MATLAB Answers

susana
0

I'm trying to build a calculator. I have a listbox and a series of pushbuttons for the operations (+,-,/,sqrt,cos,sin.). I display what the user is clicking on an edit box. When the user clicks on 'cos' e.g., it only displays 'c'. Please check the co

Asked by susana
on 6 Sep 2017
Latest activity Commented on by susana
on 7 Sep 2017
function calculator(hObject,~,~) %Calculator
handles=guidata(hObject);
h=figure(...));
(...)
uicontrol('Parent',h,'Style','pushbutton','BackgroundColor','w','FontSize',11,...
'FontWeight','bold','ForegroundColor','k','Units','Normalized','Position',[0.88,0.3667,0.0981,0.1],'String','cos','Callback',@expopup);
(...)
handles.calculator=h;
guidata(handles.calculator,handles);
%%%%%%
function expopup (hObject,~,~) %CALCULATOR visior printing;)
handles=guidata(hObject);
ed=findobj(handles.calculator.Children,'style','edit');
if hObject.Value==0
list=hObject.String;
else
list=hObject.String(hObject.Value);
end
txtstr=get(ed,'String');
txtstr=strcat(txtstr,list);
set(ed,'String',txtstr);

  2 Comments

There isn't an obvious mistake that jumps out to me. Can you make this code into an MWE, which reproduces the problem in as few lines of code you can?
Hello Rik, Thanks for your quick answer. Yes, please see the attached code. You should be able to run this. Hope you can help me. Best regards, Susana

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1 Answer

Answer by Greg
on 6 Sep 2017
 Accepted Answer

The 'Value' property of a pushbutton uicontrol is set to 1 during callback execution. Therefore, your button vs. list logic:
if hObject.Value==0
list=hObject.String;
else
list=hObject.String(hObject.Value);
end
enters the "else" statement and chooses only the first character of hObject.String. Try looking at a property of hObject that is guaranteed to be listbox-specific ("style" maybe?).

  2 Comments

Good catch.
This section of code looks to me as if it was written with popups or listbox in mind rather than push buttons. For popups and listbox, you would have logic similar to
if isempty(hObject.Value)
list = '?? Nothing Selected ??';
else
list = hObject.String{hObject.Value};
end
But for push buttons, you would just copy the entire String property without indexing
if hObject.Value==0
list = '?? Button is up ??';
else
list = hObject.String;
end
Excellent catch. Thanks a lot. It solved my problem..

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