Creating an empty file in C#

Question

Using just File.Create will leave the file open, which probably isn't what you want.

You could use:

using (File.Create(filename)) ;

That looks slightly odd, mind you. You could use braces instead:

using (File.Create(filename)) {}

Or just call Dispose directly:

File.Create(filename).Dispose();

Either way, if you're going to use this in more than one place you should probably consider wrapping it in a helper method, e.g.

public static void CreateEmptyFile(string filename)
{
    File.Create(filename).Dispose();
}

Note that calling Dispose directly instead of using a using statement doesn't really make much difference here as far as I can tell - the only way it could make a difference is if the thread were aborted between the call to File.Create and the call to Dispose. If that race condition exists, I suspect it would also exist in the using version, if the thread were aborted at the very end of the File.Create method, just before the value was returned...

File.WriteAllText("path", String.Empty);

or

File.CreateText("path").Close();

System.IO.File.Create(@"C:\Temp.txt");

As others have pointed out, you should dispose of this object or wrap it in an empty using statement.

using (System.IO.File.Create(@"C:\Temp.txt"));

To avoid accidentally overwriting an existing file use:

using (new FileStream(filename, FileMode.CreateNew)) {}

...and handle the IOException which will occur if the file already exists.

File.Create, which is suggested in other answers, will overwrite the contents of the file if it already exists. In simple cases you could mitigate this using File.Exists(). However something more robust is necessary in scenarios where multiple threads and/or processes are attempting to create files in the same folder simultaneously.

You can chain methods off the returned object, so you can immediately close the file you just opened in a single statement.

File.Open("filename", FileMode.Create).Close();

A somewhat common use case for creating an empty file is to trigger something else happening in a different process in the absence of more sophisticated in process communication. In this case, it can help to have the file creation be atomic from the outside world's point of view (particularly if the thing being triggered is going to delete the file to "consume" the trigger).

So it can help to create a junk name (Guid.NewGuid.ToString()) in the same directory as the file you want to create, and then do a File.Move from the temporary name to your desired name. Otherwise triggered code which checks for file existence and then deletes the trigger may run into race conditions where the file is deleted before it is fully closed out.

Having the temp file in the same directory (and file system) gives you the atomicity you may want. This gives something like.

public void CreateEmptyFile(string path)
{
    string tempFilePath = Path.Combine(Path.GetDirectoryName(path),
        Guid.NewGuid.ToString());
    using (File.Create(tempFilePath)) {}
    File.Move(tempFilePath, path);
}