How to set the default value for Edit Text in GUI ? If not input a number , I hope the contents auto changed to be '5'

Question

Lisa Wu 2012-11-19

1
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/54082-how-to-set-the-default-value-for-edit-text-in-gui-if-not-input-a-number-i-hope-the-contents-au

In the function edit1_callback(),it is writed as :

   edit1 = str2double(get(hObject,'string'));
   if isempty(edit1)
      edit1 = 5;     % when not input a number ,the contents is 5;
   end 
   handles.edit1 = edit1;
   guidata(gcbo,handles);

As a matter of fact,when I do not input a number,the edit text contents is not 5,Why?

And ,how can I set the default value of edit text??

Thank you for your attention!

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Answer 1

Teja Muppirala 2012-11-19

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https://ww2.mathworks.cn/matlabcentral/answers/54082-how-to-set-the-default-value-for-edit-text-in-gui-if-not-input-a-number-i-hope-the-contents-au#answer_65751

在 MATLAB Online 中打开

STR2DOUBLE returns NaN for non-numeric data. Instead of checking for empty input using ISEMPTY, use ISNAN instead.

if isnan(edit1)
  set(handles.edit1,'string','5');
end

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Lisa Wu 2012-11-19

编辑：Lisa Wu 2012-11-19

As you said: function edit1_callback() edit1 = str2double(get(hObject,'string')); if isnan(edit1) set(handles.edit1,'string','5'); end guidata(gcbo,handles);

funciton pushbutton1_callback() x = handles.edit1; y = x+7; plot(x,y,'*r'); guidata(gcbo,handles);

When run it ,the default value of x is not 5 ,i'm puzzled. Thank you !

Arthur 2012-11-19

在 MATLAB Online 中打开

You forgot to store edit1. And, I think it's better to retrieve the value of handles.edit1 in the pushbutton callback. Try this:

function edit1_callback() 
edit1 = str2double(get(hObject,'string')); 
if isnan(edit1) 
set(handles.edit1,'string','5'); 
end 
function pushbutton1_callback() 
x = str2double(get(handles.edit1,'String')); 
y = x+7; 
plot(x,y,'*r');