Hi, I stumbled over a mistake which I don't really understand. I'd like to plot a 2D histogram and then draw a box into it with TBox. First I started with a macro like: { ntuple->Draw("deltaE:mB"); TBox box(4,-4,5,0); box.Draw(); } When I execute this macro on the root command line it works as expected. Well, then lets make a class out of it: class myBox { public: myBox() {} void draw() { ntuple->Draw("deltaE:mB"); TBox _box(4,-4,5,0); _box.Draw(); } }; Using this class on the command line with root [1] .L myBox.C root [2] myBox *box = new myBox(); root [3] box->draw(); does draw the histogram but no box is drawn. Finally I relized that I have to define the _box as pointer inside the class myBox to make it work: TBox *_box = new TBox(4,-4,5,0); _box->Draw(); I don't understand why it worked in the first place (as macro), but does not work when I use it inside a class. Could somebody enlighten me? Thanks a lot and best regards Remi ********************************************************************* Remigius K. Mommsen e-mail: mommsen@slac.stanford.edu University of California, Irvine URL: home.cern.ch/mommsen c/o SLAC voice: ++1 (650) 926-3595 2575 Sand Hill Road #35 mobile: ++1 (650) 387-1402 Menlo Park, CA 94025, US fax: ++1 (650) 926-8522 *********************************************************************
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