MakeClass & TDirectoryFile NTuple

Hello, I have a .root file with this header (see below), and I need to extract the class using the MakeClass tool. But I need to get first the TTree, and I don’t really know how to do that. Can you help me?
Thanks in advance,

root [0] TFile hfile = new TFile(“run_0008_hpdpanel.root”);
root [1] hfile->ls();
* run_0008_hpdpanel.root Gaudi Trees
TFile* run_0008_hpdpanel.root Gaudi Trees
KEY: TDirectoryFile HitNtuple;1 HitNtuple

Assuming a Tree named “mytree” in the subdir HitNtuple, just do

TTree *T = (TTree*)hfile->Get("HitNtuple/mytree"); T.MakeClass("xxx");