[ROOT] STL vectors in trees

From: Nicola Amapane (nicola.amapane@cern.ch)
Date: Wed Aug 21 2002 - 02:27:53 MEST 

Hi,

I am trying to write some STL vectors in a Tree. Apparently this should be
easy, however it does not work for me. I tried to  find some examples but
I could only find quite an old one:
http://root.cern.ch/cgi-bin/print_hit_bold.pl/root/roottalk/roottalk99/2746.html

I tried to remplement it as enclosed here; it seems to write the tree
correctly, but when I read it back the vector size is always 0...

I tried to play with split level, Bronch instead that Branch, etc., with
no luck.

I am using 3.03.07.

What I do wrong? Is there any simple example to do something
similar?

Thanks!
	Nicola

//------------------file EventSTL.h
#include "TObject.h"
#include <vector>

class EventSTL : public TObject
{
 public:
 EventSTL();
 virtual ~EventSTL();
 void Electron(Double_t x);
 void VI();
 void Clear();
 vector<Double_t> A;

 ClassDef(EventSTL,1)
};


//------------------file EventSTL.cxx
#include "EventSTL.h"

ClassImp(EventSTL)

EventSTL::EventSTL() {}
EventSTL::~EventSTL() {}
void EventSTL::Electron(Double_t x)
{
 A.push_back(x); 
}

void EventSTL::Clear()
{
 A.clear();      
}

void EventSTL::VI() 
{
 cout << "Size: " << A.size() << " - Contents : " ;
 for (Int_t i=0;i<A.size();i++)
  {
   cout << " " << A[i];
  }
 cout << endl;
}


//------------------file myLinkDef.h
#ifdef __CINT__

#pragma link off all globals;
#pragma link off all classes;
#pragma link off all functions;

#pragma link C++ class EventSTL;
#endif


//------------------file STLW.C
//
{
  gSystem->Load("EventSTL.so");
  TFile myfile("STL.root","RECREATE","TTree Dynamic ROOT file");

  EventSTL *CC = new EventSTL;
  TTree *mytree = new TTree("T","My tree");
  mytree->Branch("abc","EventSTL",&CC,16000,0);

  for (Int_t i=0;i<20;++i) {
    for (Int_t j=0;j<i;++j) {
      CC->Electron(i);
    }
    mytree->Fill();
    CC->VI();
    CC->Clear();
  }
  
  mytree->Write();
  mytree->Print();
}


//------------------file STLr.C
//
{
  gSystem->Load("EventSTL.so");
  TFile myfile("STL.root");

  EventSTL *CC = 0;
  TTree *T = (TTree*)myfile.Get("T");
  T->SetBranchAddress("abc",&CC);

  T->Print();

  T->GetEntry(15);
  CC->VI();
}


-----------------------------------
Nicola Amapane                                   []=-
INFN +39-011-6707374                             //    _-=__-=
CERN +41-22-7671519                            _/|]    ) ___ \
Mobile/SMS +39-(0)3471411410                  (_) \___/_(___)_|
mailto:nicola.amapane@cern.ch                  @          @

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