Required and Optional Arguments Using Boost Library Program Options

Question

I\'m using Boost Program Options Library to parse the command line arguments.

I have the following requirements:

1. Once \"help\" is provided, all the oth

Answer 1

Here is complete program as per rcollyer and Tim, whom the credits go to:

#include 
#include 
#include 
namespace po = boost::program_options;

bool process_command_line(int argc, char** argv,
                          std::string& host,
                          std::string& port,
                          std::string& configDir)
{
    int iport;

    try
    {
        po::options_description desc("Program Usage", 1024, 512);
        desc.add_options()
          ("help",     "produce help message")
          ("host,h",   po::value(&host)->required(),      "set the host server")
          ("port,p",   po::value(&iport)->required(),             "set the server port")
          ("config,c", po::value(&configDir)->required(), "set the config path")
        ;

        po::variables_map vm;
        po::store(po::parse_command_line(argc, argv, desc), vm);

        if (vm.count("help"))
        {
            std::cout << desc << "\n";
            return false;
        }

        // There must be an easy way to handle the relationship between the
        // option "help" and "host"-"port"-"config"
        // Yes, the magic is putting the po::notify after "help" option check
        po::notify(vm);
    }
    catch(std::exception& e)
    {
        std::cerr << "Error: " << e.what() << "\n";
        return false;
    }
    catch(...)
    {
        std::cerr << "Unknown error!" << "\n";
        return false;
    }

    std::stringstream ss;
    ss << iport;
    port = ss.str();

    return true;
}

int main(int argc, char** argv)
{
  std::string host;
  std::string port;
  std::string configDir;

  bool result = process_command_line(argc, argv, host, port, configDir);
  if (!result)
      return 1;

  // else
  std::cout << "host:\t"   << host      << "\n";
  std::cout << "port:\t"   << port      << "\n";
  std::cout << "config:\t" << configDir << "\n";

  // Do the main routine here
}

/* Sample output:

C:\Debug>boost.exe --help
Program Usage:
  --help                produce help message
  -h [ --host ] arg     set the host server
  -p [ --port ] arg     set the server port
  -c [ --config ] arg   set the config path


C:\Debug>boost.exe
Error: missing required option config

C:\Debug>boost.exe --host localhost
Error: missing required option config

C:\Debug>boost.exe --config .
Error: missing required option host

C:\Debug>boost.exe --config . --help
Program Usage:
  --help                produce help message
  -h [ --host ] arg     set the host server
  -p [ --port ] arg     set the server port
  -c [ --config ] arg   set the config path


C:\Debug>boost.exe --host 127.0.0.1 --port 31528 --config .
host:   127.0.0.1
port:   31528
config: .

C:\Debug>boost.exe -h 127.0.0.1 -p 31528 -c .
host:   127.0.0.1
port:   31528
config: .
*/