using System;

public class Program

{

    public static void Main()

    {

        DateTime dt = Convert.ToDateTime("2019-10-16T17:00:00");

        Print(dt, "*DateTime Without Offset*", false);

        dt = Convert.ToDateTime("2019-10-16T17:00:00-5:00");

        Print(dt, "\n\n*DateTime with Offset*", true);

    }

    private static void Print(DateTime dt, string print, bool isWithOffset)

    {

        Console.WriteLine(print + "\n");

        Console.WriteLine("Input: " + dt);

        Console.WriteLine("UTC without offset: " + dt.ToUniversalTime());

        Console.WriteLine("Local without offset: " + dt.ToLocalTime());

​

        if(isWithOffset) 

            WithOffset(dt);

        else

            WithoutOffset(dt);

    }

    private static void WithOffset(DateTime dt)

    {

        // Convert from CST to UTC when source is passign Offset information

        TimeZoneInfo cstZone = TimeZoneInfo.FindSystemTimeZoneById("Central Standard Time");

        Console.WriteLine("Converted from CST to UTC: " + dt.ToUniversalTime());

        Console.WriteLine("DateTime with Daylight Check: {0} {1}.", dt, cstZone.IsDaylightSavingTime(dt) ? cstZone.DaylightName : cstZone.StandardName);

    }

    private static void WithoutOffset(DateTime dt)

    {

        // Convert from CST to UTC

        // If server sending DateTime information moves from CST to some other time zone then following conversion logic will be incorrect

        TimeZoneInfo cstZone = TimeZoneInfo.FindSystemTimeZoneById("Central Standard Time");

        DateTime utcTime = TimeZoneInfo.ConvertTimeToUtc(dt, cstZone);

        Console.WriteLine("Converted from CST to UTC: " + utcTime);

        Console.WriteLine("DateTime with Daylight Check: {0} {1}.", utcTime, cstZone.IsDaylightSavingTime(utcTime) ? cstZone.DaylightName : cstZone.StandardName);

    }

}