MATLAB Answers

1

Check if filename is valid.

Asked by Qingyang on 20 Jul 2012
Latest activity Answered by Thomas on 1 Dec 2017
Hi, is there a native function or a simple code to check if a user-typed filename is valid for saving a file? (In that it doesn't contain illegal characters like /\":?<>|, etc.)

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4 Answers

Sean de Wolski
Answer by Sean de Wolski
on 20 Jul 2012
 Accepted Answer

regexp it!

  3 Comments

Qingyang on 20 Jul 2012
So it would be like this?
if regexp(fname, '[/\*:?"<>|]', 'once')
do something about it?
end
Jan
on 23 Jul 2012
Let UIPUTFILE check the file name instead of using an edit control.
This code snippet will not work unless you check if it is empty.
if ~isempty(regexp(filename, '[/\*:?"<>|]', 'once'))
%Do something
end

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Answer by Daniel Shub
on 23 Jul 2012

A long time ago, probably Windows 95 on a FAT16 harddisk, I started using the following:
regexp(fname, ['^(?!^(PRN|AUX|CLOCK\$|NUL|CON|COM\d|LPT\d|\..*)', ...
'(\..+)?$)[^\x00-\x1f\\?*:\"><|/]+$'], 'once'));
At that time, Windows had the most restrictive file name conventions. I am not sure what the rules are now. You also should check for the length of the path and the total number of characters in the file name.

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Jan
on 23 Jul 2012
Windows 7: Either 260 characters, or start with //?/ and 32767 characters, while each folder can have up to 255 characters. The later works for most of the API-functions, but not e.g. for the Windows Explorer. Moving a file name with a long name to the RecycleBin fails also. The backup program and server based tools might fail also. Therefore I'd prefer the dull limit of 260 characters (including "C\:" and a trailing terminator '\0')!).

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Answer by ola bayo
on 16 Oct 2017
Edited by Walter Roberson
on 16 Oct 2017

Which following is a valid file name in MATLAB?
A) lab 2
B) lab2
C) lab-2
D) 2lab
E) LAB 2

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Walter Roberson
on 16 Oct 2017
For the question as phrased: all of them. For a slightly different question, the answer would be fairly different.

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Answer by Thomas on 1 Dec 2017

If you do not want to use UIputfile, another option is fopen. fileID = fopen(filename,'w') if fopen cannot open the file, then fileID is -1.

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