#include <vtkSmartPointer.h>
#include <vtkCellData.h>
#include <vtkCellArray.h>
#include <vtkFloatArray.h>
#include <vtkTriangle.h>
#include <vtkPoints.h>
#include <vtkPolyData.h>
#include <vtkXMLPolyDataReader.h>

int main(int argc, char *argv[])
{
  // Parse command line arguments
  if(argc != 3)
  {
    std::cout << "Required arguments: Filename ArrayName" << std::endl;
    return EXIT_FAILURE;
  }

  // Get filename from command line
  std::string filename = argv[1]; //first command line argument

  // Get array name
  std::string arrayName = argv[2]; //second command line argument
	
  //read the file
  vtkSmartPointer<vtkXMLPolyDataReader> reader =
    vtkSmartPointer<vtkXMLPolyDataReader>::New();
  reader->SetFileName(filename.c_str());
  reader->Update();
	
  vtkPolyData* polydata = reader->GetOutput();
	
  // Get the number of cells in the polydata
  vtkIdType idNumCellsInFile = polydata->GetNumberOfCells();

  vtkSmartPointer<vtkFloatArray> array =
    vtkFloatArray::SafeDownCast(polydata->GetCellData()->GetArray(arrayName.c_str()));

  if(array)
  {
    std::cout << "Got array " << arrayName
              << " with " << idNumCellsInFile << " values"
              << std::endl;
    for(int i = 0; i < idNumCellsInFile; i++)
    {
      double value;
      value = array->GetValue(i);
      std::cout << i << ": " << value << std::endl;
    }
  }
  else
  {
    std::cout << "The file " << filename
              << " does not have a CellData array named " << arrayName
              << std::endl;
  }

  return EXIT_SUCCESS;
}
