Undefined operator '==' for input arguments of type 'struct'. netcdf files

I'm trying to do a loop to open netcdf files (14 files) and to extract some variables(temperature, salinity and velocity). This is what I've got so far. But I get the error:

Undefined operator '==' for input arguments of type 'struct'.

And I don't understand how to fix it. I know it must be something very simple, but I'm still quite new with matlab. Thanks for your time

clear
myFolder = ('C:\modelana\netcdf_2019\');
if ~isfolder(myFolder)
    errorMessage = sprintf('Error: The following folder does not exist:\n%s', myFolder);
    uiwait(warndlg(errorMessage));
    return;
end

ncFilename = dir([myFolder '*.nc']);

for k = 1:length(ncFilename)
    myfolder = fullfile(ncFilename(k).folder,ncFilename(k).name);
    if isempty(ncFilename == 1)
        continue;
    else
        ncfile =([myFolder ncFilename]);
        s(k,:) = ncread(ncfile,'salinity')  ;
        t(k,:) = ncread(ncfile,'temp')  ;
        u(k,:) = ncread(ncfile,'u') ;
    end
end

[KSSV]

isempty(ncFilename)

[Ana Corrochano]

Thank you for your answer. Now I'm having the following error:

Error using horzcat

The following error occurred converting from char to struct:

Conversion to struct from char is not possible.

[jessupj]

where it that occurring? i suspect that it doesn't like

[myFolder ncFilename]

because you're trying to concatenate a string (my Folder) with whatever kind of non-string object 'ncFilename' is. Note that 'ncFilename' is the object whose length you're iterating over in the loop. You maybe need:

[myFolder ncFilename(k).name]  % or something like that.

Just a tip on some other programming: it looks like you use both 'myfolder' and 'myFolder' as different variables. I would avoid that by calling them something more distinguishable, like 'folder1' and 'folder2' so that 'errors' and 'typos' are easier to tell apart.

[per isakson]

See

• Debug a MATLAB Program and
• Examine Values While Debugging

Answer 1

[Chidvi Modala]

In the provided code the resultant variable 'ncFilename' is of struct datatype. By doing this ([myFolder ncFilename]) operation you are trying to concatenate a struct with character array. Hence the error. To avoid the error, you can replace ([myFolder ncFilename]) with something like below

ncfile =([myFolder ncFilename(k).name]);

To get a proper ncfile value, you might need to add '\' as shown below

ncfile =([myFolder '\' ncFilename(k).name]);

To know more about 'struct' datatype you can refer to this

[jessupj]

OP's 'myFolder' already includes the backslash, so the second line of code here isn't necessary. Just use the first one as we both suggested. Also, one wouldn't need need parenteses around brackets.