Boost program options iterate over variables_map

Question

po::options_description desc("This are the options that are available");
    desc.add_options()("help", "print help")(
        "deer", po::value<uint32_t>(), "set how many deer you want")(
        "rating", po::value<uint32_t>(), "how good ?")(
        "name", po::value<std::string>(), "and your name is ... ?");

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

in a following section of the code I tried to iterate over vm

for (const auto& it : vm) {
      std::cout << it.first.c_str() << " "
                << it.second.as<it.pair::second_type>() << "\n";
    }

The main point here is that vm contains keys of the same type, but values with different types, in this example I have uint32_t mixed with a std::string.

How I can iterate over this kind of containers ? I would like to avoid a verbose approach so I'm trying to just iterate over this data structure.

EDIT:

I forgot to write this down, but obviously

namespace po = boost::program_options;

Answer 1

boost variable_map use boost::any as the value so you can try to use boost::any_cast<T> to find out the type. perhaps something like this

for (const auto& it : vm) {
  std::cout << it.first.c_str() << " ";
  auto& value = it.second.value();
  if (auto v = boost::any_cast<uint32_t>(&value))
    std::cout << *v;
  else if (auto v = boost::any_cast<std::string>(&value))
    std::cout << *v;
  else
    std::cout << "error";
}