Re: cout << vector<string>

From:

Jeff Schwab <jeff@schwabcenter.com>

Newsgroups:

comp.lang.c++

Date:

Fri, 07 Nov 2008 09:19:14 -0500

Message-ID:

<A6ydnTlXIaX-04nUnZ2dnUVZ_s_inZ2d@giganews.com>

Juha Nieminen wrote:

Jeff Schwab wrote:

template<typename T>
std::ostream& operator<<(std::ostream& out, std::vector<T> const& v) {
    if (!v.empty()) {
        typedef std::ostream_iterator<T> out_iter;
        copy(v.begin(), v.end() - 1, out_iter( out, " " ));
        out << v.back();
    }
    return out;
}

  Is there some advantage of that code over a shorter and simpler:

template<typename T>
std::ostream& operator<<(std::ostream& out, std::vector<T> const& v) {
    for(std::size_t i = 0; i < v.size()-1; ++i)
        out << v[i] << " ";
    out << v.back();
    return out;
}

The use of the standard algorithm (rather than a hand-rolled loop) helps
separate the different levels of abstraction. In your example, the code
that works with an individual datum of type T is all mixed up with the
code that works with the vector as a whole. There are decent
discussions of this in Effective STL (Scott Meyers) and Clean Code
(Robert Martin).