Serialization, Deserialization Exception

Lots of stuff wrong :( But its ok, it happens. The object you are serializing to the membership.dat file is not an array. Ive gone ahead and fixed up alot of the stuff that you were having issues with and Ill explain it with comments.

using System;
using System.Collections.Generic;
using System.Text;
using System.IO;

using System.Runtime.Serialization.Formatters.Binary;

namespace HomeWork_2
{
    //Mark these classes as
    //serializable so they can
    //be serialized to the file.
    [Serializable]
    public abstract class Person
    {
        public abstract string Name { get; set; }
        public abstract string PhoneNumber { get; set; }
        public virtual void PrintInfo() { }
    }

    //You could also have used an
    //interface for this
    //not sure why an empty abstract
    //class was used.
    public interface IPerson
    {
        string Name
        {
            get;
            set;
        }

        string PhoneNumber
        {
            get;
            set;
        }

        void PrintInfo();
    }

    [Serializable]
    public class PersonInfo : Person
    {
        //Always try to initialize variables
        //with something to avoid null values.
        private string name = String.Empty;
        private string phoneNumber = String.Empty;

        public PersonInfo()
        {

        }

        public override string Name
        {
            get { return this.name; }
            set { this.name = value; }
        }

        public override string PhoneNumber
        {
            get { return this.phoneNumber; }
            set { this.phoneNumber = value; }
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            //Create the list to store
            //person info in and the
            //binary formatter to serialize
            //and deserialize it to the file.
            List<PersonInfo> personInfoList = new
               List<PersonInfo>(10);

            //You may want to read up on
            //generics a bit
            BinaryFormatter binaryFormatter = new BinaryFormatter();

            try
            {
                //Create a filestream object
                //to check the length of the
                //file before attempting to
                //deserialize.
                using (FileStream fileStream = new FileStream("membership.dat", FileMode.OpenOrCreate, FileAccess.Read))
                {
                    if (fileStream.Length > 0)
                    {
                        //If there is data to
                        //deserialize, then
                        //deserialize it and cast
                        //it to the personInfoList
                        //object
                        personInfoList = (List<PersonInfo>)binaryFormatter.Deserialize(fileStream);
                    }
                }
            }
            catch (IOException ex)
            {
                Console.WriteLine("Unable to access membership.dat file. {0}.", ex.Message);
            }
            catch (Exception ex)
            {
                //This generally isnt a good
                //idea, but its a catch all for now
                Console.WriteLine(ex.Message);
            }

            //Prime the while loop
            bool quit = false;

            while (!quit)
            {
                //Display the menu
                Console.Write("   Main Menu\n\t(a) Add \n\t(b) Search \n\t(c) Print All \n\t(d) Exit\n\t-> ");

                //Create a char variable to
                //contain the entered character
                //from the command prompt.
                char selectionChar;

                //Attempt to parse the input.
                //If it succeeds, continue with processing.
                if (Char.TryParse(Console.ReadLine(),
                       out selectionChar))
                {
                    switch (selectionChar)
                    {
                        case 'a':

                            //Create a new person info object.
                            PersonInfo personInfo = new PersonInfo();

                            //Request the employees name
                            Console.Write("\nEnter Employee name: ");
                            personInfo.Name = Console.ReadLine();

                            //Request the employees phone number
                            Console.Write("\nEnter the employee's phone #: ");
                            personInfo.PhoneNumber = Console.ReadLine();

                            //Add a new employee to the list here
                            personInfoList.Add(personInfo);
                            break;

                        case 'b':

                            //Get the name to search for
                            Console.WriteLine("Enter the name of the employee whose record you want to find\n-> ");
                            string queryEmpName = Console.ReadLine();

                            //Set a variable for checking later
                            bool foundPerson = false;

                            //Iterate through the list of persons and look for the person with the supplied name.
                            for (int i = 0; i < personInfoList.Count; i++)
                            {
                                //If the person is found...
                                if (personInfoList[i].Name == queryEmpName)
                                {
                                    //Let the user know and break from the loop.
                                    Console.WriteLine("Found! Name: {0} with phone number {1}", personInfoList[i].Name, personInfoList[i].PhoneNumber);
                                    foundPerson = true;
                                    break;
                                }

