pdal::StageFactory factory;
pdal::PointTable table;
std::string sReaderDriver = pdal::StageFactory::inferReaderDriver(inputfilename);
if (!sReaderDriver.empty())
{
  pdal::Stage *pReader = factory.createStage(sReaderDriver);
  pdal::Options readerOptions;
  readerOptions.add("filename", inputfilename);
  if (pReader)
  {
    pReader->setOptions(readerOptions);
    pdal::PointViewSet set;
    pdal::PointViewPtr pView;
    pReader->prepare(table);
    set = pReader->execute(table);
    pView = *set.begin();
	int nSize = pView->size();
    for (int i = 0; i < nSize; i++)
	{
	...
	}
  ...
}