tictactoe.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
	class Program
	{
		static FieldValue[,] fields = new FieldValue[3, 3];
		static FieldValue turn = FieldValue.X;

		static void Main(string[] args)
		{
			while (true)
			{
				DisplayField();

				var winner = CheckWinner();
				if (winner != FieldValue.Empty)
				{
					Console.WriteLine(winner + " won!");
					break;
				}

				Turn();
			}

			Console.ReadLine();
		}

		static void DisplayField()
		{
			Console.Clear();

			for (int y = 0; y < 3; ++y)
			{
				for (int x = 0; x < 3; ++x)
				{
					var chr = fields[y, x] == FieldValue.Empty ? "_" : fields[y, x].ToString();
					Console.Write(chr + " ");
				}
				Console.WriteLine();
				Console.WriteLine();
			}
		}

		static void Turn()
		{
			while (true)
			{
				if (turn == FieldValue.X)
					Console.Write("X: ");
				else
					Console.Write("O: ");

				var move = Console.ReadLine();

				var split = move.Split(',');
				int x, y;

				if (split.Length != 2 || !int.TryParse(split[0], out x) || !int.TryParse(split[1], out y))
				{
					Console.WriteLine("Invalid move, try again.");
					continue;
				}

				fields[y, x] = turn;
				turn = (turn == FieldValue.X ? FieldValue.O : FieldValue.X);
				break;
			}
		}

		static FieldValue CheckWinner()
		{
			for (int y = 0; y < 3; ++y)
			{
				if (fields[y, 0] != 0 && fields[y, 0] == fields[y, 1] && fields[y, 1] == fields[y, 2])
					return fields[y, 0];
			}

			for (int x = 0; x < 3; ++x)
			{
				if (fields[0, x] != 0 && fields[0, x] == fields[1, x] && fields[1, x] == fields[2, x])
					return fields[0, x];
			}

			if (fields[0, 0] != 0 && fields[0, 0] == fields[1, 1] && fields[1, 1] == fields[2, 2])
				return fields[0, 0];

			if (fields[0, 2] != 0 && fields[0, 2] == fields[1, 1] && fields[1, 1] == fields[2, 0])
				return fields[0, 2];

			return FieldValue.Empty;
		}

		enum FieldValue
		{
			Empty,
			X,
			O,
		}
	}
}