Re: [ROOT] reading fromm root files

From: Sebastien Greder (greder@in2p3.fr)
Date: Thu Oct 10 2002 - 23:06:18 MEST


the error may come from the fact you don't do anyting with 
the file File12 in you below example ...

seb.


On Thu, 10 Oct 2002, Rene Brun wrote:

> Please provide more information, in particular extend
> the "I get error ..." to something more useful.
> 
> Note that instead of:
>    TH2D* TwoHisto = File1->Get("h2");
> you should do:
>    TH2D* TwoHisto = (TH2D*)File1->Get("h2");
> 
> Rene Brun
> 
> 
> On Thu, 10 Oct 2002 kmakonyi@nist.gov wrote:
> 
> > Dear RooTers,
> > 
> > It is possible a very beginner question, but I don't know the solution.
> > I have several directory. All of them contains many data, which are analized 
> > directory by directory, so after the analysis in every directory conains a root 
> > file also.
> > In the root files there are two histogram.
> > I would need to the "same" histogram from every directory.
> > 
> > The problem is, if I do this:
> > {
> > TFile* File1 = new TFile("one.root");
> > TH2D* OneHisto = File1->Get("h2");
> > 
> > TFile* File12 = new TFile("two.root");
> > TH2D* TwoHisto = File1->Get("h2");
> > 
> > cout << OneHisto->GetNbinsX();
> > }
> > 
> > I get error ...
> > 
> > What can I do, What do I do wrong?
> > Thanks, k.
> > 
> 
> 



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