How to check 2 Dimensional array for a winner in a game of tic tac toe

Question

I am creating a game of tic tac toe as a project with a 2dimensional array and I am having some trouble checking the spots to see if there is a winner. Can someone help me debug this? Here is the checkwinner function and the main function.

char CheckWinner( char board[3][3])
{
    int i = 0;
    int j = 0;

                    if ( board[i][j] =='X' && board[i][j+1] == 'X' && board[i][j+2]== 'X' )
                    { W = X;}
                    else if (board[i+1][j] && board[i+1][i+1] && board[i+1][j+2]== 'X' )
                    { W = X;}
                    else if (board[i+2][j] && board[i+2][j+1] && board[i+2][j+2]== 'X')
                    { W = X;}
                    else if (board[i][j] && board[i+1][j] && board[i+2][j]== 'X')
                    { W = X;}
                    else if (board[i][j+1] && board[i+1][j+1] && board[i+2][j+1]== 'X')
                    { W = X;}
                    else if (board[i][j+2] && board[i+1][j+2] && board[i+2][j+2]== 'X')
                    { W =X;}
                    else if (board[i][j] && board[i+1][j+1] && board[i+2][j+2]=='X')
                    { W = X;}
                    else if (board[i+2][j] && board[i+1][j+1] && board[i][j+2]== 'X')
                    { W = X;}

                    else if (board[i][j] && board[i][j+1] && board[i][j+2]== 'O' )
                    { W = O;}
                    else if (board[i+1][j] && board[i+1][j+1] && board[i+1][j+2]== 'O')
                    { W = O;}
                    else if (board[i+2][j] && board[i+2][j+1] && board[i+2][j+2]== 'O')
                    { W = O;}
                    else if (board[i][j] && board[i+1][j] && board[i+2][j]== 'O')
                    { W = O;}
                    else if (board[i][j+1] && board[i+1][j+1] && board[i+2][j+1]== 'O')
                    { W = O;}
                    else if (board[i][j+2] && board[i+1][j+2] && board[i+2][j+2]== 'O')
                    { W = O;}
                    else if (board[i][j] && board[i+1][j+1] && board[i+2][j+2]== 'O')
                    { W = O;}
                    else if (board[i+2][j] && board[i+1][j+1] && board[i][j+2]== 'O')
                    { W = O;}



    return W;
}
int main () 
{ 
    char board[3][3];
    char Win = CheckWinner(board);
    int r = 0;


    InitializeBoard(board);

     for (int r = 0; r < 4 ; r++)
     { 
        PlayX(board);
        PlayO(board); 
        PrintBoard(board);
    }
     CheckWinner(board);
     cout << Win ;

    if (Win == X)
    {
        cout << "The winner is Player 1.";
    }
    else if (Win == O)
    {
        cout << "The winner is Player 2.";
    }
    else if (Win == TIE)
    {
        cout << " IT'S A TIE";
    }
    else; 


    system("PAUSE");
return 0; 

Answer 1

You can optimize your conditional code with the following:

typedef char piece;

piece iswin() const
{
    piece ret = 'T';

    // Checks for horizontal win
    for (int i = 0; i < 3; ++i)
        if (*arr[i] == arr[i][1] && arr[i][1] == arr[i][2])
            if ((ret = *arr[i]) != 'T')
                return ret;

    // Checks for vertical win
    for (int i = 0; i < 3; ++i)
        if (arr[0][i] == arr[1][i] && arr[1][i] == arr[2][i])
            if ((ret = arr[0][i]) != 'T')
                return ret;

    // Check for diagonal win (upper left to bottom right)
    if (**arr == arr[1][1] && arr[1][1] == arr[2][2])
        if ((ret = **arr) != 'T')
            return ret;

    // Check for diagonal win (upper right to bottom left)
    if (arr[0][2] == arr[1][1] && arr[1][1] == arr[2][0])
        if ((ret = arr[0][2]) != 'T')
            return ret;

    return ret;
}

// checking the result:
switch (winner) {
    case 'T': /* tie */ break;
    case 'X': /* X won */ break;
    case 'O': /* O won */ break;
}

This is little bit cleaner. And it does 6 loops instead of 9.

Answer 2

You immediately assign the CheckWinner result to Win, then play the game out, then call CheckWinner again without assigning its result to Win. Thus when you check Win in the following line, you have the original result from when the board wasn't even initialized.

Answer 3

Probably has to do with assigning a literal O or X into a return value that is supposed to be a char. Thus instead of O or X it should be 'O' or 'X'. Unless O or X is defined as a char variable outside the posted code.