#include <iostream>
#include <sstream>
#include <iterator>
#include <boost/program_options.hpp>
#include <boost/foreach.hpp>

namespace po = boost::program_options;
using namespace std;

int main(int argc, char* argv[])
{
    istringstream is("unknown_option = something_unknown"); // Input "File"

    po::options_description generic("Generic options");
    po::parsed_options parsed_file
        = po::parse_config_file(is, generic, true /* allow unregistered */);

    cout << "Unregistered options parsed...\n";
    vector<string>::size_type unregistered_count = 0;
    BOOST_FOREACH(po::option option, parsed_file.options) {
        if (option.unregistered) {
            ++unregistered_count;
            cout << option.string_key << ": ";
            ostream_iterator<string> out_it(cout, " ");
            copy( option.original_tokens.begin(), option.original_tokens.end(),
                  out_it);
            cout << endl;
        }
    }

    cout << "\nUnrecognized options collected...\n";
    vector<string> unrecognized
        = po::collect_unrecognized(parsed_file.options, po::include_positional);
    BOOST_FOREACH(string option, unrecognized) {
        cout << option << endl;
    }

    return !(unregistered_count == unrecognized.size()); // 0 on pass
}