How set default value in edittext in GUI

Hi everyone, I have a problem with my GUI. I have to set default value for edittext (if edittext is empty ---> set variable to double 50 or string 'hello', but if not empty set variable from edittext.I do not know how can i do that. Please help me (Im working on Matlab 2013b or 2015b mac edition)

Answer 1

[Walter Roberson]

S = get(handles.editbox1, 'string');
if isempty(S)
  S = 'hello';
end

[Walter Roberson]

http://matlab.wikia.com/wiki/FAQ#How_can_I_share_data_between_callback_functions_in_my_GUI.28s.29.3F

And remember it is legal to check isempty() before you do the str2double()

Answer 2

[Filip M]

It doesnt work. I have tried this:

function edit1_Callback(hObject, eventdata, handles)
Tstr=get(handles.edit1,'string');
Tstr=str2double(Tstr);
if isnan(Tstr)
Tstr = 58;
end
handles.T=Tstr;

It works but only if i write sth in edit1 and delete it. If i do not write sth, Matlab answer "Reference to non-existent field 'T'."

[Adam]

You can't get a reference to non-existent field error during an assignment so that error cannot be coming from the code you posted.

[Filip M]

Seriously, i have to copy all code? i have used pushbutton.

function pushbutton1_Callback(hObject, eventdata, handles)
T=handles.T

[Adam]

You need to show all code relevant to what you are asking. In this case the one line you just added is enough.

And did you not use

guidata( hObject, handles )

at the end of your edit1_Callback? Without this any changes you make to the handles structure in your callback are just local and are lost when the callback scope finishes. So pushbutton1_callback will see exactly the same handles structure as was passed into edit1_callback.

The above code replaces the handles structure stored in the GUI with the one you have edited so that when you trigger the next callback you get the updated 'handles' struct.

Answer 3

[Filip M]

Ok i have added guidata to edit1 funcition but still doesnt work. With if isnan works only if I first write sth and immediately delete it. But if i start program with blank edit1 and i push button i have error

[Adam]

Walter's isempty test should deal with that.

[Filip M]

What do you mean?

[Walter Roberson]

I have tested and confirm that if you have not changed the String property of a uicontrol style edit, then applying str2double() to it will result in NaN, which can be caught with isnan() like you show.

Answer 4

[MARIA RODRIGUEZ SANZ]

I have the same problem. Did you fix it??

Thanl you very much!