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

From: Rene Brun (Rene.Brun@cern.ch)
Date: Mon Dec 02 2002 - 20:09:13 MET


Hi Mike,

Unfortunately, I still see many people running with non released versions
like 3.03/07. We are making substantial efforts to promote released
versions. A substantial fraction of our support effort is spent in
answering questions or problems that would not exist if people
were using PRO versions.

Rene Brun

On Mon, 2 Dec 2002, Mike Miller wrote:

> 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
> 



This archive was generated by hypermail 2b29 : Sat Jan 04 2003 - 23:51:22 MET