Pop-up Menu Issue

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Zeeshan Abbas 2019-7-26

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/473620-pop-up-menu-issue

评论： Zeeshan Abbas 2019-7-27

在 MATLAB Online 中打开

I have a pop-up menu having two options:

Get message from user
Upload message from file

The 2nd option is working fine but when I choose 1st option it's giving error:

    Reference to non-existent field 'message'.
    Error in mainmain>Embed_Callback (line 201)
    message=handles.message;

The pop-up buttons function is as below:

function popupmenu1_Callback(hObject, eventdata, handles)
% hObject    handle to popupmenu1 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)
% Hints: contents = cellstr(get(hObject,'String')) returns popupmenu1 contents as cell array
%        contents{get(hObject,'Value')} returns selected item from popupmenu1
Contents =cellstr(get(hObject,'String'));
pop_choice=Contents(get(hObject,'Value'));
pop_choice;
if (strcmp(pop_choice,'Enter Message'))
message=get(handles.EnterMessage,'string');
handles.message=message;
elseif (strcmp(pop_choice,'Upload Message'))
 [file,Path]=uigetfile('*.txt','Select file to read message,'.')
  message = fileread(fullfile(Path,file));
  handles.message=message;
end
guidata(hObject,handles)

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Rik 2019-7-26

The string property contains a char array, not a string. This confusion was created when Mathworks introduced strings as a new data type, but (luckily) didn't rename properties or change their data types. That means both paths in your code should lead to char arrays.

So now the question is: have you made sure the message field contains a non-empty char array? And what do you mean with decoding?

Zeeshan Abbas 2019-7-27

Oh thanks for the clarification. Actually I am working on steganography so when I am embedding message using the uploading file I can extract the message properly but when I am getting input from user and then extracting the message it’s giving garbage value. Might be the field is not getting the user input. Making clear that both is working fine in editor and creating issue on GUI only.

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