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 |_| | ------------------------------------------------------------- | | Address: Sankt Hansgade 23, 1. th. Phone: (+45) 35 35 96 91 _| DK-2200 Copenhagen N Cell: (+45) 24 61 85 91 _| Denmark Office: (+45) 353 25 305 ____| Email: cholm@nbi.dk Web: www.nbi.dk/~cholm | |
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