Member reference type 'TCanvas *' is a pointer; maybe you meant to use '->'?

lululu · May 9, 2016, 1:59pm

Hello,

I am trying to run a file named plot.C in root, but I got the error below. Can anyone help me see where went wrong? Thank you!

Try ‘.help’, ‘.demo’, ‘.license’, ‘.credits’, ‘.quit’/’.q’

root [0]
Processing plot.C…
/home/lulu/Desktop/geant4.10.02.p01/examples/extended/medical/dna/dnaphysics/./plot.C:18:3: error:
member reference type ‘TCanvas ’ is a pointer; maybe you meant to use
’->’?
c1.Divide(2,1);
~~^
->
/home/lulu/Desktop/geant4.10.02.p01/examples/extended/medical/dna/dnaphysics/./plot.C:23:22: error:
member reference type ‘TFile’ is not a pointer; maybe you meant to use
’.’?
ntuple0 = (TNtuple)f->Get(“ntuple0”);
~^~
.
/home/lulu/Desktop/geant4.10.02.p01/examples/extended/medical/dna/dnaphysics/./plot.C:25:3: error:
member reference type ‘TCanvas *’ is a pointer; maybe you meant to use
’->’?
c1.cd(1);
~~^
->
/home/lulu/Desktop/geant4.10.02.p01/examples/extended/medical/dna/dnaphysics/./plot.C:65:3: error:
member reference type ‘TCanvas *’ is a pointer; maybe you meant to use
’->’?
c1.cd(2);
~~^
->
root [1]

dpiparo · May 9, 2016, 2:43pm

Hi,

this seems to be a mistake in the Geant4 macro at line 18. A method of tcanvas is being accessed with a “.” rather than “->” even if c1 is a pointer.

Cheers,
Danilo

pamputt · May 9, 2016, 3:14pm

Danilo is right. You should open a bug report on the Geant4 bugtracker in order to point out this problem.

dpiparo · May 10, 2016, 4:31am

Hi,

very good idea: it is through reports like this one that open source products improve.
I just stopped after proposing a workaround explaining the issue without pointing out the real solution which is fixing G4

Cheers,
Danilo

lululu · May 10, 2016, 8:05am

Hi,

Thank you both for helping out. I changed the plot.C file according to what it tells me, but now I’m getting another problem.

Try ‘.help’, ‘.demo’, ‘.license’, ‘.credits’, ‘.quit’/’.q’

root [0]
Processing plot.C…

*** Break *** segmentation violation

===========================================================
There was a crash.
This is the entire stack trace of all threads:

