using System;

using System.Collections.Generic;

using System.Text;

using System.Linq;

using System.Xml.Serialization;

using System.Xml;

using System.Xml.Linq;

using System.IO;

using System.Data;

using System.Runtime.Serialization;

using System.Runtime.Serialization.Formatters.Binary;

using System.IO.Compression;

using System.Globalization;

​

using NUnit.Framework; //NUnit.Framework.AssertionException

​

    //https://stackoverflow.com/questions/52584308/convert-unicode-surrogate-pair-to-literal-string

    class TestClass

    {

        public static void UnicodeTest()

        {

            var highUnicodeChar = "𝐀"; //Not the standard A

            var hamiltonian = "H\u0302=T\u0302+V\u0302"; // "Ĥ=T̂+V̂" (hamiltonian)

            Assert.IsTrue(UnicodeTest(highUnicodeChar) == highUnicodeChar);

            Assert.IsTrue(UnicodeTest(hamiltonian) == "Ĥ");

            Assert.IsTrue(UnicodeTest("") == "");

            Console.WriteLine("Done");

        }

        static string UnicodeTest(string highUnicodeChar)

        {

            var result1 = highUnicodeChar; //this works

            var result2 = highUnicodeChar.TextElements().FirstOrDefault() ?? "";

​

            Console.WriteLine(result1);

            Console.WriteLine(result2);

            return result2;

        }

    }

​

​

    public static class TextExtensions

    {

        public static IEnumerable<string> TextElements(this string s)

        {

            // StringInfo.GetTextElementEnumerator is a .Net 1.1 class that doesn't implement IEnumerable<string>, so convert

            if (s == null)

                yield break;

            var enumerator = StringInfo.GetTextElementEnumerator(s);

            while (enumerator.MoveNext())

                yield return enumerator.GetTextElement();

        }

    }

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Roslyn 2.0 Compiler; Environment version: " + Environment.Version);

            Console.WriteLine();

​

            try

            {

                TestClass.UnicodeTest();

            }

            catch (Exception ex)

            {

                Console.WriteLine("Uncaught exception: ");

                Console.WriteLine(ex);

                throw;

            }

        }

    }

​