use the ToFileTime() method to convert a DateTime to an operating system file timestamp

   
   

using System;

class MainClass {

    public static void Main() {
        DateTime myDateTime10 = new DateTime(2004, 1, 15, 23, 2, 5);
        long myFileTime = myDateTime10.ToFileTime();
        Console.WriteLine("myDateTime10.ToFileTime() = " + myDateTime10.ToFileTime());

    }
}