#0 0x00007f0cbbb2464a in GI_waitpid (pid=2955, stat_loc=stat_loc
entry=0x7ffd1114ad80, options=options
entry=0) at …/sysdeps/unix/sysv/linux/waitpid.c:29
#1 0x00007f0cbba9dfab in do_system (line=) at …/sysdeps/posix/system.c:148
#2 0x00007f0cbcaa1784 in TUnixSystem::StackTrace() () from /home/lulu/Downloads/root-6.06.02/lib/libCore.so
#3 0x00007f0cbcaa386c in TUnixSystem::DispatchSignals(ESignals) () from /home/lulu/Downloads/root-6.06.02/lib/libCore.so
#4
#5 0x00007f0cbd016345 in ?? ()
#6 0x00007ffd1114e180 in ?? ()
#7 0x000000000224e530 in ?? ()
#8 0x00007ffd1114e180 in ?? ()
#9 0x00007ffd1114d730 in ?? ()
#10 0x000000000349fc20 in ?? ()
#11 0x0000000000000015 in ?? ()
#12 0x00007f0cbd0162d0 in ?? ()
#13 0x00007f0cb8a5db64 in cling::Interpreter::RunFunction(clang::FunctionDecl const, cling::Value) () from /home/lulu/Downloads/root-6.06.02/lib/libCling.so
#14 0x00007f0cb8a62dee in cling::Interpreter::EvaluateInternal(std::__cxx11::basic_string<char, std::char_traits, std::allocator > const&, cling::CompilationOptions, cling::Value*, cling::Transaction**) () from /home/lulu/Downloads/root-6.06.02/lib/libCling.so
#15 0x00007f0cb8a62f47 in cling::Interpreter::process(std::__cxx11::basic_string<char, std::char_traits, std::allocator > const&, cling::Value*, cling::Transaction**) () from /home/lulu/Downloads/root-6.06.02/lib/libCling.so
#16 0x00007f0cb8b172ee in cling::MetaProcessor::process(char const, cling::Interpreter::CompilationResult&, cling::Value) () from /home/lulu/Downloads/root-6.06.02/lib/libCling.so
#17 0x00007f0cb8b17ab8 in cling::MetaProcessor::readInputFromFile(llvm::StringRef, cling::Value, bool) () from /home/lulu/Downloads/root-6.06.02/lib/libCling.so
#18 0x00007f0cb89cb30b in TCling::ProcessLine(char const, TInterpreter::EErrorCode) () from /home/lulu/Downloads/root-6.06.02/lib/libCling.so
#19 0x00007f0cb89bcc97 in TCling::ProcessLineSynch(char const, TInterpreter::EErrorCode) () from /home/lulu/Downloads/root-6.06.02/lib/libCling.so
#20 0x00007f0cbca3cb87 in TApplication::ExecuteFile(char const, int, bool) () from /home/lulu/Downloads/root-6.06.02/lib/libCore.so
#21 0x00007f0cbca3dadf in TApplication::ProcessLine(char const, bool, int) () from /home/lulu/Downloads/root-6.06.02/lib/libCore.so
#22 0x00007f0cbc5f3c45 in TRint::ProcessLineNr(char const, char const, int) () from /home/lulu/Downloads/root-6.06.02/lib/libRint.so
#23 0x00007f0cbc5f515f in TRint::Run(bool) () from /home/lulu/Downloads/root-6.06.02/lib/libRint.so
#24 0x000000000040106c in main ()

The lines below might hint at the cause of the crash.
If they do not help you then please submit a bug report at
root.cern.ch/bugs. Please post the ENTIRE stack trace
from above as an attachment in addition to anything else
that might help us fixing this issue.

#5 0x00007f0cbd016345 in ?? ()
#6 0x00007ffd1114e180 in ?? ()
#7 0x000000000224e530 in ?? ()
#8 0x00007ffd1114e180 in ?? ()
#9 0x00007ffd1114d730 in ?? ()
#10 0x000000000349fc20 in ?? ()
#11 0x0000000000000015 in ?? ()
#12 0x00007f0cbd0162d0 in ?? ()
#13 0x00007f0cb8a5db64 in cling::Interpreter::RunFunction(clang::FunctionDecl const, cling::Value) () from /home/lulu/Downloads/root-6.06.02/lib/libCling.so
#14 0x00007f0cb8a62dee in cling::Interpreter::EvaluateInternal(std::__cxx11::basic_string<char, std::char_traits, std::allocator > const&, cling::CompilationOptions, cling::Value*, cling::Transaction**) () from /home/lulu/Downloads/root-6.06.02/lib/libCling.so
#15 0x00007f0cb8a62f47 in cling::Interpreter::process(std::__cxx11::basic_string<char, std::char_traits, std::allocator > const&, cling::Value*, cling::Transaction**) () from /home/lulu/Downloads/root-6.06.02/lib/libCling.so
#16 0x00007f0cb8b172ee in cling::MetaProcessor::process(char const, cling::Interpreter::CompilationResult&, cling::Value) () from /home/lulu/Downloads/root-6.06.02/lib/libCling.so
#17 0x00007f0cb8b17ab8 in cling::MetaProcessor::readInputFromFile(llvm::StringRef, cling::Value*, bool) () from /home/lulu/Downloads/root-6.06.02/lib/libCling.so

Root >

dpiparo · May 10, 2016, 8:24am

Hi,

hard to tell. Are you by chance dereferencing a null pointer or calling a method on an invalid pointer?

