[ROOT] TTree::GetEntry(int) vs. TChain::GetEntry(int)

From: Mike Miller (miller@star1.physics.yale.edu)
Date: Mon Dec 02 2002 - 17:09:53 MET 

Hi all, I have a tree with 4 branches.  I know that the tree and the file
it is stored in are fine, since I can open the file and draw all elementes
of the tree.  Further, I can open the file, and (in compiled code) use
TTree->SetBramchStatus() and TTree->SetBranchAddress() to set the address
for three of the branches.  I can then call TTree::GetEntry() and read
into memory all elements of these three branches for all events.  The 
information read into memory is fine.  However, if I now make a TChain 
object from the file, instead of simply retrieving the TTree itself, I 
can't use TTree->SetBranchAddress() to properly read the info from my 
branches.  It sef-faults in TBuffer::operator>> on the first call to 
TTree::GetEntry().  Is there something fundamentally different between 
TChain and TTree regarding how branches are treated and read?  Thanks, 
Mike

-- 
Michael L. Miller (Yale Physics) michael.miller@yale.edu

Seattle:	206.543.2908	EPE group, 2nd floor physics.
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