is_in_check.m

国际象棋程序,解压到当前目录,在matlab窗口输入chess即可应用

function [answer, color] = is_in_check(from, to)
% is_in_check  Whether a figure will be in check.
% If a figure is moved from a to b, whether and if, which color is in check
% 
% This function is useful for the castling and to check whether a move is legal.
%
% Inputs:
% * from ... field from where the chess figure will move
% * to ... field to which it is supposed to move
% * global history ... the game history
% * global board ... the chess board and realted information
%
% Outputs:
% * answer ... Boolean answer (true if the figure was moved once).
% * color ... the color of the king which is checked (default black)
%
% Example
% Assume there is a certain chess postion and you like to try to move
% a chess figure from d4 [5 4] to d3 [6 4], then |is_in_check([5 4],[6 4])|
% will tell you whether this move will cause any king to be in check and
% "color" will tell you which king it will be. (Note, that the figure is
% not moved.)
%
% See also: King, Chess
%
% ToDo:
% It is possible that both kings are checked!
%
%% Signature
% Author: W.Garn
% E-Mail: [e-mail]
% Date: 2006/03/23 12:00:00 
% 
% Copyright 2006 W.Garn
%

answer = 0; % not in check
color = 0;
try_moving = 0;
global board
persistent avoid_recursion %empty when called the first time

if isempty(avoid_recursion)
    avoid_recursion = 1;
    if nargin==2 % move first the figure
        if board.figures(from(1),from(2)) ~= ' ' %there is a figure moved
            try_moving=1;
            %figures
            fig_to = board.figures(to(1),to(2)); %remember
            board.figures(to(1),to(2))=board.figures(from(1),from(2));
            board.figures(from(1),from(2))=' ';
            %values
            w_to = board.white(to(1),to(2)); %remember
            board.white(to(1),to(2))=board.white(from(1),from(2));
            board.white(from(1),from(2))=0; %free it up
            b_to = board.black(to(1),to(2)); %remember
            board.black(to(1),to(2))=board.black(from(1),from(2));
            board.black(from(1),from(2))=0; %free it up
        end
    end


    % look whether king is in check
    [answer, color] = in_check;

    % move figure back from where it came
    if try_moving %then reset
        %figures
        board.figures(from(1),from(2))=board.figures(to(1),to(2));
        board.figures(to(1),to(2)) = fig_to;

        %values
        board.white(from(1),from(2)) = board.white(to(1),to(2));
        board.white(to(1),to(2)) = w_to;
        board.black(from(1),from(2)) = board.black(to(1),to(2));
        board.black(to(1),to(2)) = b_to;
    end % finished reversing move
    avoid_recursion = []; %lift recursion prohibtion
end


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