使用C++语言创建一个学生管理系统，并可以在vc6环境下运行要求如下： 一.使用构造函数，类函数 二.拥有一个主界面，主界面要有1.初始化程序 2.菜单程序 3.退出程序 三.输入主界面2.菜单程序后进入子界面 四.子界面要求实现新增、显示、查找、删除、修改、统计、按照学号排序、退出返回主界面等功能，并将信息保存至txt文件中。

好的，这是一个比较大的项目，需要仔细设计和编写。以下是一些基本的思路和代码示例，希望对你有所帮助：

1. 设计学生类

class Student {
public:
    Student();
    Student(int id, string name, int age, string gender, string major, int score);
    ~Student();
    void setId(int id);
    int getId();
    void setName(string name);
    string getName();
    void setAge(int age);
    int getAge();
    void setGender(string gender);
    string getGender();
    void setMajor(string major);
    string getMajor();
    void setScore(int score);
    int getScore();
    void printInfo();
    string toString();
private:
    int id;
    string name;
    int age;
    string gender;
    string major;
    int score;
};

2. 设计学生管理系统类

class StudentManagementSystem {
public:
    StudentManagementSystem();
    ~StudentManagementSystem();
    void init();
    void showMenu();
    void submenuAdd();
    void submenuShow();
    void submenuSearch();
    void submenuDelete();
    void submenuModify();
    void submenuStatistics();
    void submenuSort();
    void exit();
private:
    vector<Student> students;
};

3. 实现学生类的构造函数、析构函数和类函数

Student::Student() {
    id = 0;
    name = "";
    age = 0;
    gender = "";
    major = "";
    score = 0;
}

Student::Student(int id, string name, int age, string gender, string major, int score) {
    this->id = id;
    this->name = name;
    this->age = age;
    this->gender = gender;
    this->major = major;
    this->score = score;
}

Student::~Student() {}

void Student::setId(int id) {
    this->id = id;
}

int Student::getId() {
    return id;
}

void Student::setName(string name) {
    this->name = name;
}

string Student::getName() {
    return name;
}

void Student::setAge(int age) {
    this->age = age;
}

int Student::getAge() {
    return age;
}

void Student::setGender(string gender) {
    this->gender = gender;
}

string Student::getGender() {
    return gender;
}

void Student::setMajor(string major) {
    this->major = major;
}

string Student::getMajor() {
    return major;
}

void Student::setScore(int score) {
    this->score = score;
}

int Student::getScore() {
    return score;
}

void Student::printInfo() {
    cout << toString() << endl;
}

string Student::toString() {
    stringstream ss;
    ss << "ID: " << id << ", Name: " << name << ", Age: " << age << ", Gender: " << gender << ", Major: " << major << ", Score: " << score;
    return ss.str();
}

4. 实现学生管理系统类的构造函数、析构函数和类函数

StudentManagementSystem::StudentManagementSystem() {}

StudentManagementSystem::~StudentManagementSystem() {}

void StudentManagementSystem::init() {
    // 读取学生信息文件
    ifstream fin("students.txt");
    if (fin.is_open()) {
        int id, age, score;
        string name, gender, major;
        while (fin >> id >> name >> age >> gender >> major >> score) {
            Student student(id, name, age, gender, major, score);
            students.push_back(student);
        }
        fin.close();
    }
}

void StudentManagementSystem::showMenu() {
    cout << "=================== Menu ===================" << endl;
    cout << " 1. Add a student" << endl;
    cout << " 2. Show all students" << endl;
    cout << " 3. Search a student" << endl;
    cout << " 4. Delete a student" << endl;
    cout << " 5. Modify a student" << endl;
    cout << " 6. Statistics" << endl;
    cout << " 7. Sort by ID" << endl;
    cout << " 8. Exit" << endl;
    cout << "=============================================" << endl;
}

void StudentManagementSystem::submenuAdd() {
    int id, age, score;
    string name, gender, major;
    cout << "Please input student ID: ";
    cin >> id;
    cout << "Please input student name: ";
    cin >> name;
    cout << "Please input student age: ";
    cin >> age;
    cout << "Please input student gender: ";
    cin >> gender;
    cout << "Please input student major: ";
    cin >> major;
    cout << "Please input student score: ";
    cin >> score;
    Student student(id, name, age, gender, major, score);
    students.push_back(student);
    // 保存学生信息到文件
    ofstream fout("students.txt", ios::app);
    if (fout.is_open()) {
        fout << student.getId() << " " << student.getName() << " " << student.getAge() << " " << student.getGender() << " " << student.getMajor() << " " << student.getScore() << endl;
        fout.close();
    }
    cout << "Add student successfully!" << endl;
}

