using System;

using System.IO;

using System.Xml;

using System.Xml.Serialization;

​

public class Program

{

    public static void Main(string[] args)

    {

        double _invoiceInvoiceLineQuantityQuantity = 1;

​

               string invoiceInvoiceLineQuantityQuantity = "0";

​

               double.TryParse(invoiceInvoiceLineQuantityQuantity, out _invoiceInvoiceLineQuantityQuantity);

​

               var Quantity = String.Format("{0:0}", _invoiceInvoiceLineQuantityQuantity);

        Console.WriteLine(Quantity);

    }

}