Storing an Array in a Branch

ROOT
1

Hello,

probably this is a quite stupid question, but I did not find
the answer by myself (well, I am C++ newbie).

The following code illustrates my problem:

#include <TObject.h>
#include <TFile.h>
#include <TTree.h>
#include <TBranch.h>
#include <stdlib.h>
#include <time.h>
#include <iostream>

using namespace std;

int main(){


	Int_t ntimebins = 10;
        Int_t nochannels = 10;
      

	Int_t ADCcounts [nochannels][ntimebins];



	TFile *f = new TFile("test.root","RECREATE");
	TTree*	fTree = new TTree("Test","Test");


	fTree->Branch("ADCcounts", &ADCcounts, "ADCcounts[10][10]/I");

//	But I would like to have something like this:
//	fTree->Branch("ADCcounts", &ADCcounts, "ADCcounts[nochannels][ntimebins]/I");
//	which produces the following error message:
//      tlux@dhcp018:~/roottest> testroot
//      Error in <TBranch::TBranch>: Illegal leaf:ADCcounts/ADCcounts[nochannels][ntimebins]/I



//      The rest is just there for having an output

 	for (Int_t iEvent=0;iEvent<10;iEvent++) {

		for (Int_t itest=0;itest<nochannels;itest++) {
			for (Int_t idummy=0; idummy<ntimebins; idummy++){ 

				ADCcounts[itest][idummy]=idummy;

			     }
		}

		fTree->Fill();		
	}
	f->Write();
	f->Close();

	return 0;}

I create an array which size depends on nchannels and ntimebins, but in the definition of the TBranch I have to
use the hardcoded numbers.
Otherwise I get the following error message:

How can I solve this problem?
I am using root 4.03/02 and kernel 2.4.21-291.

Thanks for helping me

Thorsten

2

Use:

fTree->Branch("ADCcounts", &ADCcounts, Form("ADCcounts[%d][%d]/I",nochannels,ntimebins));

Cheers,
Philippe.

3

Yes, this works.

Thanks a lot!

Thorsten

4

Could you please tell me how to solve the problem? The solution is not displayed on the webpage

5

Note that the solution offered above is only valid when all array dimensions have fixed lengths.