Error: illegal pointer to class object

From: Gian Piero Di Giovanni <digiovan_at_fnal.gov>
Date: Fri, 01 Jul 2005 11:13:25 +0200

Hi,  

     I'm using the version 4.02/00 on Fedora Core 3. This is the following script "test.C".
Using root I get:

root [0] .L test.C
root [1] test()

---

TRACK_ALL
dilptRel_ALL
dilplRel_ALL
dilpt_ALL

---

../rootfiles/bu-jpsik-BDStest.root:/TRACK_ALL Error: illegal pointer to class object graph_data 0x0 634 FILE:test.C LINE:82
*** Interpreter error recovered ***

This is strange for me because the values of TString are also printed on the screen.
Can someone help me?

Thank you a lot,

    Gian Piero.

1 int test(int Ntrk=0)

      2 {
      3
      4   gROOT->Reset();
      5
      6   // gStyle->SetOptStat(111111);
      7   // gStyle->SetOptFit(1111);
      8
      9
     10   TObjArray Data;
     11
     12   TString folder = "TRACK_";
     13   TString dilptRel = "dilptRel_";
     14   TString dilplRel = "dilplRel_";
     15   TString dilpt = "dilpt_";
     16
     17
     18   if (Ntrk != 0) {
     19
     20     folder           +=  Ntrk;
     21     dilptRel         +=  Ntrk;
     22     dilplRel         +=  Ntrk;
     23     dilpt            +=  Ntrk;
     24
     25   }else{
     26
     27     folder.Append("ALL");
     28     dilptRel.Append("ALL");
     29     dilplRel.Append("ALL");
     30     dilpt.Append("ALL");
     31   }
     32
     33
     34   TString graphs[3]={dilptRel, dilplRel, dilpt};
     35   cout << "===============================\n";
     36   cout << folder << endl;
     37   cout << graphs[0] << endl;
     38   cout << graphs[1] << endl;
     39   cout << graphs[2] << endl;
     40   cout << "===============================\n";
     41
     42
     43   //----- Taking DATA -----
     44   TFile* file = new TFile("../rootfiles/bu-jpsik-BDStest.root");
     45   TDirectory* dir= (TDirectory*) file->Get(folder);
     46   dir->pwd();
     47   dir->cd();
     48
     49   for (int i=0;i<3;i++)
     50     {
     51
     52       TGraphErrors* graph= (TGraphErrors*) file->Get(graphs[i]);
     53       Data.Add(graph);
     54
     55     }
     56
     57
     58   file->Close();
     59
     60   TCanvas* CANVAS1 = new TCanvas("CANVAS1","CANVAS1",950,750);
     61    CANVAS1->Divide(2,2,0,0);
     62
     63
     64
     65   for (int i=1;i<4;i++)
     66     {
     67
     68       CANVAS1->cd(i);
     69
     70       char PadName[200];
     71       sprintf(PadName,"%s_%d",CANVAS1->GetName(),i);
     72
     73
     74       TPad* pad = (TPad*) CANVAS1->FindObject(PadName);
     75       pad->SetGridx();
     76       pad->SetGridy();
     77
     78
     79       TGraphErrors* graph_data= (TGraphErrors*) Data[i-1];
     80
     81
     82       graph_data->SetMarkerColor(2);
     83       graph_data->SetFillColor(1);
     84       graph_data->GetXaxis()->SetTitle("Pt Cut (GeV)");
     85       //graph_data->GetYaxis()->SetTitle("Dilution");
     86       //graph_data->GetYaxis()->SetTitleOffset(1.5);
     87       graph_data->SetMarkerSize(1.0);
     88       graph_data->SetMarkerStyle(8);
     89       graph_data->SetMinimum(-0.15);
     90       graph_data->SetMaximum(0.28);
     91
     92       graph_data->Draw("AP");
     93
     94
     95       pad->SetFillColor(0);
     96       pad->Update();
     97       TPaveText* text = (TPaveText*) pad->FindObject("title");
     98       text->SetFillColor(0);
     99       pad->Update();
    100     }

    101
    102 return 0;
    103 } Received on Fri Jul 01 2005 - 11:12:48 MEST