.NET Unix Time to Date Time After .Net 4.6

TestForUnxTime.cs

using System;

namespace TestForUnxTime
{
	//reference : https://msdn.microsoft.com/ko-kr/library/system.datetimeoffset.fromunixtimeseconds(v=vs.110).aspx
	class MainClass
    {
        public static void Main(string[] args)
        {   
            //before Net 4.6 
            //miliSeconds 단위, 만약 unixtime 이 second단위로 온다면, 1000을 곱한다.
            var date = UnixTimeStampToDateTimeForOld(1495985199000);
            String fortmatedDateStr = String.Format("{0:yyyy/MM/dd hh:mm:ss}", date);
            Console.WriteLine(fortmatedDateStr);

            //After Net 4.6
            var dateTime = UnixTimeStampToDateTimeForNew(1495985199);
	        String fortmatedDateStr2 = String.Format("{0:yyyy/MM/dd hh:mm:ss}", dateTime);
            Console.WriteLine("Test Time to UnixTime : {0}", fortmatedDateStr2);
			Console.WriteLine(fortmatedDateStr2);

            var testUnixTime = DateTimeToUnixTimeStamp();
            Console.WriteLine("Test Unix Time For 2017.05.30 : {0}", testUnixTime);
        }

        //after 4.6 
	
	private static DateTime UnixTimeStampToDateTimeForNew(long unixTimeStamp)
	{
	     var dateTimeOffset = DateTimeOffset.FromUnixTimeSeconds(unixTimeStamp);
	     var dateTime = dateTimeOffset.DateTime;
             return dateTime;
	}

	//before 4.6
	//refernce: https://stackoverflow.com/questions/28305153/how-convert-unix-timestamp-to-datetime
	private static DateTime UnixTimeStampToDateTimeForOld(long unixTimeStamp)
	{
	     var epoch = new DateTime(1970, 1, 1, 0, 0, 0, DateTimeKind.Local);
	     return epoch.AddMilliseconds(unixTimeStamp);
	}


	//Seconds 단위
	private static long DateTimeToUnixTimeStamp() 
        {
            //Test
	    var dateTime = new DateTime(2017, 05, 30, 11, 14, 0, DateTimeKind.Local);
	    var dateTimeOffset = new DateTimeOffset(dateTime);
	    var unixDateTime = dateTimeOffset.ToUnixTimeSeconds();
            return unixDateTime;
        }

    }
}