Adding vector to TTree as an array

ROOT
1

Hello,

I would like to add multidimensional vector of simple type to a TTree as an array of known size. It theory it should work, since casting of vector to arrays works. However, I get bad values stored in TTree. Here is an example code:

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

using namespace std;

int main()
{
	TFile *f = new TFile("test.root", "RECREATE");
	TTree *t = new TTree("t", "t");

	int arr[2][2];
	vector<vector<int> > v;

	t->Branch("one", arr, "one[2][2]/I");


	arr[0][0]=1;arr[0][1]=2;arr[1][0]=3;arr[1][1]=4;


	v.resize(2,vector<int>(2));

//	v = arr;

	v[0][0]=1;v[0][1]=2;v[1][0]=3;v[1][1]=4;

	cout << v[0][0] << " " << v[0][1] << " " << v[1][0] << " " << v[1][1] << endl;

	t->Branch("two", &v[0], "two[2][2]/I");

	t->Fill();
	t->Write();
	f->Close();

	return 9;
}
2

OK, I answer myself: the vector is continuous in memory only in 1D case, not in multidimensional case, so such a cast is not possible. A shame, I hoped that I can easily store multidimensional vectors as arrays in the TTree, without copying them to standard arrays.