How to use the value of a pop up window and store it as a handle in Matlab GUI

Question

I am getting an error in my code. I have no idea why it is giving an error. I am building a GUI in matlab. I am using the following code:

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'));

a=contents{get(hObject,'Value')};

if a=='CRI'

    b=1

end


if 
a=='GAI'

    b=2

end


if
 a=='CQS'

    b=3


end



handles.indices=b;

guidata(hObject,handles);


when I use this, I am not getting any error. but when I increase my code to the following:


% --- Executes on selection change in popupmenu1.

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'))

a=contents{get(hObject,'Value')}

if 
a=='CRI'

    b=1

end


if 
a=='GAI'

    b=2

end

if
 a=='CQS'

    b=3

end


if
 a=='CRI-CAM02UCS'

    b=4

end


if 
a=='nCRI'

    b=5

end


if
 a=='Luminous Efficacy'

    b=6

end




handles.indices=b;

guidata(hObject,handles);

The error that I get is:

Error using ==

Matrix dimensions must agree.

Error in input_spd>popupmenu1_Callback (line 108)

if a=='CRI-CAM02UCS'

Error in gui_mainfcn (line 96)

    feval(varargin{:});

Error in input_spd (line 42)

gui_mainfcn(gui_State, varargin{:});

Error in

@(hObject,eventdata)input_spd('popupmenu1_Callback',hObject,eventdata,guidata(hObject))

Error while evaluating uicontrol Callback

Answer 1

If you use directly a=='CRI-CAM02UCS' is doing a character-wise comparison of both strings. In case both strings don't have the same number of characters, an error will appear. You can try to change this line by strcmp(a,'CRI-CAM02UCS').