Fread problem...

Question

jason beckell 2012-1-26

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/27153-fread-problem

Hello to everyone!

I have a problem with the following simple portion of code:

b = rand(5, 1);
fid = fopen('prova.bin', 'w');
fwrite(fid, b);
fclose(fid);
% Read the contents back into an array
fid = fopen('prova.bin');
B = fread(fid, 5, 'double');
fclose(fid);

Fread doesn't seem to work, how come ? Has any of you got an idea?

Thank you very much and my best regards! Jason.

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Answer 1

Thomas 2012-1-26

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Add type 'double' in your fwrite

b = rand(5, 1);
fid = fopen('prova.bin', 'w');
fwrite(fid, b,'double');       % add type double here
fclose(fid);
% Read the contents back into an array
fid = fopen('prova.bin');
B = fread(fid, 5, 'double');
fclose(fid);

should work

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Answer 2

Bård Skaflestad 2012-1-26

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/27153-fread-problem#answer_35330

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You need to specify the precision of the data you output using fwrite is double. Otherwise, the subsequent fread operation fail. I'd write the above as

b = rand(5, 1);
fid = fopen('prova.bin', 'w');
fwrite(fid, b, 'double');
fclose(fid);
% Read the contents back into an array
fid = fopen('prova.bin');
B = fread(fid, 5, 'double');
fclose(fid);