Tic Tac Toe, Help/Determine Winner

Question

I'm creating a TicTacToe class that contains a 3 by 3 rectangular array of integers & is played by 2 human players. "1" is used for the first player's move & "2" is used for the second player's move. Currently, I am stuck and have no clue on how to determine/check whether the game has been won or whether its a draw after each and every move has been made.

Unfortunately, I'm stuck in checking if the game is won or drawn after each player makes a move & was hoping someone could help.

This is my code thus far: Main class:

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

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            TicTacToe game = new TicTacToe();
            game.PrintBoard();
            game.Play();
        }
    }
}

TicTacToe class:

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


namespace ConsoleApplication1
{
    class TicTacToe
    {
        private const int BOARDSIZE = 3; //size of the board
        private int[,] board = new int [BOARDSIZE,BOARDSIZE]; // board representation
        string player1row, player1column, player2row, player2column;
        enum DONE {win1, win2, win3, win4, win5, win6, win7,win8,
                   win9, win10, win11, win12, win13, win14, win15, win16};


        //Default Constructor
        public TicTacToe(){
            board = new int [3,3] { {0,0,0},{0,0,0},{0,0,0} };
        }

        int win1 = 1;  

        public void PrintBoard(){
            Console.WriteLine("-----------------------\n"+
                              "|       |       |       |\n"+
                              "|   {0}   |   {1}   |   {2}   |\n" +
                              "|_______|_______|_______|\n"+
                              "|       |       |       |\n"+
                              "|   {3}   |   {4}   |   {5}   |\n" +
                              "|_______|_______|_______|\n"+
                              "|       |       |       |\n"+
                              "|   {6}   |   {7}   |   {8}   |\n" +
                              "|_______|_______|_______|\n",
                              board[0,0],board[0,1],board[0,2],
                              board[1,0],board[1,1],board[1,2],
                              board[2,0],board[2,1],board[2,2]);
        }// end PrintBoard method

        public void Play(){
            while (true)
            {
                Console.WriteLine("Player 1's turn.");
                Console.Write("Player 1: Enter row ( 0 <= row < 3 ): "); //prompt user
                player1row = Console.ReadLine(); //get string from user           
                Console.Write("Player 1: Enter column ( 0 <= row < 3 ): "); //prompt user 
                player1column = Console.ReadLine(); //get string from user

                //Convert string to ints
                int p1r = Convert.ToInt32(player1row);
                int p1c = Convert.ToInt32(player1column);
                // assign marker to desired position
                board[p1r, p1c] = 1;

                PrintBoard(); // Update board
                checkWinner();

                Console.WriteLine("\nPlayer 2's turn.");
                Console.Write("Player 2: Enter row ( 0 <= row < 3 ): ");
                player2row = Console.ReadLine(); //get string from user     
                Console.Write("Player 2: Enter column ( 0 <= row < 3 ): ");
                player2column = Console.ReadLine(); //get string from user

                //Convert string to ints
                int p2r = Convert.ToInt32(player2row);
                int p2c = Convert.ToInt32(player2column);
                // assign marker to desired position
                board[p2r, p2c] = 2;

                PrintBoard(); // Update board
                checkWinner();

            }
        }//end Play method

        private bool checkWinner()
        {
            for (int i = 0; i < 3; i++)
                for (int j = 0; j < 3; j++)

                    //I WANT TO CHECK FOR A WIN OR DRAW HERE BUT DONT KNOW HOW TO






    }}// end class

I want to check for a winner using 2 for loops, the first checking the rows, then another checking for columns, then adding 2 separate if statements to check the diagonals, but i really don't know how to & have been stuck for a while now.

Answer 1

I will try to answer how to detect the draw, as all others have focused only on checking if someone won.

The game can only be drawn when the board is fully completed, and no other winning combination is formed. So it's not difficult to detect after you checked for winner and haven't found one.

• Check for winner, if not found, continue detecting for ties.
• Scan the whole array of the board, no matter in what order.
• If found an empty spot, it's NOT a tie (further moves are possible), interrupt the loop and continue playing.
• Once you've reached the end of the loop, declare a draw (all spaces are filled without a winning combination).

Answer 2

As Iiya has said, you're going to have to through through all the win cases. There's many ways to do that but the very gist of it in code would be

private bool checkWinner(int player)
{
    // check rows
    if (board[0, 0] == player && board[0, 1] == player && board[0, 2] == player) { return true; }
    if (board[1, 0] == player && board[1, 1] == player && board[1, 2] == player) { return true; }
    if (board[2, 0] == player && board[2, 1] == player && board[2, 2] == player) { return true; }

    // check columns
    if (board[0, 0] == player && board[1, 0] == player && board[2, 0] == player) { return true; }
    if (board[0, 1] == player && board[1, 1] == player && board[2, 1] == player) { return true; }
    if (board[0, 2] == player && board[1, 2] == player && board[2, 2] == player) { return true; }

    // check diags
    if (board[0, 0] == player && board[1, 1] == player && board[2, 2] == player) { return true; }
    if (board[0, 2] == player && board[1, 1] == player && board[2, 0] == player) { return true; }

    return false;
}

You can optimise this however which way you'd like (using for loops or matrices). Note the checkWinner() function requires a player input.

Answer 3

I wont code it for you but here is the logic you can use:

1) For each column check if all rows are the same, if yes declare winner. If not go to step 2.

2) For each row check if all column values are the same, if yes declare winner. If not go to step 3.

3) Now check diagonals, there are only two possibilities here [0,0] [1,1] [2,2] and also [0,2] [1,1] [2,0] if they are the same declare winner, if not check whether all values in array are filled, if yes declare draw if not make users enter values.

Answer 4

One simple approach is to try every square (for i = 0; i < 3; for j = 0; j < 3) then if that square is not blank go in every of the eight possible directions, counting each square with the same 'color' until you go off the board. If your count ever reaches the value three then you have a winner position for the color of the starting square.