用visualc++2010做一个学生成绩管理系统，功能包含添加学生成绩,删除学生成绩，查询学生成绩，修改学生成绩，按成绩平均分大到小排序，最后存档存档

好的，下面是一个简单的学生成绩管理系统的实现，参考以下代码：

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

using std;

// 定义学生成绩结构体
struct Student {
    string name;
    int math;
    int english;
    int computer;
    int total;
    double avg;
};

// 添加学生信息
void addStudent(vector<Student>& students) {
    Student s;
    cout << "请输入学生姓名：";
    cin >> s.name;
    cout << "请输入学生数学成绩：";
    cin >> s.math;
    cout << "请输入学生英语成绩：";
    cin >> s.english;
    cout << "请输入学生计算机成绩：";
    cin >> s.computer;
    s.total = s.math + s.english + s.computer;
    s.avg = s.total / 3.0;
    students.push_back(s);
    cout << "添加成功！" << endl;
}

// 删除学生信息
void deleteStudent(vector<Student>& students) {
    string name;
    cout << "请输入要删除的学生姓名：";
    cin >> name;
    for (vector<Student>::iterator it = students.begin(); it != students.end(); it++) {
        if (it->name == name) {
            students.erase(it);
            cout << "删除成功！" << endl;
            return;
        }
    }
    cout << "找不到该学生！" << endl;
}

// 查询学生信息
void queryStudent(vector<Student>& students) {
    string name;
    cout << "请输入要查询的学生姓名：";
    cin >> name;
    for (vector<Student>::iterator it = students.begin(); it != students.end(); it++) {
        if (it->name == name) {
            cout << "姓名：" << it->name << endl;
            cout << "数学成绩：" << it->math << endl;
            cout << "英语成绩：" << it->english << endl;
            cout << "计算机成绩：" << it->computer << endl;
            cout << "总分：" << it->total << endl;
            cout << "平均分：" << it->avg << endl;
            return;
        }
    }
    cout << "找不到该学生！" << endl;
}

// 修改学生信息
void modifyStudent(vector<Student>& students) {
    string name;
    cout << "请输入要修改的学生姓名：";
    cin >> name;
    for (vector<Student>::iterator it = students.begin(); it != students.end(); it++) {
        if (it->name == name) {
            cout << "请输入该学生新的数学成绩：";
            cin >> it->math;
            cout << "请输入该学生新的英语成绩：";
            cin >> it->english;
            cout << "请输入该学生新的计算机成绩：";
            cin >> it->computer;
            it->total = it->math + it->english + it->computer;
            it->avg = it->total / 3.0;
            cout << "修改成功！" << endl;
            return;
        }
    }
    cout << "找不到该学生！" << endl;
}

// 按成绩平均分大到小排序
bool cmp(const Student& s1, const Student& s2) {
    return s1.avg > s2.avg;
}

// 显示所有学生信息
void showAllStudents(vector<Student>& students) {
    if (students.empty()) {
        cout << "暂无学生信息！" << endl;
        return;
    }
    sort(students.begin(), students.end(), cmp);
    cout << "姓名\t数学\t英语\t计算机\t总分\t平均分" << endl;
    for (vector<Student>::iterator it = students.begin(); it != students.end(); it++) {
        cout << it->name << "\t" << it->math << "\t" << it->english << "\t" << it->computer << "\t" << it->total << "\t" << it->avg << endl;
    }
}

// 存档
void saveData(vector<Student>& students) {
    ofstream ofs("data.txt");
    if (!ofs) {
        cout << "文件打开失败！" << endl;
        return;
    }
    for (vector<Student>::iterator it = students.begin(); it != students.end(); it++) {
        ofs << it->name << " " << it->math << " " << it->english << " " << it->computer << endl;
    }
    ofs.close();
    cout << "存档成功！" << endl;
}

// 读档
void loadData(vector<Student>& students) {
    ifstream ifs("data.txt");
    if (!ifs) {
        cout << "文件打开失败！" << endl;
        return;
    }
    students.clear();
    string name;
    int math, english, computer;
    while (ifs >> name >> math >> english >> computer) {
        Student s;
        s.name = name;
        s.math = math;
        s.english = english;
        s.computer = computer;
        s.total = s.math + s.english + s.computer;
        s.avg = s.total / 3.0;
        students.push_back(s);
    }
    ifs.close();
    cout << "读档成功！" << endl;
}

int main() {
    vector<Student> students;
    int choice;
    loadData(students);
    while (true) {
        cout << "====================================" << endl;
        cout << "1. 添加学生信息" << endl;
        cout << "2. 删除学生信息" << endl;
        cout << "3. 查询学生信息" << endl;
        cout << "4. 修改学生信息" << endl;
        cout << "5. 按成绩平均分大到小排序" << endl;
        cout << "6. 显示所有学生信息" << endl;
        cout << "7. 存档" << endl;
        cout << "0. 退出" << endl;
        cout << "====================================" << endl;
        cout << "请选择操作：";
        cin >> choice;
        switch (choice) {
        case 1:
            addStudent(students);
            break;
        case 2:
            deleteStudent(students);
            break;
        case 3:
            queryStudent(students);
            break;
        case 4:
            modifyStudent(students);
            break;
        case 5:
            showAllStudents(students);
            break;
        case 6:
            showAllStudents(students);
            break;
        case 7:
            saveData(students);
            break;
        case 0:
            cout << "谢谢使用！" << endl;
            return 0;
        default:
            cout << "输入有误，请重新输入！" << endl;
            break;
        }
    }
    return 0;
}

这个程序包含了添加学生成绩、删除学生成绩、查询学生成绩、修改学生成绩、按成绩平均分大到小排序以及最后存档的功能。你可以根据自己的需要进行修改和完善。同时，你需要自己在 Visual Studio 中创建一个工程，并把上述代码复制到工程中，然后进行编译和运行。如果需要存档，程序会在当前目录下创建一个名为 data.txt 的文件。