sad face on move and won fifteen

Question

i can't figure out why i get the sad faces on move and won.Help will be appreciated.i am an able to post the code right in this forum. https://pastebin.com/RXwnUqaz

  */
bool move(int tile)
{//to do
int blank_space=0;
for(int i=0;i<d;i++)
{
for(int j=0;j<d;j++)
{
 if(board[i][j]==blank_space)
 {
 //iterate to check the position of of blank tile;left to right up and down 
if not return false
 if( (i-1)>=0 && board[i-1][j]==tile)
 {
  int temp=board[i-1][j];
  board[i-1][j]=board[i][j];
  board[i][j]=temp;
    return true;
}
  if((j-1)>=0 && board[i][j-1]==tile)
{
  int temp=board[i][j];
  board[i][j]=board[i][j-1];
  board[i][j-1]=temp;
  return true;
}
 if((i+1)<=(d-1) && board[i+1][j]==tile)
{
  int temp=board[i][j];
  board[i][j]=board[i+1][j];
  board[i+1][j]=temp;
  return true;
}
if((j+1)<=(d-1) && board[i][j+1]==tile)
{
   int temp=board[i][j];
   board[i][j]=board[i][j+1];
   board[i][j+1]=temp;
   return true;
}
}
}
}
return false;
}

  /**
* Returns true if game is won (i.e., board is in winning configuration),
* else false.
*/
bool won(void)
{
// TODO
int checker=1;
for(int i=0;i<=d;i++)
{
for(int j=0;j<=d;j++)
{
    if (checker!=board[i][j] && board[d-1][d-1]==0)
    {
        return false;
    }
    checker++;
    }
 }
 return true;
 }

Answer 1

&& tile<d*d && tile>0 doesn't add value. Won't hurt either.

(i-1)>=0 should be placed before board[i-1][j]==blank_space. The && operator tests the left side first, and if it is zero, won't evaluate the right side (short-circuit evaluation). So by placing (i-1)>=0 first, you don't risk a segfault.

The move function is not the most efficient one, but looks valid otherwise.

won, however, is wrong in two ways.

1. if (checker!=board[i][j] ) does not account for the empty tile, like for example if (checker % (d * d) != board[i][j]) would, using the remainder operator for the wrap-around.
2. With board[i][j]=checker++;, you change the board's content. Based on the code around, you would see an effect only after fixing 1. and winning the game, as this would turn the empty tile from value 0 to d*d then. Just use checker++; without an assignment.