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

21 Sep 2009

      On Mon, Sep 21, 2009 at 10:04 AM, aiooua  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 
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,
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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 

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()->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::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

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

David Doria