How to detect new or modified files

Question

I found there are two ways to approach it, ReadDirectoryChangesW and FindFirstChangeNotification.

I want to know what’s the difference between them, performance or otherwise?

Answer 1

This is tagged for Winapi, but I give it a shot with .net anyway.

You can use the FileSystemWatcher class from System.IO for this.

static void Main(string[] args)
{
    FileSystemWatcher fsw = new FileSystemWatcher("C:\\");
    fsw.Changed += new FileSystemEventHandler(fsw_Changed);
    fsw.Created += new FileSystemEventHandler(fsw_Created);
    fsw.Deleted += new FileSystemEventHandler(fsw_Deleted);
    fsw.EnableRaisingEvents = true;
    fsw.IncludeSubdirectories = true;
    fsw.Renamed += new RenamedEventHandler(fsw_Renamed);

    Console.Read();
}

static void fsw_Renamed(object sender, RenamedEventArgs e)
{
    Console.WriteLine("{0} was changed to {1}", e.OldName, e.Name);
}

static void fsw_Deleted(object sender, FileSystemEventArgs e)
{
    Console.WriteLine("{0} was deleted", e.Name);
}

static void fsw_Created(object sender, FileSystemEventArgs e)
{
    Console.WriteLine("{0} was created", e.Name);
}

static void fsw_Changed(object sender, FileSystemEventArgs e)
{
    Console.WriteLine("{0} was changed", e.Name);
}