P.1命令行通讯录

命令行通讯录：

1、功能：添加联系人（姓名/电话号码(9位数)/邮箱）、移除、查询、修改、显示所有联系人、保存到本地文本文件/从文件加载
2、训练重点：结构体/类的封装、vector存储自定义对象、map<string, 结构体>快速查询、文件流（fstream）的读写、函数分模块实现（增删改查各写一个函数）

#include <iostream>
#include <string>
#include <unordered_map>
#include <fstream>
#include <stdexcept>
#include <limits>
using namespace std;

class AddressBook {
private:
    struct Contact {
        string phone;
        string email;
        Contact() = default;
        Contact(string p, string e) : phone(std::move(p)), email(std::move(e)) {}
    };
    unordered_map<string, Contact> contacts;
    const string filename = "contacts.txt";

    // 私有辅助函数：清屏
    void clearScreen() const {
        system("cls||clear");
    }

    // 私有辅助函数：暂停
    void pause() const {
        system("pause");
    }

public:
    // 添加联系人
    void addContact(const string &name, const string &phone, const string &email) {
        if (contacts.count(name)) {
            cout << "联系人 " << name << " 已存在！" << endl;
            return;
        }
        contacts.emplace(name, Contact(phone, email));
        cout << "添加成功！" << endl;
    }

    // 删除联系人
    void removeContact(const string &name) {
        if (!contacts.count(name)) {
            cout << "联系人 " << name << " 不存在！" << endl;
            return;
        }
        contacts.erase(name);
        cout << "删除成功！" << endl;
    }

    // 查询联系人
    void searchContact(const string &name) const {
        auto it = contacts.find(name);
        if (it == contacts.end()) {
            cout << "联系人 " << name << " 不存在！" << endl;
            return;
        }
        cout << "姓名：" << name 
            << "，电话：" << it->second.phone 
            << "，邮箱：" << it->second.email << endl;
    }

    // 修改联系人
    void modifyContact(const string &name) {
        auto it = contacts.find(name);
        if (it == contacts.end()) {
            cout << "联系人 " << name << " 不存在！" << endl;
            return;
        }
        int choice;
        cout << "1.修改电话 2.修改邮箱：";
        cin >> choice;
        if (choice == 1) {
            string newPhone;
            cout << "新电话：";
            cin >> newPhone;
            it->second.phone = newPhone;
        } else if (choice == 2) {
            string newEmail;
            cout << "新邮箱：";
            cin >> newEmail;
            it->second.email = newEmail;
        } else {
            cout << "无效选择！" << endl;
            return;
        }
        cout << "修改成功！" << endl;
    }

    // 显示所有联系人
    void showAll() const {
        if (contacts.empty()) {
            cout << "通讯录为空！" << endl;
            return;
        }
        int i = 1;
        for (const auto &[name, info] : contacts) { // C++17结构化绑定
            cout << i++ << ". 姓名：" << name 
                << "，电话：" << info.phone 
                << "，邮箱：" << info.email << endl;
        }
    }

    // 保存到文件
    void saveToFile() const {
        ofstream ofs(filename, ios::out);
        if (!ofs) {
            cerr << "文件打开失败！" << endl;
            return;
        }
        for (const auto &[name, info] : contacts) {
            ofs << name << "," << info.phone << "," << info.email << "\n";
        }
        ofs.close();
        cout << "保存成功！" << endl;
    }

    // 从文件加载
    void loadFromFile() {
        ifstream ifs(filename, ios::in);
        if (!ifs) {
            cerr << "文件打开失败！" << endl;
            return;
        }
        contacts.clear();
        string line;
        while (getline(ifs, line)) {
            size_t p1 = line.find(',');
            size_t p2 = line.find(',', p1+1);
            if (p1 == string::npos || p2 == string::npos) continue;
            string name = line.substr(0, p1);
            string phone = line.substr(p1+1, p2-p1-1);
            string email = line.substr(p2+1);
            contacts.emplace(name, Contact(phone, email));
        }
        ifs.close();
        cout << "加载成功！" << endl;
    }

    // 菜单界面
    void showMenu() {
        while (true) {
            clearScreen();
            cout << "===== 通讯录 =====" << endl;
            cout << "1.添加 2.删除 3.查询" << endl;
            cout << "4.修改 5.显示 6.保存" << endl;
            cout << "7.加载 8.退出" << endl;
            cout << "==================" << endl;
            cout << "请选择：";
            int choice;
            if (!(cin >> choice)) {
                cin.clear();
                cin.ignore(numeric_limits<streamsize>::max(), '\n');
                cout << "输入无效！" << endl;
                pause();
                continue;
            }
            cout << endl;

            string name, phone, email;
            switch (choice) {
            case 1:
                cout << "姓名："; cin >> name;
                cout << "电话："; cin >> phone;
                cout << "邮箱："; cin >> email;
                addContact(name, phone, email); break;
            case 2:
                cout << "姓名："; cin >> name;
                removeContact(name); break;
            case 3:
                cout << "姓名："; cin >> name;
                searchContact(name); break;
            case 4:
                cout << "姓名："; cin >> name;
                modifyContact(name); break;
            case 5:
                showAll(); break;
            case 6:
                saveToFile(); break;
            case 7:
                loadFromFile(); break;
            case 8:
                cout << "退出成功！" << endl;
                return;
            default:
                cout << "无效选择！" << endl;
            }
            pause();
        }
    }
};

int main()
{
	AddressBook myAddressBook;
	myAddressBook.showMenu();
	return 0;
}

Attention:代码可能有更简洁更高效的写法，此处只是分享本人的学习过程。如果你有好的建议或意见，欢迎在评论区分享，我都会看的并且会一一答复☆: .｡. o(≧▽≦)o .｡.:☆