//g++ check_commonhash.C -o  check_commonhash  `root-config --cflags --libs` -std=c++11
#include <iostream>
#include <string>
#include <TFile.h>
#include <TTree.h>

using namespace std;

int main(){
  
TFile *f = new TFile("group.perf-muons.19055269.EXT0._000480.NTUP_MCPTP.root","update");
 
TTree *tree;
f->GetObject("ZmumuTPMerged/Trees/MuonProbes_OC/TPTree_MuonProbes_OC",tree);

 
ULong64_t commonhash = 0;
//Float_t probe_eta = 0;
 
tree->SetBranchAddress("CommonEventHash", &commonhash);
//tree->SetBranchAddress("probe_eta", &probe_eta);

 
for (ULong64_t i = 0; i<tree->GetEntries(); i++){
  tree->GetEntry(i);
  cout << "commonhash:"<<commonhash<<endl; // not working
  //cout << "probe_eta:"<<probe_eta<<endl; //works
 }

 return 0;

}