The constructor allows you to specify the names of the input files using command line syntax. If you do not specify input files, the defaults will be used. This constructor will be called from the main function. It calls the following functions: addDimensions, createIloNodes, createVehicles, and createVisits. The following code is provided for you:

   RoutingModel::RoutingModel( IloEnv env,
                            int argc,
                            char* argv[]):
  _env(env), _mdl(env) {
  addDimensions();

  //create IloNodes
  char * nodeFileName;
  if(argc < 2)  nodeFileName =
       (char*) "../../../examples/data/vrp20/vrp20nodes.csv";
  else          nodeFileName = argv[1];
  createIloNodes(nodeFileName);

  //create vehicles
  char * vehiclesFileName;
  if(argc < 3)  vehiclesFileName =
       (char*) "../../../examples/data/vrp20/vrp20vehicles.csv";
  else          vehiclesFileName = argv[2];
  createVehicles(vehiclesFileName);

  //create visits
  char * visitsFileName;
  if(argc < 4)  visitsFileName =
       (char*)  "../../../examples/data/vrp20/vrp20visits.csv";
  else          visitsFileName = argv[3];
  createVisits(visitsFileName);
}