using System;

public class Program

{

    public static void Main()

    {

        //var guidArray = guid.ToByteArray();

​

        var baseDate = new DateTime(1900, 1, 1);

        var now = DateTime.Now;

​

        // Get the days and milliseconds which will be used to build the byte string 

        var daysSinceBaseDate = new TimeSpan(now.Ticks - baseDate.Ticks);

        var timeOfDay = now.TimeOfDay;

​

        // Convert to a byte array 

        var daysArray = BitConverter.GetBytes(daysSinceBaseDate.Days);

        var millisecondArray = BitConverter.GetBytes((long)(timeOfDay.TotalMilliseconds));

        Console.WriteLine(daysSinceBaseDate.Days);

        Console.WriteLine(BitConverter.ToString(daysArray));

    }

}