Writting multiple files with fopen 'w'

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Cristian Martin
Cristian Martin on 20 May 2022
Commented: Voss on 20 May 2022
fileID = fopen('text\test.txt','w');
fprintf(fileID,'Comments:');
fclose(fileID);
Hi,
What can I do to not overwrite the previous file
There is a way for every time I run the script to make another file and not rewritte the old one, like test1.txt, test2.txt and so on?

Accepted Answer

Voss
Voss on 20 May 2022
Here's a function (get_unused_file_name) you can use for this purpose. It takes a file name and check if that file already exists. If it does, the function appends '1' to the name and checks if that exists. If it does, it tries '2', and so on until it gets one that doesn't already exist, and returns that unused file name.
Here's a demonstration of it:
fn_orig = fullfile(pwd(),'text','test.txt') % file name to try
fn_orig = '/users/mss.system.Cr4l4C/text/test.txt'
mkdir('text')
% calling the function 4 times
for ii = 1:4
fn = get_unused_file_name(fn_orig)
% create the file so that next time around
% this file name is already taken:
fid = fopen(fn,'w');
fclose(fid);
end
fn = '/users/mss.system.Cr4l4C/text/test.txt'
fn = '/users/mss.system.Cr4l4C/text/test1.txt'
fn = '/users/mss.system.Cr4l4C/text/test2.txt'
fn = '/users/mss.system.Cr4l4C/text/test3.txt'
function file_name = get_unused_file_name(file_name)
[pn,fn,ext] = fileparts(file_name);
ii = 0;
while isfile(file_name)
ii = ii+1;
file_name = fullfile(pn,sprintf('%s%d%s',fn,ii,ext));
end
end
  7 Comments
Voss
Voss on 20 May 2022
You're welcome! Sorry about the snag with isfile, but I'm glad it's working now!

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