using System;

using System.IO;

using System.Collections.Generic;

using System.Xml;

using System.Xml.Serialization;

public class Program

{

    public static void Main()

    {

        // Create a sample object

        var message = new MessageBody()

        {

            CheckList = new CustomArray<Check>

            {

                new Check

                {

                    CheckNumber = "111",

                    Amount = 1.00M

                },

                new Check

                {

                    CheckNumber = "112",

                    Amount = 2.00M,

                    InvoiceList = new CustomArray<Invoice>

                    {

                        new Invoice

                        {

                            ID = 1,

                            InvoiceNum = "1"

                        }

                    }

                }

            }

        };

        // Create custom settings

        var settings = new XmlWriterSettings

        {

            OmitXmlDeclaration = true,

            Indent = true

        };

​

        // Serialize item and print it to console

        using (var sw = new StringWriter())

        using (var writer = XmlWriter.Create(sw, settings))

        {

            var serializer = new XmlSerializer(message.GetType());

            serializer.Serialize(writer, message, new XmlSerializerNamespaces(new[] { XmlQualifiedName.Empty }));

            Console.WriteLine(sw.ToString());

        }

    }

}

​

public class CustomArray<T> : List<T>

{

    [XmlAttribute("type")]

    public string Type { get; set; }

    public CustomArray()

    {

        Type = "array";

    }

}

​

[XmlRoot("message")]

public class MessageBody

{

    [XmlArray("Checks"), XmlArrayItem("CheckItem")]

    public CustomArray<Check> CheckList { get; set; }

}

​

public class Check

{

    [XmlElement("C_CHECK_NUMBER")]

    public string CheckNumber { get; set; }

​

    [XmlElement("C_CHECK_AMOUNT")]

    public decimal Amount { get; set; }

​

    [XmlArray("InvoiceList"), XmlArrayItem("Invoice")]

    public CustomArray<Invoice> InvoiceList { get; set; }

}

​

public class Invoice

{

    [XmlElement("C_INVOICE_ID")]

    public long ID { get; set; }

​

    [XmlElement("C_INVOICE_NUM")]

    public string InvoiceNum { get; set; }

}

​

​