Memory resident tree

Dear rooters,

    I have a problem with a method of a class where I have to build a tree starting from some other trees saved in files (the final tree is created with CopyEntries inside a loop). In particular, the problem lies on the fact that I first create the final tree, and the open the files where the others are in read mode. Here you can find the code:

void AliTOFcalib::CreateTreeFromGrid(Int_t minrun, Int_t maxrun){

// creating the chain with the trees for calibration
// collecting them from reference data
// from minrun to maxrun

  Float_t p[CHENTRIESSMALL];
  Int_t nentries;
  fTree = new TTree("TOFCalib","Tree for TOF Calibration");   fTree->Branch("nentries",&nentries,"nentries/I");   fTree->Branch("TOFentries",p,"TOFentries[nentries]/F");   AliInfo("connected to alien");
  TGrid::Connect("alien://");  

  Char_t filename[100];
  for (Int_t irun = minrun;irun<=maxrun;irun++){     

sprintf(filename,"alien:///alice/cern.ch/user/c/czampolli/TOFCalibReference_%i.root",irun);

    TFile *filegrid = TFile::Open(filename,"READ");     TTree *tree = (TTree*)filegrid->Get("T");     tree->SetBranchAddress("nentries",&nentries);     tree->SetBranchAddress("TOFentries",p);     fTree->CopyEntries(tree);
    delete tree;
    fNruns++;
  }  

The fTree, as you can see, is a private member of the class. Moreover, I don't need to write fTree on a file, for this reason I create it without opening any file.
How should I avoid this error?
Thank you a lot in advance.
Best Regards,

          Chiara
  AliInfo(Form("Number of runs being analyzed %i",fNruns)); } Received on Fri Sep 28 2007 - 10:14:41 CEST