boost_1_45_0/libs/program_options/example/options_description.cpp

// Copyright Vladimir Prus 2002-2004.
// Distributed under the Boost Software License, Version 1.0.
// (See accompanying file LICENSE_1_0.txt
// or copy at http://www.boost.org/LICENSE_1_0.txt)

#include <boost/program_options.hpp>

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

#include <iostream>
#include <algorithm>
#include <iterator>
using namespace std;


// A helper function to simplify the main part.
template<class T>
ostream& operator<<(ostream& os, const vector<T>& v)
{
    copy(v.begin(), v.end(), ostream_iterator<T>(cout, " ")); 
    return os;
}

int main(int ac, char* av[])
{
    try {
        int opt;
        int portnum;
        po::options_description desc("Allowed options");
        desc.add_options()
            ("help", "produce help message")
            ("optimization", po::value<int>(&opt)->default_value(10), 
                  "optimization level")
            ("verbose,v", po::value<int>()->implicit_value(1),
                  "enable verbosity (optionally specify level)")
            ("listen,l", po::value<int>(&portnum)->implicit_value(1001)
                  ->default_value(0,"no"),
                  "listen on a port.")
            ("include-path,I", po::value< vector<string> >(), 
                  "include path")
            ("input-file", po::value< vector<string> >(), "input file")
        ;

        po::positional_options_description p;
        p.add("input-file", -1);
        
        po::variables_map vm;
        po::store(po::command_line_parser(ac, av).
                  options(desc).positional(p).run(), vm);
        po::notify(vm);
    
        if (vm.count("help")) {
            cout << "Usage: options_description [options]\n";
            cout << desc;
            return 0;
        }

        if (vm.count("include-path"))
        {
            cout << "Include paths are: " 
                 << vm["include-path"].as< vector<string> >() << "\n";
        }

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

        if (vm.count("verbose")) {
            cout << "Verbosity enabled.  Level is " << vm["verbose"].as<int>()
                 << "\n";
        }

        cout << "Optimization level is " << opt << "\n";                

        cout << "Listen port is " << portnum << "\n";                
    }
    catch(std::exception& e)
    {
        cout << e.what() << "\n";
        return 1;
    }    
    return 0;
}