编写一个简单的学生信息管理程序及菜单系统。 1、定义学生类和管理员类。以学生类为基础，派生出本科生类和研究生类。学生包括学号、姓名、性别、年龄、专业、班级、成绩等成员；研究生还包括导师等信息，本科生还包括学制（4年或3年）等信息。 2、定义管理员类，然后编写一个登录界面，登录后才能进行各项操作；完成对学生信息进行管理，体现管理员类和学生类之间的组合关系，用链表组织学生信息。具体功能包括： (1） 学生信息显示：显示每个学生的所有信息； (2） 查找：可分别按学号、姓名、班级查询学生，并显示信息； (3） 删除：按学号或姓名删除某一学生； (4） 修改：对某一学生的信息进行修改； (5） 学生成绩汇总：求平均值，或某一分数段人数。 3、设计对应虚函数，构建多态体系，使得运行期能进行对象类型识别，实现研究生和本科生的统一管理。定义基类指针组成的数组链表，实现学生数据统一管理；在学生基类、本科生类、研究

生类中定义虚函数，实现多态。管理员类中可以定义一个基类指针数组，用于存储学生的信息，可以实现对学生信息的统一管理。

以下是一个简单的实现：

#include <iostream>
#include <string>
#include <vector>

using namespace std;

class Student {
public:
    string id;
    string name;
    string gender;
    int age;
    string major;
    string clazz;
    double score;

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

    virtual void display() {
        cout << "ID: " << id << endl;
        cout << "Name: " << name << endl;
        cout << "Gender: " << gender << endl;
        cout << "Age: " << age << endl;
        cout << "Major: " << major << endl;
        cout << "Class: " << clazz << endl;
        cout << "Score: " << score << endl;
    }

    virtual double getScore() {
        return score;
    }
};

class Undergraduate : public Student {
public:
    string studyTime;

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

    virtual void display() {
        Student::display();
        cout << "Study Time: " << studyTime << endl;
    }
};

class Graduate : public Student {
public:
    string supervisor;

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

    virtual void display() {
        Student::display();
        cout << "Supervisor: " << supervisor << endl;
    }
};

class Admin {
private:
    vector<Student *> students;

public:
    void login() {
        // 进行登录操作
    }

    void add(Student *student) {
        students.push_back(student);
    }

    void displayAll() {
        for (auto student : students) {
            student->display();
            cout << endl;
        }
    }

    void findByID(string id) {
        for (auto student : students) {
            if (student->id == id) {
                student->display();
                return;
            }
        }
        cout << "Student not found." << endl;
    }

    void findByName(string name) {
        for (auto student : students) {
            if (student->name == name) {
                student->display();
                return;
            }
        }
        cout << "Student not found." << endl;
    }

    void findByClass(string clazz) {
        for (auto student : students) {
            if (student->clazz == clazz) {
                student->display();
                cout << endl;
            }
        }
    }

    void removeByID(string id) {
        for (auto it = students.begin(); it != students.end(); ++it) {
            if ((*it)->id == id) {
                delete *it;
                students.erase(it);
                return;
            }
        }
        cout << "Student not found." << endl;
    }

    void removeByName(string name) {
        for (auto it = students.begin(); it != students.end(); ++it) {
            if ((*it)->name == name) {
                delete *it;
                students.erase(it);
                return;
            }
        }
        cout << "Student not found." << endl;
    }

    void modifyByID(string id, string name, string gender, int age, string major, string clazz, double score) {
        for (auto student : students) {
            if (student->id == id) {
                student->name = name;
                student->gender = gender;
                student->age = age;
                student->major = major;
                student->clazz = clazz;
                student->score = score;
                return;
            }
        }
        cout << "Student not found." << endl;
    }

    void summary(double minScore, double maxScore) {
        int count = 0;
        double sum = 0;
        for (auto student : students) {
            double score = student->getScore();
            if (score >= minScore && score <= maxScore) {
                count++;
                sum += score;
            }
        }
        cout << "Count: " << count << endl;
        cout << "Average score: " << (count == 0 ? 0 : sum / count) << endl;
    }
};

int main() {
    Admin admin;
    admin.add(new Undergraduate("1001", "Alice", "Female", 20, "Computer Science", "Class 1", 90.0, "4 years"));
    admin.add(new Undergraduate("1002", "Bob", "Male", 21, "Computer Science", "Class 2", 85.0, "4 years"));
    admin.add(new Graduate("2001", "Charlie", "Male", 25, "Mathematics", "Class 3", 95.0, "Dr. Smith"));

    admin.displayAll();
    cout << endl;

    admin.findByID("1001");
    admin.findByID("1003");
    cout << endl;

    admin.findByName("Bob");
    admin.findByName("David");
    cout << endl;

    admin.findByClass("Class 1");
    cout << endl;

    admin.removeByID("1002");
    admin.displayAll();
    cout << endl;

    admin.modifyByID("1001", "Alice Smith", "Female", 20, "Computer Science", "Class 2", 95.0);
    admin.findByID("1001");
    cout << endl;

    admin.summary(80.0, 90.0);

    return 0;
}

该程序定义了一个学生类和两个派生类（本科生和研究生类），并且定义了一个管理员类用于管理学生信息。管理员类中包含了一些基本的操作，例如添加学生、显示所有学生信息、按学号或姓名查找学生、按学号或姓名删除学生、修改学生信息、以及计算学生成绩汇总等功能。程序中使用了虚函数实现了多态，使得可以对不同类型的学生进行统一管理。