如何使用C++编写一个简单的医院挂号系统？

#include <iOStream>
#include <vector>

struct Doctor {
    int id;
    std::string name;
    std::string specialty;
};

struct Patient {
    int id;
    std::string name;
    int age;
};

struct Appointment {
    int id;
    Doctor doctor;
    Patient patient;
    std::string date;
};

std::vector<Appointment> database;

void aDDDoctor() {
    Doctor doctor;
    
    // 从用户输入获取医生的信息
    std::cout << "请输入医生的编号：";
    std::cin >> doctor.id;
    std::cout << "请输入医生的姓名：";
    std::cin >> doctor.name;
    std::cout << "请输入医生的专业：";
    std::cin >> doctor.specialty;
    
    // 将医生添加到数据库中
    database.push_back(doctor);
}

void addPatient() {
    Patient patient;
    
    // 从用户输入获取患者的信息
    std::cout << "请输入患者的编号：";
    std::cin >> patient.id;
    std::cout << "请输入患者的姓名：";
    std::cin >> patient.name;
    std::cout << "请输入患者的年龄：";
    std::cin >> patient.age;
    
    // 将患者添加到数据库中
    database.push_back(patient);
}

void createAppointment() {
    Appointment appointment;
    
    // 从用户输入获取预约的信息
    std::cout << "请输入预约的编号：";
    std::cin >> appointment.id;
    
    // 从数据库中选择医生和患者
    std::cout << "医生列表：" << std::endl;
    for (const auto& doctor : database) {
        if (doctor.id >= 0) {
            std::cout << doctor.id << ": " << doctor.name << " - " << doctor.specialty << std::endl;
        }
    }
    std::cout << "请选择医生编号：";
    std::cin >> appointment.doctor.id;
    
    std::cout << "患者列表：" << std::endl;
    for (const auto& patient : database) {
        if (patient.id >= 0) {
            std::cout << patient.id << ": " << patient.name << " - " << patient.age << std::endl;
        }
    }
    std::cout << "请选择患者编号：";
    std::cin >> appointment.patient.id;
    
    std::cout << "请输入预约的日期：";
    std::cin >> appointment.date;
    
    // 将预约添加到数据库中
    database.push_back(appointment);
}

int main() {
    while (true) {
        std::cout << "欢迎使用医院挂号系统！" << std::endl;
        std::cout << "[1] 添加医生" << std::endl;
        std::cout << "[2] 添加患者" << std::endl;
        std::cout << "[3] 创建预约" << std::endl;
        std::cout << "[4] 退出系统" << std::endl;
        
        int choice;
        std::cout << "请选择功能：";
        std::cin >> choice;
        
        switch (choice) {
            case 1:
                addDoctor();
                break;
            case 2:
                addPatient();
                break;
            case 3:
                createAppointment();
                break;
            case 4:
                return 0;
        }
        
        std::cout << std::endl;
    }
    
    return 0;
}