请写一个学生成绩管理系统C++

好的，我可以为您提供一个简单的学生成绩管理系统的C++代码。以下是代码：

#include <iostream>
using namespace std;

struct Student {
    string name;
    int id;
    double grade;
};

int main() {
    const int MAX_STUDENTS = 100;
    Student students[MAX_STUDENTS];
    int numStudents = 0;

    while (true) {
        cout << "1. 添加学生信息" << endl;
        cout << "2. 显示学生信息" << endl;
        cout << "3. 计算平均成绩" << endl;
        cout << "4. 退出程序" << endl;
        cout << "请选择: ";

        int choice;
        cin >> choice;

        if (choice == 1) {
            if (numStudents >= MAX_STUDENTS) {
                cout << "学生信息已满，无法添加！" << endl;
            } else {
                Student student;
                cout << "请输入学生姓名: ";
                cin >> student.name;
                cout << "请输入学生学号: ";
                cin >> student.id;
                cout << "请输入学生成绩: ";
                cin >> student.grade;

                students[numStudents] = student;
                numStudents++;

                cout << "学生信息添加成功！" << endl;
            }
        } else if (choice == 2) {
            if (numStudents == 0) {
                cout << "没有学生信息！" << endl;
            } else {
                for (int i = 0; i < numStudents; i++) {
                    cout << "姓名: " << students[i].name << ", 学号: " << students[i].id << ", 成绩: " << students[i].grade << endl;
                }
            }
        } else if (choice == 3) {
            if (numStudents == 0) {
                cout << "没有学生信息！" << endl;
            } else {
                double totalGrade = 0;
                for (int i = 0; i < numStudents; i++) {
                    totalGrade += students[i].grade;
                }
                double avgGrade = totalGrade / numStudents;
                cout << "平均成绩为: " << avgGrade << endl;
            }
        } else if (choice == 4) {
            cout << "退出程序！" << endl;
            break;
        } else {
            cout << "选择无效，请重新选择！" << endl;
        }
    }

    return 0;
}

这个程序实现了四个功能：添加学生信息、显示学生信息、计算平均成绩和退出程序。您可以根据需要进行修改和扩展。