智能指针和STL库学习思维导图和练习

 思维导图：

 

#include <iostream>
#include <vector>
#include <string>
using namespace std;

// 用户结构体
struct User {
    string username;
    string password;
};

vector<User> users; // 存储所有注册用户

// 使用迭代器查找用户名是否存在
vector<User>::iterator findUser(const string& username) {
    auto it = users.begin();
    for (; it != users.end(); ++it) {
        if (it->username == username) {
            return it;
        }
    }
    return users.end(); // 未找到返回结束迭代器
}

void registerUser() {
    User newUser;
    cout << "请输入用户名: ";
    cin >> newUser.username;

    // 使用迭代器查重
    if (findUser(newUser.username) != users.end()) {
        cout << "用户名已存在！" << endl;
        return;
    }

    cout << "请输入密码: ";
    cin >> newUser.password;
    users.push_back(newUser); // 使用vector的push_back添加元素
    cout << "注册成功！" << endl;
}

void loginUser() {
    string username, password;
    cout << "请输入用户名: ";
    cin >> username;
    cout << "请输入密码: ";
    cin >> password;

    // 使用迭代器遍历验证
    auto it = users.begin();
    for (; it != users.end(); ++it) {
        if (it->username == username && it->password == password) {
            cout << "登录成功！" << endl;
            return;
        }
    }
    cout << "用户名或密码错误！" << endl;
}

int main() {
    int choice;
    do {
        cout << "\n1. 注册\n2. 登录\n3. 退出\n请选择操作: ";
        cin >> choice;
        
        switch (choice) {
            case 1:
                registerUser();
                break;
            case 2:
                loginUser();
                break;
            case 3:
                cout << "系统已退出。" << endl;
                break;
            default:
                cout << "无效选项，请重新输入！" << endl;
        }
    } while (choice != 3);

    return 0;
}