Create a file only if doesn't exists

Question

I want to create a file ONLY if it doesn't already exists.
A code like:

if (!File.Exists(fileName))
{
    fileStream fs = File.Create(fileName);
}

Leave it open for a race-condition in case the file will be created between the "if" to the "create".

How can I avoid it?

EDIT:
locks can't be used here because it's a different processes (multiple instances of the same application).

Answer 1

You can also use

FileStream fs = new FileStream(fileName, FileMode.OpenOrCreate);

However, you should look into thread locking as if more than one thread tries to access the file you'll probably get an exception.

Answer 2

Kristian Fenn answer was almost what I needed, just with a different FileMode. This is what I was looking for:

FileStream fs = new FileStream(fileName, FileMode.CreateNew);

Answer 3

Is this not a better solution. Also notice the using(var stream...) Use it to close the stream to avoid IO Exceptions.

if (!File.Exists(filePath))
{
    using (var stream = File.Create(filePath)) { }
}