Using a variable in fopen

I want to run a loop that will access files from multiple folders

I used dir to retrieve the names of the folders and I want to be able to feed the names into fopen.

ex:

folder = dir('W:\Examples')

#_of_folders = numel(folder)

for i=1:#_of_folders

fid = fopen('W:\Examples\folder([i])')

...

end

How can I enter that variable into fopen? Is there a better way of achieving this?

I did take a look at this thread, but I am still having trouble.

http://www.mathworks.com/matlabcentral/answers/114582-how-i-use-a-variable-name-to-do-a-fid-fopen

Thank you

[Stephen23]

Don't forget to use fclose after you have read the file data! This will save a lot of bug-finding nightmares later...

Answer 1

[Iain]

 init = 'W:\Examples';

 folder = dir(init)
 for i  = 1:numel(folder)
  % do something with folder(i) to figure out if it's a file you want to open, or a folder you want to search, and if so:
 filename = [init '\' folder(i).name]; % or  filename = [init '\' folder(i).name '\' folder(i).name '.abc']; if you know that the folders contain files with the same name as the folder and a fixed extension...
 % do something with filename
 fid =  fopen(filename,'r');
 end

Answer 2

[Ken Atwell]

You can use fullfile as a convenient way to create a full path from parts. 'folder' as returned by dir will be an array of structs -- you are interested in the 'name' field.

(Note you can't use "#" as part of a MATLAB variable name, so I've use "num_files" instead)

 folder = dir('W:\Examples')
 num_files = numel(folder)
 for i=1:num_files
     fid = fopen(fullfile('W:\Examples', folder(i).name))
     ...
 end

[Andrew]

Thank you for your answer.

An addition question, I need access to files in those folders.

Initially i had:

fid = fopen('W:\Examples\foldername\folder\file')

In the line above, I am retrieving the foldername (through dir)as mentioned in my original question. The folder in those " foldernames" and the file in that are the same for each on of those " foldernames".

How can I write this?

[Ken Atwell]

I'm not quite following, but you can pass an arbitrary number of pieces to fullpath:

 fid = fopen(fullpath('W:\Examples', folder(i).name, 'folder', 'file'))

[Andrew]

Thank you, this worked perfectly