function pushbuttonLoadfiles_Callback(hObject, eventdata, handles)
[filename,pathname,filterindex] = uigetfile('*.xls;*.xlsx;*.xlsm;*.xlsb', 'Multiselect', 'on');
set(handles.listboxExcelfiles, 'string', fullfile(pathname, cellstr(filename)) );
function pushbuttonExtract_Callback(hObject, eventdata, handles)
source_files = numel(get(handles.listboxExcelfiles,'value'));
len = length(source_files);
for i = 1 : len
[~ , sheets] = xlsfinfo(source_files{i});
sheetIndex = find(strncmp(sheets, '~', 1));
wanted_sheets = sheets(1, sheetIndex);
set(handles.listboxDatasheets, 'string',wanted_sheets);
end
The cellstr() compensates for the fact that if the user only selects a single file then 'MultiSelect', 'on' returns a char vector, but if more than one is selected then it returns a cell array of char vector. The cellstr() detects the char vector case and wraps it in a cell.
The fullfile is needed because you need to know the directory to read from, as you indicated that the directory is not always the same.
The change from source_files(i) to source_files{i} is needed for xlsfinfo to not give the message you were seeing.
Note that for every different selected file, you overwrite the listboxDatasheets controls. If you want to support a different sheet selection for each file then you will need to build controls for that, since any one listbox item cannot be a cell array of character vectors in turn.
