[c#] Creating an empty file in C#

What's the simplest/canonical way to create an empty file in C#/.NET?

The simplest way I could find so far is:

System.IO.File.WriteAllLines(filename, new string[0]);

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);
}

Path.GetTempFileName() will create a uniquly named empty file and return the path to it.

If you want to control the path but get a random file name you can use GetRandomFileName to just return a file name string and use it with Create

For example:

string fileName=Path.GetRandomFileName();
File.Create("custom\\path\\" + fileName);

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"));

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

or

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

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();

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.