RE: Run Graph array macro

From: Fine, Valeri <fine_at_bnl.gov>
Date: Thu, 16 Mar 2006 08:42:13 -0500

I would like to call your attention, even though CINT does not complain one MUST use the " TGraph *gr[4]" - array of the TGraph pointers rather the array of TGraph objects, to avoid the memory leak and any future confusions.

To see what I am speaking about one should add two extra lines to the macro and edit the $ROOTSYS/etc/system.rootrc to make sure it contains "Root.ObjectStat: 1"
The updated macro:
{

   int i;
   TGraph gr[4];
   gObjectTable->Print(); // <---- NEW LINE    Float_t a[4]={450,1050,1431,1983};
   Float_t b[4][4]=
     {1576,3420,4854,6635,117,262,402,528,21,53,71,93,4,18,24,28};   TCanvas *c1=new TCanvas("c1","",1);
  c1->Divide(2,2);
  for(i=1;i<5;i++)
  {

     c1->cd(i);
    gr[i-1]=new TGraph(4,a,b[i-1]);
    gr[i-1]->Draw("AL*");
  }
  gObjectTable->Print(); // <---- NEW LINE }

It should produce you 2 "Object tables". The first contains:

Object statistics

class                         cnt    on heap     size    total size    heap size
TGraph                          4          4      104           416          416

The second one:

Object statistics

class                         cnt    on heap     size    total size    heap size
TGraph                          8          8      104           832          832

I.e. the macro in question did create 8 TGraph objects instead of the expected 4. In fact this behavior is the bug in CINT to be fixed.

Replacing "TGraph gr[4];" with "TGraph *gr[4];" removes the trace of the memory leak. The second object table contains the correct number of the objects: Object statistics

class                         cnt    on heap     size    total size    heap size
TGraph                          4          4      104           416          416

HTH, Valeri

From: Ding Hengtong
Sent: Wed 3/15/2006 10:36 PM
To: Zhu FengRong
Cc: roottalk_at_pcroot.cern.ch
Subject: Re: [ROOT] Run Graph array macro

Hi ,

   You should define "gr[4]" and "i",
that is to say you should add "TGraph gr[4];" and change "for(i=1;i<5;i++)" into "for(Int_t i=1;i<5;i++)" in your macro, then it'll gonna be ok.

uOn Thu, 16 Mar 2006, Zhu FengRong wrote:

> Hello,
> In the root_v4.01.02.Linux.RH7.3.gcc296 environment,I failed to run the
> macro like this:
>
> {
> Float_t a[4]={450,1050,1431,1983};
> Float_t b[4][4]=
> {1576,3420,4854,6635,117,262,402,528,21,53,71,93,4,18,24,28};
> TCanvas *c1=new TCanvas("c1","",1);
> c1->Divide(2,2);
> for(i=1;i<5;i++)
> {
> c1->cd(i);
> gr[i-1]=new TGraph(4,a,b[i-1]);
> gr[i-1]->Draw("AL*");
>
> }
> }
> Would you help me to succeed in running it?
> Thank you in advance.
>
> with best wishes,
> Fengrong Zhu
> Institute of High Energy Physics,
> C.A.S P.R.C
> zhufr_at_ihep.ac.cn
> --
> Open WebMail Project (http://openwebmail.org)
>

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Received on Thu Mar 16 2006 - 14:42:50 MET