How to convert data byte by byte

Question

Tayyaba Abro 2021-1-27

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回答： Jan 2021-1-27

I have read a file and data im getting is shown below. I have to convert this data byte by byte in decimal number please tell me how can I do that ?

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Jan 2021-1-27

Typing an answer would be easier, if the file or its contents is provided as text.

James Tursa 2021-1-27

https://www.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer?s_tid=ta_ans_results

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Answer 1

Jan 2021-1-27

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编辑：Jan 2021-1-27

在 MATLAB Online 中打开

Do you really mean byte by byte? The variable read conatins 16 bit characters of the text as unicode, so a byte by byte conversion is:

read = '|0|01|00|5e|'
typecast(uint16(read), 'uint8')

The original text might be a ASCII text, then import it as bytes directly:

fid = fopen('packettext.txt', 'r');
if fid < 0, error('Cannot open file.'); end
bytes = fread(fid, inf, '*uint8');
fclose(fid);

Maybe you want to import the numbers and convert them from hex to decimal?

S = fileread('packettext.txt');
values = sscanf(S, '|%x', [1, inf]);

To clarify this, please post an example with input data and the wanted output.

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Tayyaba Abro 2021-1-27

编辑：Tayyaba Abro 2021-1-27

Actually I am taking data from wireshark in text format so it is showing like the picture that I have shared above. When taking data in pcap format it shows ASCII data but im unable to extract that

Jan 2021-1-27

编辑：Jan 2021-1-27

在 MATLAB Online 中打开

Another option:

fid = fopen('packettext.txt', 'r');
if fid < 0, error('Cannot open file.'); end
bytes = fscanf(fid, '|%x', [1, inf]);
fclose(fid);

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Answer 2

David Hill 2021-1-27

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d=hex2dec(regexp(a,'[0-9a-f]+','match'));

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Answer 3

Steven Lord 2021-1-27

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s = '|0|01|00|5e|'
s = '|0|01|00|5e|'
data = split(s, '|')
data = 6x1 cell array
    {0×0 char}
    {'0'     }
    {'01'    }
    {'00'    }
    {'5e'    }
    {0×0 char}
d = hex2dec(data)
d = 6×1
     0
     0
     1
     0
    94
     0

If you want to eliminate the first and last 0 in d, trim the leading and trailing | characters from s before splitting.

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Answer 4

Jan 2021-1-27

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A comparison of the runtimes:

s = repmat('|0|01|00|5e', 1, 2000);
tic
for k = 1:100
    d = hex2dec(regexp(s, '[0-9a-f]+', 'match'));
end
toc
tic
for k = 1:100
    d = hex2dec(split(s, '|'));
end
toc
tic
for k = 1:100
    d = sscanf(s, '|%x');
end
toc
tic
for k = 1:100
    d = sscanf(strrep(s, '|', ' '), '%x');
end
toc
% Elapsed time is 0.909770 seconds.
% Elapsed time is 0.424414 seconds.
% Elapsed time is 0.272269 seconds.
% Elapsed time is 0.163054 seconds.