用C++设计一个通讯录管理系统，并指出其中的数据结构

一个通讯录管理系统可以使用以下数据结构：

1. 结构体（struct）：用于存储每个联系人的信息，包括姓名、电话号码、地址等。

2. 动态数组（vector）：用于存储所有联系人的结构体，可以方便地进行添加、删除、修改等操作。

3. 链表（linked list）：用于实现联系人的排序和查找功能，可以根据姓名首字母或者其他字段进行排序，并且可以快速查找指定联系人。

4. 文件（file）：用于将联系人信息保存到磁盘上，保证数据的持久化。

以下是一个简单的通讯录管理系统的 C++ 代码示例：

#include <iostream>
#include <vector>
#include <algorithm>
#include <fstream>

using namespace std;

struct Contact {
    string name;
    string phone_number;
    string address;
};

vector<Contact> contacts;

void add_contact() {
    Contact contact;
    cout << "Enter name: ";
    getline(cin, contact.name);
    cout << "Enter phone number: ";
    getline(cin, contact.phone_number);
    cout << "Enter address: ";
    getline(cin, contact.address);
    contacts.push_back(contact);
}

void delete_contact() {
    string name;
    cout << "Enter name to delete: ";
    getline(cin, name);
    for (auto it = contacts.begin(); it != contacts.end(); it++) {
        if (it->name == name) {
            contacts.erase(it);
            cout << "Contact deleted." << endl;
            return;
        }
    }
    cout << "Contact not found." << endl;
}

void modify_contact() {
    string name;
    cout << "Enter name to modify: ";
    getline(cin, name);
    for (auto& contact : contacts) {
        if (contact.name == name) {
            cout << "Enter new phone number: ";
            getline(cin, contact.phone_number);
            cout << "Enter new address: ";
            getline(cin, contact.address);
            cout << "Contact modified." << endl;
            return;
        }
    }
    cout << "Contact not found." << endl;
}

void search_contact() {
    string name;
    cout << "Enter name to search: ";
    getline(cin, name);
    for (auto& contact : contacts) {
        if (contact.name == name) {
            cout << "Name: " << contact.name << endl;
            cout << "Phone number: " << contact.phone_number << endl;
            cout << "Address: " << contact.address << endl;
            return;
        }
    }
    cout << "Contact not found." << endl;
}

void list_contacts() {
    sort(contacts.begin(), contacts.end(), [](const Contact& a, const Contact& b) {
        return a.name < b.name;
    });
    for (const auto& contact : contacts) {
        cout << "Name: " << contact.name << endl;
        cout << "Phone number: " << contact.phone_number << endl;
        cout << "Address: " << contact.address << endl;
        cout << endl;
    }
}

void save_contacts() {
    ofstream file("contacts.txt");
    for (const auto& contact : contacts) {
        file << contact.name << "," << contact.phone_number << "," << contact.address << endl;
    }
    file.close();
    cout << "Contacts saved." << endl;
}

void load_contacts() {
    ifstream file("contacts.txt");
    if (file.is_open()) {
        string line;
        while (getline(file, line)) {
            Contact contact;
            size_t pos = line.find(",");
            contact.name = line.substr(0, pos);
            line.erase(0, pos + 1);
            pos = line.find(",");
            contact.phone_number = line.substr(0, pos);
            line.erase(0, pos + 1);
            contact.address = line;
            contacts.push_back(contact);
        }
        file.close();
        cout << "Contacts loaded." << endl;
    } else {
        cout << "Unable to open file." << endl;
    }
}

int main() {
    load_contacts();

    while (true) {
        cout << "1. Add contact" << endl;
        cout << "2. Delete contact" << endl;
        cout << "3. Modify contact" << endl;
        cout << "4. Search contact" << endl;
        cout << "5. List contacts" << endl;
        cout << "6. Save contacts" << endl;
        cout << "7. Exit" << endl;
        cout << "Enter your choice: ";

        int choice;
        cin >> choice;
        cin.ignore();

        switch (choice) {
            case 1:
                add_contact();
                break;
            case 2:
                delete_contact();
                break;
            case 3:
                modify_contact();
                break;
            case 4:
                search_contact();
                break;
            case 5:
                list_contacts();
                break;
            case 6:
                save_contacts();
                break;
            case 7:
                return 0;
            default:
                cout << "Invalid choice." << endl;
                break;
        }

        cout << endl;
    }

    return 0;
}

这个程序使用了结构体、动态数组、文件以及字符串处理等多种数据结构和技术，可以实现基本的通讯录管理功能。