@Nicholas Mun If you have an object stored in your handles structure called "text_input", e.g., an edit box where the user enters the string to be encoded, then you don't want to be doing this:
function text_input_Callback(hObject, eventdata, handles)
text_input=get(hObject,'string');
handles.text_input=text_input;
guidata(hObject,handles);
because these two lines:
handles.text_input=text_input;
guidata(hObject,handles);
overwite the value of handles.text_input, and set it to be the 'String' of the uicontrol that was previously known as handles.text_input.
So then any part of the code that expects handles.text_input to be an edit box (or whatever type of uicontrol) will have a problem because handles.text_input is now a character vector (or a string or a cell array - but not a uicontrol).
In your code, as it's shown here, that's not a problem because nowhere in the code refers to handles.text_input expecting it to be a uicontrol. However, there is the potential for the opposite problem: parts of the code expect handles.input_text to be a string (or whatever) when it is actually a uicontrol. Consider what happens if pushbutton2_Callback is executed before text_input_Callback is ever executed (i.e., the user clicks pushbutton2 without having entered text into text_input):
function pushbutton2_Callback(hObject, eventdata, handles)
% handles.text_input here is expected to be the string entered by the user,
% but if text_input_Callback has not been executed yet, then it is still the
% uicontrol handles.text_input ...
userinput = handles.text_input;
output_string = '';
userinput = upper(userinput);
% ... so you'll get an error here, trying to strsplit a uicontrol:
userinput = strjoin(strsplit(userinput));
In order to avoid this problem, you can still store the string the user entered, but don't use a name that's used by a uicontrol you might still need to access. For instance, you might call it text_input_by_user:
function text_input_Callback(hObject, eventdata, handles)
text_input=get(hObject,'string');
handles.text_input_by_user=text_input;
guidata(hObject,handles);
and then in pushbutton2_Callback obviously you would refer to that new name:
function pushbutton2_Callback(hObject, eventdata, handles)
userinput = handles.text_input_by_user;
However, you don't need to store it at all; you can always just get it from the uicontrol itself whenever you need it:
function pushbutton2_Callback(hObject, eventdata, handles)
userinput = get(handles.text_input,'String');
and the uicontrol handles.text_input doesn't need to have a Callback in that case.
