Part of the "Chess in C" blog post series. Code to calculate the up-right diagonal.

chessInCPart6-upRightDiagonal.c

    /* Calculate possible up-right diagonal destinations.
	 *  This requires the loop to iterate backwards as we are
	 *  checking cells before the bishop. */
	for (i=7; i>=0; i--) {
	  for (j=7; j>=0; j--){
			/* If 1) the cell to left is inbounds of the array and
			*     2) the cell isn't not on the final row */
		if ((j-1 != -1) && (i != 7)) {
		  /* ...and the below-left cell has a bishop OR a breadcrumb... */
		  if (board[i+1][j-1] == BISHOP || board[i+1][j-1] == POTENTIAL_MOVE_BISHOP_UR) {
			/* ...then leave a breadcrumb */
			board[i][j] = POTENTIAL_MOVE_BISHOP_UR;
		  }
		}
	  }