Tic Tac Toe Console Game with error/exception handling by M MUKIT.

CS_TicTacToe.cs

using System;

namespace _1.Tic_Tac_Toe
{
    public class TicTacToe
    {   
        public char[,] gameBoard = new char[3,3];
        public char choice;

        public int player = 0;


        public void resetGameBoard()
        {
            char a = '1';

            for (int i = 0; i < 3; i++)
            {
                for (int j = 0; j < 3; j++)
                {
                    gameBoard[i, j] = a;
                    a++;
                }
            }
        }

        public void printGameBoard()
        {
            Console.Write("\n\n");

            for (int i = 0; i < 3; i++)
            {
                for (int j = 0; j < 3; j++)
                {
                    if (j != 2)
                    {
                        Console.Write(" " + gameBoard[i, j] + " |");
                    }
                    else
                    {
                        Console.Write(" " + gameBoard[i, j]);
                    }
                }

                if (i != 2)
                {
                    Console.Write("\n---+---+---\n");
                }
            }

            Console.Write("\n\n\n");

        }

        public bool isValidChoice(char choice, int player)
        {
            switch (choice)
            {
                case '1':
                    if (gameBoard[0, 0] != 'X' && gameBoard[0, 0] != 'O')
                    {
                        if (player == 1)
                        {
                            gameBoard[0, 0] = 'X';
                        }
                        else
                        {
                            gameBoard[0, 0] = 'O';
                        }
                        return true;
                    }
                    else
                    {
                        return false;
                    }
                    
                     

                case '2':
                    if (gameBoard[0, 1] != 'X' && gameBoard[0, 1] != 'O')
                    {
                        if (player == 1)
                        {
                            gameBoard[0, 1] = 'X';
                        }
                        else
                        {
                            gameBoard[0, 1] = 'O';
                        }
                        return true;
                    }
                    return false;
                     

                case '3':
                    if (gameBoard[0, 2] != 'X' && gameBoard[0, 2] != 'O')
                    {
                        if (player == 1)
                        {
                            gameBoard[0, 2] = 'X';
                        }
                        else
                        {
                            gameBoard[0, 2] = 'O';
                        }
                        return true;
                    }
                    return false;
                     

                case '4':
                    if (gameBoard[1, 0] != 'X' && gameBoard[1, 0] != 'O')
                    {
                        if (player == 1)
                        {
                            gameBoard[1, 0] = 'X';
                        }
                        else
                        {
                            gameBoard[1, 0] = 'O';
                        }
                        return true;
                    }
                    return false;
                     

                case '5':
                    if (gameBoard[1, 1] != 'X' && gameBoard[1, 1] != 'O')
                    {
                        if (player == 1)
                        {
                            gameBoard[1, 1] = 'X';
                        }
                        else
                        {
                            gameBoard[1, 1] = 'O';
                        }
                        return true;
                    }
                    return false;
                     

                case '6':
                    if (gameBoard[1, 2] != 'X' && gameBoard[1, 2] != 'O')
                    {
                        if (player == 1)
                        {
                            gameBoard[1, 2] = 'X';
                        }
                        else
                        {
                            gameBoard[1, 2] = 'O';
                        }
                        return true;
                    }
                    return false;
                     

                case '7':
                    if (gameBoard[2, 0] != 'X' && gameBoard[2, 0] != 'O')
                    {
                        if (player == 1)
                        {
                            gameBoard[2, 0] = 'X';
                        }
                        else
                        {
                            gameBoard[2, 0] = 'O';
                        }
                        return true;
                    }
                    return false;
                     

                case '8':
                    if (gameBoard[2, 1] != 'X' && gameBoard[2, 1] != 'O')
                    {
                        if (player == 1)
                        {
                            gameBoard[2, 1] = 'X';
                        }
                        else
                        {
                            gameBoard[2, 1] = 'O';
                        }
                        return true;
                    }
                    return false;
                     

                case '9':
                    if (gameBoard[2, 2] != 'X' && gameBoard[2, 2] != 'O')
                    {
                        if (player == 1)
                        {
                            gameBoard[2, 2] = 'X';
                        }
                        else
                        {
                            gameBoard[2, 2] = 'O';
                        }

                        return true;
                    }
                    return false;
                     

                default:

                    return false;