void StudentManagementSystem::submenuShow() {
    cout << "All students:" << endl;
    for (int i = 0; i < students.size(); i++) {
        students[i].printInfo();
    }
}

void StudentManagementSystem::submenuSearch() {
    int id;
    cout << "Please input student ID: ";
    cin >> id;
    for (int i = 0; i < students.size(); i++) {
        if (students[i].getId() == id) {
            students[i].printInfo();
            return;
        }
    }
    cout << "Student not found!" << endl;
}

void StudentManagementSystem::submenuDelete() {
    int id;
    cout << "Please input student ID: ";
    cin >> id;
    for (int i = 0; i < students.size(); i++) {
        if (students[i].getId() == id) {
            students.erase(students.begin() + i);
            // 重新写入学生信息文件
            ofstream fout("students.txt");
            if (fout.is_open()) {
                for (int j = 0; j < students.size(); j++) {
                    fout << students[j].getId() << " " << students[j].getName() << " " << students[j].getAge() << " " << students[j].getGender() << " " << students[j].getMajor() << " " << students[j].getScore() << endl;
                }
                fout.close();
            }
            cout << "Delete student successfully!" << endl;
            return;
        }
    }
    cout << "Student not found!" << endl;
}

void StudentManagementSystem::submenuModify() {
    int id, age, score;
    string name, gender, major;
    cout << "Please input student ID: ";
    cin >> id;
    for (int i = 0; i < students.size(); i++) {
        if (students[i].getId() == id) {
            cout << "Please input new student name (old: " << students[i].getName() << "): ";
            cin >> name;
            cout << "Please input new student age (old: " << students[i].getAge() << "): ";
            cin >> age;
            cout << "Please input new student gender (old: " << students[i].getGender() << "): ";
            cin >> gender;
            cout << "Please input new student major (old: " << students[i].getMajor() << "): ";
            cin >> major;
            cout << "Please input new student score (old: " << students[i].getScore() << "): ";
            cin >> score;
            students[i].setName(name);
            students[i].setAge(age);
            students[i].setGender(gender);
            students[i].setMajor(major);
            students[i].setScore(score);
            // 重新写入学生信息文件
            ofstream fout("students.txt");
            if (fout.is_open()) {
                for (int j = 0; j < students.size(); j++) {
                    fout << students[j].getId() << " " << students[j].getName() << " " << students[j].getAge() << " " << students[j].getGender() << " " << students[j].getMajor() << " " << students[j].getScore() << endl;
                }
                fout.close();
            }
            cout << "Modify student successfully!" << endl;
            return;
        }
    }
    cout << "Student not found!" << endl;
}

void StudentManagementSystem::submenuStatistics() {
    int sum = 0;
    double avg = 0;
    int maxScore = students[0].getScore();
    int minScore = students[0].getScore();
    for (int i = 0; i < students.size(); i++) {
        sum += students[i].getScore();
        if (students[i].getScore() > maxScore) {
            maxScore = students[i].getScore();
        }
        if (students[i].getScore() < minScore) {
            minScore = students[i].getScore();
        }
    }
    avg = sum / (double)students.size();
    cout << "Statistics:" << endl;
    cout << "  Number of students: " << students.size() << endl;
    cout << "  Total score: " << sum << endl;
    cout << "  Average score: " << avg << endl;
    cout << "  Max score: " << maxScore << endl;
    cout << "  Min score: " << minScore << endl;
}

void StudentManagementSystem::submenuSort() {
    sort(students.begin(), students.end(), [](Student a, Student b) {return a.getId() < b.getId(); });
    cout << "Sort by ID:" << endl;
    for (int i = 0; i < students.size(); i++) {
        students[i].printInfo();
    }
}

void StudentManagementSystem::exit() {
    cout << "Goodbye!" << endl;
    // 清空学生信息文件
    ofstream fout("students.txt");
    fout.close();
}

5. 主程序流程

int main() {
    StudentManagementSystem sms;
    sms.init();
    while (true) {
        sms.showMenu();
        int choice;
        cout << "Please input your choice: ";
        cin >> choice;
        switch (choice) {
        case 1:
            sms.submenuAdd();
            break;
        case 2:
            sms.submenuShow();
            break;
        case 3:
            sms.submenuSearch();
            break;
        case 4:
            sms.submenuDelete();
            break;
        case 5:
            sms.submenuModify();
            break;
        case 6:
            sms.submenuStatistics();
            break;
        case 7:
            sms.submenuSort();
            break;
        case 8:
            sms.exit();
            return 0;
        default:
            cout << "Invalid choice, please try again!" << endl;
            break;
        }
    }
    return 0;
}

以上是一个简单的学生管理系统的设计和实现，你可以根据实际需求进行修改和完善。