#include "TCanvas.h"
#include "TTree.h"
#include "TString.h"
#include <string>

void tmp()
{
  TTree* tree1 = new TTree("tree1", "tree1");
  std::string* str1 = new std::string;
  tree1->Branch("str", "std::string", &str1);

  TTree* tree2 = new TTree("tree2", "tree2");
  char str2[10];
  tree2->Branch("str", &str2, "str[10]/C");

  const Int_t kN = 10;
  for(Int_t i = 0; i < kN; i++){
    str1->assign(Form("%02d", i));
     sprintf(str2, Form("%02d", i));
    for(Int_t j = 0; j < i + 1; j++){
      tree1->Fill();
      tree2->Fill();
    } // j
  } // i

  TCanvas* can = new TCanvas;
  can->Divide(2, 1);
  can->cd(1);
  //  tree1->Draw("str>>htemp1(10)"); <= this works, but ugly
  tree1->Draw("str");
  can->cd(2);
  tree2->Draw("str");
}