Re: cout << vector<string>

From:

Maxim Yegorushkin <maxim.yegorushkin@gmail.com>

Newsgroups:

comp.lang.c++

Date:

Fri, 7 Nov 2008 03:03:15 -0800 (PST)

Message-ID:

<c406748a-0df4-4c85-b8b1-0e24f3a316e3@c36g2000prc.googlegroups.com>

On Nov 6, 11:06 pm, "barcaroller" <barcarol...@music.net> wrote:

In the boost::program_options tutorial, the author included the following
code:

    cout << "Input files are: "
         << vm["input-file"].as< vector<string> >()
         << "\n";

Basically, he is trying to print a vector of string, in one line. I co=

uld

not get this compile (let alone run). To get it to compile and run, I =

had

to re-write it as:

    vector<string> v = vm["input-file"].as< vector<string> >();

    vector<string>::const_iterator i;

    for ( i = v.begin();
            i != v.end();
          ++i )
    {
        cout << *citer << " ";
    }

Does anyone know if the original line of code is correct? If so, what =

was I

missing?

The example probably assumes there is an overloaded operator<<() for
std::ostream and std::vector<>, something like this:

    #include <ostream>
    #include <iterator>
    #include <algorithm>

    namespace std {

        template<class A1, class A2>
        ostream& operator<<(ostream& s, vector<A1, A2> const& vec)
        {
            copy(vec.begin(), vec.end(), ostream_iterator<A1>(s, "
"));
            return s;
        }

    }

--
Max