信息。" << endl;
            system("pause");
            return;
        }
    }

    cout << "----------------------------------------------------" << endl;
    cout << "ID" << "\t" << "name" << "\t" << "nature" << "\t"
        << "hour" << "\t" << "credir" << "\t" << "count" << endl;
    cout << "----------------------------------------------------" << endl;
    cout << cour[i].id << "\t" << cour[i].name << "\t" << cour[i].nature << "\t"
        << cour[i].hour << "\t" << cour[i].credir << "\t" << cour[i].count << endl;

    cout << "please reenter the message of course." << endl;
    cout << "name of course: ";
    cin >> cour[i].name;
    cout << "elective or compilsory(0 or 1): ";
    cin >> cour[i].nature;
    cout << "class hour: ";
    cin >> cour[i].hour;
    cout << "credir: ";
    cin >> cour[i].credir;

    // save
    char sign;
    cout << "whether save the data(y or n): ";
    cin >> sign;
    if (sign != 'n' && sign != 'N')
    {
        Write_course(cour, n);
        cout << "=============== Modify succeed ===============" << endl;
        system("pause");
    }
}

void Lookup_course(vector<Course>& cour)
{
    system("cls");
    int n = Read_course(cour);
    int i = 0;
    char id[20];

    cout << "=============== Lookup the course ===============" << endl;
    cout << "please input the course ID you want to seek: ";
    cin >> id;

    while (i < n && strcmp(id, cour[i].id))
        i++;

    if (i == n)
    {
        cout << "no found." << endl;
    }
    else
    {
        cout << "---------------------------------------------" << endl;
        cout << "ID: " << cour[i].id << endl;
        cout << "name: " << cour[i].name << endl;
        cout << "nature: " << (cour[i].nature ? "compulsory" : "elective") << endl;
        cout << "class hour: " << cour[i].hour << endl;
        cout << "credir: " << cour[i].credir << endl;
        cout << "student count: " << cour[i].count << endl;
    }
    system("pause");
}

void Show_course(vector<Course>& cour)
{
    system("cls");
    int n = Read_course(cour);

    cout << "================ display all course ================" << endl;
    cout << "----------------------------------------------------" << endl;
    cout << "ID" << "\t" << "name" << "\t" << "nature" << "\t"
        << "hour" << "\t" << "credir" << "\t" << "count" << endl;

    cout << "----------------------------------------------------" << endl;
    for (int i = 0; i < n; i++)
    {
        cout << cour[i].id << "\t" << cour[i].name << "\t" << cour[i].nature << "\t" << cour[i].hour << "\t" << cour[i].credir << "\t" << cour[i].count << endl;
    }
    system("pause");
}

void Add_course(vector<Course>& cour)
{
    system("cls");
    int n = Read_course(cour);
    char sign = '0';
    Course temp;

    cout << "=============== add course ===============" << endl;
    while (sign != 'n' && sign != 'N')
    {
    loop:
        cout << "ID: ";
        cin >> temp.id;
        int c = 0;
        while (c < n)
        {
            c++;
            if (!strcmp(temp.id, cour[n - c].id))
            {
                cout << "ID repeat, please input again." << endl;
                goto loop;
            }
        }

        cout << "name of course: ";
        cin >> temp.name;
        cout << "elective or compulsory(0 or 1): ";
        cin >> temp.nature;
        cout << "class hour: ";
        cin >> temp.hour;
        cout << "credir: ";
        cin >> temp.credir;
        temp.count = 0;

        n++;

        cour.push_back(temp);

        cout << "whether continue(y or n): ";
        cin >> sign;
    }

    // save
    Write_course(cour, n);
}

Input函数只适用于第一次数据的录入,如果文件中有数据,使用Input函数会将原内容覆盖。追加课程使用函数Add

关于课程的增删改查,没有太多要说的点,需要注意一个细节,就是如果该课程的选课人数不为零,那么是不允许对该课程进行修改或删除操作的,需要先联系选该课的学生全部退选,才可以进行修改或删除,不然就太坑了。

删除课程时,我使用了算法库中的函数swap,这个函数的参数是一个模版参数,可以交换任意类型的数据。

void Input_stu(vector<Student>& stu)
{
    system("cls");
    stu.clear();
    int i = 0;
    char sign = '\0';
    Student temp;

    cout << "============ please input the message ============" << endl;
    while (sign != 'n' && sign != 'N')
    {
    loop:
        cout << "student ID: ";
        cin >> temp._id;

        int c = 0;
        while (c < i)
        {
            c++;
            if (!strcmp(temp._id, stu[i - c]._id))
            {
                cout << "ID repeat, please input again." << endl;
                goto loop;
            }
        }

        cout << "name: ";
        cin >> temp._name;
        cout << "class: ";
        cin >> temp._class;

        stu.push_back(temp);            // push_back
        cout << "whether continue(y or n): ";
        cin >> sign;
        i++;
    }
    Write_stu(stu, i);
}

void Delete_stu(vector<Student>& stu)
{
    system("cls");
    int n = Read_stu(stu);
    int m = Read_course(cour);  // number of course
    int i = 0;
    char id[20];

    cout << "============ delete student ============" << endl;
    cout << "please input the ID of student who you want to delete: ";
    cin >> id;

    while (i < n && strcmp(id, stu[i]._id))
        i++;

    if (i == n)
    {
        cout << "no fount." << endl;
        system("pause");
        return;
    }

    if (stu[i]._num_compulsory)
    {
        while (stu[i]._num_compulsory > 0)
        {
            stu[i]._num_compulsory--;

            int c = 0;
            while (c < m)
            {
                if (!strcmp(stu[i]._cour_compulsory[stu[i]._num_compulsory].id, cour[c].id))
                {
                    cour[c].count--;
                    break;
                }
                c++;
            }
        }
    }
    else if (stu[i]._num_elective)
    {
        while (stu[i]._num_elective > 0)
        {
            stu[i]._num_elective--;

            int c = 0;
            while (c < m)
            {
                if (!strcmp(stu[i]._cour_elective[stu[i]._num_elective].id, cour[c].id))
                {
                    cour[c].count--;
                    break;
                }
                c++;
            }
        }
    }

    for (int j = i; j < n - 1; j++)
        swap(stu[j], stu[j + 1]);

    // save
    char sign;
    cout << "whether delete(y or n): ";
    cin >> sign;
    if (sign != 'n' && sign != 'N')
    {
        stu.erase(stu.end() - 1);
        Write_stu(stu, n - 1);
        Write_course(cour, m);
        cout << "============ delete succeed ============" << endl;
        system("pause");
    }
}

void Modify_stu(vector<Student>& stu)
{
    system("cls");
    int n = Read_stu(stu);
    char id[20];
    int i = 0;

    cout << "============ Modify the message of student ============" << endl;
    cout << "please input the ID of student who you want to modify: ";
    cin >> id;

    while (i < n && strcmp(id, stu[i]._id))
        i++;

    if (i == n)
    {
        cout << "no found." << endl;
        system("pause");
        return;
    }

    cout << "-------------------------------------------------------" << endl;
    cout << "ID: " << stu[i]._id << endl;
    cout << "class: " << stu[i]._class << endl;
    cout << "name: " << stu[i]._name << endl;
    cout << "-------------------------------------------------------" << endl;

    cout << "please reenter the message." << endl;
    cout << "class: ";
    cin >> stu[i]._class;
    cout << "name: ";
    cin >> stu[i]._name;

