TTree with user defined class

From: Bob <bob.velghe_at_gmail.com>
Date: Mon, 27 Sep 2010 11:30:03 +0200

Hello,

I'm a Root beginner, I'm trying to save a class to a TTree. Until now I managed to store and read "simple" type like int and STL objects, but not homemade objects.

I'm made a short example :

Code snippet :

#include <TFile.h>
#include <TTree.h>
#include <vector>
#include <iostream>

class Sample {

	public:
		int i;
		std::vector<int> hits;

};

int main() {

	Sample *s = new Sample();
	TFile *f1 = new TFile("debug.root","RECREATE");
	if (f1->IsZombie()) {
		std::cerr << "! Unable to create debug.root" << std::endl;
		return -1;
	}
	TTree *tree = new TTree("T","Debug");
	//Case C
	//  MyClass object;
        //  TBranch *branch = tree->Branch(branchname, &object,
bufsize, splitlevel)
	//
	tree->Branch("debug",s);
	for(int j=0;j<10;j++) {
                s->hits.empty();
		for(int i=0;i<100;i++) {
			s->hits.push_back(42+i);
		}
		tree->Fill();
	}
	f1->Write();
	delete s;
	delete tree;
	delete f1;
	return 0;

}

I compile with

g++ -Wall -pedantic -pthread -m32
-I/home/bob/root/root-5.26.00d/include -c ttree_write.cxx -o ttree_write.o

and I link with

g++ -L/home/bob/root/root-5.26.00d/lib -lNew -lCore -lCint -lRIO

-lNet -lHist -lGraf -lGraf3d -lGpad -lTree -lRint -lPostscript
-lMatrix -lPhysics -lMathCore -lThread -pthread -lm -ldl -rdynamic
-L/home/bob/root/root-5.26.00d/lib -lNew -lCore -lCint -lRIO -lNet
-lHist -lGraf -lGraf3d -lGpad -lTree -lRint -lPostscript -lMatrix
-lPhysics -lMathCore -lThread -lGui -pthread -lm -ldl -rdynamic

ttree_write.o -o ttree_write

When I run the program I got
Error in <TTree::Branch>: The pointer specified for debug is not of a class known to ROOT

I'm sure that I miss an important step but I'm out of ideas ! Any tips ? Received on Mon Sep 27 2010 - 11:30:10 CEST