c++实现以下程序：学生成绩管理系统 基本要求： 定义学生（student）类，其中至少包括姓名、性别、学号、班级和四门功课的成绩。 功能要求： 1、设计菜单实现功能选择； 2、输入功能：输入学生信息，并保存到文件中； 3、计算每个学生的总分与平均分并能按照学生的不同信息排序整理，如按学号，按单科成绩、按平均成绩等； 4、能根据学号修改学生信息； 5、能根据学号删除学生信息； 6、查询功能： 1）能够根据学号查询学生信息； 2）能够根据姓名、班级查询学生信息； 3）统计学生成绩，按照班级和科目计算平均分。 7、所有的增加、修改、删除能同步到文件；也从文件读取数据到程序。

以下是C++实现的学生成绩管理系统，包含基本要求和功能要求：

#include <iostream>
#include <fstream>
#include <string>
#include <vector>
#include <algorithm>

using namespace std;

// 学生类
class Student {
public:
    string name;        // 姓名
    string gender;      // 性别
    string id;          // 学号
    string cls;         // 班级
    int scores[4];      // 四门功课的成绩

    // 构造函数
    Student() {}

    // 构造函数
    Student(string name, string gender, string id, string cls, int s1, int s2, int s3, int s4) {
        this->name = name;
        this->gender = gender;
        this->id = id;
        this->cls = cls;
        scores[0] = s1;
        scores[1] = s2;
        scores[2] = s3;
        scores[3] = s4;
    }

    // 获取总分
    int getTotal() {
        int total = 0;
        for (int i = 0; i < 4; i++) {
            total += scores[i];
        }
        return total;
    }

    // 获取平均分
    double getAverage() {
        return getTotal() / 4.0;
    }

    // 根据学号排序
    static bool compareById(Student& s1, Student& s2) {
        return s1.id < s2.id;
    }

    // 根据单科成绩排序
    static bool compareByScore(Student& s1, Student& s2) {
        int total1 = 0, total2 = 0;
        for (int i = 0; i < 4; i++) {
            total1 += s1.scores[i];
            total2 += s2.scores[i];
        }
        return total1 < total2;
    }

    // 根据平均分排序
    static bool compareByAverage(Student& s1, Student& s2) {
        return s1.getAverage() < s2.getAverage();
    }

    // 显示学生信息
    void display() {
        cout << "姓名：" << name << endl;
        cout << "性别：" << gender << endl;
        cout << "学号：" << id << endl;
        cout << "班级：" << cls << endl;
        cout << "语文成绩：" << scores[0] << endl;
        cout << "数学成绩：" << scores[1] << endl;
        cout << "英语成绩：" << scores[2] << endl;
        cout << "物理成绩：" << scores[3] << endl;
        cout << "总分：" << getTotal() << endl;
        cout << "平均分：" << getAverage() << endl;
    }

    // 获取学生信息字符串
    string getInfoString() {
        string info = "";
        info += name + " ";
        info += gender + " ";
        info += id + " ";
        info += cls + " ";
        info += to_string(scores[0]) + " ";
        info += to_string(scores[1]) + " ";
        info += to_string(scores[2]) + " ";
        info += to_string(scores[3]);
        return info;
    }

    // 从字符串中解析学生信息
    static Student parseFromInfoString(string info) {
        vector<string> tokens;
        size_t pos = 0;
        while ((pos = info.find(" ")) != string::npos) {
            tokens.push_back(info.substr(0, pos));
            info.erase(0, pos + 1);
        }
        tokens.push_back(info);

        Student s;
        s.name = tokens[0];
        s.gender = tokens[1];
        s.id = tokens[2];
        s.cls = tokens[3];
        s.scores[0] = stoi(tokens[4]);
        s.scores[1] = stoi(tokens[5]);
        s.scores[2] = stoi(tokens[6]);
        s.scores[3] = stoi(tokens[7]);
        return s;
    }
};

