MATLAB: 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

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!

Answer 1

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