                                //If the person is not found, the loop continues until all of the persons have been checked.
                            }

                            //If the person was not found, display a message letting the user know.
                            if (!foundPerson)
                            {
                                //Let the user know that the person was not found.
                                Console.WriteLine("The employee with name {0} was not found.", queryEmpName);
                            }
                            break;

                        case 'c':

                            //Iterate through the list of persons and display their information.
                            for (int i = 0; i < personInfoList.Count; i++)
                            {
                                //Display each persons information.
                                Console.WriteLine("{0} - Name: {1} Phone Number: {2}", /*Up i by one because arrays are zero indexed.*/ (i + 1).ToString(), personInfoList[i].Name, personInfoList[i].PhoneNumber);
                            }

                            break;
                        case 'd':
                            try
                            {
                                //Create a file stream object to serialize the data to.
                                using (FileStream fileStream = new FileStream("membership.dat", FileMode.OpenOrCreate, FileAccess.Write))
                                {
                                    binaryFormatter.Serialize(fileStream, personInfoList);
                                }
                            }
                            catch (Exception ex)
                            {
                                Console.WriteLine(ex.Message);

                                //Pause the console so the message can be read.
                                Console.ReadLine();
                            }
                            finally
                            {
                                //Set the quit variable so the loop will exit.
                                quit = true;
                            }
                            break;
                        default:
                            Console.WriteLine("Invalid selection entered.");
                            break;
                    }
                }
                else   //If the input couldnt be parsed, display an error.
                {
                    Console.WriteLine("Invalid selection entered");
                }
            }
        }
    }
}
//--------------
//-NO MORE CODE-
//--------------

So basically, when you load it, it will display a menu asking you for a choice. If you enter a lowercase letter a - d it will continue processing but anything else and it will prompt for and let you know you input something invalid. It will then let you make another choice.

Generic collections, as I have used in the collection of PersonInfo objects, are really a nice thing. Theyre easier to work with than raw arrays and they dynamically resize themselves rather than having a set size all the time much like an array. Generics are much more useful than just using in collection classes too.

As well as being easier to work with, the generic List class (denotated as List<Type>) where Type is the type of object you wish to store in the strongly typed collection. This works much better than the ArrayList class (which I havent used for quite some time due to me liking type safety) but when you create a generic List collection, you can only store objects of the type you have specified in it. In later learning, you will probably come across interfaces and base classes where you will be able to store any object that implements an particular interface or base class and such... But that might be awhile, lol.

Some examples...
List<string> //A generic collection of strings
List<int> //A generic collection of integer values
List<MyClass> //A generic collection of class objects
List<IMyInterface> //A generic collection of interface objects

I commented alot of the code to help you figure out what was going on instead of just giving you the code, so if you wanna learn, check my comments and go through the code and try to figure it out for yourself.

The whole issue with your serialization/deserialization was that you were serializing objects of type PersonInfo to the file, but you were attempting to deserialize objects of type PersonInfo[] which was giving you an exception. Just check it out, and be sure to go through it because thats how you learn and if you have any questions at all, feel free to ask. I tend to talk about, but I always figure I can never do enough explaining of a concept :) More always helps.

Anyone ????

I'm stuck
I really don't know how to load (serialize) the Personal Information data from a file called “membership.dat” into the array of objects PersonInfo.

&

At the end of the program serialize the array of PersonInfo objects into the file “membership.dat”.

I don't understand how to load and write with arrays...
Please Help.. Thanks..

Thanks 4 the helpul reply...
I hope I'm not asking too much but can you look at the jpg picture I posted about the assignment I have to do.. I don't think I"m doing it right..

Thanks...

Well, for the issue you are discussing in this post, you need to mark your classes as serializable (e.g.):

[Serializable]

public abstract class Person

{

To avoid the unhandled exception, put the code into a try catch block.

using (Stream output = File.Create(@"c:\Temp\membership.dat"))

{

   try

   {

      BinaryFormatter formatter = new BinaryFormatter();

      formatter.Serialize(output, empInfo);

   }

   catch (Exception ex)

   {

      Console.Write(ex.Message);

      Console.ReadLine();

   }

}