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Handles not getting updated from pushbutton using GUIDE

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Pratik Chachad
Pratik Chachad on 10 Aug 2021
Commented: Pratik Chachad on 10 Aug 2021
Hello Everyone,
For my own understanding, I am trying to create a simple counter GUI with 2 pushbuttons namely 'Start counting' and 'Stop counting'
Start counting - Starts the counter
Stop counting - Stops the counter
I am having troubles to Stop the running counter using the Stop pushbutton. For some reason the handles.stop which gets set to 1 in the StopCounter_Callback does not reflect in the StartCounter_Callback.
Here is the piece of code.
Any help will be much appreciated. Thanks in advance.
function StartCounter_Callback(hObject, eventdata, handles)
counter = 0;
handles.start = 1;
while (1)
guidata(hObject, handles);
if (handles.stop == 0)
counter = counter + 1;
myString = sprintf('Value is %d', counter);
set(handles.text1, 'String', myString);
drawnow;
pause(0.1);
else
% Reset the Start & Stop button
handles.stop = 0;
handles.start = 0;
return;
end
end
% --- Executes on button press in StopCounter.
function StopCounter_Callback(hObject, eventdata, handles)
if(handles.start == 1)
handles.stop = 1;
end
guidata(hObject, handles);

Accepted Answer

Rik
Rik on 10 Aug 2021

Your looping function doesn't store the modified handle struct.

guidata(hObject, handles);
%put this before your return statement 
  1 Comment
Pratik Chachad
Pratik Chachad on 10 Aug 2021
Hello @Rik Thanks for your response. I think I found the answer. The issue was that I was not retriving the updated elements from handles structure.
"handles = guidata(handles.figure1);"
My updated code is here. Everything works now as expected. Thanks.
function StartCounter_Callback(hObject, eventdata, handles)
% Run the loop once, if start is already running do nothing
if(handles.start == 0)
handles.start = 1;
%save the data
guidata(hObject, handles);
counter = 0;
while (handles.start)
handles = guidata(handles.figure1);
if (handles.stop == 0)
counter = counter + 1;
myString = sprintf('Value is %d', counter);
set(handles.text1, 'String', myString);
drawnow;
else
% Reset the Start & Stop button
handles.stop = 0;
handles.start = 0;
%save the data
guidata(hObject, handles);
end
end
end
function StopCounter_Callback(hObject, eventdata, handles)
% hObject handle to StopCounter (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
if(handles.start == 1)
handles.stop = 1;
end
guidata(hObject, handles);

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