Using C++ to write to a file

swatward · 04-24-2006, 08:30 PM

This is in windows, but I don't believe it's much different than in linux..

Code:

// basic file operations
#include <iostream>
#include <fstream>
using namespace std;

int main () {
  ofstream myfile;
  myfile.open ("file.txt");
  while (1 == 1)
  {
  myfile << "Writing this to a file.\n";
  myfile.close();
  }
  return 0;
}

Instead of this overwriting "file.txt" every time it runs, i want it to add that line to the next. So if i ran it twice it would be

Writing this to a file.
Writing this to a file.

I'm new to the language and don't know of a way to do it. Thanks.

ataraxia · 04-24-2006, 08:33 PM

Try

Code:

  myfile.open ("file.txt", O_APPEND);

That's how "open" works in plain C - hopefully it does the same in C++.

exvor · 04-25-2006, 12:44 AM

Yea in C thats the lowlevel way i belive.

im sure C++ has something more simpler like fopen for regular C

MichaelZ · 04-25-2006, 04:31 AM

Quote:

Originally Posted by exvor

im sure C++ has something more simpler like fopen for regular C

Hello,

Have a look at here:

http://www.cplusplus.com/ref/iostrea.../ofstream.html

Best wishes,
Michael

swatward · 04-25-2006, 07:01 AM

thanks a ton

swatward · 04-25-2006, 07:45 PM

If anyone wanted to know, this is how i did it.

Code:

#include <iostream>
#include <fstream>
using namespace std;

int main () {
    int x = 1;
  
  while (x != 10000)
  {
        ofstream myfile ("file.txt", ios::app);
  myfile << "Writing this to a file.  " << x  << "\n";
  myfile.close();
  x++;
  }
  return 0;
}