https://stackoverflow.com/questions/1123718/format-xml-string-to-print-friendly-xml-string

CSharp · Console

/Program.cs

using System;
using System.Collections.Generic;
using System.Text;
using System.Linq;
using System.Xml;
using System.Xml.Linq;
using System.IO;

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

#nullable enable

//https://stackoverflow.com/questions/1123718/format-xml-string-to-print-friendly-xml-string

	public static class XmlExtensions
	{
		public static string FormatXml(this string xml, 
									   bool indent = true, bool newLineOnAttributes = false, string indentChars = "  ", 
									   ConformanceLevel conformanceLevel = ConformanceLevel.Document, bool ignoreWhitespace = true) => 
			// By default we ignore the incoming whitespace, since the purpose of this method is to reformat the incoming xml.
			xml.FormatXml( new XmlWriterSettings { Indent = indent, NewLineOnAttributes = newLineOnAttributes, IndentChars = indentChars, ConformanceLevel = conformanceLevel }, 
						  new XmlReaderSettings { ConformanceLevel = conformanceLevel, IgnoreWhitespace = ignoreWhitespace });

		public static string FormatXml(this string xml, XmlWriterSettings writerSettings, XmlReaderSettings? readerSettings = default)
		{
			using (var textReader = new StringReader(xml))
			using (var xmlReader = XmlReader.Create(textReader, readerSettings ))
			using (var textWriter = new StringWriter())
			{
				using (var xmlWriter = XmlWriter.Create(textWriter, writerSettings))
					xmlWriter.WriteNode(xmlReader, true);
				return textWriter.ToString();
			}
		}
	}

    public class TestClass
    {
        public static void Test()
        {
			foreach (var inXml in GetXml())
			{
				var newXml = inXml.FormatXml(indentChars : "", newLineOnAttributes : false); // Or true, if you prefer
				Console.WriteLine(newXml);
				Assert.IsTrue(XNode.DeepEquals(XDocument.Parse(inXml), XDocument.Parse(newXml)));
				Console.WriteLine();
			}
        }
		
		static IEnumerable<string> GetXml() => new []
		{
			@"<?xml version='1.0'?><response><error code='1'> Success</error></response>",
			"""
			<?xml version='1.0'?>
						<response>
								<error code='1'> Success</error>
				</response>
			""",
"""
<?xml version="1.0" encoding="iso-8859-1"?>
    <reportResponse>
      <report>
	<b>Now</b> is the winter of our discontent
Made glorious summer by this sun of York;
And all the clouds that lour'd upon our house
In the deep bosom of the ocean buried.
</report>
    </reportResponse>
""",
				
		};
    }

	public class Program
	{
		public static void Main()
		{
			Console.WriteLine("Environment version: {0} ({1}, {2}, NewLine: {3}).", 
							  System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription , Environment.Version, Environment.OSVersion,
							  System.Text.Json.JsonSerializer.Serialize(Environment.NewLine));
			Console.WriteLine();

			try
			{
				TestClass.Test();
			}
			catch (Exception ex)
			{
				Console.WriteLine("Failed with unhandled exception: ");
				Console.WriteLine(ex);
				throw;
			}
		}
	}