/// <summary>
        /// Compare details
        /// </summary>
        /// <param name="x"></param>
        /// <param name="y"></param>
        /// <returns></returns>
        public int Compare(AddressBookModel x, AddressBookModel y)
        {
            Console.WriteLine("Enter choice for sorting:");
            Console.WriteLine("1. FirstName 2. City 3. State 4. ZipCode");
            String choice  = Console.ReadLine();
            int    choice1 = Convert.ToInt32(choice);

            switch (choice1)
            {
            case 1:
                return(x.FirstName.CompareTo(y.FirstName));

            case 2:
                return(x.City.CompareTo(y.City));

            case 3:
                return(x.State.CompareTo(y.State));

            case 4:
                return(x.ZipCode.CompareTo(y.ZipCode));
            }
            return(0);
        }
        /// <summary>
        /// Ability to edit existing contact person using their name
        /// </summary>
        /// <param name="firstName"></param>
        /// <param name="lastName"></param>
        public void EditContact(string firstName, string lastName)
        {
            int check = 0;

            for (int i = 0; i < this.list.Count; i++)
            {
                if (this.list[i].FirstName.Equals(firstName) && this.list[i].LastName.Equals(lastName))
                {
                    while (check == 0)
                    {
                        AddressBookModel addressBook = this.list[i];
                        Console.WriteLine(addressBook);
                        Console.WriteLine("Enter your choice for editing: ");
                        Console.WriteLine("1.Address 2.City 3.State 4.Zip Code 5.Phone Number 6.Email ID 7.Exit");
                        string choice = Console.ReadLine();
                        int    ch     = Convert.ToInt32(choice);
                        switch (ch)
                        {
                        case 1:
                            Console.WriteLine("enter new address");
                            string address = Console.ReadLine();
                            addressBook.Address = address;
                            break;

                        case 2:
                            Console.WriteLine("enter new city");
                            string city = Console.ReadLine();
                            addressBook.City = city;
                            break;

                        case 3:
                            Console.WriteLine("enter new state");
                            string state = Console.ReadLine();
                            addressBook.State = state;
                            break;

                        case 4:
                            Console.WriteLine("enter new zipCode");
                            string zipCode = Console.ReadLine();
                            addressBook.ZipCode = zipCode;
                            break;

                        case 5:
                            Console.WriteLine("enter new phoneNumber");
                            string mobileNumber = Console.ReadLine();
                            addressBook.MobileNumber = mobileNumber;
                            break;

                        case 6:
                            Console.WriteLine("enter new Email ID");
                            string emailID = Console.ReadLine();
                            addressBook.EmailID = emailID;
                            break;

                        case 7:
                            check = 1;
                            break;
                        }
                    }
                }
            }
        }