MATLAB: Fopen gives negative fid in GUI

fopenguiguideuigetdir

I started a GUI using GUIDE. I have a browse button that uses uigetdir to get path to folder where I have some excel files, that later on I will read with my script. Problem is in fopen who gives message: No such file or dir. I used debugger and went step by step and to me everything seems to be ok, file path is correctly stored, I don't know what could be the problem. I tried with uigetfile but he only gets path to specific file, and I will have maybe 400 files in that folder.

Help is greatly appreciated.

This part of the code is from gui:

function Browse_1_Callback(hObject, eventdata, handles)
% hObject    handle to Browse_1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
FileName = uigetdir;
handles.FileName = FileName;
guidata(hObject,handles)

This part from script that runs after button press:

myFolderPV = handles.FileName;
  PVFiles = dir(fullfile(myFolderPV,'*.js'));
   numfilesPV= length(PVFiles);  
  for k = 1:numfilesPV
    [fid, message] = fopen(PVFiles(k).name);
  ...

Best Answer

Your filename is wrong.

You need to have the full path and filename for fopen to work.

[myfolderPV '\' PVFiles(k).name] is your full filename.

Related Solutions

MATLAB: How to use path- and filename from GUI in matlab script

Thore - rather than using global variables, try changing your script into a function which accepts the path to and name of some file. For example,

 function FixedLineString(filename, pathname)
 if isempty(filename) || isempty(pathname) 
     [filename,pathname] = uigetfile('*.DAT','Select the .DAT file');
 end
 % etc.

The above code allows for the filename and pathname to be optional so that if at least one is not provided, then the user is prompted to choose a file.

Now in your GUI, you would save the path to and the name of the file to your handles structure as

 function pushbutton1_Callback(hObject, eventdata, handles)
 [filename, pathname] = uigetfile('*.DAT');
 set(handles.text3, 'String', filename);
 handles.filename = filename;
 handles.pathname = pathname;
 guidata(hObject,handles);

Then, when you want to pass the path and name of the file to your (new) function, you would do

 function Start_button_Callback(hObject, eventdata, handles)
 pathname = [];
 filename = [];
 if isfield(handles,'pathname') && isfield(handles,'filename')
    pathname = handles.pathname;
    filename = handles.filename;
 end
 FixedLineString(pathname,filename);

In the above, we check to make sure that handles has fields for both pathname and filename before trying to access either. If both exist, then we pass both to your function. Else we pass empty input parameters which will cause your function to request the the user choose a file.

Try the above and see what happens!

As an aside, I noticed that in your callbacks you typically did

 handles = guidata(hObject);

This is unnecessary as the third input to all callbacks is already the handles structure and so calling the above just duplicates what already has been done. Also, you only need to call

 uidata(hObject, handles);

if you have updated the handles structure as we did in pushbutton1_Callback. Otherwise, there is no need to call it.

MATLAB: Importing .txt file into matlab push button

Hi Faiza,

change

handles.fileData = fscanf(fileID,'%d');

to

temp = fscanf(fileID,'%d',[8 Inf]);
handles.fileData = temp';

That should work

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