[ROOT] Use of TClonesArray in Event

From: GENTIT Francois-Xavier DAPNIA (GENTIT@dapnia.cea.fr)
Date: Wed Nov 06 2002 - 10:36:51 MET 

  Dear Rooters,
  I am now studiing the example Event provided in root/test. I thought that
the condition for using TClonesArray instead of TObjArray in Event was that
the objects put into the TClonesArray (here of class Track) was that they
had to have a fixed length.
  No I see the following into the definition of Track:

   Int_t        fNsp;          //Number of points for this track with a
special value
   Float_t*     fPointValue;   //[fNsp] a special quantity for some point.

  and into its implementation:

     fNsp = Int_t(3*gRandom->Rndm(1));
   if (fNsp) {
      fPointValue = new Float_t[fNsp];

  So the length of Track is not fixed! How can it work?
  Thanks a lot in advance

François-Xavier Gentit
DAPNIA/SPP CEA Saclay
http://gentit.home.cern.ch/gentit/

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