请用C++实现：1． 订票系统 任务：请根据以下要求，设计航班信息、订票信息的存储结构，设计程序完成订票系统的相关功能。 要求： （1）录入：可以录入航班情况，数据可以存储在一个数据文件中，数据结构自定； （2）查询：可以查询某个航线的情况（如，输入航班号，查询起降时间，起飞抵达城市，航班票价，票价折扣，确定航班是否满仓）；可以输入起飞抵达城市，查询飞机航班情况； （3）订票：（订票情况可以存在一个数据文件中，结构自己设定）可以订票，如果该航班已经无票，可以提供相关可选择航班； （4）退票： 可退票，退票后修改相关数据文件；客户资料有姓名，证件号，订票数量及航班情况，订单要有编号； （5）修改航班信息：当航班信息改变可以修改航班数据文件。

好的，我会为您解答。以下是一个简单的订票系统的C++实现，包括录入航班信息、查询、订票、退票和修改航班信息等功能。

#include <iostream>
#include <fstream>
#include <cstring>
using namespace std;

struct Flight {
    char flight_no[10]; // 航班号
    char departure_time[20]; // 起飞时间
    char arrival_time[20]; // 抵达时间
    char departure_city[20]; // 起飞城市
    char arrival_city[20]; // 抵达城市
    double price; // 票价
    double discount; // 折扣
    int seats; // 座位数
};

struct Order {
    int id; // 订单编号
    char name[20]; // 姓名
    char id_no[20]; // 身份证号
    char flight_no[10]; // 航班号
    int num; // 订票数量
};

void save_flight(Flight f) {
    ofstream out("flights.dat", ios::app | ios::binary);
    out.write((char*)&f, sizeof(f));
    out.close();
}

void read_flights() {
    ifstream in("flights.dat", ios::binary);
    Flight f;
    while (in.read((char*)&f, sizeof(f))) {
        cout << "航班号：" << f.flight_no << endl;
        cout << "起飞时间：" << f.departure_time << endl;
        cout << "抵达时间：" << f.arrival_time << endl;
        cout << "起飞城市：" << f.departure_city << endl;
        cout << "抵达城市：" << f.arrival_city << endl;
        cout << "票价：" << f.price << endl;
        cout << "折扣：" << f.discount << endl;
        cout << "座位数：" << f.seats << endl << endl;
    }
    in.close();
}

void query_flight(char flight_no[10]) {
    ifstream in("flights.dat", ios::binary);
    Flight f;
    bool found = false;
    while (in.read((char*)&f, sizeof(f))) {
        if (strcmp(f.flight_no, flight_no) == 0) {
            cout << "航班号：" << f.flight_no << endl;
            cout << "起飞时间：" << f.departure_time << endl;
            cout << "抵达时间：" << f.arrival_time << endl;
            cout << "起飞城市：" << f.departure_city << endl;
            cout << "抵达城市：" << f.arrival_city << endl;
            cout << "票价：" << f.price << endl;
            cout << "折扣：" << f.discount << endl;
            cout << "座位数：" << f.seats << endl << endl;
            found = true;
            break;
        }
    }
    if (!found) {
        cout << "未找到该航班信息！" << endl;
    }
    in.close();
}

void query_flight(char departure_city[20], char arrival_city[20]) {
    ifstream in("flights.dat", ios::binary);
    Flight f;
    bool found = false;
    while (in.read((char*)&f, sizeof(f))) {
        if (strcmp(f.departure_city, departure_city) == 0 && strcmp(f.arrival_city, arrival_city) == 0) {
            cout << "航班号：" << f.flight_no << endl;
            cout << "起飞时间：" << f.departure_time << endl;
            cout << "抵达时间：" << f.arrival_time << endl;
            cout << "起飞城市：" << f.departure_city << endl;
            cout << "抵达城市：" << f.arrival_city << endl;
            cout << "票价：" << f.price << endl;
            cout << "折扣：" << f.discount << endl;
            cout << "座位数：" << f.seats << endl << endl;
            found = true;
        }
    }
    if (!found) {
        cout << "未找到符合条件的航班信息！" << endl;
    }
    in.close();
}

void book_ticket(int id, char name[20], char id_no[20], char flight_no[10], int num) {
    ifstream in("flights.dat", ios::binary);
    Flight f;
    bool found = false;
    while (in.read((char*)&f, sizeof(f))) {
        if (strcmp(f.flight_no, flight_no) == 0) {
            if (f.seats < num) {
                cout << "该航班已满仓，请选择其他航班！" << endl;
            } else {
                f.seats -= num;
                save_flight(f);
                Order o;
                o.id = id;
                strcpy(o.name, name);
                strcpy(o.id_no, id_no);
                strcpy(o.flight_no, flight_no);
                o.num = num;
                ofstream out("orders.dat", ios::app | ios::binary);
                out.write((char*)&o, sizeof(o));
                out.close();
                cout << "订票成功！" << endl;
            }
            found = true;
            break;
        }
    }
    if (!found) {
        cout << "未找到该航班信息！" << endl;
    }
    in.close();
}

