C++ std::stringstream operator<< overloading

Question

I have the following class(prototipe):

class Token
{
public:
    //members, etc.
    friend std::stringstream& operator<< (std::stringstream &o         


        

Answer 1

std::stringstream & operator<< (std::stringstream &out, Token &t)

should be

std::ostream & operator<< (std::ostream &out, Token const &t)