Problems while reading a data file and filling a histogram with the read date

[CaueEvangelista]

Hello rooters, I hope you’re doing well!!
I’m trying to read a data file and use the read data to fill a TH1F histogram, but I’m having some strange erros. I followed the steps of this topic To fill a histogram by reading text file but i just cant get it done right. I’ve write my code in two versions, one using a for loop and the another one using a while loop. Here is the two version:
While version:

#include <iostream>
#include <fstream>

/*Reading a data file and creating a histogram with the data: while version*/

void pte_distribution()
{

	TH1F *hist = new TH1F("hist","Pt Distribution(e)",1000,0,100); //Create the histogram called hist
	ifstream pt_e("pt_e.txt");//Load the data file

	int pt; //declare the variable to store the value of the momentum that will be read from the data file later on


	
	while(pt_e >> pt){    //while there is lines to be read...
		hist -> Fill(pt); //...the Fill command will fill the histogram hist with the values of pt	
	}
	


  	TCanvas * c1 = new TCanvas("c", "c", 800, 600); // Create a canvas 800x600
	

	hist->Draw("E"); //Draw the histogram hist


	c1->Update(); // Update the canvas created 

	c1->SaveAs("Pt Distribution(e).pdf"); //Saves the histogram
}

For version:

#include <iostream>
#include <fstream>

/*Reading a data file and creating a histogram with the data: for version*/

void pte_distribution()
{

	TH1F *hist = new TH1F("hist","Pt Distribution(e)",1000,0,100); //Create the histogram called hist
	ifstream pt_e("pt_e.txt");//Load tge data file

	int pt; //declare the variable to store the value of the momentum that will be read from the data file later on

	for (int i = 0; i < 1000000; ++i)//My data file have 1000000 lines...
	{
		pt_e >> pt;
		hist->SetBinContent(i,pt);
	}
	


  	TCanvas * c1 = new TCanvas("c", "c", 800, 600); // Create a canvas 800x600
	

	hist->Draw("E"); //Draw the histogram hist


	c1->Update(); // Update the canvas created 

	c1->SaveAs("Pt Distribution(e).pdf"); //Saves the histogram
}

While version result:

For version result:

Ps1: My data file is a .txt file
Ps2: as you can see, my for version produced an empty histogram. The same problem appeared in the topic that I’ve posted here, but i don’t know the reason why.

Thank you very much for all the help,
Cauê

[behrenhoff]

The code looks ok - but the 2 versions are doing different things - so they are expecting different inputs.

How does your input file look like?

[Wile_E_Coyote]

Try:

{
  TTree *t = new TTree("t", "t");
  t->ReadFile("pt_e.txt", "pt");
  t->Draw("pt");
}

[CaueEvangelista]

It’s simply a .txt file with 100k lines, one number in each line