Hello rooters,
According to the userguide, I wrote the following:
Note:
1. "vario.root" is the root file in which I have stored my ntuple.
2. "front" is the name of my ntuple (in "vario.root" there are many
other ntuples!).
3. "p" is the variable that I want to plot. ("p" is either the name of
the TLeaf inside the ntuple "front" and of the variable the histogram I
fill with)
The problem I get is that I actually do NOT Get the Entry value, but
something like 5.30784e-315!!!!!
Thank you very much!
void plot()
{
gROOT->Reset();
TFile *f = new TFile("vario.root");
TNtuple *nf = (TNtuple*)f->Get("front");
Int_t entries = (Int_t)nf->GetEntries();
cout<<"Number of Entries: "<<entries<< endl;
Double_t p=0;
nf->SetBranchAddress("p",&p);
TH1F *htp = new TH1F("htp","p",100,0,10);
for (Int_t ki=1;ki<entries;ki++)
{
nf->GetEntry(ki);
htp->Fill(p);
}
TCanvas *c1 = new TCanvas("c1", "c1",515,210,540,376);
c1->Draw();
htp->Draw();
//
}
Tommaso
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