Simples Simulação

#include <iostream>
#include <fstream>
#include <cstdlib>
#include <string>
using namespace std;

void mainMenu();
void start();

class UserRoot
{
public:
    std::string root_username;
    std::string root_password;

    void setRootUsername(std::string _root_username_)
    {
        this->root_username = _root_username_;
    }

    void setRootPassword(std::string _root_password_)
    {
        this->root_password = _root_password_;
    }

    friend ostream& operator<<(ostream& archive, const UserRoot& root)
    {
        archive << std::endl << "USER: " << root.root_username << std::endl <<
                "PASSWORD: " << root.root_password;
        return archive;
    }
};

UserRoot root;

int main()
{
    mainMenu();
}

void mainMenu()
{
    char user_option;

    std::cout << std::endl << "\t\tWELCOME TO LINUX OS" << std::endl;
    std::cout << std::endl << "\t\t1_SET YOUR SETTINGS" <<std::endl;
    std::cout << "\t\t2_ENTER IN SYSTEM" << std::endl;
    std::cout << "\t\t3_EXIT" << std::endl;
    std::cout << std::endl << "\t\tOption: ";
    std::cin >> user_option;

      switch(user_option)
      {
          case '1':
          {
                try
                {
                  start();
                } catch(const char *Exception) {
                  std::cerr << Exception;
                }
          }

          case '2':
          {

          }

          case '3':
          {

          }
      }
}

void start()
{
    std::string username;
    std::string password;

    std::cout << std::endl << "\t\tSET YOUR NEW SETTINGS" << std::endl;
    std::cin.ignore();

     std::cout << std::endl << "\t\tUSERNAME: ";
     std::getline(cin, username);
       if(username.empty())
           throw "\t\tFAIL. STR EMPTY";
     root.setRootUsername(username);

     std::cout << "\t\tPASSWORD: ";
     std::getline(cin, password);
       if(password.empty())
           throw "\t\tFAIL. STR EMPTY";
     root.setRootPassword(password);

     ofstream archive("RootSettings.txt", fstream::app);

     archive << root;

     archive.close();
     exit(0);
}