// 学生管理类
class StudentManager {
private:
    vector<Student> students;   // 学生列表
    string filename;            // 文件名

    // 从文件中读取学生信息
    void readFromFile() {
        ifstream infile(filename);
        string line;
        while (getline(infile, line)) {
            students.push_back(Student::parseFromInfoString(line));
        }
        infile.close();
    }

    // 将学生信息写入文件
    void writeToFile() {
        ofstream outfile(filename);
        for (auto student : students) {
            outfile << student.getInfoString() << endl;
        }
        outfile.close();
    }

public:
    // 构造函数
    StudentManager(string filename) {
        this->filename = filename;
        readFromFile();
    }

    // 显示菜单
    void displayMenu() {
        cout << "请选择以下操作：" << endl;
        cout << "1. 输入学生信息" << endl;
        cout << "2. 修改学生信息" << endl;
        cout << "3. 删除学生信息" << endl;
        cout << "4. 查询学生信息" << endl;
        cout << "5. 统计学生成绩" << endl;
        cout << "6. 退出程序" << endl;
    }

    // 输入学生信息
    void addStudent() {
        string name, gender, id, cls;
        int s1, s2, s3, s4;
        cout << "请输入学生姓名：";
        cin >> name;
        cout << "请输入学生性别：";
        cin >> gender;
        cout << "请输入学生学号：";
        cin >> id;
        cout << "请输入学生班级：";
        cin >> cls;
        cout << "请输入语文成绩：";
        cin >> s1;
        cout << "请输入数学成绩：";
        cin >> s2;
        cout << "请输入英语成绩：";
        cin >> s3;
        cout << "请输入物理成绩：";
        cin >> s4;
        Student student(name, gender, id, cls, s1, s2, s3, s4);
        students.push_back(student);
        writeToFile();
        cout << "添加成功！" << endl;
    }

    // 修改学生信息
    void updateStudent() {
        string id;
        cout << "请输入要修改的学生学号：";
        cin >> id;
        for (auto& student : students) {
            if (student.id == id) {
                string name, gender, cls;
                int s1, s2, s3, s4;
                cout << "请输入学生姓名：";
                cin >> name;
                cout << "请输入学生性别：";
                cin >> gender;
                cout << "请输入学生班级：";
                cin >> cls;
                cout << "请输入语文成绩：";
                cin >> s1;
                cout << "请输入数学成绩：";
                cin >> s2;
                cout << "请输入英语成绩：";
                cin >> s3;
                cout << "请输入物理成绩：";
                cin >> s4;
                student.name = name;
                student.gender = gender;
                student.cls = cls;
                student.scores[0] = s1;
                student.scores[1] = s2;
                student.scores[2] = s3;
                student.scores[3] = s4;
                writeToFile();
                cout << "修改成功！" << endl;
                return;
            }
        }
        cout << "未找到该学生！" << endl;
    }

    // 删除学生信息
    void deleteStudent() {
        string id;
        cout << "请输入要删除的学生学号：";
        cin >> id;
        for (auto it = students.begin(); it != students.end(); it++) {
            if (it->id == id) {
                students.erase(it);
                writeToFile();
                cout << "删除成功！" << endl;
                return;
            }
        }
        cout << "未找到该学生！" << endl;
    }

    // 查询学生信息
    void queryStudent() {
        int choice;
        cout << "请选择查询方式：" << endl;
        cout << "1. 根据学号查询" << endl;
        cout << "2. 根据姓名、班级查询" << endl;
        cin >> choice;
        switch (choice) {
        case 1:
            queryById();
            break;
        case 2:
            queryByNameOrClass();
            break;
        default:
            cout << "无效的选择！" << endl;
            break;
        }
    }

    // 根据学号查询学生信息
    void queryById() {
        string id;
        cout << "请输入要查询的学生学号：";
        cin >> id;
        for (auto student : students) {
            if (student.id == id) {
                student.display();
                return;
            }
        }
        cout << "未找到该学生！" << endl;
    }

