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

From: Mike Miller (miller@star1.physics.yale.edu)
Date: Mon Dec 02 2002 - 20:00:41 MET


Hi Rene, I was running on 3.02.07 (STAR libraries).  When I recompile 
and run with 3.03.09, it's fine.  Many thanks (though still a little 
confused!), Mike

On Mon, 2 Dec 2002, Rene Brun wrote:

> Hi Mike,
> 
> when using a TChain, you must set the branch addresses via
> TChain::SetBranchAddress, not TTree::SetBranchAddress.
> 
> You do not indicate which version of Root that you are using.
> I assume 3.03/09. If this does not work, please send me a script as short
> as possible reproducing the problem and tell me where I can get your
> files.
> 
> Rene Brun
> 
> 
> On Mon, 2 Dec 2002, Mike Miller wrote:
> 
> > 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.
> > BNL: 		631.344.8342	Building 118 Yale Software
> > Yale:   	203.432.6615	Room 301 WNSL
> > 
> 

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

Seattle:	206.543.2908	EPE group, 2nd floor physics.
BNL: 		631.344.8342	Building 118 Yale Software
Yale:   	203.432.6615	Room 301 WNSL



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