#include "TFile.h"
#include "TTree.h"

struct MData {
  int id;
  double posX;
  double posY;
  double posZ;
  double energy;
};

int spooky(char* rootfn){

  MData data;
 
  dataFile = new TFile(rootfn,"RECREATE");
  dataTree = new TTree("tree","simulation data");
  dataTree->Branch("Events",&data.id,"id/I:posX/D:posY/D:posZ:energy");
  

//fill with some numbers ...
  for(int i=0; i<250; i++){
    data.id=i;
    data.posX=i;
    data.posY=0.52345*i;
    data.posZ=i;
    data.energy=234.123557*i;
    dataTree->Fill();
  }

  dataFile->Write();
  dataFile->Close();

  spookyread(rootfn);

}

int spookyread(char* rootfn){

  dataFile = new TFile(rootfn,"READ");
  tree=(TTree*)gROOT->FindObject("tree");

  for(int i=1;i<12;i++) tree->Show(i);

  dataFile->Close();
}