cern root histogram file read plot projection

 TCanvas* c0 = new TCanvas("c0", "c0", 500, 500);
  _file0 = new TFile("name.root");
    _file0->GetListOfKeys()->Print();
  TString hname="name_key"; // From list of keys
  f8= (THnSparseF*)_file0->Get(hname);
  f8->Projection(6)->Draw();