c++ - Overloading output stream operator for vector<T>

Question

What is a recommended way to overload the output stream operator? The following can not be done. It is expected that compilation will fail if the operator << is not defined for a type T.

template < class T >
inline std::ostream& operator << (std::ostream& os, const std::vector<T>& v) 
{
    os << "[";
    for (std::vector<T>::const_iterator ii = v.begin(); ii != v.end(); ++ii)
    {
        os << " " << *ii;
    }
    os << " ]";
    return os;
}

EDIT: It does compile, the problem was unrelated and was in the namespace. Thanks for assistance.

Answer 1

This is what you want:

template < class T >
std::ostream& operator << (std::ostream& os, const std::vector<T>& v) 
{
    os << "[";
    for (typename std::vector<T>::const_iterator ii = v.begin(); ii != v.end(); ++ii)
    {
        os << " " << *ii;
    }
    os << "]";
    return os;
}

You forgot the std:: on the first ostream

You put an extra space after [ in os << "[".

and you need typename before std::vector<T>::const_iterator