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CSharp · Console

/Program.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Xml.Linq;
using System.Globalization;

public class Program
{
	public static void Main()
	{
		var result = "2020-01-16T14:29:17.9743131Z0";
		Console.WriteLine("dateTime : {0}", result);
		
		Console.WriteLine("result : {0}", formats.First(x => TryParseISO8601String(x, out DateTime d)));
	}
	
		static readonly string[] formats = { 
    // Basic formats
    "yyyyMMddTHHmmsszzz",
    "yyyyMMddTHHmmsszz",
    "yyyyMMddTHHmmssZ",
    // Extended formats
    "yyyy-MM-ddTHH:mm:sszzz",
    "yyyy-MM-ddTHH:mm:sszz",
    "yyyy-MM-ddTHH:mm:ssZ",
    // All of the above with reduced accuracy
    "yyyyMMddTHHmmzzz",
    "yyyyMMddTHHmmzz",
    "yyyyMMddTHHmmZ",
    "yyyy-MM-ddTHH:mmzzz",
    "yyyy-MM-ddTHH:mmzz",
    "yyyy-MM-ddTHH:mmZ",
    // Accuracy reduced to hours
    "yyyyMMddTHHzzz",
    "yyyyMMddTHHzz",
    "yyyyMMddTHHZ",
    "yyyy-MM-ddTHHzzz",
    "yyyy-MM-ddTHHzz",
    "yyyy-MM-ddTHHZ"
    };

	public static bool TryParseISO8601String(string str, out DateTime d)
	{
		return DateTime.TryParseExact(str, formats, CultureInfo.InvariantCulture, DateTimeStyles.None, out d);
	}
}