// Read data (CERN staff) from an ascii file and create a root file with a Tree.
// see also a variant in staff.C
// Author: Rene Brun
   
TFile *cernbuild(Int_t get=0, Int_t print=1) {

   Int_t           Category;
   UInt_t          Flag;
   Int_t           Age;
   Int_t           Service;
   Int_t           Children;
   Int_t           Grade;
   Int_t           Step;
   Int_t           Hrweek;
   Int_t           Cost;
   Char_t          Division[4];
   Char_t          Nation[3];

   //The input file cern.dat is a copy of the CERN staff data base
   //from 1988
   TString filename = "cernstaff.root";
   TString dir = gSystem->UnixPathName(gInterpreter->GetCurrentMacroName());
   dir.ReplaceAll("cernbuild.C","");
   dir.ReplaceAll("/./","/");
   FILE *fp = fopen(Form("%scernstaff.dat",dir.Data()),"r");

   TFile *hfile = 0;
   if (get) {
      // if the argument get =1 return the file "cernstaff.root"
      // if the file does not exist, it is created
      if (!gSystem->AccessPathName(dir+"cernstaff.root",kFileExists)) {
         hfile = TFile::Open(dir+"cernstaff.root"); //in $ROOTSYS/tutorials/tree
         if (hfile) return hfile;
      }
      //otherwise try $PWD/cernstaff.root
      if (!gSystem->AccessPathName("cernstaff.root",kFileExists)) {
         hfile = TFile::Open("cernstaff.root"); //in current dir
         if (hfile) return hfile;
      }
   }
   //no cernstaff.root file found. Must generate it !
   //generate cernstaff.root in $ROOTSYS/tutorials/tree if we have write access
   if (!gSystem->AccessPathName(dir,kWritePermission)) {
      filename = dir+"cernstaff.root";
   } else if (!gSystem->AccessPathName(".",kWritePermission)) {
      //otherwise generate cernstaff.root in the current directory
   } else {
      printf("you must run the script in a directory with write access\n");
      return 0;
   }
   hfile = TFile::Open(filename,"RECREATE");
   TTree *tree = new TTree("T","CERN 1988 staff data");
   tree->Branch("Category",&Category,"Category/I");
   tree->Branch("Flag",&Flag,"Flag/i");
   tree->Branch("Age",&Age,"Age/I");
   tree->Branch("Service",&Service,"Service/I");
   tree->Branch("Children",&Children,"Children/I");
   tree->Branch("Grade",&Grade,"Grade/I");
   tree->Branch("Step",&Step,"Step/I");
   tree->Branch("Hrweek",&Hrweek,"Hrweek/I");
   tree->Branch("Cost",&Cost,"Cost/I");
   tree->Branch("Division",Division,"Division/C");
   tree->Branch("Nation",Nation,"Nation/C");
   char line[80];
   while (fgets(&line,80,fp)) {
      sscanf(&line[0],"%d %d %d %d %d",&Category,&Flag,&Age,&Service,&Children);
      sscanf(&line[32],"%d %d  %d %d %s %s",&Grade,&Step,&Hrweek,&Cost,Division,Nation);
      tree->Fill();
   }
   if (print) tree->Print();
   tree->Write();

   fclose(fp);
   delete hfile;
   if (get) {
      //we come here when the script is executed outside $ROOTSYS/tutorials/tree
      hfile = TFile::Open(filename);
      return hfile;
   }
   return 0;
}