using System;

public class Program

{

​

    public static void Main()

    {

        // provided Unix string = "1628718908367130365";

        // the above, converted via https://www.unixtimestamp.com/index.php, returns the following:

        // Wed Aug 11 2021 21:55:08 GMT+0000 (to the seconds), plus:

        // milliseconds: 367

        // microseconds: 130

        // nanoseconds: 365

        Console.WriteLine($"provided unix timestamp:              1628718908367130365");

        var testDateTime = new DateTime(2021, 08, 11, 21, 55, 08, 367); // millisecond precision

        var testDto = new DateTimeOffset(testDateTime);

        var asUnixTime = testDto.ToUnixTimeMilliseconds();

        Console.WriteLine($"unix time with milli precision:       {asUnixTime}");

        Console.WriteLine($"unix time with nano (fake) precision: {asUnixTime * 1000 * 1000}");

        var asTicks = testDateTime.Ticks;

        Console.WriteLine($"ticks since microsoft epoch:          {asTicks}");

        var unixEpoch = new DateTime(1970, 1, 1, 0, 0, 0, 0);

        TimeSpan span = testDateTime - unixEpoch;

        Console.WriteLine($"ticks since unix epoch:               {span.Ticks}");

        Console.WriteLine($"times 100 for unix-like format:       {span.Ticks * 100}");

    }

}