    // save
    char sign;
    cout << "whether save the data(y or n): ";
    cin >> sign;
    if (sign != 'n' && sign != 'N')
    {
        cout << "modify succeed." << endl;                                                                                    
        Write_stu(stu, n);
        system("pause");
    }
}

void Lookup_stu(vector<Student>& stu)
{
    system("cls");    
    int n = Read_stu(stu);
    Read_course(cour);
    int i = 0;
    char id[20];  
    
    cout << "============ Lookup the score of student ============" << endl;    
    cout << "please input the ID of student you want to seek: ";
    cin >> id;

    while (i < n && strcmp(id, stu[i]._id))
        i++;
    
    if (i == n)
    {
        cout << "no found." << endl;
    }
    else
    { 
        cout << "ID: " << stu[i]._id << endl;
        cout << "class: " << stu[i]._class << endl;
        cout << "name: " << stu[i]._name << endl;
        cout << "compulsory: " << (!strcmp(stu[i]._cour_compulsory[0].id, "None") ? "None" : stu[i]._cour_compulsory[0].c_name())
             << " " 
             << (!strcmp(stu[i]._cour_compulsory[1].id, "None") ? "None" : stu[i]._cour_compulsory[1].c_name()) 
             << endl;
        cout << "elective: " 
             << (!strcmp(stu[i]._cour_elective[0].id, "None") ? "None" : stu[i]._cour_elective[0].c_name()) 
             << endl;
    }
    system("pause");
}

void Add_stu(vector<Student>& stu) 
{
    system("cls");
    int n = Read_stu(stu);
    char sign = '0';
    Student temp;

    cout << "============ add student ============" << endl;
    while (sign != 'n' && sign != 'N')
    {
    loop:
        cout << "student ID: ";
        cin >> temp._id;

        int c = 0;
        while (c < n)
        {
            c++;
            if (!strcmp(temp._id, stu[n - c]._id))
            {
                cout << "ID repeat, please input again." << endl;
                goto loop;
            }
        }

        cout << "class: ";
        cin >> temp._class;
        cout << "name: ";
        cin >> temp._name;
        n++;

        stu.push_back(temp);                    // push_back

        cout << "whether continue(y or n): ";
        cin >> sign;
    }

    // save
    Write_stu(stu, n);
}

void Show_stu(vector<Student>& stu)
{   
    system("cls");                                                                                                        
    int n = Read_stu(stu);

    cout << "============================ diplay all student ==========================" << endl;
    cout << "ID" << "\t" << "class" << "\t" << "name" << "\t" 
         << "compulsory" << "\t\t" << "elective" << endl;   
    cout << "--------------------------------------------------------------------------" << endl;
    for (int i = 0; i < n; i++)
    {
        cout << stu[i]._id << "\t" << stu[i]._class << "\t" << stu[i]._name << "\t" 
            << (!strcmp(stu[i]._cour_compulsory[0].id, "None") ? "None" : stu[i]._cour_compulsory[0].name)
            << " "
            << (!strcmp(stu[i]._cour_compulsory[1].id, "None") ? "None" : stu[i]._cour_compulsory[1].c_name())
            << "\t"
            << (!strcmp(stu[i]._cour_elective[0].id, "None") ? "None" : stu[i]._cour_elective[0].c_name()) 
            << endl;
    }

    system("pause");
}

以上是学生信息的增删查改,细节较多,在这里一一说明。首先,删除学生时,如果该学生选的有课,那么将学生删除后,对应课程的选课人数也应该减减;其次,打印学生所选课程时,需要先判断课程的id是否为None,如果是就打印None,表示没有选课,id不为None就说明选的有课,就打印该课程的课程名。


2.2.4登入模块设计


int choose_user()
{
loop:
    system("cls");
    int c = 0;
    cout << "=================================================================" << endl;
    cout << "-------------- welcome to course selection system ---------------" << endl;
    cout << "please choose your identity, admin or student(1 or 2)(input 0 to exit): ";
    cin >> c;

    char passwd[20];
    if (c == 1)
    {
        cout << "please input password: ";
        cin >> passwd;
        if (!strcmp(passwd, "123456"))
        {
            flag = 1;
            cout << "log on succeed." << endl;
            system("pause");
        }
        else
        {
            cout << "password error." << endl;
            system("pause");
            goto loop;
        }
    }
    else
        flag = 0;

    if (c < 0 || c > 2)
    {
        cout << "please input 0-2." << endl;
        system("pause");
        goto loop;
    }

    return c;
}

void menu_course()
{
    int c = 0;
    while (1)
    {
        system("cls");
        cout << "============ menu of course ============" << endl;
        cout << "               1. input                 " << endl;
        cout << "               2. delete                " << endl;
        cout << "               3. modify                " << endl;
        cout << "               4. lookup                " << endl;
        cout << "               5. add                   " << endl;
        cout << "               6. show all              " << endl;
        cout << "               0. return                " << endl;
        cout << "----------------------------------------" << endl;
        cout << "please choose your operation(0-6): ";
        cin >> c;
        switch (c)
        {
        case 1:
            if (flag)
                Input_course(cour);
            else
            {
                cout << "request denied." << endl;
                system("pause");
            }
            break;
        case 2:
            if (flag)
                Delete_course(cour);
            else
            {
                cout << "request denied." << endl;
                system("pause");
            }
            break;
        case 3:
            if (flag)
                Modify_course(cour);
            else
            {
                cout << "request denied." << endl;
                system("pause");
            }
            break;
        case 4:
            Lookup_course(cour);
            break;
        case 5:
            if (flag)
                Add_course(cour);
            else
            {
                cout << "request denied." << endl;
                system("pause");
            }
            break;
        case 6:
            Show_course(cour);
            break;
        case 0:
            cout << "------------ return succeed ------------" << endl;
            system("pause");
            return;
        default:
            cout << "please input 0-6." << endl;
            system("pause");
            break;
        }
    }
}

