How to convert data byte by byte

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Tayyaba Abro
Tayyaba Abro 2021-1-27
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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采纳的回答

Jan
Jan 2021-1-27
编辑：Jan 2021-1-27
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.
  2 个评论
Tayyaba Abro
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
Jan 2021-1-27
编辑：Jan 2021-1-27
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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更多回答（3 个）

David Hill
David Hill 2021-1-27
d=hex2dec(regexp(a,'[0-9a-f]+','match'));
Steven Lord
Steven Lord 2021-1-27
Ran in:
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.
Jan
Jan 2021-1-27
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.

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