PSET3- Game of fifteen, function move();

Question

So, my move function is ALMOST working, but sometimes when swaping numbers both tile AND blank space shows up as a blank space...can you guys check my code? Thanks! Ps..Blank is a global variable, where the function draw(); keeps the location of the blank space.

bool move(int tile)
{
    int row;
    int column;
    //iterates over the board until tile user typed is found
    for (int i=0; i<d; i++){
        for (int j=0; j<d; j++){
            if (board[i][j] == tile){
                row = i;
                column= j;
            }
        }
    }
                //check if tile is valid: left, right, top or bottom to underline, and return true.
                if (board[row+1][column] == blank) 
             {
                    int aux = board[row][column];
                    board[row][column]=blank;
                    board[row+1][column]=aux;
                    return true;
                }
                else 
                if (board[row-1][column] == blank){
                    int aux = board[row][column];
                    board[row][column]=blank;
                    board[row-1][column]=aux;
                    return true;
                }
                else
                if (board[row][column+1] == blank){
                   int aux = board[row][column];
                    board[row][column]=blank;
                    board[row][column+1]=aux;
                    return true;
                }
                else
                if (board[row][column-1] == blank){
                   int aux = board[row][column];
                    board[row][column]=blank;
                     board[row][column-1]=aux;
                    return true;
                }
                //otherwise return false.
                return false;
  }

Answer 1

This is a common problem. The code is going off the edge of the board. Look at the following:

if (board[row][column+1] == blank){

Let's assume d=3 and column=2. What is at board[row][column+1]? Probably 0. Remember, the two dimensions can't go past d-1 or below 0. In this case, column + 1 = 3 which is too far. Similar logic applies to each of the other cases.

Because its going off the edge, and depending which edge, the code will pull either a 0 (usually) or an unpredictable number (uncommon) into the board.

You need to address this so that the row and column values don't exceed the dimensions of the board.

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