TBasket error when reading a TTree

ROOT
1

I have some strange error when reading and writing a TTree.

I have two macros:
one is creating a root-file “input.root” with a TTree,
another is reading this TTree from the file, creates another TTree,
and writes both to a new root-file “output.root”.
When I open output.root with TBrowser and draw the branch of the TTree read from input.root, I get an error:

========
(class TFile*)0x17ec810
Error R__unzip_header: error in header
Error in TBasket::ReadBasketBuffers: Inconsistency found in header (nin=0, nbuf=0)
Error in TBasket::ReadBasketBuffers: fNbytes = 0, fKeylen = 17999, fObjlen = 262144, noutot = 0, nout=0, nin=0, nbuf=0
Error in TBranch::GetBasket: File: output.root at byte:65536, branch:k, entry:-1, badread=1, nerrors=1, basketnumber=0
Error R__unzip_header: error in header
Error in TBasket::ReadBasketBuffers: Inconsistency found in header (nin=0, nbuf=0)
Error in TBasket::ReadBasketBuffers: fNbytes = 0, fKeylen = 17999, fObjlen = 262144, noutot = 0, nout=0, nin=0, nbuf=0
Error in TBranch::GetBasket: File: output.root at byte:65536, branch:k, entry:-1, badread=1, nerrors=2, basketnumber=0

Here are the two simple macros:

createFile()
{
TFile * f = new TFile(“input.root”,“RECREATE”);

    double k;

    TTree * myTree = new TTree("myTree", "myTree");
    TBranch * kBranch = myTree->Branch("k",&k);

    k = 1;
    myTree->Fill();
    k = 2;
    myTree->Fill();

    f->cd();
    myTree->Write();
    f->Close();

}

readFile()
{
TFile * output = new TFile(“output.root”,“RECREATE”);

    TFile * input = new TFile("input.root","READ");

    TTree * myTreeFromFile = (TTree*)input->Get("myTree;1");

    TTree * myNewTree = new TTree("myNewTree", "myNewTree");

    double d;
    TBranch * dBranch = myNewTree->Branch("d",&d);

    d = 4;
    myNewTree->Fill();
    d = 8;
    myNewTree->Fill();

    output->cd();

    myNewTree->Write();
    myTreeFromFile->Write();

    output->Close();

}

I use:
ROOT 5.34/09
Scientific Linux release 6.6 (Carbon)

What can be the problem?
Thank you!

2

Ok, Rene Brun suggested me to move the statement
output->cd();
before the statement
TTree * myNewTree = new TTree(“myNewTree”, “myNewTree”);
beacause otherwise myNewTree is created in directory “input”.

This didn’t solve the error, but using
myTreeFromFile->CloneTree()->Write();
instead of
myTreeFromFile->Write();
(otherwise one copy only the Tree header and not the data)
solved it! Hooray!

Thank you, Rene!