登錄系統C ++：輸入我的字符串User＆Pass之后，要求我重新輸入它們

Question

我的代碼是我要建立的商店，它可以正常運行（注冊系統），直到輸入用戶名和密碼（登錄系統）為止。輸入用戶名后，程序會要求我重新登錄並繼續進行操作（可以肯定是因為這是一會兒真實循環）。 （這是一個項目，因此存在帶有構造函數和類的單獨的不同文件。）

這是我的代碼的一部分：

while(true)
{
    cout << "Would you like to register or login?" << endl;
    string answer = "";
    cin >> answer;

    if(answer == "register" || answer == "Register")
    {
        cout << "What would be your designated username?: " << endl;
        string newUser;
        cin >> newUser;
        for(int i = 0; i < 20; i++)
        {
            if(customers[i] -> username != newUser)
            {
                cout << "what would be your designated password?: " << endl;
                string newPass;
                cin >> newPass;
                customers[lastRegisteredID] = new Customer(newUser, newPass);
                lastRegisteredID++;
                break;
            }
        }

        //^Register Part.
    }

    if(answer == "login" || answer == "Login")
    {
        cout << "Your username: " << endl;
        string UserAttempt;
        cin >> UserAttempt;
        for(int j = 0; j < 20; j++)
        {
            if(customers[j] -> username == UserAttempt)
            {
                cout << "Username Found!" << endl;
                tempCustomer = customers[j];

                cout << "Your password: " << endl;
                string PassAtempt;
                cin >> PassAtempt;

                if(tempCustomer -> password == PassAtempt)
                {
                    cout << "Password correct \n Successfully logged in." << endl;
                    loggedin = true;
                    break;
                }
            }
        }
    }

    //^Login part.
}

Answer 1

您要問的問題（正如您對問題的評論所說）來自事實，您break; 只會使您脫離for循環（最里面的循環），而不會進入while循環。 解決此問題的最簡單方法是將while(true)替換為while(!loggedin) 。 還要注意，您發布的代碼中還有其他一些問題。 因為我不知道這些錯誤是否也在您的最終代碼中，所以我只會列出它們（我發現的幾個）：

• 妊娠系統中存在內存泄漏：您不會刪除舊客戶
• 在陣列中注冊/保存用戶的方式可能與您預期的方式不同。 嘗試用不同的用戶名注冊兩個用戶，然后用相同的用戶名注冊更多用戶，並檢查會發生什么；）

Answer 2

執行成功的login操作后，您不會脫離while循環。

另外，如果注冊的客戶少於20個，您的代碼也會崩潰。

另外，您的代碼允許多個用戶使用相同的用戶名甚至相同的密碼進行注冊。

嘗試類似這樣的方法：

Customer* customers[20];
int numCustomers = 0;
bool loggedin = false;

Customer* findCustomer(const std::string &user)
{
    for(int i = 0; i < numCustomers; ++i)
    {
        if (customers[i]->username == user)
            return customers[i];
    }
    return NULL;
}

...

while (true)
{
    std::cout << "Would you like to register or login?" << std::endl;
    std::string answer;
    std::cin >> answer;

    std::transform(answer.begin(), answer.end(), ::tolower);

    if (answer == "register")
    {
        std::cout << "What would be your designated username?: " << std::endl;
        string newUser;
        std::cin >> newUser;

        Customer *cust = findCustomer(newUser);
        if (cust)
        {
            std::cout << "That username is already taken!" << endl;
            continue;
        }

        if (numCustomers >= 20)
        {
            std::cout << "Too many users are registered!" << endl;
            continue;
        }

        std::cout << "what would be your designated password?: " << std::endl;
        std::string newPass;
        std::cin >> newPass;

        customers[numCustomers] = new Customer(newUser, newPass);
        ++numCustomers;

        continue;
    }

    if (answer == "login")
    {
        std::cout << "Your username: " << std::endl;
        std::string UserAttempt;
        std::cin >> UserAttempt;

        std::cout << "Your password: " << std::endl;
        std::string PassAttempt;
        std::cin >> PassAttempt;

        Customer *cust = findCustomer(UserAttempt);
        if ((cust) && (cust->password == PassAttempt))
        {
            std::cout << "Successfully logged in" << std::endl;
            loggedin = true;
            break;
        }

        std::cout << "Not logged in!" << std::endl;
        continue;
    }

    std::cout << "Unknown command! Try again" << std::endl;
}