public void AddContactToBook()
        {
            Console.WriteLine("Add new contact");
            string[] detailsOfPerson;
            //enter details from user
            Console.WriteLine("Enter the following details seperated by comma");
            Console.WriteLine("First Name, Last Name, Address, City, State, ZipCode, Phone Number, Email ID");
            detailsOfPerson = Console.ReadLine().Split(",");
            PersonContactDetails personContactDetails = new PersonContactDetails(detailsOfPerson[0], detailsOfPerson[1], detailsOfPerson[2], detailsOfPerson[3], detailsOfPerson[4], detailsOfPerson[5], detailsOfPerson[6], detailsOfPerson[7]);

            set.Add(personContactDetails);
            string path = @"C:\Users\USER\source\repos\Address_Book_Problem\Address_Book_Problem\PersonInput.txt";

            if (File.Exists(path))
            {
                using (StreamWriter writer = File.AppendText(path))
                {
                    writer.WriteLine(personContactDetails.firstName + " " + personContactDetails.lastName + " " + personContactDetails.address + " " + personContactDetails.city + " " + personContactDetails.state + " " + personContactDetails.zipCode + " " + personContactDetails.phoneNumber + " " + personContactDetails.emailID);
                    writer.Close();
                }
            }
            else
            {
                Console.WriteLine("No such file exists");
            }
            Console.WriteLine("Contact added");
        }
        public Dictionary <string, PersonContactDetails> StateDictionaryCollection()
        {
            Dictionary <string, PersonContactDetails> stateDictionary = new Dictionary <string, PersonContactDetails>();

            Dictionary <string, AddressBookMain> .Enumerator enumerator = multipleAddressBooks.GetEnumerator();
            while (enumerator.MoveNext())
            {
                AddressBookMain searchAddressBook = enumerator.Current.Value;
                HashSet <PersonContactDetails>             addressBook = searchAddressBook.GetAddressBook();
                HashSet <PersonContactDetails> .Enumerator enumerator1 = addressBook.GetEnumerator();
                while (enumerator1.MoveNext())
                {
                    PersonContactDetails c = enumerator1.Current;
                    stateDictionary.Add(enumerator1.Current.state, c);
                }
            }
            return(stateDictionary);
        }