[ROOT] problem with tree->GetEntry

From: Ursula Berthon (berthon@in2p3.fr)
Date: Wed Oct 18 2000 - 17:12:49 MEST


Dear all,
I have a problem (or is it a feature?) with TTree::GetEntry(..).
Have a look at the following:
root [0] TFile * f = new TFile("../../files/philippe.root")
root [1] TTree * tree = (TTree*)f->Get("ODS")
root [2] tree->GetEntry(20,0)
(Int_t)49090                   <-- ok, that is the whole event
root [3] tree->SetBranchStatus("*",0)
root [4] tree->SetBranchStatus("HEAD",1)
root [5] tree->GetEntry(20,0)
(Int_t)1   <---- why only 1 byte? the HEAD branch contains more
root [6] tree->SetBranchStatus("*",1)
root [7] tree->GetEntry(20,0)
(Int_t)140

The GetEntry(20,0), after what I understand, should read all active
branches, in my case the whole event since I set all branches active, that
means 49090 bytes. It seems to read something (the HEAD-branch??), but not
the whole event (only 140 bytes).
Thanks for your help!                                                                             


        Gruss/greetings/A bientot!
  
                         Ursula

*************************************************************
                                                Ursula Berthon
                                      E-mail  berthon@in2p3.fr
                                    Tel. 33 - 1 - 69 33 31 21
                                    Fax  33 - 1 - 69 33 30 02



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