using System;

using System.Collections.Generic;

using System.Linq;

public class Program

{

    public static void Main()

    {

        PhoneNumbers[] num1 = new[]

                {

                    new PhoneNumbers { Number = "2344432" },

                    new PhoneNumbers { Number = "4535345" },

                    new PhoneNumbers { Number = "456456" }

                };

​

            BillToContact btc1 = new BillToContact { CompanyName = "XYZ", Name = "ABC", PhoneNumbers = num1 };

​

            PhoneNumbers[] num2 = new[]

                {

                    new PhoneNumbers { Number = "453453455" },

                    new PhoneNumbers { Number = null },

                    new PhoneNumbers { Number = "25253456" }

                };

​

            BillToContact btc2 = new BillToContact { CompanyName = "TYU", Name = "JLK", PhoneNumbers = num2 };

​

​

            PhoneNumbers[] num3 = new[]

                {

                    new PhoneNumbers { Number = "12345" },

                    new PhoneNumbers { Number = null },

                    new PhoneNumbers { Number = "667654" }

                };

​

            BillToContact btc3 = new BillToContact { CompanyName = "LPA", Name = "YUE", PhoneNumbers = num3 };

​

            List<Account> accounts = new List<Account>

            {

                new Account { Id = 1, Balance = 2000, AccountNumber = 1234, BillToContact = btc1 },

                new Account { Id = 2, Balance = 5000, AccountNumber = 8954, BillToContact = btc2 },

                new Account { Id = 3, Balance = 8000, AccountNumber = 7414, BillToContact = btc3 }

            };

​

​

            var FlatenedList = from x in accounts

                               orderby x.Id

​

                               select new

                               {

                                   AccountNumber = x.AccountNumber,

                                   Balance = x.Balance,

                                   BillToCompanyName = x.BillToContact.CompanyName,

                                   BillToName = x.BillToContact.Name,

​

                                   BillToPhoneNumber1 = x.BillToContact.PhoneNumbers[0].Number == null ? String.Empty : (x.BillToContact.PhoneNumbers[0].Number),

                                   BillToPhoneNumber2 = x.BillToContact.PhoneNumbers[1].Number == null ? String.Empty : (x.BillToContact.PhoneNumbers[1].Number),

                                   BillToPhoneNumber3 = x.BillToContact.PhoneNumbers[2].Number == null ? String.Empty : (x.BillToContact.PhoneNumbers[2].Number),

                               };

​

            var result = accounts.OrderBy(x => x.Id)

                                 .Select(x => new 

                                     {

                                         AccountNumber = x.AccountNumber,

                                         Balance = x.Balance,

                                         BillToCompanyName = x.BillToContact.CompanyName,

                                         BillToName = x.BillToContact.Name,

                                         PhoneNumbersCount = x.BillToContact.PhoneNumbers.Count(),  //All phone numbers count including null

                                         PhoneNumbersList = x.BillToContact.PhoneNumbers

                                                                            .Select(z => z.Number ?? String.Empty).ToList()

                                     });

​

            foreach (var item in result)

            {

                Console.WriteLine("AccountNumber: {0}", item.AccountNumber);

                Console.WriteLine("Balance: {0}", item.Balance);

                Console.WriteLine("BillToCompanyName: {0}", item.BillToCompanyName);

                Console.WriteLine("BillToName: {0}", item.BillToName);

                Console.WriteLine("PhoneNumbersCount: {0}", item.PhoneNumbersCount);

                foreach (var number in item.PhoneNumbersList)

                {

                    Console.WriteLine(String.IsNullOrEmpty(number) ? "Number not provided" : number);

                }

                Console.WriteLine();

            }

    }

}

​

class Account

    {

        public int Id { get; set; }

        public int AccountNumber { get; set; }

        public decimal Balance { get; set; }

        public BillToContact BillToContact { get; set; }

    }

​

    class BillToContact

    {

        public string Name { get; set; }

        public string CompanyName { get; set; }

        public PhoneNumbers[] PhoneNumbers{ get; set; }

    }

​

    class PhoneNumbers

    {

        public string Number { get; set; }

    }