void menu_student()
{
    int c = 0;
    while (1)
    {
        system("cls");
        cout << "============ menu of student ============" << endl;
        cout << "               1. input                 " << endl;                                                        
        cout << "               2. delete                " << endl;                                                         
        cout << "               3. modify                " << endl;                                                          
        cout << "               4. lookup                " << endl;                                                           
        cout << "               5. add                   " << endl;
        cout << "               6. show all              " << endl;
        cout << "               7. select course         " << endl;
        cout << "               8. deselect              " << endl;
        cout << "               0. return                " << endl;
        cout << "----------------------------------------" << endl;                                                          
        cout << "please choose your operation(0-6): ";
        cin >> c;
        switch (c) 
        {
        case 1:                                                                                                                        
            if (flag)
                Input_stu(stu);
            else
            {
                cout << "request denied." << endl;
                system("pause");
            }
            break;                                                                                                         
        case 2:
            if (flag)                                                                                                                   
                Delete_stu(stu);                                                                                                 
            else
            {
                cout << "request denied." << endl;
                system("pause");
            }
            break;                                                                                                         
        case 3:                                                                                                                       
            if (flag)                                                                                                             
                Modify_stu(stu);                                                                                           
            else
            {
                cout << "request denied." << endl;
                system("pause");
            }
            break;                                                                                                       
        case 4:                                                                                                                     
            Lookup_stu(stu);                                                                                                   
            break;                                                                                                       
        case 5:                                                                                                                    
            if (flag)                                                                                                                      
                Add_stu(stu);                                                                                              
            else
            {
                cout << "request denied." << endl;
                system("pause");
            }
            break;                                                                                                      
        case 6:                                                                                                                   
            Show_stu(stu);                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
            break;
        case 7:
            Select(cour, stu);
            break;
        case 8:
            Deselect(cour, stu);
            break;
        case 0:
            cout << "------------ return succeed ------------" << endl;
            system("pause");
            return;
        default:
            cout << "please input 0-6." << endl;
            system("pause");
            break;
        }
    }
}

int menu_main()
{
    int c = 0;
    while (1)
    {
        system("cls");
        cout << "====================================================" << endl;
        cout << "               1. course message                    " << endl;
        cout << "               2. student message                   " << endl;
        cout << "               0. go back to higher-leve menu       " << endl;
        cout << "choose your operation: ";
        cin >> c;

        if (c < 0 || c > 2)
        {
            cout << "please input 0-2." << endl;
            system("pause");
        }
        else
            break;
    }

    return c;
}


int main()
{
    cour.reserve(100);
    stu.reserve(100);
    while (1)
    {
    loop:
        if (!choose_user())
        {
            cout << "=============== thank you for using ===============" << endl;
            return 0;
        }
        while (1)
        {
            switch (menu_main())
            {
            case 1:
                menu_course();
                break;
            case 2:
                menu_student();
                break;
            case 0:
                cout << "=============== return scceed ===============" << endl;
                system("pause");
                goto loop;
            default:
                cout << "please input 0-2." << endl;
                system("pause");
                break;
            }
        }
    }
    return 0;
}

可以看到,在进入系统后,需要先选择用户,如果选择管理员身份登入需要输入密码,选择学生身份则不用。随后会进入主菜单,有三个选项,1.课程菜单,2.学生菜单,0.返回上级目录。选择1或2就会跳转到相应的子菜单,选择0则会回到选择用户身份的界面。进入子菜单后,可以看到,课程菜单和学生菜单的前几个选项是一样的,唯一不同的是学生菜单中多了两个选项,选课和退选。

选择身份界面:

在这里插入图片描述

主菜单:

在这里插入图片描述

子菜单:

在这里插入图片描述

在这里插入图片描述


2.2.5选课模块设计


void Select(vector<Course>& cour, vector<Student>& stu) 
{
    system("cls");
    int n_cour = Read_course(cour);
    int n_stu = Read_stu(stu);   
    int i = 0;              // student
    int j = 0;              // course

    char id_c[20];          // course  
    char id_s[20];          // student                                                                               
    cout << "============ select system ============" << endl;
    cout << "please input the ID of student: ";
    cin >> id_s;
    while ( i < n_stu && strcmp(stu[i]._id, id_s))
        i++;

    if (i == n_stu) 
    {
        cout << "no found." << endl;
        system("pause");
        return;
    }

    cout << ("please input the ID of course you want to select: ");
    cin >> id_c;
    while ( j < n_cour && strcmp(cour[j].c_id(), id_c))
        j++;


    if (j == n_cour)
    {
        cout << "no found." << endl;
        system("pause");
        return;
    }

    if (cour[j].count >= 60)
    {
        cout << "student number full, select failed." << endl;
        system("pause");
    }
    else
    {
        if (cour[j].c_nature())
            if (stu[i]._num_compulsory < 2)
            {
                int c = 0;
                while (c < stu[i]._num_compulsory && strcmp(cour[j].id, stu[i]._cour_compulsory[c].id))
                    c++;

                if (c < stu[i]._num_compulsory)
                {
                    cout << "course repeat." << endl;
                    system("pause");
                    return;
                }
                stu[i]._cour_compulsory[stu[i]._num_compulsory] = cour[j];  
                stu[i]._num_compulsory++;
                cour[j].count++;
                Write_course(cour, n_cour);
                Write_stu(stu, n_stu);
                cout << "select succeed." << endl;
                system("pause");
            }
            else
            {
                cout << "class number upper limit, select failed." << endl;
                system("pause");
            }
        else
        {
            if (stu[i]._num_elective < 1)
            {
                int c = 0;
                while (c < stu[i]._num_elective && strcmp(cour[j].id, stu[i]._cour_elective[c].id))
                    c++;

                if (c < stu[i]._num_elective)
                {
                    cout << "course repeat." << endl;
                    system("pause");
                    return;
                }

                stu[i]._cour_elective[stu[i]._num_elective] = cour[j];
                stu[i]._num_elective++;
                cour[j].count++;
                Write_course(cour, n_cour);
                Write_stu(stu, n_stu);
                cout << "select succeed." << endl;
                system("pause");
            }
            else
            {
                cout << "class number upper limit, select failed." << endl;
                system("pause");
            }
        }
    }
}

需要先从文件中读取到数据,然后需要输入学生id,确定身份,再输入你想选择的课程编号。如果找不到该学生或课程,就会打印no found.。找到之后,先判断的就是该课程的选课人数是否达到上限60人,如果达到,就会提示人数上限,选课失败,没达到,就进入下一环。接着判断所选择的课程类型,是必修,就判断该学生选择的必修课程数量是否达到上限,没有达到上限才会提示选课成功;是选修,就判断该学生选择的选修课数量是否达到上限,没有达到才会提示选课成功。


