Hi Christian,
First, never use gROOT->Reset() in a named function or main program.
gROOT->Reset() should only be used in unnamed macros to clear the
current variables definitions.
Are you sure you have a TH2D object in your file ?
Could you do:
histofile->ls();
after the TFile *histofile = new.. statement
Rene Brun
Christian Veelken wrote:
>
> Hi Rooters,
>
> I have some problem when I try to read some histogramms from file:
>
> In Root the following code works
>
> TFile* file=new
> root [0] TFile("Triggereff.root","READ");
> root [1] TH2D* histo = (TH2D*) file->Get("ST66orST67orST71orST77eff");
> root [2] histo->FindBin(0.2,50,0)
> (Int_t)574
> root [3] histo->GetBinContent(574)
> (Stat_t)1.00000000000000000e+00
>
> but when I wrap the above in a small main program and compile it
> the same code chrashes
>
> ... (includes)
>
> TROOT root("Test","file test");
>
> int main(int argc, char* argv[])
> {
> TApplication theApp("App", &argc, argv);
>
> cout << "starting program initialisation...";
> gROOT->Reset();
> cout << " done";
>
> cout << "loading trigger efficiencies...";
> TFile* histofile = new TFile("Triggereff.root","READ");
> cout << "still living 1" << endl;
> TH2D* ST66orST67orST71orST77histo = (TH2D*) histofile->Get("ST66orST67orST71or77eff");
> cout << "still living 2" << endl;
> if ( ST66orST67orST71orST77histo == 0 )
> cout << "POINTER to histogramm == NULL !" << endl;
> cout << "still living 3" << endl;
> cout << ST66orST67orST71orST77histo->FindBin(0.2,50,0) << endl;
> cout << "still living 4" << endl;
>
> ...
> }
>
> with the output
>
> starting program initialisation... done
> loading trigger efficiencies...
> still living 1
> still living 2
> POINTER to histogramm == NULL !
> still living 3
>
> *** Break *** segmentation violation
> zsh: 6007 abort publish
>
> Does anybody have an idea what I did wrong here ?
>
> Thanks in advance,
>
> Christian Veelken
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