I'm having trouble reading and iterating over a TClonesArray. I have
a program that writes events to a root file. Each event contains 3
objects where on one object contains a TClonesArray of a fourth
object (all objects inherit from TOject). I believe that this program
is working.
Using a macro, I read these events in CINT. But I cannot access the first
event's TClonesArray. If I do not skip it, the macro dies with this error:
Error: illegal pointer to class object particle 0x0 358 FILE:/tmp_mnt/home/halld/source/root/./macro2.C LINE:71
*** Interpreter error recovered ***
Below is a watered down version of my macro that doesworks. Maybe I'm not
iterating properly or I have missed something important.
Any help is greatly appreciated.
Paul Eugenio
{
gROOT->Reset();
gSystem.Load("libTMCFast.so");
TFile f("Event.rdt");
TTree *tree = (TTree*)f.Get("T");
TBranch *b1 = tree->GetBranch("hepevt");
TBranch *b2 = tree->GetBranch("trace");
TBranch *b3 = tree->GetBranch("offtrk");
TMCFastHepEvt *hepevt;
TMCFastTOF *trace;
TMCFastOfflineTrack *offtrk;
hepevt = new TMCFastHepEvt();
trace = new TMCFastTOF();
offtrk = new TMCFastOfflineTrack();
b1->SetAddress(&hepevt);
b2->SetAddress(&trace);
b3->SetAddress(&offtrk);
TH1F *h1 = new TH1F("h1", "x momentum",100,0.0,1.0);
TCanvas *c1;
c1 = new TCanvas("c1","MCFast histos",200,10,700,900);
Int_t nentries = (Int_t)tree->GetEntries();
for (Int_t ev = 0; ev < nentries; ev++) {
tree->GetEvent(ev); //read event in memory
TIter next(hepevt->GetHepParticles());
TMCFastHepParticle *particle = (TMCFastHepParticle *)next();
if(ev != 0){ // SKIP THIS EVENT OR IT DIES!!!
h1->Fill(particle->GetPx());
}
hepevt->Clear();
trace->Clear();
offtrk->Clear();
}
h1->Draw();
}
-- Paul M. Eugenio Dept. of Physics Carnegie Mellon University (412) 268 6949 eugenio@ernest.phys.cmu.edu
_____________________________________________________ / The scholar should know; one builds science with \ o O 0 / the facts just like a house can be built of stones; \ o | but an accumulation of facts is not a science just like | `\|||/ \ that a pile of stones is not a house. / (o o) \_____________________________________________________/ ooO_(_)_Ooo___________________________________________Henri Poincare'_ _____|_____|_____|_____|_____|_____|_____|_____|_____|_____|_____|____ __|_____|_____|_____|_____|_____|_____|_____|_____|_____|_____|_____|_ _____|_____|_____|_____|_____|_____|_____|_____|_____|_____|_____|____