Making a button display a value in a message box

I have a button that produces a value and puts it in a listbox. I would like to add a new button that displays that value in a message box. Please help!

[Jan]

It is impossible to help you based on the currently given information. What is "a value"? What is the problem with calling msgbox? Are you working with Guide, AppDesigner or do you create the GUI by code? Please edit the question and provide more information.

[Edwin Froelich]

Hello Jan,

The value produced is a mean. One button calculates that mean and I would like to store that value and retrieve it on call from a different button. I tried declaring a global variable but matlab didn't like when I did that. I am working in guide but I am trying to edit the code part of it to pass the value around.

[Adam]

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

I use the guidata approach when using GUIDE and attach things to the handles struct.

Answer 1

[Jan]

Global variables are a bad programming practice, which can cause serious troubles and which impede the debugging massively. Therefore it is recommended to avoid globals - not only in Matlab, but in other programming languages also.

You can store data inside a GUI, e.g. in the UserData of the figure or any object, or in the ApplicationData. The latter works e.g. with guidata:

function OpeningFcn(hObject, EventData, handles)
% Define a default value:
handles.MeanValue = 'undefined';
% Store updated struct in the figure's ApplicationData:
guidata(hObject, handles);
end

function button1_callback(hObject, EventData, handles)
% Update the field MeanValue in the handles struct:
handles.MeanValue = mean(handles.Data);
% Store updated struct in the figure's ApplicationData:
guidata(hObject, handles);
end

function button2_callback(hObject, EventData, handles)
disp(handles.MeanValue);
end