Creating files in C++

Question

I want to create a file using C++, but I have no idea how to do it. For example I want to create a text file named Hello.txt.

Can anyone help me?

Answer 1

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

string filename = "/tmp/filename.txt";

int main() {
  std::ofstream o(filename.c_str());

  o << "Hello, World\n" << std::endl;

  return 0;
}

This is what I had to do in order to use a variable for the filename instead of a regular string.

Answer 2

#include <iostream>
#include <fstream>

int main() {
  std::ofstream o("Hello.txt");

  o << "Hello, World\n" << std::endl;

  return 0;
}

Answer 3

Here is my solution:

#include <fstream>

int main()
{
    std::ofstream ("Hello.txt");
    return 0;
}

File (Hello.txt) is created even without ofstream name, and this is the difference from Mr. Boiethios answer.

Answer 4

One way to do this is to create an instance of the ofstream class, and use it to write to your file. Here's a link to a website that has some example code, and some more information about the standard tools available with most implementations of C++:

ofstream reference

For completeness, here's some example code:

// using ofstream constructors.
#include <iostream>
#include <fstream>  

std::ofstream outfile ("test.txt");

outfile << "my text here!" << std::endl;

outfile.close();

You want to use std::endl to end your lines. An alternative is using '\n' character. These two things are different, std::endl flushes the buffer and writes your output immediately while '\n' allows the outfile to put all of your output into a buffer and maybe write it later.

Answer 5

Do this with a file stream. When a std::ofstream is closed, the file is created. I personally like the following code, because the OP only asks to create a file, not to write in it:

#include <fstream>

int main()
{
    std::ofstream file { "Hello.txt" };
    // Hello.txt has been created here
}

The temporary variable file is destroyed right after its creation, so the stream is closed and thus the file is created.