Re: [Boost-users] [program_options] vector parameters not working.

Subject: Re: [Boost-users] [program_options] vector parameters not working.
From: David Doria (daviddoria+boost_at_[hidden])
Date: 2009-09-21 15:33:29

On Mon, Sep 21, 2009 at 10:04 AM, aiooua <aiooua_at_[hidden]> wrote:

> hello,
>
> I recently picked up boost to make use of the various libraries it
> includes. Unfortunately, I got stuck with the very first one
> (program_options) I used in my code. Any help would be appreciated
> very much.
>
> I want an option "bunch" which goes along with a bunch of numbers. I
> thought the following code would do the job:
>
>
> ---------------------------------------------------------------------------------------
> #include <iostream>
> #include <string>
> #include <vector>
> #include <boost/program_options.hpp>
>
> using namespace std;
> namespace po = boost::program_options;
>
> int main(int argc, char* argv[])
> {
>  try
>    {
>      vector<int> numbers;
>      po::options_description params("parameters");
>      po::variables_map options;
>      params.add_options()
>        ("bunch,b", po::value< vector<int> >(&numbers), "a bunch of
> numbers");
>      po::store(po::parse_command_line(argc, argv, params), options);
>      po::notify(options);
>      if(options.count("bunch")!=0)
>        {
>          copy (numbers.begin(), numbers.end(),
> std::ostream_iterator<int>(cout, "\n"));
>        }
>    }
>  catch(exception & e)
>    {
>      cerr << e.what() << endl;
>    }
>  return 0;
> };
>
> ---------------------------------------------------------------------------------------
>
> However, it doesn't seem to work as it should. When I run this as follows:
>
>
> ---------------------------------------------------------------------------------------
> > test --bunch 4 2 42
> 4
>
> ---------------------------------------------------------------------------------------
>
> It is just printing the first value - Am I doing something wrong here?
> I'm using 'boost_1_40_0' which I compiled using MS Visual Studio 2005.
>
> thanks,
> _______________________________________________
> Boost-users mailing list
> Boost-users_at_[hidden]
> http://lists.boost.org/mailman/listinfo.cgi/boost-users
>

You have to use the multitoken() function - here is a short example (which
should DEFINITELY be included on the documentation page). Unfortunately, the
multitoken list has to appear at the end of the argument list (i.e. you
cannot have "--param1 something --NumberList 1 2 3 4 --param3
something_else", instead you must have "--param1 something --param3
something_else --NumberList 1 2 3 4") because the multitoken argument will
just keep eating the arguments until it gets to the very end!).

#include <iostream>
#include <vector>
#include <cstdlib>

#include <cmath>
#include <boost/program_options.hpp>

namespace po = boost::program_options;

int main(int argc, char* argv[])
{

    po::options_description desc("Allowed options");
    desc.add_options()
            ("help", "produce help message")
            ("NumberList,N", po::value<std::vector<int> >()->multitoken(),
"List of numbers.")//lets you use --NumberList or -N
    ;

    po::variables_map vm;
    po::store(po::parse_command_line(argc, argv, desc), vm);
    po::notify(vm); //assign the variables (if they were specified)

    if(vm.count("help"))
    {
        std::cout << desc << std::endl;;
        return 1;
    }

    if (vm.count("NumberList"))
    {
        std::cout << "count: " << vm.count("NumberList") << std::endl;
        std::vector<int> NumberList = vm["NumberList"].as<std::vector<int>
>();
        std::cout << "NumberList is length " << NumberList.size() <<
std::endl;
        for(unsigned int i = 0; i < NumberList.size(); i++)
            std::cout << NumberList[i] << std::endl;
    }
    else
    {
        std::cout << "NumberList was not set." << std::endl;
    }

    return 0;
}

I hope this answers your question.

Thanks,

David