Pset3 fifteen - move: Tiles wont switch, “illegal move” error even when valid

Question

I have been trying to get the tiles of the move function to switch if any adjacent cells are blank. The initiation and draw functions work fine, I just need to get the move function to make the actual switch instead of giving me "illegal move errors" even though a blank adjacent cell qualifies to be switched. FYI all of this code compiles just fine, only issues are incorrect implementation of the move function.

Here is the code:

// function declarations
void init(void) ;
bool move(int tile) ;

// board, whereby board[i][j] represents row i and column j
int board[MAX][MAX]; 

// board's dimension
int dimension = 5 ;

int blank = 95;

int main(void)
{
    init();
    for (int row = 0; row < dimension ; row++)
    {
        for (int column = 0; column < dimension; column++)
        {
            if (board[row][column] > 9)
                printf("%i ", board[row][column]);
            else if (board[row][column] > 0)
                printf("%2i ",board[row][column]);
            else
                printf("%c", blank);
        } 
    printf("\n");
    }

    // prompt for move
        printf("\n");
        printf("Tile to move: ");
        int tile = GetInt();

        // move if possible, else report illegality
        if (!move(tile))
        {
            printf("\nIllegal move.\n");
            usleep(500000);
        }
} 

void init(void)
{
    bool even = false;
    int size = dimension*dimension ;
    if (size % 2 == 0)
    {
        even = true;
    }

    for (int row = 0; row < dimension ; row++)// row count
    {
        for (int column = 0; column < dimension ; column++)// column count
        {
            board[row][column] = size - 1;
            size -- ;
        }       
    }

    if (even)
    {    
        board[dimension-1][dimension-2] = 2;
        board[dimension-1][dimension-3] = 1;
    }
}

bool move(int tile)
{
    // TODO
    for(int row = 0; row < dimension; row++)
    {
        for(int column = 0; column < dimension; column++)
        {   // the loop to execute the switch should only execute if current x;y coordinates match tile
            if (board[row][column] == tile)
            {   
                // if top block is blank ('_' or ACII charachter no 95)
                if (board[row-1][column] == blank)
                {   
                    // switch blank and tile
                    board[row-1][column] = tile;
                    board[row][column] = blank;
                    return true;
                }
                // if left block is blank ('_' or ACII charachter no 95)
                else if (board[row][column-1] == blank)
                {
                    // switch blank and tile
                    board[row][column-1] = tile;
                    board[row][column] = blank;
                    return true;
                }
                // if right block is blank ('_' or ACII charachter no 95)
                else if (board[row][column+1] == blank)
                {
                    // switch blank and tile
                    board[row][column+1] = tile;
                    board[row][column] = blank;
                    return true;
                }
                // if bottom block is blank ('_' or ACII charachter no 95)
                else if (board[row+1][column] == blank)
                {
                    // switch blank and tile
                    board[row+1][column] = tile ;
                    board[row][column] = blank ;
                    return true ;
                }
                // in all other cases return false
                return false ;
             }
          }
       }
       return 0 ;
 }

Answer 1

I don't see where you ever set the blank board value in init to blank; your if statements in move will therefore never be true.

Also, not sure if this is just a practice program, but it's best not to modify main in the distribution code. (or if you do, be sure not to remove the logging portion that is used for grading).