TicTacToe_OO

using System;
using System.Text;

namespace TicTacToe_OO // object oriented implementation of tic tac toe
{
    class Program
    {
        static void Main()
        {
            while (true)
            {
                Console.WriteLine("\nTic Tac Toe");
                Console.WriteLine("Please enter an integer from 1 to 9 to make a move, or 0 to quit game.\n");
                Game game = new Game();
                string result = game.Start();
                Console.WriteLine("\nGame Over. Result: " + result + ".");
                if (result == "Quit")
                {
                    return;
                }
            }
        }
    }

    class Game
    {
        public String Start()
        {
            Board board = new Board();
            board.Display();
            while (true) // each iteration of this loop is the placement of an "X" or a "O as a single move
            {
                int move; // must get integer 0 to 9, 0 means terminate game, other values are move positions
                if (!int.TryParse(Console.ReadKey(true).KeyChar.ToString(), out move))
                {
                    Console.WriteLine("\nPlease enter an integer from 1 to 9 to make a move, or 0 to quit game.");
                    continue;
                }
                if (move == 0)
                {
                    return "Quit";
                }
                board.MakeMove(move); // move is 1 -> 9
                string result = board.WhoIfAnyoneHasWon();
                if (result == "Still in play")
                {
                    continue; // continue playing game
                }
                return result;
            }
        }
    }

    class Board
    {
        char player = 'X'; // X always plays first move
        char[] cells = { ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ', ' ' }; // 9 cells in 3x3 grid
        int[] translate = { 1, 5, 9, 25, 29, 33, 49, 53, 57 };          // translate int to offset in display string
        int moveCounter = 0; // must never go greater than 9 moves
        public void Display()
        {
            Console.WriteLine();
            StringBuilder sb = new StringBuilder(
                "   |   |   \n" +  //  1,  5,  9 <- offsets in display string for indexes 1, 2, 3
                "---+---+---\n" +
                "   |   |   \n" +  // 25, 29, 33 <- offsets in display string for indexes 4, 5, 6
                "---+---+---\n" +
                "   |   |   \n");  // 49, 53, 57 <- offsets in display string for indexes 7, 8, 9
            for (int i = 0; i < 9; i++)
            {
                sb[translate[i]] = cells[i];
            }
            Console.WriteLine(sb);
        }
        public void MakeMove(int move) // move is integer from 1 to 9 inclusive
        {
            move = move - 1;
            if (cells[move] != ' ') { Console.Beep(); return; } // cell must be open for move
            cells[move] = player;
            Display();
            if (player == 'X') player = 'O'; else player = 'X'; // alternate current player after every move
            moveCounter++;
        }
        public string WhoIfAnyoneHasWon() // returns "X", "O", "Draw" "Still in play";
        {
            // check to see if X won yet
            if ((cells[0] == 'X' && cells[1] == 'X' && cells[2] == 'X') || // row 1
                (cells[3] == 'X' && cells[4] == 'X' && cells[5] == 'X') || // row 2
                (cells[6] == 'X' && cells[7] == 'X' && cells[8] == 'X') || // row 3
                (cells[0] == 'X' && cells[3] == 'X' && cells[6] == 'X') || // col 1
                (cells[1] == 'X' && cells[4] == 'X' && cells[7] == 'X') || // col 2
                (cells[2] == 'X' && cells[5] == 'X' && cells[8] == 'X') || // col 3
                (cells[0] == 'X' && cells[4] == 'X' && cells[8] == 'X') || // diag 1
                (cells[6] == 'X' && cells[4] == 'X' && cells[2] == 'X'))   // diag 2
                return "X wins";

            // check to see if O won yet
            if ((cells[0] == 'O' && cells[1] == 'O' && cells[2] == 'O') || // row 1
                (cells[3] == 'O' && cells[4] == 'O' && cells[5] == 'O') || // row 2
                (cells[6] == 'O' && cells[7] == 'O' && cells[8] == 'O') || // row 3 
                (cells[1] == 'O' && cells[4] == 'O' && cells[7] == 'O') || // col 2
                (cells[2] == 'O' && cells[5] == 'O' && cells[8] == 'O') || // col 3
                (cells[0] == 'O' && cells[4] == 'O' && cells[8] == 'O') || // diag 1
                (cells[6] == 'O' && cells[4] == 'O' && cells[2] == 'O'))   // diag 2
                return "O wins";

            // if max number of completed moves is 9 and nobody has won yet then it is a draw
            if (moveCounter == 9) return "Draw";

            return "Still in play";
        }
    }
}