Saving and Loading objects: Serialization using System.Xml.Serialization

• You need a default constructor on the object you want serialized
• You need to mark your class [Serializable]
• Serialization of multi-dimensional arrays is not supported
• Anything you want serialized, you need both get and set properties
• Don't expect serialization to save anything you have going on in your object internally: it invokes the public properties for serialization, and deserialized by setting them back

//gmcs Game.cs Main.cs /out:Main.exe
using System;
using System.IO;
using System.Xml.Serialization;

namespace rootsilver.serialization{
	public class Test{
		public static void Main(){
			
			Console.WriteLine("Starting new game ...");			

			Game game = new Game();
			game.BoardSize = 3;

			game.Move(1, 1, "X");
			game.Move(2, 2, "O");
			game.Move(3, 3, "X");
			game.Move(3, 1, "O");
			game.Move(1, 3, "O");
			
			game.PrintBoard();
			
			Console.WriteLine();	
			Console.WriteLine("Saving game (serializing to file) ...");			

			string savedGameFile = SaveGame(game);	

			Console.WriteLine("Loading saved game (deserializing from file) ...");
			Console.WriteLine();	

			Game game2 = LoadGame(savedGameFile);

			game2.PrintBoard();

			
		}
		
		public static Game LoadGame(string filePath) {

			Game game = null;

			using (Stream stream = File.Open(filePath, FileMode.Open)) {
				XmlSerializer serializer = new XmlSerializer(typeof(Game));

				game = (Game)serializer.Deserialize(stream);
			}
			return game;

		}

		public static String SaveGame(Game game) {
			string filePath = typeof(Game).ToString() + ".xml";

			using (Stream stream = File.Open(filePath, FileMode.Create)) {
				XmlSerializer serializer = new XmlSerializer(typeof(Game));

				serializer.Serialize(stream, game);
			}
			return filePath;
		}

	}
}

using System;
using System.Collections.Generic;
using System.Xml.Serialization;

namespace rootsilver.serialization{

	[Serializable]
	public class Game{
		//(multi-dimensional arrays can not be serialized)
		private String[] board;
		private int boardWidth;
		private int boardSquareCount;
	
		//xml serialization requires a default constructor
		public Game() { } 

		public int BoardSize{
			get {
				return this.boardWidth;
			}
			set { 
				this.boardWidth = value;
	
				this.boardSquareCount = boardWidth * boardWidth;

				this.board = new String[this.boardSquareCount];

				this.InitializeBoard(".");
			}
		}
		public String[] Board{
			get { return board; }
			//set will get called by the deserializer
			set { this.board = value; }
		}


		private void InitializeBoard(string defaultValue){
			for(int i = 0; i < this.boardSquareCount; i++){
				this.board[i] = defaultValue;	
			}
		}


		public void Move(int x, int y, string move){
			--x;
			--y;
			int square = x  + ( y + (y * (this.boardWidth - 1)));
			this.board[square] = move;
		}

		public void PrintBoard(){
			Console.WriteLine("---------");
			for(int i = 0; i < this.boardSquareCount; i++){
				if(i > 0 && (i  % this.boardWidth  == 0) )
					Console.WriteLine();	

				Console.Write(this.board[i] + " ");
		
			}
			Console.WriteLine();
			Console.WriteLine("---------");
		}
	}
}

<?xml version="1.0" encoding="utf-8"?>
<Game xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
  <BoardSize>3</BoardSize>
  <Board>
    <string>X</string>
    <string>.</string>
    <string>O</string>
    <string>.</string>
    <string>O</string>
    <string>.</string>
    <string>O</string>
    <string>.</string>
    <string>X</string>
  </Board>
</Game>