Author: Normand M. Blais
Date: 11:11:57 09/23/99
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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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