GUI is remembering values entered last time it was open, how to stop this?

I have edit boxes and a push-button that takes their values and runs it through a different function (Some edit boxes don't need to be filled in depending the circumstances). I had used the GUI to test it and it worked fine but after closing it and running it again with some different values, I noticed that it was retrieving data that was in the boxes the last time I ran it and is causing a disruption in the code. I even decided to make it so that if the edit box is empty to make the value equal to 0 but it did not fix the problem! It is still somehow accessing previous values entered? Any idea what might be the problem?

[Stephen23]

@Steve Hermida: please edit your question and upload your code by clicking the paperclip button.

[MechE1]

Just attached it. Apparently the same is happening with my popup menus! If I happen to need the first choice from the menu I obviously wouldn't need to re-click it so I leave it as is, but my values are showing that it is what I previously had chosen from the last time I ran it. Also, my code for making the variables 0 if it is empty isn't working because it thinks there's stuff inside (values from testing before). I even close it to see if that will help but it does not. I'm very confused...

Just tried pressing the push button without entering anything in, and it still somehow managed to retrieve numbers that weren't placed inside.

[Stephen23]

Attack of the global variables!

https://blogs.mathworks.com/videos/2010/03/08/top-10-matlab-code-practices-that-make-me-cry/

Do NOT use global variables. Pass data between functions as input/output arguments or nested functions. Pass data within a GUI by using guidata or nested functions.

https://www.mathworks.com/help/matlab/creating_guis/share-data-among-callbacks.html

https://www.mathworks.com/help/matlab/matlab_prog/share-data-between-workspaces.html

[MechE1]

Seeing my code not work made me cry as well haha! Thank you for your assistance!

Answer 1

[OCDER]

Oh... global variables are used. You should NOT pass GUI data to other functions via global variables. Otherwise your GUI will memorize previous global values until it's cleared with clear global command in the OutputFcn or a CloseRequestFcn.

Looking at your other code, the better fix is to save your "global" variables as handle variable - you almost had it right. Here's an example of your popupmenu1:

function popupmenu1_Callback(hObject, eventdata, handles)
%global n    %DELETE GLOBAL !
n=(get(hObject,'Value'))-1;
handles.n=n; %GOOD! Just need to save the handles now via guidata
guidata(hObject, handles)

%To use these "global" variable in another function, do:
n_value = handles.n;

You'll have to do a lot of similar edits to your code, but it'll be much better than using global.

[MechE1]

Ah okay I did not know this! So once I use guidata for every single edit box/popup menu I would need to do this in the pushbutton callback?

 CV1=handles.CV1; CV2=handles.CV2 ..etc (for every variable)

 FlowAutomator(CV1, CV2, etc)

[OCDER]

instead of saving CV# as:
handles.CV11=CV11;

save numbered variable as a cell like this:
handles.CV{11} = CV11;
guidata(hObject, handles)

When you call the pushbutton at the end that uses FlowAutomator
Do something like this:

function pushbutton1_Callback(hObject, eventdata, handles)
FlowCurveAutomator(handles.CV{1:12}, handles.MOP{1:12},...
handles.Fsg, handles.temp, handles.n, handles.M, handles.gName, handles.savAs)

[MechE1]

Ah okay, that makes it a lot neater. Thank you so much for your help!

[OCDER]

You're welcome!

[MechE1]

Hello, sorry to bother you again, but would I have to define CV as something prior to saving using handles.CV{1}=CV1? I'm confused because wouldn't the GUI not be able to access the "CV" handle if I dont have any object called CV? Only CV1 - CV12

[OCDER]

It should just create the 'CV' field.

handles %doesn't have 'CV'
handles.CV{11} = 12; %creates the 'CV' field and 
                     %assumes it's a cell with 11 elements 
                     %11th element stores 12.

BUT, the better way is initialize CV, and any important variables, in the OpeningFcn to prevent the "index exceeds dimension" error if a value is not given from the user.

 function myGUI_OpeningFcn(hObject, eventdata, handles, varargin)
 handles.output = hObject;
 handles.CV = repelem({0}, 1, 12);
 handles.MOP = repelem({0}, 1, 12);
 guidata(hObject, handles);

[MechE1]

Oh okay, sorry I'm new to GUI's I had assumed that when doing 'handles.Variable' it had to be a GUI object like a text box or button! Thank you again!

[OCDER]

The handle object is indeed a special object of matlab. Behaves almost like a structure, but not exactly the same.

https://www.mathworks.com/help/matlab/matlab_oop/handle-objects.html

Answer 2

[Image Analyst]

Put this line in your OpeningFcn():

clear global;