2.2.6退选模块设计


void Deselect(vector<Course>& cour, vector<Student>& stu)
{
    system("cls");
    int n_cour = Read_course(cour);
    int n_stu = Read_stu(stu);
    int i = 0;              // student
    int j = 0;              // course

    char id_c[20];          // course  
    char id_s[20];          // student                                                                               
    cout << "============ deselect system ============" << endl;
    cout << "please input the ID of student: ";
    cin >> id_s;
    while (i < n_stu && strcmp(stu[i]._id, id_s))
        i++;

    if (i == n_stu)
    {
        cout << "no found." << endl;
        system("pause");
        return;
    }

    cout << ("please input the ID of course you want to deselect: ");
    cin >> id_c;
    while (j < n_cour && strcmp(cour[j].c_id(), id_c))
        j++;

    if (j == n_cour)
    {
        cout << "no found." << endl;
        system("pause");
        return;
    }
    
    if (stu[i]._num_compulsory)
    {
        int c = stu[i]._num_compulsory - 1;
        while (c >= 0)
        {
            if (!strcmp(stu[i]._cour_compulsory[c].id, id_c))
            {
                cour[j].count--;
                stu[i]._num_compulsory--;
                strcpy(stu[i]._cour_compulsory[c].id, "None");
                strcpy(stu[i]._cour_compulsory[c].name, "None");

                // 重新排序
                for (; c < stu[i]._num_compulsory; c++)
                    swap(stu[i]._cour_compulsory[c], stu[i]._cour_compulsory[c + 1]);

                Write_stu(stu, n_stu);
                Write_course(cour, n_cour);
                cout << "退选成功。" << endl;
                system("pause");
                return;
            }
            c--;
        }

        if (stu[i]._cour_elective)
        {
            int c = stu[i]._num_elective - 1;
            while (c >= 0)
            {
                if (!strcmp(stu[i]._cour_elective[c].id, id_c))
                {
                    cour[j].count--;
                    stu[i]._num_elective--;
                    strcpy(stu[i]._cour_elective[c].id, "None");
                    strcpy(stu[i]._cour_elective[c].name, "None");

                    for (; c < stu[i]._num_elective; c++)
                        swap(stu[i]._cour_elective[c], stu[i]._cour_elective[c + 1]);

                    Write_stu(stu, n_stu);
                    Write_course(cour, n_cour);
                    cout << "退选成功。" << endl;
                    system("pause");
                    return;
                }
                c--;
            }
            cout << "你并未选择该课程。" << endl;
            system("pause");
            return;
        }
    }
    
    if (stu[i]._cour_elective)
    {
    	int c = stu[i]._num_elective - 1;
   	    while (c >= 0)
 	    {
   		    if (!strcmp(stu[i]._cour_elective[c].id, id_c))
            {
       		     cour[j].count--;
                stu[i]._num_elective--;
                strcpy(stu[i]._cour_elective[c].id, "None");
                strcpy(stu[i]._cour_elective[c].name, "None");

                for (; c < stu[i]._num_elective; c++)
                swap(stu[i]._cour_elective[c], stu[i]._cour_elective[c + 1]);

                Write_stu(stu, n_stu);
                Write_course(cour, n_cour);
                cout << "退选成功。" << endl;
                system("pause");
                return;
       		}
       		c--;
     	}
       	cout << "你并未选择该课程。" << endl;
       	system("pause");
       	return;
  	}
}

退选功能实现的前半部分和选课功能类似,先从文件中读取信息,输入学生id,确定身份,再输入想退选的课程id,确定要退选的课程是否存在。如果存在,接着判断该学生是否选择了该课程,只有选择了该课程,才会提示退选成功,否则提示退选失败。

退选功能中有一个细节需要尤其注意,就是每回退选课程,都需要对学生信息中的课程数组重新排序,相当于在学生信息的课程数组中,删除了这个课程。为什么要排序呢?因为我在实现选课和退选功能的时候,都是用学生成员变量中的_num_compulsory_num_elective来做课程数组的下标的,如果不进行重新排序,会导致逻辑混乱。举个例子,现在有一个学生选了两门必修课,_cour_compulsory[0]存的是第一门课,_cour_compulsory[1]存的是第二门课,那_num_compulsory毫无疑问就是2。现在我们退选第一门课,也就是将_cour_compulsory[0]的数据改成默认值,idNonename也是None,再对_num_compulsory减减。现在没有进行排序,此时_num_compulsory为1,再对该学生进行选课操作时,执行代码stu[i]._cour_compulsory[stu[i]._num_compulsory] = cour[j]; 会将_cour_compulsory[1]中的有效数据覆盖,而_cour_compulsory[0]中仍然是无效数据,出现逻辑错误。所以我们需要对数组重新排序,让_cour_compulsory[1]的先值给到_cour_compulsory[0]


3.完整代码


#define _CRT_SECURE_NO_WARNINGS

#include<iostream>
#include<fstream>
#include<vector>
#include<string.h>  
#include<stdlib.h>
using namespace std;

int flag = 0;                   // default is student

class Course 
{
public:
    friend void Input_course(vector<Course>& cour);
    friend void Delete_course(vector<Course>& cour);
    friend void Modify_course(vector<Course>& cour);
    friend void Lookup_course(vector<Course>& cour);
    friend void Show_course(vector<Course>& cour);
    friend void Add_course(vector<Course>& cour);                                                                       
    friend int Read_course(vector<Course>& cour);
    friend void Write_course(vector<Course>& cour, int n);

    const char* c_id() { return id; }
    const char* c_name() { return name; }
    const bool c_nature() { return nature; }

    Course()
        : id("None")
        , name("None")
        , count(0)
    {}

public:
    char id[20];
    char name[20];
private:
    bool nature;            // 0 indicates elective and 1 indicates compulsory
    int hour;               // class time                                                                             
    int credir;             // credit
public:
    int count;              // count of student 0-60
};

class Student
{
public:
    friend void Input_stu(vector<Student>& stu);
    friend void Delete_stu(vector<Student>& stu);
    friend void Modify_stu(vector<Student>& stu);
    friend void Lookup_stu(vector<Student>& stu);
    friend void Add_stu(vector<Student>& stu);
    friend void Show_stu(vector<Student>& stu);
    friend int Read_stu(vector<Student>& stu);
    friend void Write_stu(vector<Student>& stu, int n);

    friend void Select(vector<Course>& cour, vector<Student>& stu);
    friend void Deselect(vector<Course>& cour, vector<Student>& stu);
public:
    char _id[20];
    char _class[20];
    char _name[20];
    Course _cour_compulsory[2];
    Course _cour_elective[1];
    int _num_compulsory = 0;
    int _num_elective = 0;
};

vector<Course> cour;
vector<Student> stu;

// ========================================== Course ==================================================== //

void Write_course(vector<Course>& cour, int n)
{
    fstream myfile;
    myfile.open("course.txt", ios::out | ios::binary);
    if (!myfile)
    {
        cout << "ERROR!course.txt can't open." << endl;
        abort();
    }

    myfile << n << endl << endl;
    for (int i = 0; i < n; i++)
    {
        myfile << cour[i].id << "\t" << cour[i].name << "\t"
            << cour[i].nature << "\t" << cour[i].hour << "\t"
            << cour[i].credir << "\t" << cour[i].count << endl;
    }
    myfile.close();
}

int Read_course(vector<Course>& cour)
{
    cour.clear();                           // clear
    fstream myfile;
    myfile.open("course.txt", ios::in | ios::binary);
    if (!myfile)
    {
        cout << "ERROR!course.txt can't open." << endl;
        abort();
    }

    int n;                                  // count of course
    myfile.seekg(0);
    myfile >> n;

