https://github.com/root-project/root
Tip revision: 5a1d381a622ce5c08a58ba45f60f9abb66086d99 authored by Axel Naumann on 19 May 2020, 08:23:43 UTC
"Update ROOT version files to v6.23/01."
"Update ROOT version files to v6.23/01."
Tip revision: 5a1d381
eventa.cxx
// @(#)root/test:$Id$
// Author: Rene Brun 10/01/97
{
// This macro read all events generated by the test program Event
// provided in $ROOTSYS/test.
//
// NOTE: Before executing this macro, you must have executed the macro eventload.
//
// This small program simply counts the number of bytes read and dump
// the first 3 events.
gROOT->Reset();
// Connect file generated in $ROOTSYS/test
TFile f("Event.root");
// Read Tree named "T" in memory. Tree pointer is assigned the same name
TTree *T = (TTree*)f.Get("T");
// Create a timer object to benchmark this loop
TStopwatch timer;
timer.Start();
// Start main loop on all events
Event *event = new Event();
T->SetBranchAddress("event", &event);
Int_t nevent = T->GetEntries();
Int_t nb = 0;
for (Int_t i=0;i<nevent;i++) {
if(i%50 == 0) printf("Event:%d\n",i);
nb += T->GetEntry(i); //read complete event in memory
if (i < 3) event->Dump(); //dump the first 3 events
}
// Stop timer and print results
timer.Stop();
Float_t mbytes = 0.000001*nb;
Double_t rtime = timer.RealTime();
Double_t ctime = timer.CpuTime();
printf("RealTime=%f seconds, CpuTime=%f seconds\n",rtime,ctime);
printf("You read %f Mbytes/Realtime seconds\n",mbytes/rtime);
printf("You read %f Mbytes/Cputime seconds\n",mbytes/ctime);
printf("%d events and %d bytes read.\n",nevent,nb);
f.Close();
}