Fifteen move not working in last row only

Question

I am very new to this, so I am at a loss as to why my code isn't working. I am trying to make my move function work in the game of fifteen, and it works as long as I am not going to the left or right over the two or one. I think this has to do with the fact that they are swapped in itit, but I don't know how to make this problem go away! If I move to the left toward a 2 on an even board, I end up with extra underscores.... Here is my init:

void init(void)
{
// Declares variables
int k = (d * d) - 1;

// Iterates across 2D array
for (int i = 0; i < d; i++)
    {
        for (int j = 0; j < d; j++)
        {
            board[i][j] = k;
            k--;
        }
    }

if (d % 2 == 0)
    {
        int swap = board[d-1][d-2];
        board[d-1][d-2] = board[d-1][d-3];
        board[d-1][d-3] = swap;
    }

}

here is my draw:

// Iterates across 2D array
for (int i = 0; i < d; i++)
    {
        for (int j = 0; j < d; j++)
        {
            if (board[i][j] == 0)
            {
                printf ("__\t");
            }
            else
            {
                printf ("%2d\t", board[i][j]);
            }
        }
        printf ("\n");
    }

and here is my move function:

for (int i = 0; i < d; i++)
    {
        for (int j = 0; j < d; j++)
        {
            if (tile == board[i][j])
            {
                if (i > 0 && board[i - 1][j] == 0)
                    {
                        int swap = board[i][j];
                        board[i][j] = board[i - 1][j];
                        board[i - 1][j] = swap;
                        return true;
                    }

                else if (i < d && board[i + 1][j] == 0)
                    {
                        int swap = board[i][j];
                        board[i][j] = board[i + 1][j];
                        board[i + 1][j] = swap;
                        return true;
                    }

                else if (j > 0 && board[i][j - 1] == 0)
                    {
                        int swap = board[i][j];
                        board[i][j] = board[i][j - 1];
                        board[i][j - 1] = swap;
                        return true;
                    }

                else if (j < d && board[i][j + 1] == 0)
                    {
                        int swap = board[i][j];
                        board[i][j] = board[i][j + 1];
                        board[i][j + 1] = swap;
                        return true;
                    }

            }


        }
    }

return false;

Answer 1

A very common problem. Look at the following:

 else if (i < d && board[i + 1][j] == 0)

This code attempts to swap with a tile that is off the edge of the board. If i = d-1, then what is i+1? Is it still within the valid range of board[][]? Same applies to j.

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