用c++编辑一个三百行的学生选课系统

好的，下面是一个简单的学生选课系统的代码示例，仅供参考：

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

// 定义学生和课程的结构体
struct Student {
    string name;
    string id;
    vector<string> courses;
};

struct Course {
    string name;
    string id;
    int capacity;
    int selected;
};

// 学生信息和课程信息的存储文件
const string STUDENT_FILE = "students.txt";
const string COURSE_FILE = "courses.txt";

// 读取学生和课程的信息
void readStudents(vector<Student>& students) {
    ifstream fin(STUDENT_FILE);
    if (!fin) {
        cout << "Error opening file " << STUDENT_FILE << endl;
        return;
    }

    string name, id;
    while (fin >> name >> id) {
        Student s;
        s.name = name;
        s.id = id;
        string course;
        while (fin >> course) {
            s.courses.push_back(course);
        }
        students.push_back(s);
    }

    fin.close();
}

void readCourses(vector<Course>& courses) {
    ifstream fin(COURSE_FILE);
    if (!fin) {
        cout << "Error opening file " << COURSE_FILE << endl;
        return;
    }

    string name, id;
    int capacity, selected;
    while (fin >> name >> id >> capacity >> selected) {
        Course c;
        c.name = name;
        c.id = id;
        c.capacity = capacity;
        c.selected = selected;
        courses.push_back(c);
    }

    fin.close();
}

// 保存学生和课程的信息
void saveStudents(const vector<Student>& students) {
    ofstream fout(STUDENT_FILE);
    if (!fout) {
        cout << "Error opening file " << STUDENT_FILE << endl;
        return;
    }

    for (const auto& s : students) {
        fout << s.name << " " << s.id << " ";
        for (const auto& c : s.courses) {
            fout << c << " ";
        }
        fout << endl;
    }

    fout.close();
}

void saveCourses(const vector<Course>& courses) {
    ofstream fout(COURSE_FILE);
    if (!fout) {
        cout << "Error opening file " << COURSE_FILE << endl;
        return;
    }

    for (const auto& c : courses) {
        fout << c.name << " " << c.id << " " << c.capacity << " " << c.selected << endl;
    }

    fout.close();
}

// 显示学生和课程的信息
void showStudents(const vector<Student>& students) {
    cout << "Name\tID\tCourses" << endl;
    for (const auto& s : students) {
        cout << s.name << "\t" << s.id << "\t";
        for (const auto& c : s.courses) {
            cout << c << " ";
        }
        cout << endl;
    }
}

void showCourses(const vector<Course>& courses) {
    cout << "Name\tID\tCapacity\tSelected" << endl;
    for (const auto& c : courses) {
        cout << c.name << "\t" << c.id << "\t" << c.capacity << "\t\t" << c.selected << endl;
    }
}

// 学生选课和退课的操作
void selectCourse(vector<Student>& students, vector<Course>& courses, const string& studentId, const string& courseId) {
    // 查找学生和课程
    auto s = find_if(students.begin(), students.end(), [studentId](const Student& s) { return s.id == studentId; });
    auto c = find_if(courses.begin(), courses.end(), [courseId](const Course& c) { return c.id == courseId; });
    if (s == students.end() || c == courses.end()) {
        cout << "Invalid student ID or course ID" << endl;
        return;
    }

    // 检查课程容量和学生是否已选该课程
    if (c->selected >= c->capacity) {
        cout << "Course is full" << endl;
        return;
    }
    if (find(s->courses.begin(), s->courses.end(), courseId) != s->courses.end()) {
        cout << "Student has selected this course" << endl;
        return;
    }

    // 更新学生和课程的信息
    s->courses.push_back(courseId);
    c->selected++;
    saveStudents(students);
    saveCourses(courses);
    cout << "Select course successfully" << endl;
}

void dropCourse(vector<Student>& students, vector<Course>& courses, const string& studentId, const string& courseId) {
    // 查找学生和课程
    auto s = find_if(students.begin(), students.end(), [studentId](const Student& s) { return s.id == studentId; });
    auto c = find_if(courses.begin(), courses.end(), [courseId](const Course& c) { return c.id == courseId; });
    if (s == students.end() || c == courses.end()) {
        cout << "Invalid student ID or course ID" << endl;
        return;
    }

    // 检查学生是否选了该课程
    auto it = find(s->courses.begin(), s->courses.end(), courseId);
    if (it == s->courses.end()) {
        cout << "Student has not selected this course" << endl;
        return;
    }

    // 更新学生和课程的信息
    s->courses.erase(it);
    c->selected--;
    saveStudents(students);
    saveCourses(courses);
    cout << "Drop course successfully" << endl;
}

// 主函数
int main() {
    vector<Student> students;
    vector<Course> courses;
    readStudents(students);
    readCourses(courses);

    int choice;
    string studentId, courseId;
    while (true) {
        cout << "======== Student Course Selection System ========" << endl;
        cout << "1. Show students" << endl;
        cout << "2. Show courses" << endl;
        cout << "3. Select course" << endl;
        cout << "4. Drop course" << endl;
        cout << "5. Exit" << endl;
        cout << "Enter your choice: ";
        cin >> choice;

        switch (choice) {
        case 1:
            showStudents(students);
            break;
        case 2:
            showCourses(courses);
            break;
        case 3:
            cout << "Enter student ID: ";
            cin >> studentId;
            cout << "Enter course ID: ";
            cin >> courseId;
            selectCourse(students, courses, studentId, courseId);
            break;
        case 4:
            cout << "Enter student ID: ";
            cin >> studentId;
            cout << "Enter course ID: ";
            cin >> courseId;
            dropCourse(students, courses, studentId, courseId);
            break;
        case 5:
            return 0;
        default:
            cout << "Invalid choice" << endl;
            break;
        }
    }

    return 0;
}

这份代码实现了学生选课系统的基本功能，包括学生信息和课程信息的录入和查询，学生选课和退课的操作等。需要注意的是，这份代码并不是完整的实现，可能还需要根据具体需求进行修改和完善。