Object-oriented Software in Ada 95

110 Arrays
Note:
That the case statement which effects the change between the player’s mark has a when others
clause. This is required as in theory a player can take any character value. The code for this
‘impossible’ eventuality is the null statement.
The character object player holds a representation of the current player’s mark, in this case either the
character 'X' or 'O'. The object player is initially set to 'X', and after each player's move is changed to the
other player’s mark.
8.4.3 Displaying the Board
The procedure Display uses the method Cell in class Board to help display a textual representation of the
board on the user’s terminal. The procedure Display is implemented as follows:
with Class_Board, Ada.Text_Io;
use Class_Board, Ada.Text_Io;
procedure Display( The:in Board ) is
begin
for I in 1 .. 9 loop
Put( Cell( The, I ) );
case I is
--after printing counter
when 3 | 6 => -- print Row Separator
New_Line; Put("---------"); --
New_Line;
when 9 => -- print new line
New_Line;
when 1 | 2 | 4 | 5 | 7 | 8 => -- print Col separator
Put(" | ");
end case;
end loop;
end Display;
The procedure Display prints the board on to the player’s terminal. The strategy for printing the board is to
print each cell followed by a character sequence appropriate for its position on the board. The text to be printed
after each square of the array sqrs has been printed is as follows:
Printed board showing
array index of cell in array
Sqrs
1 | 2 | 3
---------
4 | 5 | 6
---------
7 | 8 | 9
After printing cell:
Text to be printed
(Using Ada.Text_Io)
1,2,4,5,7 and 8 Put(" | ");
3 and 6 New_Line;
Put("---------");
New_Line;
9 New_Line;
© M A Smith - May not be reproduced without permission