Re: [ROOT] Reading 2D arrays from a Tree

From: Rene Brun (Rene.Brun@cern.ch)
Date: Tue Nov 13 2001 - 17:08:58 MET


Hi Ben,

The TTree constructor expects two arguments (name,title). You give only
one argument. Do, eg
   TTree *tree = new TTree("tree","tree title");

Rene Brun

Ben Morgan wrote:
> 
> Thanks Philippe,
>                 I should have remembered, I'm using ROOT v3.01/06 on an
> Intel PC running Red Hat 6.2.
> Yes, Glen's codes run fine when run as macros in an interactive session,
> but simply cutting and pasting them into a very simplistic C++ code like:
> 
> #include<iostream.h>
> #include<iomanip.h>
> #include<fstream.h>
> #include<stdio.h>
> #include <stdlib.h>
> #include<math.h>
> 
> //ROOT Headers
> #include "TROOT.h"
> #include "TFile.h"
> #include "TNetFile.h"
> #include "TRandom.h"
> #include "TTree.h"
> #include "TBranch.h"
> #include "TClonesArray.h"
> #include "TStopwatch.h"
> 
> int main(int argc, char **argv)
> {
> 
> Float_t na[10][10];
> TFile file("adc.root");
> TTree *tree = new TTree("tree");
> 
> TBranch *b = tree->GetBranch("adc");
> TLeaf *l = b->GetLeaf("adc");
> tree->SetBranchAddress("adc",&na);
> 
> for (Int_t i=0; i<150; i++) {
>   b->GetEvent(i);
>   printf("na[1][1] = %f, ",na[1][1]);
> }
> 
>  return 0;
> }
> 
> This doesn't compile. The problem seems to be with the line:
> TTree *tree = new TTree("tree");
> This doesn't appear in Glen's code, but something like this appears to be
> neccessary in a C++ program otherwise the compiler complains about 'tree'
> being undefined in the next line, i.e. leaving this line out produces:
> 
> twodread.C: In function `int main(int, char **)':
> twodread.C:25: `tree' undeclared (first use this function)
> 
> on compilation. Equally, using a line like
> 
> TTree *tree = (TTree*)file->Get("tree")
> 
> as used in the examples of reading trees in the manual doesn't compile
> properly either. Hope this makes things clearer,
> 
> Thanks,
> 
> Ben Morgan.
> 
> --
> -------------------------------------------------------------------------------
> Mr. Ben Morgan
> Postgraduate Student
> University of Sheffield
> Department of Physics & Astronomy
> Hicks Building
> Hounsfield Road
> Sheffield  S3 7RH
> -------------------------------------------------------------------------------



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