can not find a file list with fonction ( dir)

hello

I used a function (dir) to get a list of wav files, but it returns an empty list

Folder = 'the folder which contain files';

List= dir([folder '*.wav']);

Why the list is empty?

thank you

[Stephen23]

"Why the list is empty?"

Because you forgot the file separator character between the path and the filename. Use FULLFILE to fix that.

[ChihabEddine CHIHEB]

thank you , it was it

list = dir([folder ,'/*.wav']);

[Stephen23]

Best avoided. Using FULLFILE is more robust (e.g. it will take into acount if the path already has a trailing path separator character, which your code does not do). The best approach by far is to use FULLFILE. You should use FULLFILE.

Answer 1

[Cris LaPierre]

Variables in MATLAB are case sensitive. So Folder is not the same as folder. You define Folder, but then use folder in your dir command.

If that is just a typo here, then the next most likely reason is that you have forgotten to include backslash (or forward slash, depending on your system) at the end of your folder path. A good way to avoid this is by using fullfile to build your path. Here's a simple example using a relative folder path.

Folder = '.\MATLAB Answers'
dir(fullfile(Folder, '*.wav'))

[ChihabEddine CHIHEB]

i got it

it was actuallu in th syntax, i forgot the '/ ' befor the extention

list = dir([folder ,'/*.wav']);

[Steven Lord]

Should you use '/' or '\' before the extension? And what happens if whoever specified the folder actually added the correct slash in the folder path?

Use fullfile as @Cris LaPierre suggested and you don't have to remember which one to use or worry whether your user (who may have selected the folder in question) added the slash themselves. MATLAB will use the correct slash for your operating system and take care of both scenarios.

[ChihabEddine CHIHEB]

i tried it with fullfile without '/ ' i didn't work , the list is empty

but when i useu the '/' it works

dir(fullfile([folder ,'/*.wav']));

[Cris LaPierre]

Steven's point (and mine) is that, with fullfile, you do not need to include the "/" (or the square brackets) at all:

dir(fullfile(folder,'*.wav'));

[Stephen23]

"i tried it with fullfile without '/ ' i didn't work , the list is empty"

The code you showed does not work because you are still concatenating everything together using square brackets:

dir(fullfile([folder ,'/*.wav']));
%            ^                ^ why did you add these?

Look at Cris LaPierre's answer again: is that how they used FULLFILE? (hint: no).

The whole point of FULLFILE is that it joins its input arguments together with file separator characters, just as its documentation shows. However what you did is to concatenate everything together first and then call FULLFILE with only one input argument.... which does nothing.

In contrast the syntax that the FULLFILE documentation shows and that Cris LaPierre used is the robust, best approach. It works. That is why FULLFILE exists.

[ChihabEddine CHIHEB]

yes i understand what you said Cris, i tried it , and the list was empty,

but when i put the / mark , it works , now the algorithm is working , im trying to understand why .

i did this :

list = dir(fullfile([folder ,'*.wav'])); % and the l ist was empty 
% but with :
list = dir(fullfile([folder ,'/*.wav']));% i got my table correctly 

[Cris LaPierre]

Use the Copy option from my post rather than typing the code yourself.

You are erroneously including square brackets "[]", which is preventing fullfile from doing its thing.

dir(fullfile(folder,'*.wav'));

[Stephen23]

@ChihabEddine CHIHEB: compare:

dir(fullfile(Folder, '*.wav')) % the correct code, as Chris LaPierre showed you.
dir(fullfile([folder ,'*.wav'])); % your code, with square brackets.
%            ^               ^ why do you keep adding these?