Adding entries to a tree

ROOT
1

Hi,

I’m trying to add entries to a tree:

{
gROOT->Reset();

TFile *oldfile = new TFile(“clasnt_049669_00.root”);
TTree oldtree = (TTree)oldfile->Get(“h10”);

TFile *newfile = new TFile(“out.root”,“update”);
TTree newtree = (TTree)newfile->Get(“h10”);

Int_t nentries = newtree->GetEntries();

cout << "nentries " << nentries <GetEntry(223);
newtree->Fill();

oldtree->Show(223);
newtree->Show(nentries);

oldtree->Delete();
newtree->Delete();

oldfile->Close();
newfile->Close();

delete newfile;
delete oldfile;

}

The GetEntry - Fill combination is how I initially created the “newtree”, but when I open the file with it and try to add new entries, it doesn’t seem to work. Could you, please, tell me what is wrong here.

Thank you.

2

Hi,

Because you did not turn of HTML in your post, your code has been mangled (in the most interesting part :slight_smile: ).

Completely guessing, I would have to bet that you are missing the part where you should be connecting new and old tree together: oldtree->CopyAddresses(newtree);
Also by doing:oldtree->Delete(); newtree->Delete(); unless you also did an explicit newfile->Write before those, then you prevent the writing of the file.

Cheers,
Philippe

3

Sorry about the mangling. Anyway, your guess was correct. It works now. Thank you.