MATLAB Programming

6 Data Import and Export
disp('ANSWER server is awaiting message');
filename = fullfile(tempdir, 'talk_answer.dat');
% Create the communications file if it is not already there.
if ~exist(filename, 'file')
[f, msg] = fopen(filename, 'wb');
if f ~= -1
fwrite(f, zeros(1,256), 'uint8');
fclose(f);
else
error('MATLAB:demo:answer:cannotOpenFile', ...
'Cannot open file "%s": %s.', filename, msg);
end
end
% Memory map the file.
m = memmapfile(filename, 'Writable', true, 'Format', 'uint8');
while true
% Wait till first byte is not zero.
while m.Data(1) == 0
pause(.25);
end
end
% The first byte now contains the length of the message.
% Get it from m.
msg = char(m.Data(2:1+m.Data(1)))';
% Display the message.
disp('Received message from SEND:')
disp(msg)
% Transform the message to all uppercase.
m.Data(2:1+m.Data(1)) = upper(msg);
% Signal to SEND that the response is ready.
m.Data(1) = 0;
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