C++大作业——学生选课系统
C++大作业——学生选课系统
- 前言
- 1.系统概述
- 2.系统设计
-
- 2.1概要设计
- 2.2详细设计
-
- 2.2.1学生类和课程类模块设计
- 2.2.2文件信息读取和录入模块设计
- 2.2.3增删改查模块设计
- 2.2.4登入模块设计
- 2.2.5选课模块设计
- 2.2.6退选模块设计
- 3.完整代码
- 4.总结与展望
-
- 4.1设计总结
- 4.2设计展望
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
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和_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：
主菜单：
子菜单：
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和_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，id是None，name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！