Hi Guy,
Guy Ron <ronguy@tauphy.tau.ac.il> wrote concerning
[ROOT] C++ Problem [Mon, 10 Mar 2003 17:19:49 +0200]
----------------------------------------------------------------------
> Dear Rooters,
> I'm running root on a linux machine (root version 3.05) and am trying to
> produce a simple histogram, the source code runs fine under CINT but once
> I compile it in C++ I can only access the entries in the tree but not draw
> them (neither the histogram nor directly through tree->Draw()).
You need an instance of the TApplication class (or a derived class
like TRint) - see mods below.
> The source code I'm using is:
int main (int argc, char** argv) {
// Next line needed to get access to X server
TAppliction app("app", &argc, argv);
TH1F *hpx = new TH1F("hpx","distribution",100,0,100);
TFile* hfile = TFile::Open("bbtreefile.root");
TTree* tree = (TTree*)hfile->Get("bbtree");
hfile->Print();
tree->Show(20);
tree->Draw("inipp");
cout << tree->GetEntries() << "\n";
Event ev;
tree->SetBranchAddress("mainE plane energy loss",&ev.zekind);
for (Int_t i = 1; i < 10; i++) {
cout << tree->GetEntry(nb) << "\n";
cout << ev.zekind << "\n";
hpx->Fill(ev.zekind);
}
hpx->Draw();
// Next line needed for interactive manipulation of canvas, etc.
app.Run();
hfile->Close();
return 0;
}
> Please HELP, I've been trying this for a few days now and am really
> falling behind on my work.
I think it's explained in the manual somewhere :-)
Yours,
___ | Christian Holm Christensen
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