Hi Rooters,
I'm having a problem with the class generated by MakeClass() and
initialization with a TChain. I start with a TChain object containing
several files and call MakeClass(). When I produce an object of this
class and start the Loop(), all branches (one leaf per branch) are read
as zeros. If I call TChain::Draw(), everything works as expected (i.e.
leaves are non-zero).
Another oddity: I start root, read the Classfile, set up the TChain, but
when I initialize the ClassObject with the Chain, I get a segfault. If I
call the Draw()-function first, the Object is initialized !?
------------- start session log ---------------------
ifkpe1> root
*******************************************
* *
* W E L C O M E to R O O T *
* *
* Version 2.22/09 19 July 1999 *
* *
* You are welcome to visit our Web site *
* http://root.cern.ch *
* *
*******************************************
CINT/ROOT C/C++ Interpreter version 5.14.9, Jul 17 1999
Type ? for help. Commands must be C++ statements.
Enclose multiple statements between { }.
root [0] .L bllac.C // contains macro open_all()
root [1] .L MyClass.C
root [2] open_all("crab.root_list","bllac.root_list") // set up TChain
root [3] MyClass *ana = new MyClass(con)
*** Break *** segmentation violation
Root >
root [4] con->Draw("len")
Warning in <MakeDefCanvas>: creating a default canvas with name c1
root [5] MyClass *ana = new MyClass(con)
root [6]
[...]
root [8] ana->Loop()
Alpha: 0,
*** Break *** segmentation violation
Root >
----------- end session log ------------------------
con is of type (TTree *) and points to the TChain.
The offending statement in MyClass::Loop() is obviously
b_alpha->GetEntry(i):
---- begin code snippet from MyClass::Loop() ----------
for (Int_t i=0; i<nentries;i++)
{
nb = fTree->GetEntry(i); nbytes += nb;
cout << "Alpha: " << alpha << ", ";
b_alpha->GetEntry(i);
cout << alpha << endl;
}
---- end code snippet --------------------
Any help is highly appreciated.
Regards, Oliver
--
Oliver Mang
Institut fuer Experimentelle und Angewandte Physik, CAU Kiel
Phone: ++49/431/880-2482 E-Mail: mang@ifkhep.uni-kiel.de
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