STL - copy i ostream_iterator

#include <iostream>
#include <vector>
#include <iterator>
#include <string>
#include <algorithm>

using namespace std;

class Tperson
{
private:
    string f_name;
    string l_name;
    int age;
public:
    Tperson( string first_name = "default", string last_name = "default", int how_old = 0 )
        : f_name( first_name )
         , l_name( last_name )
         , age( how_old )
    { }
   
    ~Tperson() { };
   
    string & get_fname() { return f_name; }
    string & get_lname() { return l_name; }
    int get_age() { return age; }
   
   
};

void Show( Tperson & prs )
{
    cout << "Imie " << prs.get_fname() << " Nazwisko " << prs.get_lname() << " Wiek " << prs.get_age() << endl;
}

bool operator <( Tperson & prs1, Tperson & prs2 )
{
    if( prs1.get_lname() > prs2.get_lname() ) return true;
    else return false;
   
}

ostream & operator <<( ostream & os, Tperson & prs )
{
    os << prs.get_fname() << endl;
    return os;
}

int main()
{
   
    vector < Tperson > people;
   
    people.push_back( Tperson( "Michal", "xxxx", 29 ) );
    people.push_back( Tperson( "Magalena", "uuuu", 32 ) );
    people.push_back( Tperson( "Agnieszka", "iii", 21 ) );
    people.push_back( Tperson( "Magda", "yyyyy", 25 ) );
   
    for_each( people.begin(), people.end(), Show );
    cout << endl;
    sort( people.begin(), people.end() );
    cout << endl;
    for_each( people.begin(), people.end(), Show );
    cout << endl;
   
    vector < Tperson > people2;
    people2.resize( people.size() );
   
    copy( people.begin(), people.end(), people2.begin() );
   
    for_each( people2.begin(), people2.end(), Show );
    copy( people2.begin(), people2.end(), ostream_iterator < Tperson, string >( cout ) );
   
    return 0;
}