struct Hit
{
	double x;
	double y;
	double t;
	int meth;
};

void testWrite()
{
	//create an array of hits//
	const int MaxHits = 32;
	Hit hit[MaxHits];
	int nbrOfCurrentHits = 0;

	//create a file to write the tree to//
	TFile f ("TestTree.root","RECREATE");
	
	//create the tree//
	TTree * tt = new TTree("TestTree","A test with variable lenght array of structs");

	//create the branches//
	tt->Branch("NbrHits",&nbrOfCurrentHits,"nbrHits/I");
	tt->Branch("Hit",&hit,"x/D:y:t:Meth/I");	//?is this correct?

	//try to fill the tree with 10000 events//
	for (int i=0; i< 10000;++i)
	{
		//first get the number of Hits from a random generator//
		nbrOfCurrentHits = (int) (31 * gRandom->Rndm());

		//clear all entries first//
		for (int j=0; j<MaxHits;++j)
		{
			hit[j].x = 1e5;
			hit[j].y = 1e5;
			hit[j].t = 1e5;
			hit[j].meth = 1000;
		}

		//fill the first nbrOfCurrentHits Entries with random values//
		for (int j=0; j<nbrOfCurrentHits;++j)
		{
			double x,y;
			gRandom->Rannor(x,y);
			hit[j].x = x;
			hit[j].y = y;
			hit[j].t = 10000*gRandom->Rndm();
			hit[j].meth = (int) (24*gRandom->Rndm());
		}

		//now fill the tree with these hits//
		tt->Fill();
	}
	tt->Write();
}

void testRead()
{
	//open file and load tree//
	TFile *f = new TFile("TestTree.root");
	TTree * tt = (TTree*) f->Get("TestTree");

	//create an array of hits//
	const int MaxHits = 32;
	Hit hit[MaxHits];
	int nbrOfHits = 0;

	//create Histos for testing//
	TH1D * ty = new TH1D("Y","test y", 80,-4,4);
	TH2D * det = new TH2D("det","Det",80,-4,4,80,-4,4);
	det->SetOption("colz");
	TH2D * wig = new TH2D("wig","Wiggles",100,0,10100,20,0,4);
	wig->SetOption("colz");

	//set the branches//
	tt->SetBranchAddress("NbrHits",&nbrOfHits);
	tt->SetBranchAddress("Hit",&hit);		//?Is this correct?

	//loop over all entries and get the info from it//
	int nbrEntriesInTree = tt->GetEntries();
	for(int i=0;i<nbrEntriesInTree;++i)
	{
		tt->GetEntry(i);

		for (int j=0;j<nbrOfHits;++j)
		{
			ty->Fill(hit[j].y);
			if (hit[j].meth < 15)
			{
				det->Fill(hit[j].x,hit[j].y);
				wig->Fill(hit[j].t,TMath::Sqrt(hit[j].x*hit[j].x + hit[j].y*hit[j].y));
			}
		}
	}
}