Re: [Boost-users] [program_options] unknown positional option

5 Aug 2010

      On Thu, Aug 5, 2010 at 12:21 AM, Vladimir Prus wrote:
...
positional_options_description merely specifies translation from position
to
option names. For example, the above say that every positional element of
the
command line is a value of an option named 'files'. However, such option
still
have to be declared in a regular way.
I see. That is not clear at all in the documentation, including the
tutorial.

For reference, here's the code working with boost::program_options version
1.40.0:

<code>
#include <iostream>
#include <vector>
#include <string>

#include 
#include 
#include 
#include 

namespace po = boost::program_options;

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

  po::positional_options_description positional;
  positional.add("files", -1);
  std::cout << "Declared positional options." << std::endl;

  po::options_description options;
  options.add_options()
    ("files", po::valuestd::string >()->composing(),
     "input files")
    ;

  po::variables_map vm;
  po::store(po::command_line_parser(argc, argv).options(options)
            .positional(positional).run(), vm);
  std::cout << "Stored command line arguments into vm." << std::endl;

  po::notify(vm);
  std::cout << "Notified vm that all args have been parsed" << std::endl;

  if (vm.count("files") == 0) {
    std:: cout << "No input files have been specified" << std::endl;
    return 1;
  }

  std::vectorstd::string files = vm["files"].asstd::string
...
();
  for (unsigned int i = 0; i < files.size(); ++i) {
    std::cout << "file: " << files[i] << std::endl;
  }
return 0;
}
</code>

Then compiling and running this program will result in:

<shell>
jeff@turing:~/test$ g++ -o args args.cpp -lboost_program_options
jeff@turing:~/test$ ./args file1 file2
Declared positional options.
Stored command line arguments into vm.
Notified vm that all args have been parsed
file: file1
file: file2
</shell>

Re: [Boost-users] [program_options] unknown positional option

Jeffrey Finkelstein