MATLAB: What did they change to ‘fread’ on 2020a

freadMATLABmatlab2020a

The left is 2020a, and the right is 2019a.

As the picture says, it takes significant longer time to execute and sometime it returns different resutls.

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https://www.mathworks.com/help/matlab/release-notes.html?category=data-import-export&rntext=&startrelease=R2020a&endrelease=R2020a&groupby=release&sortby=descending&searchHighlight=

File I/O functions, such as fscanf and fprintf, use automatic character set detection and UTF-8 encoding by default
Behavior change
As of R2020a, character-oriented file I/O functions such as fscanf, fgets, and fgetl trigger automatic character set detection when reading a file that was opened using fopen without a specified encoding.
Similarly, fprintf defaults to using UTF-8 encoding when writing a file that was opened using fopen without a specified encoding

You probably have a large file, and fread() is having to scan through a lot of the file to try to figure out what the character encoding is.

I would suggest that better code for you would be

beg4c = fread(fid, [1 4], 'uint8=>char');

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MATLAB: Saving data in .dat files

There is no specific format for a .dat file. You can use writematrix(): https://www.mathworks.com/help/releases/R2020a/matlab/ref/writematrix.html or dlmwrite(): https://www.mathworks.com/help/releases/R2020a/matlab/ref/dlmwrite.html in older versions.

For example,

writematrix(sr, 'filename.dat') % or dlmwrite('filename.dat', sr);

MATLAB: How to use textscan to read this .dat file? (Part 2)

Given the file formatting given in your last question, this will read the numeric data:

fmt = repmat('%f',1,8);
fmt = ['{%*q%f%*q[',fmt,']%*q[',fmt,']%*q[',fmt,']}'];
fid = fopen('temp.txt','rt');
A = cell2mat(textscan(fid,fmt,'Delimiter','":, ', 'MultipleDelimsAsOne',true));
fclose(fid);

Although strictly speaking the final group of numeric values should be strings, as they occur within double quotation marks. The quotation marks around numeric values makes parsing the data much more difficult and less robust.

The code was tested on this file:

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Related Solutions

MATLAB: Saving data in .dat files

MATLAB: How to use textscan to read this .dat file? (Part 2)

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