ivan8m8

#include <string>
#include <utility>
#include <iostream>

class CredentialsInfo {
    std::string _login, _password;

public:
    CredentialsInfo() {}
    CredentialsInfo(const std::string& login, const std::string& password)
        : _login(login)
        , _password(password)
    { }

public:
    std::string Login() const {
        return _login;
    }

    std::string Password() const {
        return _password;
    }

    void SetLogin(const std::string& newLogin) {
        _login = newLogin;
    }

    void SetPassword(const std::string& newPassword) {
        _password = newPassword;
    }

    friend std::ostream& operator<<(std::ostream&, const CredentialsInfo&);
};

std::ostream& operator<<(std::ostream& out, const CredentialsInfo& info) {
    return out << info._login << "; " << info._password;
}

template <class DataClass>
class Queue {
public:
    typedef DataClass   value_type;

private:
    struct QueueNode {
        value_type Value;
        QueueNode* Next;

        QueueNode(value_type&& value)
            : Value(std::move(value))
            , Next(nullptr)
        { }
    };

    QueueNode *_head, *_tail;

public:
    Queue()
        : _head(nullptr)
        , _tail(nullptr)
    { }

    ~Queue() {
        while(_head) {
            auto tmp = _head;
            _head = _head->Next;
            delete tmp;
        }
    }

public:
    template <class Data>
    void Add(Data&& data) {
        auto* newNode = new QueueNode(std::forward<Data>(data));
        if (_head) {
            _tail->Next = newNode;
            _tail = newNode;
        } else {
            _head = _tail = newNode;
        }
    }

    template<class... Args>
    void Add(Args&&... args) {
        Add(value_type(std::forward<Args>(args)...));
    }

    void Show(std::ostream& out) const {
        auto it = _head;
        while (it) {
            out << it->Value << '\n';
            it = it->Next;
        }
        out.flush();
    }
};

typedef Queue<CredentialsInfo> CredentialsQueue;

int main(int, char**) {
    CredentialsQueue queue;

    queue.Add("s", "ss");
    queue.Add("1", "op");
    queue.Add("1", "p");
    queue.Show(std::cout);
    return 0;
}