void cancel_ticket(int id) {
    ifstream in("orders.dat", ios::binary);
    Order o;
    bool found = false;
    while (in.read((char*)&o, sizeof(o))) {
        if (o.id == id) {
            ifstream in2("flights.dat", ios::binary);
            Flight f;
            while (in2.read((char*)&f, sizeof(f))) {
                if (strcmp(f.flight_no, o.flight_no) == 0) {
                    f.seats += o.num;
                    save_flight(f);
                    break;
                }
            }
            in2.close();
            ofstream out("temp.dat", ios::app | ios::binary);
            Order o2;
            while (in.read((char*)&o2, sizeof(o2))) {
                if (o2.id != id) {
                    out.write((char*)&o2, sizeof(o2));
                }
            }
            out.close();
            remove("orders.dat");
            rename("temp.dat", "orders.dat");
            cout << "退票成功！" << endl;
            found = true;
            break;
        }
    }
    if (!found) {
        cout << "未找到该订单信息！" << endl;
    }
    in.close();
}

void modify_flight(char flight_no[10], Flight new_f) {
    ifstream in("flights.dat", ios::binary);
    Flight f;
    bool found = false;
    while (in.read((char*)&f, sizeof(f))) {
        if (strcmp(f.flight_no, flight_no) == 0) {
            ofstream out("temp.dat", ios::app | ios::binary);
            out.write((char*)&new_f, sizeof(new_f));
            found = true;
        } else {
            ofstream out("temp.dat", ios::app | ios::binary);
            out.write((char*)&f, sizeof(f));
        }
    }
    if (!found) {
        cout << "未找到该航班信息！" << endl;
    } else {
        remove("flights.dat");
        rename("temp.dat", "flights.dat");
        cout << "修改航班信息成功！" << endl;
    }
    in.close();
}

int main() {
    int choice;
    cout << "欢迎使用订票系统！" << endl;
    do {
        cout << "请选择功能：" << endl;
        cout << "1. 录入航班信息" << endl;
        cout << "2. 查询航班信息" << endl;
        cout << "3. 订票" << endl;
        cout << "4. 退票" << endl;
        cout << "5. 修改航班信息" << endl;
        cout << "0. 退出系统" << endl;
        cout << "选择：";
        cin >> choice;
        switch (choice) {
            case 1: {
                Flight f;
                cout << "请输入航班号：";
                cin >> f.flight_no;
                cout << "请输入起飞时间：";
                cin >> f.departure_time;
                cout << "请输入抵达时间：";
                cin >> f.arrival_time;
                cout << "请输入起飞城市：";
                cin >> f.departure_city;
                cout << "请输入抵达城市：";
                cin >> f.arrival_city;
                cout << "请输入票价：";
                cin >> f.price;
                cout << "请输入折扣：";
                cin >> f.discount;
                cout << "请输入座位数：";
                cin >> f.seats;
                save_flight(f);
                cout << "录入成功！" << endl;
                break;
            }
            case 2: {
                int query_choice;
                cout << "请选择查询方式：" << endl;
                cout << "1. 查询航班号" << endl;
                cout << "2. 查询起降城市" << endl;
                cout << "选择：";
                cin >> query_choice;
                if (query_choice == 1) {
                    char flight_no[10];
                    cout << "请输入航班号：";
                    cin >> flight_no;
                    query_flight(flight_no);
                } else if (query_choice == 2) {
                    char departure_city[20], arrival_city[20];
                    cout << "请输入起飞城市：";
                    cin >> departure_city;
                    cout << "请输入抵达城市：";
                    cin >> arrival_city;
                    query_flight(departure_city, arrival_city);
                }
                break;
            }
            case 3: {
                int id, num;
                char name[20], id_no[20], flight_no[10];
                cout << "请输入订单编号：";
                cin >> id;
                cout << "请输入姓名：";
                cin >> name;
                cout << "请输入身份证号：";
                cin >> id_no;
                cout << "请输入航班号：";
                cin >> flight_no;
                cout << "请输入订票数量：";
                cin >> num;
                book_ticket(id, name, id_no, flight_no, num);
                break;
            }
            case 4: {
                int id;
                cout << "请输入订单编号：";
                cin >> id;
                cancel_ticket(id);
                break;
            }
            case 5: {
                char flight_no[10];
                cout << "请输入要修改的航班号：";
                cin >> flight_no;
                Flight new_f;
                cout << "请输入起飞时间：";
                cin >> new_f.departure_time;
                cout << "请输入抵达时间：";
                cin >> new_f.arrival_time;
                cout << "请输入起飞城市：";
                cin >> new_f.departure_city;
                cout << "请输入抵达城市：";
                cin >> new_f.arrival_city;
                cout << "请输入票价：";
                cin >> new_f.price;
                cout << "请输入折扣：";
                cin >> new_f.discount;
                cout << "请输入座位数：";
                cin >> new_f.seats;
                modify_flight(flight_no, new_f);
                break;
            }
            case 0: {
                cout << "谢谢使用！" << endl;
                break;
            }
            default: {
                cout << "输入错误，请重新输入！" << endl;
                break;
            }
        }
    } while (choice != 0);
    return 0;
}

以上代码实现了一个简单的订票系统，包括录入航班信息、查询、订票、退票和修改航班信息等功能。其中航班信息和订单信息存储在二进制文件中。