Matlab check if input is nonezero

Question

working on a project and have to make sure the input in a textbox meets a requirement for both being numeric, but also not being equal to zero. So far this is my code:

function minValue_Callback(hObject, eventdata, handles)
% hObject    handle to edit10 (see GCBO)
% eventdata  reserved - to be defined in a future version of MATLAB
% handles    structure with handles and user data (see GUIDATA)

% Hints: get(hObject,'String') returns contents of edit10 as text
%        str2double(get(hObject,'String')) returns contents of edit10 as a     double
user_entry_X = str2double(get(hObject,'string'));
if isnan(user_entry_X)
 errordlg('You must enter a numeric value','Error!','modal')
 uicontrol(hObject)
return
end

Another question is, I have two textboxes, minValue and maxValue. How can I also make sure that the data in maxValue > minValue? (Values are used in a for loop, and I thought checking before hand and showing an error would be better.)

What is your question? Where is the problem implementing that? — Daniel
– Daniel, Commented Dec 6, 2015 at 22:41
@Daniel Question is how to make sure input is not zero but is also numeric. And is it possible to call this CallBack from a different function or on a button press? — Rivasa
– Rivasa, Commented Dec 6, 2015 at 23:09
@Link For the second part, in maxValueText_callback and minValueText_callback, why not check against limits, and adjust the limits of the other according to the current value that has just changed? — Nigel Davies
– Nigel Davies, Commented Dec 21, 2015 at 15:17

houtanb · Accepted Answer · 2015-12-07 09:11:00Z

1

So, if I understand correctly, you should change the lines:

if isnan(user_entry_X)
    errordlg('You must enter a numeric value','Error!','modal');

to be:

if isnan(user_entry_X) || user_entry_X == 0
    errordlg('You must enter a non-zero numeric value','Error!','modal');

For the second part of the question, I don't understand the difficulty. Just type:

if maxValue > minValue
    ...
end

edited Dec 7, 2015 at 9:11

answered Dec 6, 2015 at 23:14

houtanb

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6 Comments

Rivasa Over a year ago

For 2nd part I need to check when they're entered in either textbox, unsure how to do that.

horchler Over a year ago

isnan is required because that's what str2double returns for invalid inputs. isnumeric returns true for NaN and str2double only returns scalar numeric values (for string inputs) by definition.

Rivasa Over a year ago

@horchler Do you have an idea of what to do then?

houtanb Over a year ago

Fixed. Thanks @horchler. FYI, this solution accepts complex numbers. If you don't want to accept complex input, change the test to if isnan(user_entry_X) || ~isreal(user_entry_X) || user_entry_X == 0

Nigel Davies Over a year ago

Do you also want to check for >= 0, or is negative input valid?

|

Nigel Davies · Accepted Answer · 2015-12-21 15:41:12Z

0

You probably want to use

errordlg('You must enter a numeric value','Error!','modal')
h = uicontrol(hObject)
uiwait(h)

So the error dialogue stays open until the user acknowledges. (I fell into the trap beleiving, possibly from windows programming, that 'modal' creates this behaviour.)

answered Dec 21, 2015 at 15:41

Nigel Davies

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