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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