I want to give list of value in popup menu and use that in push button.

Here is my code.

function SEC_Callback(hObject, eventdata, handles)
handles = guidata(hObject);  % Not sure if handles is up to date already
switch get(handles.SEC, 'value')
case 1
    S.a=7;
    S.b=20;
  case 2
    S.a=5;
    S.b=30;
  otherwise
end 
set(handles.popupmenu, 'UserData', S);
function ANS_Callback(hObject, eventdata, handles)
S = get(handles.SEC, 'UserData');
a = S.a;
b = S.b;
c = a + b;
set(handles.AANS,'string',num2str(c));

I get error 'Dot indexing is not supported for variables of this type.'

Error in pop>ANS_Callback (line 113)
a = S.a;'

Please help me.

[Walter Roberson]

You do not set a value for the Otherwise condition.

You do not check for S being empty before you use it. That can happen if you can invoke ANS_Callback before SEC_Callback has set a value with case 1 or 2.

[Yash Vaid]

Can you give me code for the same or suggest any program in which they use popup menu with push button ?

[Image Analyst]

1. What controls are ANS, AANS, popupmenu, and SEC? You have 3 tags in code but only 3 on the GUI.
2. Which one is the answer button, which one is the edit text box, and which one is the popup?
3. Which controls do you want to execute code when you interact with them? BOTH the button AND the popup?
4. What do you want to happen? Do you want the index of the popup to show up in the text edit box when you push the Answer button?

Please clarify.

[Yash Vaid]

Respected Sir,

I have some condition say, if I use this material it will take that property of material so all the material are in popup menu and the property of that material will use in push button. so I made this simple program for understanding how value from pop up menu will use in push button. Now, in this program I use one popup menu(SEC), one push button(ANS) and one edit text(AANS). What I want is if I choose first then it will take value of 'a & b' from that first category and if I choose second then do same for second .

Now I modify my code and I got error 'Reference to non-existent field 'a'.

Error in pop>ANS_Callback (line 116)

a = handles.a;'

my code is below

function SEC_Callback(hObject, eventdata, handles)
listStrings = get(handles.SEC,'String');
domaintype = listStrings{get(handles.SEC,'Value')};
switch domaintype
case 'first'
    a=7;
    b=20;
  case 'second'
    a=5;
    b=30;
end 
handles.a = a;
handles.b = b;
set(handles.SEC,'String',handles.a);
set(handles.SEC,'String',handles.b);
function ANS_Callback(hObject, eventdata, handles)
set(handles.ANS,'UserData',0);
a = handles.a;
b = handles.b;
c = a + b;
set(handles.AANS,'string',num2str(c));

Thanks.

[Walter Roberson]

You still are not checking for the case where the Value is not one of the two.

As I indicated, uicontrol of that style are initialized to Value of []. That would result in an empty string being selected into domaintype .

And you are still relying on SEC_Callback having definitely been run before ANS_Callback . As you are not manipulating the Enable property of handles.ANS then we can be almost certain that you permit ANS to be clicked before SEC has been clicked.

I already described what you need to do to fix this.

[Yash Vaid]

Thank you very much sir for your continues support. But I excatly cant understand what should I do. Please either send the code and procedure with figure file or decribe in simple way because I am beginner in GUI. Again thank you sir but please help me to fix this problem.

[Yash Vaid]

When I change popup menu option it gives error

'SWITCH expression must be a scalar or a character vector.

switch domaintype '

and when I push answer buttton it gives error

'Reference to non-existent field 'a'.

a = handles.a; '

Answer 1

[Walter Roberson]

Note that when you initialize the pop-up by loading the figure constructed in GUIDE (or by creating a uicontrol), that the default Value property is empty -- and even if the Value happened to be set to something else at the time you had saved the figure in GUIDE, then the Callback property associated withe the control is not run when the control is loaded or created.

Thus, at the beginning, even though 'first' might be showing, the action associated with clicking 'first' has not been run. Furthermore, when you click on a popup value that is already the one selected, the callback might not be run and you might have to select a different value and then click back on the original in order to have the value associated with the original be set.

Therefore you need to be careful about how you initialize the controls.

One approach is to have your OpenFcn callback for the GUI set() the Value property of the control, and then execute the callback associated with the control in order to have the sequence run as-if that value had been manually clicked.

If you take this approach, be careful about what you invoke. The callback property that GUIDE stores is not a direct reference to the function to be called: instead it has to retrieve the handles structure and pass that into the function. Historically that involved executing a character vector, but that was improved later, but you might have to fake the callback object to get it to work. More secure is to retrieve the handles structure yourself and call the function yourself.

[Walter Roberson]

function SEC_Callback(hObject, eventdata, handles)
listStrings = get(handles.SEC,'String');
idx = get(handles.SEC,'Value');
if ~isscalar(idx)
    waitfor( warndlg('No SEC entry has been selected yet') );
    return
end
domaintype = listStrings{idx};
switch domaintype
case 'first'
    a=7;
    b=20;
  case 'second'
    a=5;
    b=30;
    otherwise
      waitfor( warndlg('Select first or second') );
      return
end 
handles.a = a;
handles.b = b;
guidata(hObject, handles);


function ANS_Callback(hObject, eventdata, handles)
set(handles.ANS,'UserData',0);
if ~isfield(handles, 'a')
    waitfor( warndlg('You need to select SEC first') );
    return
end
a = handles.a;
b = handles.b;
c = a + b;
set(handles.AANS,'string',num2str(c));

[Yash Vaid]

Respected Sir,

Thank you very much for your help.