Question

Alright so this is a bizarre cross platform thing that I’m experiencing with text files. Say I have a program that very simply reads a text file

// reading a text file
#include <iostream>
#include <fstream>
#include <string>
using namespace std;

int main () {
  string line;
  ifstream myfile ("example.txt");
  if (myfile.is_open())
  {
    while ( myfile.good() )
    {
      getline (myfile,line);
      if (line == "BEGIN")
        cout << line << endl;
    }
    myfile.close();
  }

  else cout << "Unable to open file"; 

  return 0;
}

So this reads a text file and spits out the line it is reading if it encounters BEGIN. Here is the text file I am reading:

HEADER
BEGIN
X 2
Y 2
Z 1
END

Windows successfully spits out BEGIN one time, since it is encountered one time. Linux spits nothing out. Is there something fundamental that I’m missing here?

Answer 1

If the file has windows line-endings (that is, every line ends with carriage-return + line-feed, rather than just line-feed as Linux expects), then line will be "BEGIN\r" rather than "BEGIN" on Linux.

To fix this, you can run dos2unix on the file to convert it to Linux line-endings:

dos2unix example.txt

Alternatively, if you want the file to be identical on both systems, you can open it in binary mode rather than text mode:

  ifstream myfile ("example.txt", ios_base::binary);

and then both systems will read the file the same way. (If it uses Windows line-endings, then your program will have to handle the carriage returns, but at least you’ll see consistent behavior.)