This example shows how the argument parser can be used.
using namespace lemon;
int main(int argc, char **argv)
{
  
  int i;
  std::string s;
  double d = 1.0;
  bool b, nh;
  bool g1, g2, g3;
  
  ap.refOption("n", "An integer input.", i, true);
  
  ap.refOption("val", "A double input.", d);
  
  ap.doubleOption("val2", "A double input.", 3.14);
  
  ap.synonym("vals", "val");
  
  ap.refOption("name", "A string input.", s);
  
  ap.refOption("f", "A switch.", b)
    .refOption("nohelp", "", nh)
    .refOption("gra", "Choice A", g1)
    .refOption("grb", "Choice B", g2)
    .refOption("grc", "Choice C", g3);
  
  ap.optionGroup("gr", "gra")
    .optionGroup("gr", "grb")
    .optionGroup("gr", "grc");
  
  ap.mandatoryGroup("gr");
  
  ap.onlyOneGroup("gr");
  
  ap.other("infile", "The input file.")
    .other("...");
  
  
  
  ap.throwOnProblems();
  
  
  
  
  try {
    ap.parse();
  
  std::cout << "Parameters of '" << ap.commandName() << "':\n";
  std::cout << "  Value of -n: " << i << std::endl;
  if(ap.given("val")) std::cout << "  Value of -val: " << d << std::endl;
  if(ap.given("val2")) {
    d = ap["val2"];
    std::cout << "  Value of -val2: " << d << std::endl;
  }
  if(ap.given("name")) std::cout << "  Value of -name: " << s << std::endl;
  if(ap.given("f")) std::cout << "  -f is given\n";
  if(ap.given("nohelp")) std::cout << "  Value of -nohelp: " << nh << std::endl;
  if(ap.given("gra")) std::cout << "  -gra is given\n";
  if(ap.given("grb")) std::cout << "  -grb is given\n";
  if(ap.given("grc")) std::cout << "  -grc is given\n";
  switch(ap.files().size()) {
  case 0:
    std::cout << "  No file argument was given.\n";
    break;
  case 1:
    std::cout << "  1 file argument was given. It is:\n";
    break;
  default:
    std::cout << "  "
              << ap.files().size() << " file arguments were given. They are:\n";
  }
  for(unsigned int i=0;i<ap.files().size();++i)
    std::cout << "    '" << ap.files()[i] << "'\n";
  return 0;
}