/// \file

/// \ingroup tutorial_tree

/// \notebook -nodraw

/// Read data from an ascii file and create a root file with an histogram and an ntuple.

/// See a variant of this macro in basic2.C.

///

/// \macro_code

///

/// \author Rene Brun

#include "Riostream.h"

void basic() {

// read file $ROOTSYS/tutorials/tree/basic.dat

// this file has 3 columns of float data

TString dir = gROOT->GetTutorialDir();

dir.Append("/tree/");

dir.ReplaceAll("/./","/");

ifstream in;

in.open(Form("%sbasic.dat",dir.Data()));

Float_t x,y,z;

Int_t nlines = 0;

auto f = TFile::Open("basic.root","RECREATE");

TH1F h1("h1","x distribution",100,-4,4);

TNtuple ntuple("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=%8f\n",x,y,z);

h1.Fill(x);

ntuple.Fill(x,y,z);

nlines++;

}

printf(" found %d points\n",nlines);

in.close();

f->Write();

}