Re: [ROOT] Using a declared variable in a root command line

From: Reinhardt Chamonal (chamonal@ph.ed.ac.uk)
Date: Mon Mar 18 2002 - 14:43:37 MET


Thanks I didn't think about this trick



On Mon, 18 Mar 2002, Rene Brun wrote:

> Hi Reinhardt,
> 
> Modify your code as indicated below.
> 
> Rene Brun
> 
> Reinhardt Chamonal wrote:
> > 
> > Hi the experts,
> > 
> > First that's going be a very very basic question. I had a look at
> > various examples around but I am stuck and frustrated. (I am started at
> > Root)
> > What I would like to do is a little simple script to take a number and
> > then
> > plot the histogram corresponding to this number
> > Here is what I do:
> > 
> > #include <iostream.h>
> > 
> > int show(Int_t nb) {
> >   gROOT->Reset();
> >   c1 = new TCanvas("mapmt","MAPMTs",10,40,800,600);
> >   TFile *f = new TFile("r99.root"); //<================
>     //use new, otherwise when closing the file, hist will be destroyed
> >   //TFile *f = new TFILE("r99.root");
> >   gPad->SetLogy();
> >   TH1F *boundary = new TH1F("boundary","Channel Signal",500,-0.5,250.5);
>     TString cut = "pdid==0 && pixid==";
>     cut += nb;
> >   h10->Draw("norm>>+boundary","cut);
> >   c1->Update();
> >   //return 0;
> > 
> > }
> > 
> > so calling show(2) should draw the  histogram cooresponding to pixid=2
> > when calling
> > h10->Draw("norm>>+boundary","pdid==0 && pixid==nb");
> > where I put my variable nb. It obviously doesn't like it certainly because
> > of the "". What is the correct declaration in this case ?
> > Can anybody indicate me an example where this is used ?
> > 
> > Also as running my script without nb, (with the number instead) works but
> > the histogram shows up and then disappears... :(
> > I read  something about the heap.. (as my histogram boudary with my
> > personnal boundaries is declared as new). Is it the case ? What can I do
> > to let it stay ?
> > 
> > Cheers.
> > 
> > ------------------------------------------------------------
> >  Reinhardt CHAMONAL            The University of Edinburgh
> >                                Dept. of Physics & Astronomy
> >  email: chamonal@ph.ed.ac.uk   King's Buildings, JCMB, 5301
> >                                Mayfield Road
> >  phone: +44-131-650 5307       Edinburgh, EH9 3JZ
> > 
> >  web: http://www.ph.ed.ac.uk/~chamonal/
> >       http://www.reuh.fr.st
> > ------------------------------------------------------------
> 



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