    Course temp;
    for (int i = 0; i < n; i++)
    {
        myfile >> temp.id >> temp.name >> temp.nature
            >> temp.hour >> temp.credir >> temp.count;
        cour.push_back(temp);           // push_back
    }

    myfile.close();
    return n;
}

void Input_course(vector<Course>& cour)
{
    system("cls");
    cour.clear();
    int i = 0;
    char sign = '0';
    Course temp;

    cout << "=============== Please input the massage ===============" << endl;
    while (sign != 'n' && sign != 'N')
    {
    loop:
        cout << "ID: ";
        cin >> temp.id;

        int c = 0;
        while (c < i)
        {
            c++;
            if (!strcmp(temp.id, cour[i - c].id))
            {
                cout << "ID repeat, please input again." << endl;
                goto loop;
            }
        }

        cout << "name of course: ";
        cin >> temp.name;
        cout << "elective or compilsory(0 or 1): ";
        cin >> temp.nature;
        cout << "class hour: ";
        cin >> temp.hour;
        cout << "credir: ";
        cin >> temp.credir;
        temp.count = 0;                 // the default is 0

        cour.push_back(temp);           // push_back

        cout << "whether continue(y or n): ";
        cin >> sign;
        i++;
    }

    Write_course(cour, i);                  // save
}

void Delete_course(vector<Course>& cour)
{
    system("cls");
    int n = Read_course(cour);
    int i = 0;
    char id[20];
    cout << "=============== Delete the message of course ===============" << endl;
    cout << "please input the ID of course which you want to delete: ";
    cin >> id;
    while (i < n && strcmp(id, cour[i].id))
        i++;

    if (i == n)
    {
        cout << "no fount." << endl;
        system("pause");
        return;
    }
    else
    {
        if (cour[i].count)
        {
            cout << "所选人数不为零,请联系所有学生退课后,再修改课程信息。" << endl;
            system("pause");
            return;
        }
    }

    for (int j = i; j < n - 1; j++)
        swap(cour[j], cour[j + 1]);

    // save
    char sign;
    cout << "whether delete(y or n): ";
    cin >> sign;
    if (sign != 'n' && sign != 'N')
    {
        cour.erase(cour.end() - 1);
        Write_course(cour, n - 1);
        cout << "=============== Delete succeed ===============" << endl;
    }
}

void Modify_course(vector<Course>& cour)
{
    system("cls");
    int n = Read_course(cour);                      // count of course
    char id[20];
    int i = 0;

    cout << "=============== Modify course ===============" << endl;
    cout << "input the ID of course you want to modify: ";
    cin >> id;
    while ( i < n && strcmp(id, cour[i].id))        // i < n 要提前判断
        i++;

    if (i == n)
    {
        cout << "no found." << endl;
        system("pause");
        return;
    }
    else
    {
        if (cour[i].count)
        {
            cout << "所选人数不为零,请联系所有学生退课后,再修改课程信息。" << endl;
            system("pause");
            return;
        }
    }

    cout << "----------------------------------------------------" << endl;
    cout << "ID" << "\t" << "name" << "\t" << "nature" << "\t"
        << "hour" << "\t" << "credir" << "\t" << "count" << endl;
    cout << "----------------------------------------------------" << endl;
    cout << cour[i].id << "\t" << cour[i].name << "\t" << cour[i].nature << "\t"
        << cour[i].hour << "\t" << cour[i].credir << "\t" << cour[i].count << endl;

    cout << "please reenter the message of course." << endl;
    cout << "name of course: ";
    cin >> cour[i].name;
    cout << "elective or compilsory(0 or 1): ";
    cin >> cour[i].nature;
    cout << "class hour: ";
    cin >> cour[i].hour;
    cout << "credir: ";
    cin >> cour[i].credir;

    // save
    char sign;
    cout << "whether save the data(y or n): ";
    cin >> sign;
    if (sign != 'n' && sign != 'N')
    {
        Write_course(cour, n);
        cout << "=============== Modify succeed ===============" << endl;
        system("pause");
    }
}

void Lookup_course(vector<Course>& cour)
{
    system("cls");
    int n = Read_course(cour);
    int i = 0;
    char id[20];

    cout << "=============== Lookup the course ===============" << endl;
    cout << "please input the course ID you want to seek: ";
    cin >> id;

    while (i < n && strcmp(id, cour[i].id))
        i++;

    if (i == n)
    {
        cout << "no found." << endl;
    }
    else
    {
        cout << "---------------------------------------------" << endl;
        cout << "ID: " << cour[i].id << endl;
        cout << "name: " << cour[i].name << endl;
        cout << "nature: " << (cour[i].nature ? "compulsory" : "elective") << endl;
        cout << "class hour: " << cour[i].hour << endl;
        cout << "credir: " << cour[i].credir << endl;
        cout << "student count: " << cour[i].count << endl;
    }
    system("pause");
}

void Show_course(vector<Course>& cour)
{
    system("cls");
    int n = Read_course(cour);

    cout << "================ display all course ================" << endl;
    cout << "----------------------------------------------------" << endl;
    cout << "ID" << "\t" << "name" << "\t" << "nature" << "\t"
        << "hour" << "\t" << "credir" << "\t" << "count" << endl;

    cout << "----------------------------------------------------" << endl;
    for (int i = 0; i < n; i++)
    {
        cout << cour[i].id << "\t" << cour[i].name << "\t" << cour[i].nature << "\t" << cour[i].hour << "\t" << cour[i].credir << "\t" << cour[i].count << endl;
    }
    system("pause");
}

void Add_course(vector<Course>& cour)
{
    system("cls");
    int n = Read_course(cour);
    char sign = '0';
    Course temp;

    cout << "=============== add course ===============" << endl;
    while (sign != 'n' && sign != 'N')
    {
    loop:
        cout << "ID: ";
        cin >> temp.id;
        int c = 0;
        while (c < n)
        {
            c++;
            if (!strcmp(temp.id, cour[n - c].id))
            {
                cout << "ID repeat, please input again." << endl;
                goto loop;
            }
        }

        cout << "name of course: ";
        cin >> temp.name;
        cout << "elective or compulsory(0 or 1): ";
        cin >> temp.nature;
        cout << "class hour: ";
        cin >> temp.hour;
        cout << "credir: ";
        cin >> temp.credir;
        temp.count = 0;

        n++;

        cour.push_back(temp);

        cout << "whether continue(y or n): ";
        cin >> sign;
    }

    // save
    Write_course(cour, n);
}

// ============================================ student ============================================== //

void Write_stu(vector<Student>& stu, int n)
{
    fstream myfile;
    myfile.open("student.txt", ios::out | ios::binary);
    if (!myfile)
    {
        cout << "ERROR! student.txt can't open!" << endl;
        abort();
    }

