c# - How to test if a file is currently being written to

Question

I have an application that must check a folder and read any files that are copied into it. How do I test if a file in that folder is currently being written to? I only want to read files that have had all their data written to them and are closed.

Answer 1

It ain't clean, but it works:

try
{
    using (Stream stream = new FileStream("File.txt"))
    {
    }
} 
catch 
{
    // Check if file is in use (or whatever else went wrong), and do any user communication that you need to
}

I don't particularly like using exceptions as conditions, but as far as I know this is about the easiest and best (and only reliable) way to do this.