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 NUnit.Framework; //NUnit.Framework.AssertionException

​

//https://stackoverflow.com/questions/72898584/why-is-xmlwriter-failing-to-replace-characters-not-supported-by-the-current-enco

​

    public static class XmlSerializationHelper

    {

        public static string GetOuterXml(this XmlNode node, bool indent = false, Encoding encoding = null, bool omitXmlDeclaration = false)

        {

            if (node == null)

                return null;

            using var stream = new MemoryStream();

            node.Save(stream, indent : indent, encoding : encoding, omitXmlDeclaration : omitXmlDeclaration, closeOutput : false);

            stream.Position = 0;

            using var reader = new StreamReader(stream);

            return reader.ReadToEnd();

        }

​

        public static void Save(this XmlNode node, Stream stream, bool indent = false, Encoding encoding = null, bool omitXmlDeclaration = false, bool closeOutput = true) =>

            node.Save(stream, new XmlWriterSettings

                      {

                          Indent = indent,

                          Encoding = encoding ?? Encoding.UTF8,

                          OmitXmlDeclaration = omitXmlDeclaration,

                          CloseOutput = closeOutput,

                      });

​

        public static void Save(this XmlNode node, Stream stream, XmlWriterSettings settings)

        {

            using var xmlWriter = XmlWriter.Create(stream, settings);

            using var outerWriter = (settings?.Encoding != null && settings?.Encoding?.CodePage != Encoding.UTF8.CodePage) ? new TolerantCommentEncodingXmlWriter(xmlWriter, settings.Encoding) : null;

            node.WriteTo(outerWriter ?? xmlWriter);

        }

    }

​

    public class TolerantCommentEncodingXmlWriter : XmlWriterDecorator

    {

        Encoding CommentEncoding { get; }

        public TolerantCommentEncodingXmlWriter(XmlWriter baseWriter, Encoding commentEncoding) : base(baseWriter) => this.CommentEncoding = commentEncoding;

​

        public override void WriteComment(string text) =>

            base.WriteComment(CommentEncoding?.GetString(CommentEncoding?.GetBytes(text)) ?? text);

    }

​

    public class XmlWriterDecorator : XmlWriter

    {

        // Taken from this answer https://stackoverflow.com/a/32150990/3744182

        // by https://stackoverflow.com/users/3744182/dbc

        // To https://stackoverflow.com/questions/32149676/custom-xmlwriter-to-skip-a-certain-element

        // NOTE: async methods not implemented

        readonly XmlWriter baseWriter;

​

        public XmlWriterDecorator(XmlWriter baseWriter) => this.baseWriter = baseWriter ?? throw new ArgumentNullException();

​

        protected virtual bool IsSuspended { get { return false; } }

​

        public override WriteState WriteState => baseWriter.WriteState;

        public override XmlWriterSettings Settings => baseWriter.Settings;

        public override XmlSpace XmlSpace => baseWriter.XmlSpace;

        public override string XmlLang => baseWriter.XmlLang;

​

        public override void Close() => baseWriter.Close();

​

        public override void Flush() => baseWriter.Flush();

​

        public override string LookupPrefix(string ns) => baseWriter.LookupPrefix(ns);

​

        public override void WriteBase64(byte[] buffer, int index, int count)

        {

            if (IsSuspended)

                return;

            baseWriter.WriteBase64(buffer, index, count);

        }

​

        public override void WriteCData(string text)

        {

            if (IsSuspended)

                return;

            baseWriter.WriteCData(text);

        }

​

        public override void WriteCharEntity(char ch)

        {

            if (IsSuspended)

                return;

            baseWriter.WriteCharEntity(ch);

        }

​

        public override void WriteChars(char[] buffer, int index, int count)

        {

            if (IsSuspended)

                return;

            baseWriter.WriteChars(buffer, index, count);

        }

​

        public override void WriteComment(string text)

        {

            if (IsSuspended)

                return;

            baseWriter.WriteComment(text);

        }

​

        public override void WriteDocType(string name, string pubid, string sysid, string subset)

