Введенные данные сохранить в текстовый файл

#include <iostream>
#include <algorithm>
#include <conio.h>
#include <string>
#include <cstring>
using namespace std;
 
struct Note
{
    char surname[30];
    char m_Name[30];
    char m_PhoneNum[15];
    string day;
};
 
Note ReadNote()
{
    Note ret_val;
    std::cout << "Surname: ";
    std::cin.clear();
    std::cin.sync();
    gets(ret_val.surname);
    std::cout << "Name: ";
    std::cin.clear();
    std::cin.sync();
    gets(ret_val.m_Name);
    std::cout << "Phone number: ";
    std::cin >> ret_val.m_PhoneNum;
    std::cout << "Birthday (DD.MM.YYYY): ";
    std::cin >> ret_val.day;
    std::cin.get();
 
    return ret_val;
}
 
bool operator == (const Note& note, const std::string& m_PhoneNum)
{
    return note.m_PhoneNum == m_PhoneNum;
}
 
bool operator < (Note const& note1, Note const& note2)
{
    return strncmp(note1.m_PhoneNum, note2.m_PhoneNum, 3);
}
 
std::ostream& operator << (std::ostream& os, const Note& Note)
{
    std::cout << "Surname: " << Note.surname << std::endl;
    std::cout << "Name: " << Note.m_Name << std::endl;
    std::cout << "Phone number: " << Note.m_PhoneNum << std::endl;
    std::cout << "Birthday: " << Note.day << std::endl;
 
    return os;
}
 
int main(int, char**)
{
    char otv;
    do
    {
        Note Notes[2];
        int n_Notes = sizeof(Notes) / sizeof(Notes[0]);
 
        std::generate(Notes, Notes + n_Notes, ReadNote);
        std::sort(Notes, Notes + n_Notes);
        for(int i = 0; i < n_Notes; ++i)
        {
            std::cout << Notes[i] << "\n\n";
        }
        std::cout << "Person number: ";
        std::cin.clear();
        std::cin.sync();
        std::string m_PhoneNum;
        std::getline(std::cin, m_PhoneNum);
        Note* p = std::find(Notes, Notes + n_Notes, m_PhoneNum);
        if (p == Notes + n_Notes)
            std::cout << "There is no person '" << m_PhoneNum << "'" << std::endl;
        else
            std::cout << *p;
            std::cout<<"Do you want to continue?(y/n): ";
       std::cin>>(otv);
    }
    while(otv == 'y');
    std::cout<<"the end.";
    getch();
    return 0;
}