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autorename if saved file already exist

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is there an option in save (or any other function) which support automatic renaming if the filename already exists or do I need to check by myself? (like saving as file2.mat if file.mat already exist)

Accepted Answer

Jan on 14 Jan 2012
You have to check it by your own if a file is existing already.
[EDITED: Consider {File.txt, File3.txt}]
function SaveWithNumber(FileName, Data)
[fPath, fName, fExt] = fileparts(FileName);
if isempty(fExt) % No '.mat' in FileName
fExt = '.mat';
FileName = fullfile(fPath, [fName, fExt]);
if exist(FileName, 'file')
% Get number of files:
fDir = dir(fullfile(fPath, [fName, '*', fExt]);
fStr = lower(sprintf('%s*',;
fNum = sscanf(fStr, [fName, '%d', fExt, '*']);
newNum = max(fNum) + 1;
FileName = fullfile(fPath, [fName, sprintf('%d', newNum), fExt]);
save(FileName, 'Data');
Limitations: "FileNameInf.txt" and "FileNameNaN.txt" will cause troubles...
Consider, that:
exist(FileName, 'file')
replies TRUE for directories also.
Image Analyst
Image Analyst on 14 Jan 2012
Other options could be alerting the user that the file exists and to either
(1) Cancel (Skip it),
(2) Overwrite with the same name, or
(3) Use the new name determined by Jan's nice function, or
(4) call uiputfile to let the user supply a name.
You could use menu() to present the user with those options.
Jan on 14 Jan 2012
My "nice" function is too lazy: Imagine these files are existing already: File.txt, File3.txt. Now the user wants to save File.txt - now the function tries to create File3.txt and fails recursively.
I'm posting a new version, which is hopefully smarter.

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More Answers (1)

Diaa on 1 Oct 2020
Edited: Diaa on 1 Oct 2020
Revisitng this old question, I followed the idea of Jan to come up with this solution of appending the existent file name with an incremental number enclosed in parentheses.
if exist(filename,'file')
[fPath, fName, fExt] = fileparts(filename);
fDir = dir(fullfile(fPath, [fName,' (*)', fExt]));
if isempty(fDir)
filename = fullfile(fPath, [fName,' (1)', fExt]);
pattern = "(" + digitsPattern + ")" + fExt;
hasThePattern = endsWith(extractfield(fDir,'name'),pattern);
Extracted = extract(extractfield(fDir(hasThePattern),'name'),pattern);
num = max(cell2mat(cellfun(@(C) textscan(C,'(%d)') , Extracted,'UniformOutput',true)));
num = num+1;
filename = fullfile(fPath, [fName,' (',num2str(num),')', fExt]);
Mohammed Attrash
Mohammed Attrash on 9 Jul 2023
You can add to your file name the following
This will create a unique name
Walter Roberson
Walter Roberson on 9 Jul 2023
It can sometimes be important to preserve the file extension, so make sure that is added before the extension.
These days it is better to use
string(datetime('now', 'format', ''))
ans = "2023.07.09_08.27"

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