Hi,
By referring to tutorials:tree:basic.C
https://root.cern/doc/master/basic_8C.html
I would like to read data from an ascii file and create a root file with tree.
But the result is the entries is 0.
I don’t know what wrong with my code.
Here is my code:
#include "Riostream.h"
void basic() {
TString dir = gROOT->GetTutorialDir();
dir.Append("/tree/");
dir.ReplaceAll("/./","/");
ifstream in;
in.open(Form("%su_1e5.txt",dir.Data()));
Float_t x;
Int_t nlines = 0;
auto f = TFile::Open("basic.root","RECREATE");
TH1F h1("h1","x distribution",100,0,4);
TNtuple ntuple("ntuple","data from ascii file","x");
while (1) {
in >> x ;
if (!in.good()) break;
if (nlines < 5) printf("x=%8f",x);
h1.Fill(x);
ntuple.Fill(x);
nlines++;
}
printf(" found %d points\n",nlines);
in.close();
f->Write();
}
ROOT Version: 6.20/02
Platform: Not Provided
Compiler: Not Provided
u_1e5.txt (1.7 MB)