How to read data from a file into cell array keeping indents undisturbed

I am trying to read a data from a file, modify it and write to a same file which I did using,

fid  = fopen('file.ext','r');
fclose(fid);
lines = textscan(fid,'%s','Delimiter','\n');
...
fid  = fopen('file.ext','w');
for row = 1:length(lines{1})
    fprintf(fid,'%s\n',lines{1}{row});
end
fclose(fid);

But I could not reproduce the indents which were in the original file. So any suggestions to achieve this and make the above process easier?

Note: the file extension is not .txt but similar to text format. The data which I try to read has html tag elements and attributes.

I would also like to know whether there is any way to directly modify a file without reading it?

Thanks in advance!

[Jan]

If you close the file by fclose before running textscan, the code should fail with an error message.

[Shankar Santhosh]

You are right! I just misplaced the lines in this query. But I had it right in my code.

Answer 1

[Jan]

% Import file:
Str = fileread('file.ext');

% Remove trailing line break to avoid appending an additional empty line:
if ~isempty(Str) && Str(numel(Str)) == char(10)
    Str(numel(Str)) = [];
end

% Split lines:
% lines = strsplit(Str, char(10));
% Faster but uglier (this is what happens inside STRSPLIT):
lines = regexp(Str, ['(?:', char(10), ')+'], 'split');
...

% Write output:
fid = fopen('file.ext', 'w');
fprintf(fid, '%s\n', lines{:});
fclose(fid);

[Shankar Santhosh]

This is exactly what I needed !

Working fine with my scenario. Thanks a lot.

You are great ../\..

Answer 2

[Rik]

You can get my readfile function from the FEX or through the AddOn-manager (R2017a or later).

It will read a file to a cell array, one cell element per line, and it will preserve all leading and trailing spaces.

One of the advantages of a cell array is that you can trivially write out the modified file: fprintf(fid,'%s\n',txt{:}).

[Shankar Santhosh]

This is great, but I am in a situation where I need to make this change that should be compatible in all MATLAB releases starting from R2012b. Anyway thanks for the info.

[Rik]

This is compatible all the way back to Matlab 6.5, and it works on GNU Octave.

[Shankar Santhosh]

Oh Sorry that I misunderstood. This approach also seem to work well.