[ROOT] array of TClonesArray

From: Tommaso Chiarusi (ss11002@arpat.toscana.it)
Date: Wed May 21 2003 - 21:41:18 MEST 

Hello.
I have a script which works under cint.
I need to convert it into a compiled executable.
I become aware that cint automatically cures all the C++ venial sins in 
the code...
Unfortunately, my g++ compilator feels such sins become as unforgiven.

I try to cure my mistakens, so I managed to compile,
But I get Segmentation fault.

I am quite sure that my problem IS NOT on some include files or 
libraries which may lack.
It is a problem of segmentation, so it should concern the usage of  
pointers.

The problem is when I try to fill and then read an
"array of TClonesArray"


Conceptual sketch:
Imagine a  detector subdivided into several zones.
The number of interesting zone is variable, say  "ntotal_zone"

For each zone I have several tracks.
So I need to make "ntotal_zone" collection of tracks.
I decided to collect the tracks of each zone by means of a TClonesArray.
So, I find myself with an array of TClonesArray.

In the cint-script I use the following (!uncorrect! but working syntax)

      TClonesArray *vUp = new TClonesArray[ntotal_zone];
      TClonesArray *vDown = new TClonesArray[ntotal_zone];

      int *contau = new int[ntotal_zone];// vectors which counts the 
number of tracks for each zone
      int *contad = new int[ntotal_zone];

      TMatrix *notru = new TMatrix(ntotal_zone,neventUp);
      TMatrix *notrd = new TMatrix(ntotal_zone,neventDown);


      for(int in =0;in<ntotal_zone;in++) // initialization of all the 
TClonesArrays
    {
      vUp[in]= new TClonesArray("Track",neventUp);
      vDown[in]= new TClonesArray("Track",neventDown);
      contau[in]=0;
      contad[in]=0;
    }

Then when I fill I use the following (whithin a loop on  the  total 
number of the zones -
nozone is the number of the currently analysed zone, let's call this 
 procedure as (p.1) ):


                  new(vUp[nozone][contau[nozone]])
                Track(trUp->x(),trUp->y(),trUp->a(),trUp->b(),trUp->pol());


Note the array-form of the TClonesArray:
        vUp[nozone] ....... should give the pointer to a TClonesArray
vUp[nozone][contau[nozone]]  ....... should  give the component of such 
pointer
   



When trying to convert everithing into a g++ stand-alone executables, I 
noticed that I was using a unforgiven syntax and I changed it by
using the following:

      TClonesArray* *vUp = new TClonesArray*[ntotal_zone];
      TClonesArray* *vDown = new TClonesArray*[ntotal_zone];

... i.e. as a list of pointers to TClonesArray, which are initialized as 
the same as in the cint-script.


The filling procedure should remain the same as (p.1). If I do this the 
compiler prompt out the following errors

Analisi_match3.C:321: no matching function for call to `Track::operator
new (unsigned int, TClonesArray &)'
/home/applicazioni/root/include/TObject.h:153: candidates are: static 
void *TObject::operator new
(unsigned int)
/home/applicazioni/root/include/TObject.h:154:                 static 
void *TObject::operator new
(unsigned int, void *)

 Instead, if I write (note the "&" in the argument of "new()" )

                  new(&vUp[nozone][contau[nozone]])
                Track(trUp->x(),trUp->y(),trUp->a(),trUp->b(),trUp->pol());

I get the program to compile, but when I start to iterate through the 
TClonesArray, the program crashes dumping a sementation fault.

What's wrong?

My system is  

Toshiba Satellite 1800 LapTop,
Linux Mandrake 8.1
Root Version   3.03/09 18 September 2002
gcc version 2.96 20000731 (Mandrake Linux 8.1 2.96-0.62mdk)

Thank you very much

Tommaso

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