MATLAB GUI Error "Undefined function or variable 'val'"

I made a GUI using GUIDE.

It contains a Pop-up menu containing 3 items (A,B,C) and a pushbutton.

This very simple Gui is designed to simply display a different text for whichever item the user chooses.

If I select the first value of my pop-up menu, I should get a return print of Hello. Sections of the code can be seen below. Why doesn't the code work?

M-FILE sections

function A_popup_Callback(hObject, eventdata, handles)
val = get(hObject,'Value');
switch val
 case 1 
 x = 'Hello'; 
 case 2 
 y = 'goodbye' 
 case 3 
 z = 'thank you'
end
function pushbutton1_Callback(hObject, eventdata, handles)
sprint('%s',x)

Answer 1

[Walter Roberson]

http://matlab.wikia.com/wiki/FAQ#How_can_I_share_data_between_callback_functions_in_my_GUI.3F

[Jaime Zuriel Ugalde Sánchez]

Useless answer

[Sugar Daddy]

You need to learn basics of GUI and callbacks. That link above is very usefull for that purpose. Be carefull with your words

[Walter Roberson]

Jaime Zuriel Ugalde Sánchez :

Observe as I illustrate the technique of using the handles structure to share data between callbacks, as discussed at https://matlab.fandom.com/wiki/FAQ#How_can_I_share_data_between_callback_functions_in_my_GUI.28s.29.3F

function A_popup_Callback(hObject, eventdata, handles)
val = get(hObject,'Value');
switch val
 case 1 
 handles.x = 'Hello'; 
 case 2 
 handles.y = 'goodbye' 
 case 3 
 handles.z = 'thank you'
end
guidata(hObject, handles)

function pushbutton1_Callback(hObject, eventdata, handles)
  sprint('%s',handles.x)

A careful reader might note that if val is not 1, then whatever is in handles.x is left unchanged: the user's code specifically asked to display x, not to display "whatever was assigned to in the switch statement". It would probably have made more sense if the user had assigned to x in all three cases, but they didn't.