        {

            if (IsSuspended)

                return;

            baseWriter.WriteDocType(name, pubid, sysid, subset);

        }

​

        public override void WriteEndAttribute()

        {

            if (IsSuspended)

                return;

            baseWriter.WriteEndAttribute();

        }

​

        public override void WriteEndDocument()

        {

            if (IsSuspended)

                return;

            baseWriter.WriteEndDocument();

        }

​

        public override void WriteEndElement()

        {

            if (IsSuspended)

                return;

            baseWriter.WriteEndElement();

        }

​

        public override void WriteEntityRef(string name)

        {

            if (IsSuspended)

                return;

            baseWriter.WriteEntityRef(name);

        }

​

        public override void WriteFullEndElement()

        {

            if (IsSuspended)

                return;

            baseWriter.WriteFullEndElement();

        }

​

        public override void WriteProcessingInstruction(string name, string text)

        {

            if (IsSuspended)

                return;

            baseWriter.WriteProcessingInstruction(name, text);

        }

​

        public override void WriteRaw(string data)

        {

            if (IsSuspended)

                return;

            baseWriter.WriteRaw(data);

        }

​

        public override void WriteRaw(char[] buffer, int index, int count)

        {

            if (IsSuspended)

                return;

            baseWriter.WriteRaw(buffer, index, count);

        }

​

        public override void WriteStartAttribute(string prefix, string localName, string ns)

        {

            if (IsSuspended)

                return;

            baseWriter.WriteStartAttribute(prefix, localName, ns);

        }

​

        public override void WriteStartDocument(bool standalone) => baseWriter.WriteStartDocument(standalone);

​

        public override void WriteStartDocument() => baseWriter.WriteStartDocument();

​

        public override void WriteStartElement(string prefix, string localName, string ns)

        {

            if (IsSuspended)

                return;

            baseWriter.WriteStartElement(prefix, localName, ns);

        }

​

        public override void WriteString(string text)

        {

            if (IsSuspended)

                return;

            baseWriter.WriteString(text);

        }

​

        public override void WriteSurrogateCharEntity(char lowChar, char highChar)

        {

            if (IsSuspended)

                return;

            baseWriter.WriteSurrogateCharEntity(lowChar, highChar);

        }

​

        public override void WriteWhitespace(string ws)

        {

            if (IsSuspended)

                return;

            baseWriter.WriteWhitespace(ws);

        }

    }   

​

​

    public class TestClass

    {

        public static void Test()

        {

            // Construct your XmlDocument (not shown in the question)

            var xmlDoc = new XmlDocument();

            xmlDoc.LoadXml("<Root>‘<!--‘--></Root>");

            // Output to XML and escape all non-ASCII characters.

            var xml = xmlDoc.GetOuterXml(indent : true, encoding : Encoding.ASCII, omitXmlDeclaration : true);

            Console.WriteLine(xml);

​

            var fileName = "Question72348095.xml";

            using (var stream = new FileStream(fileName, FileMode.OpenOrCreate))

            {

                xmlDoc.Save(stream, indent : true, encoding : Encoding.ASCII, omitXmlDeclaration : true);

            }

            Console.WriteLine(File.ReadAllText(fileName));

​

            Console.WriteLine();

            // Check a few other encodings as well

            Console.WriteLine(xmlDoc.GetOuterXml(indent : true, encoding : Encoding.Latin1, omitXmlDeclaration : true));

            Console.WriteLine(xmlDoc.GetOuterXml(indent : true, encoding : Encoding.UTF8, omitXmlDeclaration : true));

            Console.WriteLine(xmlDoc.GetOuterXml(indent : true, encoding : Encoding.Unicode, omitXmlDeclaration : true));

            Console.WriteLine(xmlDoc.GetOuterXml(indent : true, omitXmlDeclaration : true));

​

        }

    }

​

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Environment version: {0} ({1}, {2})", System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription , Environment.Version, Environment.OSVersion);

            Console.WriteLine();

​

            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

                Console.WriteLine("Failed with unhandled exception: ");

                Console.WriteLine(ex);

                throw;

            }

        }

    }

​