fprintf can't make new line

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Gifari Zulkarnaen
Gifari Zulkarnaen on 22 Feb 2020
Edited: Stephen23 on 23 Feb 2020
I want to edit a line of a text file (tcl file actually). I tried with following code:
A = 5;
tcl = regexp(fileread('old_file.tcl'), '\n', 'split')';
tcl{3} = char(strcat("set A ",num2str(A),".0"));
fid = fopen('new_file.tcl','w');
fprintf(fid,'%s\n',tcl{:});
fclose(fid);
But it can't create new line after line 3. Instead, it create a character looks like small circle with black background, shown in figure below. I tried using fid==1 to check, it works fine in command window. How do I fix this? And if there is inefficiency in my code, suggestions are really appreciated. Thanks in advance.

Accepted Answer

Stephen23
Stephen23 on 22 Feb 2020
Edited: Stephen23 on 22 Feb 2020
Try opening the file in text mode, not binary mode:
A = 5;
tcl = regexp(fileread('old_file.tcl'), '[\n\r]+', 'split')';
tcl{3} = sprintf('set A %u.0',A);
fid = fopen('new_file.tcl','wt'); % text mode!
fprintf(fid,'%s\n',tcl{:});
fclose(fid);
  6 Comments
Gifari Zulkarnaen
Gifari Zulkarnaen on 23 Feb 2020
Edited: Gifari Zulkarnaen on 23 Feb 2020
Amazing, I understand now, thank you very much for your time answering and explaning, really appreciate it. Your last format works very well, except that I need to delete last cell element so that it doesn't create additional empty last line in each iteration. Thankyou2.
function gap = objective(A)
tcl = regexp(fileread('Truss2.tcl'), '\r?\n', 'split')'; % '\r?\n'
tcl{50} = sprintf('set A %g',A);
tcl(end) = [];
fid = fopen('Truss2.tcl','wt'); % must be text mode!
fprintf(fid,'%s\n',tcl{:}); % '%s\n'
fclose(fid);
!OpenSees.exe Truss2.tcl
clc
fid2 = fopen('example.out','r');
formatSpec = '%d %f';
sizeA = [1 Inf];
data = fscanf(fid2,formatSpec,sizeA);
fclose(fid2);
d = data(2);
gap = abs(d - 5);
end
Stephen23
Stephen23 on 23 Feb 2020
Edited: Stephen23 on 23 Feb 2020
"...except that I need to delete last cell element so that it doesn't create additional empty last line in each iteration"
This is due to a trailing newline in the file, which when the text is split by regex creates an empty cell at the end of the array, which is thus printed as another line of text... itself with a newline at the end! I don't recommend just removing the last cell, because if the file does not end with a newline, then you will delete the last line of the file without any warning.
A more robust solution would be to check if the last cell is empty before deleting it, or to remove trailing whitespace when you import the file string:
str = deblank(fileread('Truss2.tcl')); % remove trailing whitespace
tcl = regexp(str,...)

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