vectorのリロード

コードは次のとおりです.

#include 
#include 
using namespace std;

ostream& operator<< (ostream& out, vector& _vec);

int main() {
        vector vec(10, "n");
        cout << vec << endl;
}

ostream& operator<< (ostream& out, vector& _vec) {
        vector::const_iterator it = _vec.begin();
        for(; it != _vec.end(); ++it)
                out << *it;
        return out;
}
~  

卒.