D

dpiparo · May 10, 2016, 8:54am

Hi,

a note about the G4 example issue.
I forwarded it to G4 experts and it has been already fixed in the trunk. The next patch release, 10.2.p02, which should be available before summer, will fix this.

Cheers,
Danilo

pamputt · May 10, 2016, 8:55am

I tried to run the plot.C macro from my Geant4 installation (Geant 4.10.2 patch 1) with the latest ROOT version 6.06/04 and the macro wrosk fine here. This means that the script has been fixed in the latest Geant4 version.

The plot.C is as follow

[code]// -------------------------------------------------------------------
// $Id: plot.C 70323 2013-05-29 07:57:44Z gcosmo $
// -------------------------------------------------------------------
//
// *********************************************************************
// To execute this macro under ROOT after your simulation ended,
// 1 - launch ROOT (usually type ‘root’ at your machine’s prompt)
// 2 - type ‘.X plot.C’ at the ROOT session prompt
// *********************************************************************
{
gROOT->Reset();
gStyle->SetPalette(1);
gROOT->SetStyle(“Plain”);

c1 = new TCanvas (“c1”,"",20,20,1000,500);
c1->Divide(2,1);

system (“rm -rf dna.root”);
system (“hadd dna.root dna_*.root”);

TFile f(“dna.root”);

TNtuple* ntuple;
ntuple = (TNtuple*)f.Get(“dna”);

c1->cd(1);
gStyle->SetOptStat(000000);

// All
ntuple->Draw(“flagProcess”,"",“B”);
ntuple->SetFillStyle(1001);
ntuple->SetFillColor(2);

// Excitation
ntuple->Draw(“flagProcess”,“flagProcess==12||flagProcess==15||flagProcess==16||flagProcess==19||flagProcess==22||flagProcess==25||flagProcess==29”,“Bsame”);
ntuple->SetFillStyle(1001);
ntuple->SetFillColor(3);

// Elastic
ntuple->Draw(“flagProcess”,“flagProcess==11”,“Bsame”);
ntuple->SetFillStyle(1001);
ntuple->SetFillColor(4);

// Ionisation
ntuple->Draw(“flagProcess”,“flagProcess==13||flagProcess==17||flagProcess==20||flagProcess==23||flagProcess==26||flagProcess==30”,“Bsame”);
ntuple->SetFillStyle(1001);
ntuple->SetFillColor(5);

// Charge decrease
//ntuple->Draw(“flagProcess”,“flagProcess==18||flagProcess==24||flagProcess==27”,“Bsame”);
//ntuple->SetFillStyle(1001);
//ntuple->SetFillColor(6);

// Charge increase
//ntuple->Draw(“flagProcess”,“flagProcess==21||flagProcess==28||flagProcess==31”,“Bsame”);
//ntuple->SetFillStyle(1001);
//ntuple->SetFillColor(7);

gPad->SetLogy();

c1->cd(2);

ntuple->SetMarkerColor(2);
ntuple->Draw(“x:y:z/1000”,“flagParticle==1”);

//ntuple->SetMarkerColor(4);
//ntuple->SetMarkerSize(4);
//ntuple->Draw(“x:y:z/1000”,“flagParticle==4 || flagParticle==5 || flagParticle==6”,“same”);

end:
}[/code]

lululu · May 11, 2016, 9:06am

ummm… I got the latest versions of Geant4 and ROOT as well. Did you just do “root plot.C”?

Thank you!

pamputt · May 11, 2016, 11:35am

Yes, just “root plot.C” in the directory where are your ROOT files.

Member reference type 'TCanvas *' is a pointer; maybe you meant to use '->'?

=========================================================== There was a crash. This is the entire stack trace of all threads:

The lines below might hint at the cause of the crash. If they do not help you then please submit a bug report at root.cern.ch/bugs. Please post the ENTIRE stack trace from above as an attachment in addition to anything else that might help us fixing this issue.

===========================================================
There was a crash.
This is the entire stack trace of all threads:

The lines below might hint at the cause of the crash.
If they do not help you then please submit a bug report at
root.cern.ch/bugs. Please post the ENTIRE stack trace
from above as an attachment in addition to anything else
that might help us fixing this issue.