# ReadAndPrintAttributes.cxx

    /*=========================================================================

      Program: GDCM (Grassroots DICOM). A DICOM library
      Module:  $URL$

      Copyright (c) 2006-2010 Mathieu Malaterre
      All rights reserved.
      See Copyright.txt or http://gdcm.sourceforge.net/Copyright.html for details.

         This software is distributed WITHOUT ANY WARRANTY; without even
         the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
         PURPOSE.  See the above copyright notice for more information.

    =========================================================================*/
    /*
     * This small example will show how one can read and print
     * a DICOM Attribute using different technique (by tag or by name)
     */

    #include "gdcmReader.h"
    #include "gdcmGlobal.h"
    #include "gdcmDicts.h"
    #include "gdcmDict.h"
    #include "gdcmAttribute.h"
    #include "gdcmStringFilter.h"

    #include <iostream>

    int main(int argc, char *argv[])
    {
      if( argc < 2 )
        {
        std::cerr << argv[0] << " input.dcm" << std::endl;
        return 1;
        }
      const char *filename = argv[1];

      // Instanciate the reader:
      gdcm::Reader reader;
      reader.SetFileName( filename );
      if( !reader.Read() )
        {
        std::cerr << "Could not read: " << filename << std::endl;
        return 1;
        }

      // The output of gdcm::Reader is a gdcm::File
      gdcm::File &file = reader.GetFile();

      // the dataset is the the set of element we are interested in:
      gdcm::DataSet &ds = file.GetDataSet();

      const gdcm::Global& g = gdcm::Global::GetInstance();
      const gdcm::Dicts &dicts = g.GetDicts();
      const gdcm::Dict &pubdict = dicts.GetPublicDict();

      using namespace gdcm;

      // In this example we will show why using name to lookup attribute can be
      // dangerous.
      Tag tPatientName(0x0,0x0);
      const DictEntry &de1 = pubdict.GetDictEntryByName("Patient Name", tPatientName);

      std::cout << "Found: " << tPatientName << std::endl;

      // Indeed the attribute could not be found. Since DICOM 2003, Patient Name
      // has become Patient's Name.

      Tag tPatientsName;
      const DictEntry &de2 = pubdict.GetDictEntryByName("Patient's Name", tPatientsName);

      std::cout << "Found: " << tPatientsName << std::endl;

      // Let's try to read an arbitrary DICOM Attribute:
      Tag tDoseGridScaling;
      const DictEntry &de3 = pubdict.GetDictEntryByName("Dose Grid Scaling", tDoseGridScaling);

      std::cout << "Found: " << tDoseGridScaling << std::endl;

      if( ds.FindDataElement( tDoseGridScaling ) )
        {
        gdcm::StringFilter sf;
        sf.SetFile(file);
        std::cout << "Attribute Value as String: " << sf.ToString( tDoseGridScaling ) << std::endl;

        // Let's check the name again:
        std::pair<std::string, std::string> pss
          = sf.ToStringPair( tDoseGridScaling );
        std::cout << "Attribute Name Checked: " << pss.first << std::endl;
        std::cout << "Attribute Value (string): " << pss.second << std::endl;

        const DataElement &dgs = ds.GetDataElement( tDoseGridScaling );

        // Let's assume for a moment we knew the tag number:
        Attribute<0x3004,0x000e> at;
        assert( at.GetTag() == tDoseGridScaling );
        at.SetFromDataSet( ds );
        // For the sake of long term maintenance, we will not write
        // that this particular attribute is stored as a double. What if
        // a user made a mistake. It is much safer to rely on GDCM internal
        // mechanism to deduce the VR::DS type (represented as a ieee double)
        Attribute<0x3004,0x000e>::ArrayType v = at.GetValue();
        std::cout << "DoseGridScaling=" << v << std::endl;
        }

      return 0;
    }