Re: Creating and Filling Many Histogram

I thought that you were just using CINT and execute root > .x test_scrip.C

I see now that you are compiling your code. Your code compiles OK with gcc2.3 and gcc3.3. I have no way to test it right now with gcc3.4. In principle what you do is not legal C++ (it is accepted by CINT and all versions of gcc that I know, and also VC++, the Alpha/cxx and Aix/xlC compilers.

if gcc3.4 does not accept this, you must use the new operator to create a dynamic array of pointers to TH1F.

Rene Brun

On Sat, 12
Feb
2005,
zaldy wrote:

>
> Dear Rene,
>
> Still not successful even for the simple line as below.
> Thanks....
>
> void test_scrip()
> {
> const int nb = 34;
> float a=-170.;
> float b=170.;
>
> TH1F* histo_xvsz_front[nb];
> histo_xvsz_front[1] = new TH1F(Form("histo_xvsz_front_001"), Form("Histogram xvsz_front_1"), nb,a,b);
> }
>
> Error Message:
>
> Processing test_scrip.C...
> Limitation: Variable argument is not supported for this platform
> FILE:test_scrip.C LINE:8
> *** Interpreter error recovered ***
>
> Version 4.02/00 29 January 2005
> gcc version 3.4.2 20041017 (Red Hat 3.4.2-6.fc3)
>
> //---------------------------------------
> > Replace
> > for(Int_t i = 1; i <= nb; i++)
> > by
> > for(Int_t i = 0; i < nb; i++)
> >
> > Rene Brun
> >
> > On Sat, 12 Feb 2005, zaldy wrote:
> >
> > >
> > > Hi,
> > >
> > > What is wrong with this piece of code
> > >
> > > //--------------------------------
> > > void test()
> > > {
> > > const int nb = 34;
> > > float a=-170.;
> > > float b=170.;
> > >
> > > TH1F* histo_xvsz_front[nb];
> > > for(Int_t i = 1; i <= nb; i++)
> > > {
> > > histo_xvsz_front[i] = new TH1F(Form("histo_xvsz_front_%03d",i),Form("Histogram xvsz_front #%d",i), nb,a,b);
> > > }
> > >
> > > }
> > >
> > > Thanks
> > >
> > > using RootVersion 4.02/00 29 January 2005
> > > on gcc version 3.4.2 20041017 (Red Hat 3.4.2-6.fc3)
> > >
> > > //----------------------------
> > >
> > > > Hi Zaldy,
> > > >
> > > > zaldy <zaldy_at_neutrino.kek.jp> writes:
> > > >
> > > > > I have two questions.
> > > > > I would like to create many histogram simultaneously with names of the
> > > > > form: histo_1, histo_2, .... , histo_(i) where i=1,2,3,4,....,n.
> > > > >
> > > > > I figure out doing it like this:
> > > > >
> > > > > for(Int_t i=1; i<n; i++)
> > > > > {
> > > > > TH1F * histo_(i) = .....
> > > > > }
> > > >
> > > > First, you need square brackets for array dereferencing in C++.
> > > >
> > > > TH1F * histo_[i] = .....
> > > >
> > > > As for a sequence of similar histograms I often do things like:
> > > >
> > > >
> > > > const int n=100;
> > > > TH1F* histo[n];
> > > > for(Int_t i=1; i<n; i++)
> > > > {
> > > > TH1F * histo[i] = new TH1F(Form("name_%03d",i),Form("Histogram #%d",i),...);
> > > > }
> > > >
> > > > If you don't actually care about the name and will always refer to the
> > > > histogram via the pointer then you don't need a unique name but you
> > > > need to call SetDirectory(0):
> > > >
> > > > const int n=100;
> > > > TH1F* histo[n];
> > > > for(Int_t i=1; i<n; i++)
> > > > {
> > > > TH1F * histo[i] = new TH1F("blah","Blah Blah",...);
> > > > histo[i]->SetDirectory(0);
> > > > }
> > > >
> > > >
> > > > Luck,
> > > > -Brett.
> > > >
> > >
> > >
> >
>
>
Received on Sat Feb 12 2005 - 10:11:47 MET