{
//   from:
//   http://www.slac.stanford.edu/BFROOT/www/doc/workbook/root2/basic.C
//   example of macro to read data from an ascii file and
//   create a root file with an histogram and an ntuple.
gROOT->Reset();
#include "iostream.h"

ifstream in;
// we assume a file basic.dat in the current directory
// this file has 3 columns of float data
in.open("basic.dat");

Float_t x,y,z;
Int_t nlines = 0;
TFile *f = new TFile("basic.root","RECREATE");
TH1F *h1 = new TH1F("h1","x distribution",100,-4,4);
TNtuple *ntuple = new TNtuple("ntuple","data from ascii file","x:y:z");

while (1) {
  in >> x >> y >> z;
  if (!in.good()) break;
  if (nlines < 5) printf("x=%8f, y=%8f, z=%8fn",x,y,z);
  h1->Fill(x);
  ntuple->Fill(x,y,z);
  nlines++;
}
printf(" found %d pointsn",nlines);

in.close();

f->Write();
}