            }
        }

        public bool isGoal()
        {
            // Horzontal value checking

            if (gameBoard[0,0] == gameBoard[0, 1] && gameBoard[0, 1] == gameBoard[0, 2])
            {
                return true;
            }

            if (gameBoard[1, 0] == gameBoard[1, 1] && gameBoard[1, 1] == gameBoard[1, 2])
            {
                return true;
            }

            if (gameBoard[2, 0] == gameBoard[2, 1] && gameBoard[2, 1] == gameBoard[2, 2])
            {
                return true;
            }

            // Vertical value checking

            if (gameBoard[0, 0] == gameBoard[1, 0] && gameBoard[1, 0] == gameBoard[2, 0])
            {
                return true;
            }

            if (gameBoard[0, 1] == gameBoard[1, 1] && gameBoard[1, 1] == gameBoard[2, 1])
            {
                return true;
            }

            if (gameBoard[0, 2] == gameBoard[1, 2] && gameBoard[1, 2] == gameBoard[2, 2])
            {
                return true;
            }

            // Diagonal value checking

            if (gameBoard[0, 0] == gameBoard[1, 1] && gameBoard[1, 1] == gameBoard[2, 2])
            {
                return true;
            }

            if (gameBoard[0, 2] == gameBoard[1, 1] && gameBoard[1, 1] == gameBoard[2, 0])
            {
                return true;
            }

            return false;
        }

        public bool isEmptySqure()
        {
            for (int i = 0; i < 3; i++)
            {
                for (int j = 0; j < 3; j++)
                {
                    if (gameBoard[i, j] != 'X' && gameBoard[i, j] != 'O')
                    {
                        return true;
                    }
                }
            }
            
            return false;
        }

        public int getOwner()
        {
            if (player % 2 == 0)
            {
                return 2;
            }
            else
            {
                return 1;
            }
        }

    }
    class Program
    {
        static void Main(string[] args)
        {
           START_GAME:
            
            TicTacToe game = new TicTacToe();

            Console.WriteLine("\n\n**  Welcome to Tic Tac Toe Game ***");

            game.resetGameBoard();
            game.printGameBoard();

            Console.WriteLine("\nPlayer 1 : 'X' \nPlayer 2 : 'O'\n\n");
            Console.WriteLine("Press numbers 1-9 to fillup the squre...\n\n");

            while (!game.isGoal() && game.isEmptySqure())
            {
                game.player++;

                START_INPUT:

                try
                {
                    if (game.player % 2 == 0)
                    {
                        Console.Write("Player 2 : ");
                        game.choice = Char.Parse(Console.ReadLine());
                        if (!game.isValidChoice(game.choice, 2))
                        {
                            Console.WriteLine("\n###Error: Invalid input. Value already exists or choice not found! Try again...\n");
                            goto START_INPUT;
                        }
                    }
                    else
                    {
                        Console.Write("Player 1 : ");
                        game.choice = Char.Parse(Console.ReadLine());
                        if (!game.isValidChoice(game.choice, 1))
                        {
                            Console.WriteLine("\n### Error: Invalid input. Value already exists or choice not found! Try again...\n");
                            goto START_INPUT;
                        }
                    }
                }
                catch (Exception e)
                {
                    Console.WriteLine("\n\n### Error: Invalid input. Value already exists or choice not found! Try again...\n\n");
                    goto START_INPUT;
                }

                game.printGameBoard();

            };

            if (game.isGoal())
            {
                Console.WriteLine("\n****************************\n");
                Console.WriteLine("Match Won by Player {0}.", game.getOwner());
                Console.WriteLine("\n****************************\n");
            }
            else
            {
                Console.WriteLine("\n************\n");
                Console.WriteLine("Match Draw.");
                Console.WriteLine("\n************\n");
            }

        REPLAY_CONFIRM:

            try
            {
                Console.WriteLine("\n\nDo you want to play again? (Press 'y' or 'n'): ");
                char replay = Char.Parse(Console.ReadLine());

                if ( replay == 'y' || replay == 'Y')
                {
                    Console.Clear();
                    goto START_GAME;
                }
                else if (replay == 'n' || replay == 'N')
                {
                    return;
                }
                else
                {
                    throw new FormatException();
                }
            }
            catch (Exception)
            {
                Console.WriteLine("\n### Error: Invalid input. Press 'y' or 'n'...\n");
                goto REPLAY_CONFIRM;
            }

        }
    }
}