Author: Normand M. Blais
Date: 11:11:57 09/23/99
Go up one level in this thread
On September 22, 1999 at 15:30:36, Brian Nielsen wrote:
>
>Hi
>
>My name is Brian, i was thinking about writing a chess engine for fun.
>I am pretty experienced programmer/developper(c++,delpie), but have not been
>programming games, thoug i have made a packman clone a couple years ago.
>
>I have done a little research myself to get the principles in making a chess
>engine/program, and i think i now have basic understanding in how to(i hope :-))
>
>i am curious in how you chessgame programmers represent the chessboard, I have
>seen 4-5 different examples/ways in how to do it, how do you do it and why ??
>
>Second how long time does it take to make a basic engine! from scratch
>provided that i am a experienced programmer.
>
>Best regards
>
>Brian Nielsen
Hi,
I'm not using C/C++ (yet) but I thought I could share the idea that I use for
my chess program. It is probably not new but I've nerver seen it mentionned any-
where. It is easy to understand and to implement. So, just for the record, here
it is.
preliminary notes: The lower bound for array indexing is 1 (not 0) in the
explanation below.
1- The board is represented by an array of 64 integers.
1 2 3 4 5 6 7 8 - 8
9 10 11 12 13 14 15 16 - 7
17 18 19 20 21 22 23 24 - 6
25 26 27 28 29 30 31 32 - 5
33 34 35 36 37 38 39 40 - 4
41 42 43 44 45 46 47 48 - 3
49 50 51 52 53 54 55 56 - 2
57 58 59 60 61 62 63 64 - 1
A B C D E F G H
2- A 64 by 8 integer array is used for the piece movements. For each square,
8 directions is recorded:
NW(8) N(1) NE(2)
\ | /
W(7)--- ----E(3)
/ | \
SW(6) S(5) SE(4)
For a given square and a given direction, the index of the adjacent square
is stored. If there is no square (case of a border square), 0 is stored.
directions: 1 2 3 4 5 6 7 8
---------------------------------------
square(1) = 0, 0, 2,10, 9, 0, 0, 0
square(2) = 0, 0, 3,11,10, 9, 1, 0
.
.
.
square(64) = 56, 0, 0, 0, 0, 0,63,55
3- The movement of the pieces are defined in term of directions:
Rook --> 1 to 7 by 2
Bishop --> 2 to 8 by 2
Queen --> 1 to 8 by 1
King --> 1 to 8 by 1
Knight --> {1,1,2},{1,1,8},{3,3,2},{3,3,4},
{5,5,4},{5,5,6},{7,7,6},{7,7,8}
White:
pawn move one --> 1
pawn move two --> {1,1}
pawn captures --> 2,8
Black:
pawn move one --> 5
pawn move two --> {5,5}
pawn captures --> 4,6
4- Enhencements.
A 64 by 8 array can be generated for the knight where the squares stored
for a given direction is the end square of a knight move. Then the knight
movement can be defined this way:
Knight --> 1 to 8 by 1
Best Regards,
Normand M. Blais
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