using System;

using System.Globalization;

public class Program

{

    public static void Main()

    {

        var testString = "2018-03-17T00:00:00+01:00";

        DateTimeOffset test;

        var success = DateTimeOffset.TryParseExact(testString, "o", CultureInfo.InvariantCulture, DateTimeStyles.None,

                        out test);

        Console.WriteLine(success);

        testString = "2018-03-17T00:00:00.0000000+01:00";

        success = DateTimeOffset.TryParseExact(testString, "o", CultureInfo.InvariantCulture, DateTimeStyles.None,

                        out test);

        Console.WriteLine(success);

    }

}