用C++写一个通讯录管理系统，要求文件输入输出

以下是一个使用C++编写的通讯录管理系统，实现了通讯录联系人的添加、删除、查找、修改，以及通讯录的清空、备份和还原功能，并且支持文件输入输出：

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

using namespace std;

struct Contact {
    string name;
    string phone;
};

class AddressBook {
private:
    vector<Contact> contacts;

public:
    void addContact(const Contact& contact) {
        contacts.push_back(contact);
    }

    void deleteContact(const string& name) {
        for (auto it = contacts.begin(); it != contacts.end(); ++it) {
            if (it->name == name) {
                contacts.erase(it);
                break;
            }
        }
    }

    Contact* findContact(const string& name) {
        for (auto& contact : contacts) {
            if (contact.name == name) {
                return &contact;
            }
        }
        return nullptr;
    }

    void modifyContact(const string& name, const string& newPhone) {
        for (auto& contact : contacts) {
            if (contact.name == name) {
                contact.phone = newPhone;
                break;
            }
        }
    }

    void clearAddressBook() {
        contacts.clear();
    }

    void backupAddressBook(const string& filename) {
        ofstream file(filename);
        if (file.is_open()) {
            for (const auto& contact : contacts) {
                file << contact.name << "," << contact.phone << endl;
            }
            file.close();
            cout << "通讯录已备份到文件：" << filename << endl;
        } else {
            cout << "无法打开文件：" << filename << endl;
        }
    }

    void restoreAddressBook(const string& filename) {
        ifstream file(filename);
        if (file.is_open()) {
            contacts.clear();
            string line;
            while (getline(file, line)) {
                size_t pos = line.find(",");
                if (pos != string::npos) {
                    string name = line.substr(0, pos);
                    string phone = line.substr(pos + 1);
                    contacts.push_back({name, phone});
                }
            }
            file.close();
            cout << "通讯录已从文件：" << filename << " 还原" << endl;
        } else {
            cout << "无法打开文件：" << filename << endl;
        }
    }
};

int main() {
    AddressBook addressBook;

    while (true) {
        cout << "请选择操作：" << endl;
        cout << "1. 添加联系人" << endl;
        cout << "2. 删除联系人" << endl;
        cout << "3. 查找联系人" << endl;
        cout << "4. 修改联系人" << endl;
        cout << "5. 清空通讯录" << endl;
        cout << "6. 备份通讯录" << endl;
        cout << "7. 还原通讯录" << endl;
        cout << "8. 退出程序" << endl;

        int choice;
        cin >> choice;

        if (choice == 1) {
            cout << "请输入联系人姓名：";
            string name;
            cin >> name;
            cout << "请输入联系人电话：";
            string phone;
            cin >> phone;
            addressBook.addContact({name, phone});
            cout << "联系人已添加" << endl;
        } else if (choice == 2) {
            cout << "请输入要删除的联系人姓名：";
            string name;
            cin >> name;
            addressBook.deleteContact(name);
            cout << "联系人已删除" << endl;
        } else if (choice == 3) {
            cout << "请输入要查找的联系人姓名：";
            string name;
            cin >> name;
            Contact* contact = addressBook.findContact(name);
            if (contact != nullptr) {
                cout << "联系人姓名：" << contact->name << "，电话：" << contact->phone << endl;
            } else {
                cout << "未找到该联系人" << endl;
            }
        } else if (choice == 4) {
            cout << "请输入要修改的联系人姓名：";
            string name;
            cin >> name;
            cout << "请输入新的电话号码：";
            string phone;
            cin >> phone;
            addressBook.modifyContact(name, phone);
            cout << "联系人已修改" << endl;
        } else if (choice == 5) {
            addressBook.clearAddressBook();
            cout << "通讯录已清空" << endl;
        } else if (choice == 6) {
            cout << "请输入备份文件名：";
            string filename;
            cin >> filename;
            addressBook.backupAddressBook(filename);
        } else if (choice == 7) {
            cout << "请输入还原文件名：";
            string filename;
            cin >> filename;
            addressBook.restoreAddressBook(filename);
        } else if (choice == 8) {
            break;
        } else {
            cout << "无效的选择，请重新输入" << endl;
        }
    }

    return 0;
}