    myfile << n << endl << endl;
    for (int i = 0; i < n; i++)
    {
        myfile << stu[i]._id << "\t" << stu[i]._class << "\t"
            << stu[i]._name << "\t" 
            << stu[i]._cour_compulsory[0].c_id()   << "\t"
            << stu[i]._cour_compulsory[0].c_name() << "\t"
            << stu[i]._cour_compulsory[1].c_id()   << "\t"
            << stu[i]._cour_compulsory[1].c_name() << "\t"
            << stu[i]._cour_elective[0].c_id()     << "\t"
            << stu[i]._cour_elective[0].c_name()   << "\t"
            << stu[i]._num_compulsory << "\t" << stu[i]._num_elective << endl;
    }

    myfile.close();
}

int Read_stu(vector<Student>& stu)
{
    stu.clear();                            // clear
    fstream myfile;
    myfile.open("student.txt", ios::in | ios::binary);
    if (!myfile)
    {
        cout << "ERROR! student.txt can't open!" << endl;
        abort();
    }

    int n;
    myfile.seekg(0);
    myfile >> n;

    Student temp;

    for (int i = 0; i < n; i++)
    {
        myfile >> temp._id >> temp._class
            >> temp._name
            >> temp._cour_compulsory[0].id
            >> temp._cour_compulsory[0].name
            >> temp._cour_compulsory[1].id
            >> temp._cour_compulsory[1].name
            >> temp._cour_elective[0].id
            >> temp._cour_elective[0].name
            >> temp._num_compulsory >> temp._num_elective;
        stu.push_back(temp);            // push_back
    }

    myfile.close();
    return n;
}

void Input_stu(vector<Student>& stu)
{
    system("cls");
    stu.clear();
    int i = 0;
    char sign = '\0';
    Student temp;

    cout << "============ please input the message ============" << endl;
    while (sign != 'n' && sign != 'N')
    {
    loop:
        cout << "student ID: ";
        cin >> temp._id;

        int c = 0;
        while (c < i)
        {
            c++;
            if (!strcmp(temp._id, stu[i - c]._id))
            {
                cout << "ID repeat, please input again." << endl;
                goto loop;
            }
        }

        cout << "name: ";
        cin >> temp._name;
        cout << "class: ";
        cin >> temp._class;

        stu.push_back(temp);            // push_back
        cout << "whether continue(y or n): ";
        cin >> sign;
        i++;
    }
    Write_stu(stu, i);
}

void Delete_stu(vector<Student>& stu)
{
    system("cls");
    int n = Read_stu(stu);
    int m = Read_course(cour);  // number of course
    int i = 0;
    char id[20];

    cout << "============ delete student ============" << endl;
    cout << "please input the ID of student who you want to delete: ";
    cin >> id;

    while (i < n && strcmp(id, stu[i]._id))
        i++;

    if (i == n)
    {
        cout << "no fount." << endl;
        system("pause");
        return;
    }

    if (stu[i]._num_compulsory)
    {
        while (stu[i]._num_compulsory > 0)
        {
            stu[i]._num_compulsory--;

            int c = 0;
            while (c < m)
            {
                if (!strcmp(stu[i]._cour_compulsory[stu[i]._num_compulsory].id, cour[c].id))
                {
                    cour[c].count--;
                    break;
                }
                c++;
            }
        }
    }
    else if (stu[i]._num_elective)
    {
        while (stu[i]._num_elective > 0)
        {
            stu[i]._num_elective--;

            int c = 0;
            while (c < m)
            {
                if (!strcmp(stu[i]._cour_elective[stu[i]._num_elective].id, cour[c].id))
                {
                    cour[c].count--;
                    break;
                }
                c++;
            }
        }
    }

    for (int j = i; j < n - 1; j++)
        swap(stu[j], stu[j + 1]);

    // save
    char sign;
    cout << "whether delete(y or n): ";
    cin >> sign;
    if (sign != 'n' && sign != 'N')
    {
        stu.erase(stu.end() - 1);
        Write_stu(stu, n - 1);
        Write_course(cour, m);
        cout << "============ delete succeed ============" << endl;
        system("pause");
    }
}

void Modify_stu(vector<Student>& stu)
{
    system("cls");
    int n = Read_stu(stu);
    char id[20];
    int i = 0;

    cout << "============ Modify the message of student ============" << endl;
    cout << "please input the ID of student who you want to modify: ";
    cin >> id;

    while (i < n && strcmp(id, stu[i]._id))
        i++;

    if (i == n)
    {
        cout << "no found." << endl;
        system("pause");
        return;
    }

    cout << "-------------------------------------------------------" << endl;
    cout << "ID: " << stu[i]._id << endl;
    cout << "class: " << stu[i]._class << endl;
    cout << "name: " << stu[i]._name << endl;
    cout << "-------------------------------------------------------" << endl;

    cout << "please reenter the message." << endl;
    cout << "class: ";
    cin >> stu[i]._class;
    cout << "name: ";
    cin >> stu[i]._name;

    // save
    char sign;
    cout << "whether save the data(y or n): ";
    cin >> sign;
    if (sign != 'n' && sign != 'N')
    {
        cout << "modify succeed." << endl;                                                                                    
        Write_stu(stu, n);
        system("pause");
    }
}

void Lookup_stu(vector<Student>& stu)
{
    system("cls");    
    int n = Read_stu(stu);
    Read_course(cour);
    int i = 0;
    char id[20];  
    
    cout << "============ Lookup the score of student ============" << endl;    
    cout << "please input the ID of student you want to seek: ";
    cin >> id;

    while (i < n && strcmp(id, stu[i]._id))
        i++;
    
    if (i == n)
    {
        cout << "no found." << endl;
    }
    else
    { 
        cout << "ID: " << stu[i]._id << endl;
        cout << "class: " << stu[i]._class << endl;
        cout << "name: " << stu[i]._name << endl;
        cout << "compulsory: " << (!strcmp(stu[i]._cour_compulsory[0].id, "None") ? "None" : stu[i]._cour_compulsory[0].c_name())
             << " " 
             << (!strcmp(stu[i]._cour_compulsory[1].id, "None") ? "None" : stu[i]._cour_compulsory[1].c_name()) 
             << endl;
        cout << "elective: " 
             << (!strcmp(stu[i]._cour_elective[0].id, "None") ? "None" : stu[i]._cour_elective[0].c_name()) 
             << endl;
    }
    system("pause");
}

void Add_stu(vector<Student>& stu) 
{
    system("cls");
    int n = Read_stu(stu);
    char sign = '0';
    Student temp;

    cout << "============ add student ============" << endl;
    while (sign != 'n' && sign != 'N')
    {
    loop:
        cout << "student ID: ";
        cin >> temp._id;

        int c = 0;
        while (c < n)
        {
            c++;
            if (!strcmp(temp._id, stu[n - c]._id))
            {
                cout << "ID repeat, please input again." << endl;
                goto loop;
            }
        }

