using System;

using System.Diagnostics.CodeAnalysis;

using System.Text;

using System.Text.RegularExpressions;

using System.Xml;

using System.Xml.Serialization;

​

public class Program

{

    public static void Main(string[] args)

    {

        XmlWriter xw = XmlWriter.Create(System.Console.Out, new XmlWriterSettings()

        {

            ConformanceLevel = ConformanceLevel.Fragment,

            NamespaceHandling = NamespaceHandling.Default,

            NewLineChars = "\n",

            Encoding = new UTF8Encoding(encoderShouldEmitUTF8Identifier: false), // supress BOM

            Indent = true,

            NewLineHandling = NewLineHandling.Replace,

            OmitXmlDeclaration = true,

            WriteEndDocumentOnClose = false,

            CloseOutput = false,

            CheckCharacters = false,

            NewLineOnAttributes = false,

        });

        var noNamespace = new XmlSerializerNamespaces(new[] { XmlQualifiedName.Empty });

​

        // without this line I get an error:

        //   "WriteStartDocument cannot be called on writers created with ConformanceLevel.Fragment."

        xw.WriteWhitespace("");

​

        FlyingMonkey monkey = FlyingMonkey.Create();

        XmlSerializer ser = new XmlSerializer(typeof(FlyingMonkey), defaultNamespace: null);

        ser.Serialize(xw, monkey, noNamespace);

        xw.WriteWhitespace("\n\n");

        monkey.name = "New Name";

        ser.Serialize(xw, monkey, noNamespace);

    }

}

​

​

[System.Xml.Serialization.XmlTypeAttribute(TypeName = "flyingMonkey", Namespace=null)]

public class FlyingMonkey

{

    [System.Xml.Serialization.XmlAttributeAttribute()]

    public string name;

​

    public Limb[] limbs;

​

    public static FlyingMonkey Create() =>

        new FlyingMonkey()

        {

            name = "Koko",

            limbs = new Limb[]

            {

                new Limb() { name = "leg" }, new Limb() { name = "arm" },

                new Limb() { name = "tail" }, new Limb() { name = "wing" },

            }

        };

}

​

[System.Xml.Serialization.XmlTypeAttribute(TypeName = "limb", Namespace=null)]

public class Limb

{

    [System.Xml.Serialization.XmlAttributeAttribute()]

    public string name;

}

​