TGraph problem

ROOT
1

hallo;
I have two files.dat / f1.dat and f2.dat
in each file, I have two columns

When I write a program to draw the line y=f(x) in f1 or f2 I have no problem.

My problem when I draw the two in a one canvas for superposed

   Double_t *x1 = new Double_t[249];
   Double_t *y1 = new Double_t[249];
   Double_t vX1, vY1;
   Int_t vNData = 0;
   ifstream vInput;
   vInput.open(Form("%sf1.dat",dir.Data()));
   while (1) {
      vInput >> vX1 >> vY1;
      if (!vInput.good()) break;
      x1[vNData] = vX1;
      y1[vNData] = vY1;
      vNData++;
   }//while
   vInput.close();
   gr1 = new TGraph(vNData,x1,y1);
gr1->Draw("AC");
Double_t *x2 = new Double_t[249];
   Double_t *y2 = new Double_t[249];
   Double_t vX2, vY2;
   Int_t vNData = 0;
   ifstream vInput;
  vInput.open(Form("%sf2.dat",dir.Data()));
   while (1) {
     vInput >> vX2 >> vY2;
      if (!vInput.good()) break;
      x2[vNData] = vX2;
      y2[vNData] = vY2;
      vNData++;
   }//while
  vInput.close();
   gr2 = new TGraph(vNData,x2,y2);
   gr2->SetLineWidth(4);
   gr2->SetLineColor(5);
   gr2->Draw("CP);
2

It is likely that you are superimposing 2 graphs with different scales.
Instead of your long script, I suggest the following

TGraph *gr1 = new TGraph(Form("%sf1.dat",dir.Data())); TGraph *gr2 = new TGraph(Form("%sf2.dat",dir.Data())); gr2->SetLineWidth(4); gr2->SetLineColor(5); TMultiGrapg *mg = new TMultiGraph(); mg->Add(gr1,"C"); mg->Add(gr2,"CP"); mg->Draw();

Rene