        cout << "class: ";
        cin >> temp._class;
        cout << "name: ";
        cin >> temp._name;
        n++;

        stu.push_back(temp);                    // push_back

        cout << "whether continue(y or n): ";
        cin >> sign;
    }

    // save
    Write_stu(stu, n);
}

void Show_stu(vector<Student>& stu)
{   
    system("cls");                                                                                                        
    int n = Read_stu(stu);

    cout << "============================ diplay all student ==========================" << endl;
    cout << "ID" << "\t" << "class" << "\t" << "name" << "\t" 
         << "compulsory" << "\t\t" << "elective" << endl;   
    cout << "--------------------------------------------------------------------------" << endl;
    for (int i = 0; i < n; i++)
    {
        cout << stu[i]._id << "\t" << stu[i]._class << "\t" << stu[i]._name << "\t" 
            << (!strcmp(stu[i]._cour_compulsory[0].id, "None") ? "None" : stu[i]._cour_compulsory[0].name)
            << " "
            << (!strcmp(stu[i]._cour_compulsory[1].id, "None") ? "None" : stu[i]._cour_compulsory[1].c_name())
            << "\t"
            << (!strcmp(stu[i]._cour_elective[0].id, "None") ? "None" : stu[i]._cour_elective[0].c_name()) 
            << endl;
    }

    system("pause");
}

void Select(vector<Course>& cour, vector<Student>& stu) 
{
    system("cls");
    int n_cour = Read_course(cour);
    int n_stu = Read_stu(stu);   
    int i = 0;              // student
    int j = 0;              // course

    char id_c[20];          // course  
    char id_s[20];          // student                                                                               
    cout << "============ select system ============" << endl;
    cout << "please input the ID of student: ";
    cin >> id_s;
    while ( i < n_stu && strcmp(stu[i]._id, id_s))
        i++;

    if (i == n_stu) 
    {
        cout << "no found." << endl;
        system("pause");
        return;
    }

    cout << ("please input the ID of course you want to select: ");
    cin >> id_c;
    while ( j < n_cour && strcmp(cour[j].c_id(), id_c))
        j++;

    // cout << cour[j].id << endl;

    if (j == n_cour)
    {
        cout << "no found." << endl;
        system("pause");
        return;
    }

    if (cour[j].count >= 60)
    {
        cout << "student number full, select failed." << endl;
        system("pause");
    }
    else
    {
        if (cour[j].c_nature())
            if (stu[i]._num_compulsory < 2)
            {
                int c = 0;
                while (c < stu[i]._num_compulsory && strcmp(cour[j].id, stu[i]._cour_compulsory[c].id))
                    c++;

                if (c < stu[i]._num_compulsory)
                {
                    cout << "course repeat." << endl;
                    system("pause");
                    return;
                }
                stu[i]._cour_compulsory[stu[i]._num_compulsory] = cour[j];  
                // cout << stu[i]._cour_compulsory[stu[i]._num_compulsory].id << endl;
                // cout << stu[i]._cour_compulsory[stu[i]._num_compulsory].c_name() << endl;
                stu[i]._num_compulsory++;
                cour[j].count++;
                Write_course(cour, n_cour);
                Write_stu(stu, n_stu);
                // cout << stu[i]._cour_compulsory[stu[i]._num_compulsory].id << endl;
                cout << "select succeed." << endl;
                system("pause");
            }
            else
            {
                cout << "class number upper limit, select failed." << endl;
                system("pause");
            }
        else
        {
            if (stu[i]._num_elective < 1)
            {
                int c = 0;
                while (c < stu[i]._num_elective && strcmp(cour[j].id, stu[i]._cour_elective[c].id))
                    c++;

                if (c < stu[i]._num_elective)
                {
                    cout << "course repeat." << endl;
                    system("pause");
                    return;
                }

                stu[i]._cour_elective[stu[i]._num_elective] = cour[j];
                stu[i]._num_elective++;
                cour[j].count++;
                Write_course(cour, n_cour);
                Write_stu(stu, n_stu);
                cout << "select succeed." << endl;
                system("pause");
            }
            else
            {
                cout << "class number upper limit, select failed." << endl;
                system("pause");
            }
        }
    }
}

void Deselect(vector<Course>& cour, vector<Student>& stu)
{
    system("cls");
    int n_cour = Read_course(cour);
    int n_stu = Read_stu(stu);
    int i = 0;              // student
    int j = 0;              // course

    char id_c[20];          // course  
    char id_s[20];          // student                                                                               
    cout << "============ deselect system ============" << endl;
    cout << "please input the ID of student: ";
    cin >> id_s;
    while (i < n_stu && strcmp(stu[i]._id, id_s))
        i++;

    if (i == n_stu)
    {
        cout << "no found." << endl;
        system("pause");
        return;
    }

    cout << ("please input the ID of course you want to deselect: ");
    cin >> id_c;
    while (j < n_cour && strcmp(cour[j].c_id(), id_c))
        j++;

    if (j == n_cour)
    {
        cout << "no found." << endl;
        system("pause");
        return;
    }
    
    if (stu[i]._num_compulsory)
    {
        int c = stu[i]._num_compulsory - 1;
        while (c >= 0)
        {
            if (!strcmp(stu[i]._cour_compulsory[c].id, id_c))
            {
                cour[j].count--;
                stu[i]._num_compulsory--;
                strcpy(stu[i]._cour_compulsory[c].id, "None");
                strcpy(stu[i]._cour_compulsory[c].name, "None");

                // 重新排序
                for (; c < stu[i]._num_compulsory; c++)
                    swap(stu[i]._cour_compulsory[c], stu[i]._cour_compulsory[c + 1]);

                Write_stu(stu, n_stu);
                Write_course(cour, n_cour);
                cout << "退选成功。" << endl;
                system("pause");
                return;
            }
            c--;
        }

        if (stu[i]._cour_elective)
        {
            int c = stu[i]._num_elective - 1;
            while (c >= 0)
            {
                if (!strcmp(stu[i]._cour_elective[c].id, id_c))
                {
                    cour[j].count--;
                    stu[i]._num_elective--;
                    strcpy(stu[i]._cour_elective[c].id, "None");
                    strcpy(stu[i]._cour_elective[c].name, "None");

                    for (; c < stu[i]._num_elective; c++)
                        swap(stu[i]._cour_elective[c], stu[i]._cour_elective[c + 1]);

                    Write_stu(stu, n_stu);
                    Write_course(cour, n_cour);
                    cout << "退选成功。" << endl;
                    system("pause");
                    return;
                }
                c--;
            }
            cout << "你并未选择该课程。" << endl;
            system("pause");
            return;
        }
    }
    
    if (stu[i]._cour_elective)
    {
    	int c = stu[i]._num_elective - 1;
   	    while (c >= 0)
 	    {
   		    if (!strcmp(stu[i]._cour_elective[c].id, id_c))
            {
       		     cour[j].count--;
                stu[i]._num_elective--;
                strcpy(stu[i]._cour_elective[c].id, "None");
                strcpy(stu[i]._cour_elective[c].name, "None");

                for (; c < stu[i]._num_elective; c++)
                swap(stu[i]._cour_elective[c], stu[i]._cour_elective[c + 1]);

