Re: Error: illegal pointer to class object Spher3D_sig 0x0 396 plot1.C:7: *** Interpreter error recovered ***

Two remarks
  -your histogram is a TH1D, not a TH1F
  -its name is " h_Sphericity3D", not "h_Sphericity3D", ie the first character is a blank character !!
so, to read it change your statement to

TH1D *Spher3D_sig = (TH1D*)setA->Get(" h_Sphericity3D");

Rene Brun

Meera Lebbai, Mohamed R. wrote:
> I can see the histogram from my Histogram file (hist_stop_sig.root) . But when I tried to get through TFile I am getting this error. You can check my hist_stop_sig.root in my public area at lxplus.
> ~razzak/public/hist_stop_sig.root
>
> Thanks
>
> Razzak
> ________________________________________
> From: Rene Brun [Rene.Brun_at_cern.ch]
> Sent: Tuesday, October 30, 2007 6:13 AM
> To: Meera Lebbai, Mohamed R.
> Cc: ROOT Talk
> Subject: Re: [ROOT] Error: illegal pointer to class object Spher3D_sig 0x0 396 plot1.C:7: *** Interpreter error recovered ***
>
> So this means that your object with name " h_Sphericity3D" does not
> exist in the file.
> As a result the pointer Spher3D_sig is null
>
> Rene Brun
>
> Meera Lebbai, Mohamed R. wrote:
>
>> Hi Rene,
>>
>> When I do
>>
>> TH1F *Spher3D_sig = (TH1F*)setA->Get("h_Sphericity3D");
>> if(Spher3D_sig) Spher3D_sig->Draw();
>>
>> I don't get any error messages but I can't save this histogram ( I can't see the histogram).
>>
>> Is there any way to do it.
>>
>> Note: I also wanted to metion one thing this kind of illegal pointer error only occuring for particular variables such as Spehricity, Aplanarity and Planarity.
>>
>> Thanks
>>
>> Razzak
>> ________________________________________
>> From: Rene Brun [Rene.Brun_at_cern.ch]
>> Sent: Friday, October 26, 2007 9:39 AM
>> To: Meera Lebbai, Mohamed R.
>> Cc: ROOT Talk
>> Subject: Re: [ROOT] Error: illegal pointer to class object Spher3D_sig 0x0 396 plot1.C:7: *** Interpreter error recovered ***
>>
>> Instead of:
>>
>> TH1F *Spher3D_sig = setA->Get("h_Sphericity3D");
>> Spher3D_sig->Draw();
>>
>> do:
>>
>> TH1F *Spher3D_sig = (TH1F*)setA->Get("h_Sphericity3D");
>> if(Spher3D_sig) Spher3D_sig->Draw();
>>
>> Rene Brun
>>
>> Meera Lebbai, Mohamed R. wrote:
>>
>>
>>> Hi all,
>>>
>>> I am getting illegal pointer error when I try Draw() a histogram ( but I never used to get this before).
>>>
>>> I have just included a simple file
>>>
>>>
>>> // test.C
>>>
>>>
>>> { gStyle->SetOptFit(111111);
>>>
>>> // signal
>>> TFile* setA = TFile::Open("hist_stop_sig.root");
>>>
>>> TH1F *Spher3D_sig = setA->Get("h_Sphericity3D");
>>> Spher3D_sig->Draw();
>>> }
>>>
>>> Any help will be appreciated.
>>>
>>> Razzak
>>>
>>>
>>>
>>>
>>
>
>
Received on Tue Oct 30 2007 - 15:37:16 CET