// C# Extension Method

// Doc: https://csharp-extension.com/en/method/1002276/datetimeoffset-converttimebysystemtimezoneid

​

// @nuget: Z.ExtensionMethods

​

using System;

public class Program

{

    public static void Main()

    {

        // Define times to be converted.

        DateTime time1 = new DateTime(2018, 1, 1, 12, 1, 0);

        DateTime time2 = new DateTime(2018, 11, 6, 23, 30, 0);

        DateTimeOffset[] times = { new DateTimeOffset(time1, TimeZoneInfo.Local.GetUtcOffset(time1)),

                                   new DateTimeOffset(time1, TimeSpan.Zero),

                                   new DateTimeOffset(time2, TimeZoneInfo.Local.GetUtcOffset(time2)),

                                   new DateTimeOffset(time2.AddHours(3), TimeZoneInfo.Local.GetUtcOffset(time2.AddHours(3))) };

​

        // Display the current time zone name.

        Console.WriteLine("Local time zone: {0}\n", TimeZoneInfo.Local.DisplayName);

​

        // Convert each time in the array.

        foreach (DateTimeOffset timeToConvert in times)

        {

            // C# Extension Method: DateTimeOffset - ConvertTimeBySystemTimeZoneId

            DateTimeOffset targetTime = timeToConvert.ConvertTimeBySystemTimeZoneId("Tokyo Standard Time");

            Console.WriteLine("Converted {0} to {1}.", timeToConvert, targetTime);

        }

    }

}