    // 根据姓名或班级查询学生信息
    void queryByNameOrClass() {
        string keyword;
        cout << "请输入要查询的关键词：";
        cin >> keyword;
        for (auto student : students) {
            if (student.name == keyword || student.cls == keyword) {
                student.display();
            }
        }
    }

    // 统计学生成绩
    void statistics() {
        int choice;
        cout << "请选择统计方式：" << endl;
        cout << "1. 按班级统计" << endl;
        cout << "2. 按科目统计" << endl;
        cin >> choice;
        switch (choice) {
        case 1:
            statisticsByClass();
            break;
        case 2:
            statisticsBySubject();
            break;
        default:
            cout << "无效的选择！" << endl;
            break;
        }
    }

    // 按班级统计学生成绩
    void statisticsByClass() {
        string cls;
        cout << "请输入要统计的班级：";
        cin >> cls;
        int count = 0;
        int total[4] = { 0 };
        for (auto student : students) {
            if (student.cls == cls) {
                count++;
                for (int i = 0; i < 4; i++) {
                    total[i] += student.scores[i];
                }
            }
        }
        if (count == 0) {
            cout << "未找到该班级的学生！" << endl;
            return;
        }
        cout << "班级：" << cls << endl;
        cout << "人数：" << count << endl;
        cout << "语文平均分：" << total[0] / static_cast<double>(count) << endl;
        cout << "数学平均分：" << total[1] / static_cast<double>(count) << endl;
        cout << "英语平均分：" << total[2] / static_cast<double>(count) << endl;
        cout << "物理平均分：" << total[3] / static_cast<double>(count) << endl;
    }

    // 按科目统计学生成绩
    void statisticsBySubject() {
        int total[4] = { 0 };
        for (auto student : students) {
            for (int i = 0; i < 4; i++) {
                total[i] += student.scores[i];
            }
        }
        cout << "语文平均分：" << total[0] / static_cast<double>(students.size()) << endl;
        cout << "数学平均分：" << total[1] / static_cast<double>(students.size()) << endl;
        cout << "英语平均分：" << total[2] / static_cast<double>(students.size()) << endl;
        cout << "物理平均分：" << total[3] / static_cast<double>(students.size()) << endl;
    }

    // 排序学生信息
    void sortStudents() {
        int choice;
        cout << "请选择排序方式：" << endl;
        cout << "1. 按学号排序" << endl;
        cout << "2. 按单科成绩排序" << endl;
        cout << "3. 按平均成绩排序" << endl;
        cin >> choice;
        switch (choice) {
        case 1:
            sort(students.begin(), students.end(), Student::compareById);
            break;
        case 2:
            sort(students.begin(), students.end(), Student::compareByScore);
            break;
        case 3:
            sort(students.begin(), students.end(), Student::compareByAverage);
            break;
        default:
            cout << "无效的选择！" << endl;
            break;
        }
        cout << "排序完成！" << endl;
    }
};

int main() {
    string filename = "students.txt";
    StudentManager manager(filename);
    int choice;
    do {
        manager.displayMenu();
        cin >> choice;
        switch (choice) {
        case 1:
            manager.addStudent();
            break;
        case 2:
            manager.updateStudent();
            break;
        case 3:
            manager.deleteStudent();
            break;
        case 4:
            manager.queryStudent();
            break;
        case 5:
            manager.statistics();
            break;
        case 6:
            cout << "程序已退出！" << endl;
            break;
        default:
            cout << "无效的选择！" << endl;
            break;
        }
        cout << endl;
    } while (choice != 6);
    return 0;
}

使用方法：

1. 将程序保存为 `main.cpp` 文件。
2. 在同一目录下创建 `students.txt` 文件，用于存储学生信息。
3. 编译并运行程序，根据菜单选择相应的操作。