Re: Problem reading TTree/interpreting error message

From: Rene Brun (Rene.Brun@cern.ch)
Date: Thu Aug 26 1999 - 11:07:48 MEST


Peter G. Jones wrote:
> 
> Hi,
> 
> I have created a TTree which is based on a single TClonesArray of
> identical objects. I can open and interogate the resultant file to
> find all the events (keys) in place, but when I try to read the first
> complete event I get the following error.
> 
> Error in <TBuffer::ReadObject>: object tag too large, I/O buffer corrupted
> 
> I have not been able to find an explanation for this error. Could
> someone enlighten me as to what the object tag is ? and what might
> be the likely cause the error ?
> 

Hi Peter,
The problem is in your StV0MiniDstMaker::Init() function.
You use the wrong constructor when creating a branch with a
TClonesArray.
Replace your statement:
      tree->Branch("Xi","StXiMiniDst",&mClonesArray,bsize,split);
by
      tree->Branch("Xi",&mClonesArray,bsize,split);

I also suggest that in case of troubles like this one, you check quickly
what is in the TTree before closing the file with:
  tree->Print();

Rene Brun



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