Opening many root files

ROOT
1

Hello All,

I am trying to loop through many root files and print some numbers from each file. Here is a pared down version of my macro:

	Int_t	x,nosingles;
	const char filename[100];
	TFile		*file;
	
	for (x=12;x<25;x=x+2){
		sprintf(filename,"R%i.root",x);
		file = TFile::Open(filename);
		nosingles = Singles->GetEntries("energy>0.0");
		nosingles = Singles->GetEntries();
		printf ( "%i %s\n",nosingles,filename);
		file->Close();
	}

However, when I run it I get a “segmentation violation”.

Any idea what I am doing wrong? Thanks in advance.

Karthik.

2

The code should have been

instead of const char filename[100];

3

Hello, how did you define the object “Singles”?

4

Singles is a tree in the root file I am trying to open.

I noticed that if I do not close the file before opening the next one, the macro seems to work ok.

5

Hi,

You probably also need to delete the TFile object itself. Int_t x,nosingles; TString filename; for (x=12;x<25;x=x+2){ filename.Form("R%i.root",x); TFile *file = TFile::Open(filename); nosingles = Singles->GetEntries("energy>0.0"); nosingles = Singles->GetEntries(); printf ( "%i %s\n",nosingles,filename.Data()); delete file; }

Cheers.
Philippe

6

Hello Philippe,

That does not work either.

[code]$root -l -b -q test.c
root [0]
Processing test.c…
66584 R12.root

*** Break *** segmentation violation[/code]

Karthik.

[quote=“pcanal”]Hi,

You probably also need to delete the TFile object itself. Int_t x,nosingles; TString filename; for (x=12;x<25;x=x+2){ filename.Form("R%i.root",x); TFile *file = TFile::Open(filename); nosingles = Singles->GetEntries("energy>0.0"); nosingles = Singles->GetEntries(); printf ( "%i %s\n",nosingles,filename.Data()); delete file; }

Cheers.
Philippe[/quote]

7 
  Int_t x,nosingles;
  const char filename[100];
  TFile *file;
  TTree *Singles;
  for (x=12;x<25;x=x+2){
    sprintf(filename,"R%i.root",x);
    file = TFile::Open(filename);
    Singles = (TTree*)file->Get("Singles"); // or 'Singles = (TTree*)file->FindObjectAny("Singles");'
    nosingles = Singles->GetEntries("energy>0.0");
    printf ( "%i %s\n",nosingles,filename);
    delete Singles;
    delete file;
  }
8

Hi,

Was there a stack trace indicating where the crash happened? Did you try running with valgrind:valgrind root.exe -b -l -q test.cDid you try adding if statement and printing to make sure all the value are as exepected (i.e. file != 0, filename being what you expect, etc.). And as Pepe points out you could retrieve the object explicitly. The following being the recommend way:TFile *file = TFile::Open(filename); TTree * Singles; file->GetObject("Singles",Singles); if (Singles == 0) { cerr << "No TTree object named Singles are in the file " << filename << "\n"; return ; }

Cheers,
Philippe.

9

Thanks Pepe, deleting the Singles worked.

[quote=“Pepe Le Pew”] Int_t x,nosingles; const char filename[100]; TFile *file; TTree *Singles; for (x=12;x<25;x=x+2){ sprintf(filename,"R%i.root",x); file = TFile::Open(filename); Singles = (TTree*)file->Get("Singles"); // or 'Singles = (TTree*)file->FindObjectAny("Singles");' nosingles = Singles->GetEntries("energy>0.0"); printf ( "%i %s\n",nosingles,filename); delete Singles; delete file; } [/quote]