Hi Henrique, You are misusing the operator []. You can do: TH1D* h = new TH1D() TObjArray a; a.Add(h); a[0]->Draw(); a.At(0)->Draw(); or TObjArray *b = new TObjArray; b->Add(h); b->At(0)->Draw(); Absolutely no need to cast since the objects in the TObjArray are TObject and there is a TObject::Draw. Rene Brun On Fri, 29 Nov 2002, Henrique de M. J. Barbosa - mestrado wrote: > > Hello Rene, > > > At least one advantage of deriving from a common base class TObject. > > You can do > > Histo_List[0])->Draw(); > > I tried your example and it doesn't work for me. Here's what I got: > > root [0] TH1D* h = new TH1D() > root [1] h->Draw() <- this draw is ok > <TCanvas::MakeDefCanvas>: created default TCanvas with name c1 > root [2] TObjArray *t = new TObjArray() > root [3] t->GetEntries() > (const Int_t)0 > root [4] t->Add(h) > root [5] t->GetEntries() > (const Int_t)1 > root [6] t[0])->Draw() <- this draw is not ok > !!!Bad command input. Ignored!!! > root [7] ((TH1D*) t[0])->Draw() <- this draw is ok > > Am I missing something? > > thanks, > > Henrique > **************************************** > State University at Campinas - BRASIL > "Gleb Wathagin" Physics Institute > Department of Cosmic Rays and Chronology > > Henrique Barbosa The Pierre Auger > PhD Student Observatory > **************************************** >
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