readEvtFile.cc

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#include "km3net-dataformat/offline/Evt.hh"
#include "km3net-dataformat/definitions/root.hh"
#include "TFile.h"
#include "TTree.h"
#include <iostream>

int main(int argc, char* argv[]){
using namespace std;
        if (argc != 2) {
                cout << "usage: readEvtFile file.root" << endl;
                return 1;
        } 
        //TFile::Open works with local and remote files (xrootd)
        TFile *f1 = TFile::Open(argv[1]);
        //check that file is open
        if (f1 == nullptr) {
                cerr << "File can't be open." << endl;
                return 1;
        }
        //TTree *EvtTree = (TTree*)f1->Get("E");
        TTree *EvtTree = (TTree*)f1->Get(TTREE_OFFLINE_EVENT);  // TTREE_OFFLINE_EVENT is in km3net-dataformat/definitions/root.hh
        if (EvtTree == 0) {
                cerr << "File has no " << TTREE_OFFLINE_EVENT << " tree." << endl;
                return 1;
        }
        Evt *evt = nullptr;
        EvtTree->SetBranchAddress("Evt",&evt);
        Long64_t nentries = EvtTree->GetEntries();
        for (Long64_t i=0; i<nentries; i++) {
                EvtTree->GetEntry(i);
                cout << "Event ID: " <<  evt->id << endl; //an example of accessing Evt struct object
                evt->print();  //an example of using Evt struct function
        }
        f1->Close();
        return 0;
}