                Write_stu(stu, n_stu);
                Write_course(cour, n_cour);
                cout << "退选成功。" << endl;
                system("pause");
                return;
       		}
       		c--;
     	}
       	cout << "你并未选择该课程。" << endl;
       	system("pause");
       	return;
  	}
}

// =========================================== menu ========================================== //

int choose_user()
{
loop:
    system("cls");
    int c = 0;
    cout << "=================================================================" << endl;
    cout << "-------------- welcome to course selection system ---------------" << endl;
    cout << "please choose your identity, admin or student(1 or 2)(input 0 to exit): ";
    cin >> c;

    char passwd[20];
    if (c == 1)
    {
        cout << "please input password: ";
        cin >> passwd;
        if (!strcmp(passwd, "123456"))
        {
            flag = 1;
            cout << "log on succeed." << endl;
            system("pause");
        }
        else
        {
            cout << "password error." << endl;
            system("pause");
            goto loop;
        }
    }
    else
        flag = 0;

    if (c < 0 || c > 2)
    {
        cout << "please input 0-2." << endl;
        system("pause");
        goto loop;
    }

    return c;
}

void menu_course()
{
    int c = 0;
    while (1)
    {
        system("cls");
        cout << "============ menu of course ============" << endl;
        cout << "               1. input                 " << endl;
        cout << "               2. delete                " << endl;
        cout << "               3. modify                " << endl;
        cout << "               4. lookup                " << endl;
        cout << "               5. add                   " << endl;
        cout << "               6. show all              " << endl;
        cout << "               0. return                " << endl;
        cout << "----------------------------------------" << endl;
        cout << "please choose your operation(0-6): ";
        cin >> c;
        switch (c)
        {
        case 1:
            if (flag)
                Input_course(cour);
            else
            {
                cout << "request denied." << endl;
                system("pause");
            }
            break;
        case 2:
            if (flag)
                Delete_course(cour);
            else
            {
                cout << "request denied." << endl;
                system("pause");
            }
            break;
        case 3:
            if (flag)
                Modify_course(cour);
            else
            {
                cout << "request denied." << endl;
                system("pause");
            }
            break;
        case 4:
            Lookup_course(cour);
            break;
        case 5:
            if (flag)
                Add_course(cour);
            else
            {
                cout << "request denied." << endl;
                system("pause");
            }
            break;
        case 6:
            Show_course(cour);
            break;
        case 0:
            cout << "------------ return succeed ------------" << endl;
            system("pause");
            return;
        default:
            cout << "please input 0-6." << endl;
            system("pause");
            break;
        }
    }
}

void menu_student()
{
    int c = 0;
    while (1)
    {
        system("cls");
        cout << "============ menu of student ============" << endl;
        cout << "               1. input                 " << endl;                                                        
        cout << "               2. delete                " << endl;                                                         
        cout << "               3. modify                " << endl;                                                          
        cout << "               4. lookup                " << endl;                                                           
        cout << "               5. add                   " << endl;
        cout << "               6. show all              " << endl;
        cout << "               7. select course         " << endl;
        cout << "               8. deselect              " << endl;
        cout << "               0. return                " << endl;
        cout << "----------------------------------------" << endl;                                                          
        cout << "please choose your operation(0-6): ";
        cin >> c;
        switch (c) 
        {
        case 1:                                                                                                                        
            if (flag)
                Input_stu(stu);
            else
            {
                cout << "request denied." << endl;
                system("pause");
            }
            break;                                                                                                         
        case 2:
            if (flag)                                                                                                                   
                Delete_stu(stu);                                                                                                 
            else
            {
                cout << "request denied." << endl;
                system("pause");
            }
            break;                                                                                                         
        case 3:                                                                                                                       
            if (flag)                                                                                                             
                Modify_stu(stu);                                                                                           
            else
            {
                cout << "request denied." << endl;
                system("pause");
            }
            break;                                                                                                       
        case 4:                                                                                                                     
            Lookup_stu(stu);                                                                                                   
            break;                                                                                                       
        case 5:                                                                                                                    
            if (flag)                                                                                                                      
                Add_stu(stu);                                                                                              
            else
            {
                cout << "request denied." << endl;
                system("pause");
            }
            break;                                                                                                      
        case 6:                                                                                                                   
            Show_stu(stu);                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            
            break;
        case 7:
            Select(cour, stu);
            break;
        case 8:
            Deselect(cour, stu);
            break;
        case 0:
            cout << "------------ return succeed ------------" << endl;
            system("pause");
            return;
        default:
            cout << "please input 0-6." << endl;
            system("pause");
            break;
        }
    }
}

int menu_main()
{
    int c = 0;
    while (1)
    {
        system("cls");
        cout << "====================================================" << endl;
        cout << "               1. course message                    " << endl;
        cout << "               2. student message                   " << endl;
        cout << "               0. go back to higher-leve menu       " << endl;
        cout << "choose your operation: ";
        cin >> c;

        if (c < 0 || c > 2)
        {
            cout << "please input 0-2." << endl;
            system("pause");
        }
        else
            break;
    }

    return c;
}


// ============================================================================================================= //


int main()
{
    cour.reserve(100);
    stu.reserve(100);
    while (1)
    {
    loop:
        if (!choose_user())
        {
            cout << "=============== thank you for using ===============" << endl;
            return 0;
        }
        while (1)
        {
            switch (menu_main())
            {
            case 1:
                menu_course();
                break;
            case 2:
                menu_student();
                break;
            case 0:
                cout << "=============== return scceed ===============" << endl;
                system("pause");
                goto loop;
            default:
                cout << "please input 0-2." << endl;
                system("pause");
                break;
            }
        }
    }
    return 0;
}

大家可以自行复制运行。


4.总结与展望


4.1设计总结


本次课程设计是我第一次独自完成这样一个相对完整的项目,收获很多。但是我更想说一下本次设计中存在的不足。首先就是在最初设计课程类和学生类时,没有考虑的那么全面,导致出现了很多冗余的接口,和公有私有混着用的情况。其次就是,虽然是用C++写的,却没有把封装体现出来,使用了很多friend友元函数也破坏了类的封装效果。


4.2设计展望


接下来,我打算再优化一下这个系统,首先就是从友元函数入手,减少友元。我打算将增删改查都设计成成员函数,这样函数的命名也会方便很多。

然后就是将用到字符串的地方,全部使用string代替,可以避免使用很多C中的字符串操作函数。我还准备设计一下学生类和课程类的输入输出流重载,这样也能让代码量减少很多。

以上就是我对本次程序设计实习的设计展望。谢谢大家的支持!


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