i want to evaluate this textbox for validation. but i got this error.

Error

Undefined variable "handles" or class "handles.t1".
Error in DESIGN>b1_Callback (line 292)
 x=get(handles.t1,'string');
Error while evaluating UIControl Callback

For this code

f=figure;
t1= uicontrol(f,'Style','edit','String','','Position',[180 580 130 20]);
b1 = uicontrol(f,'Style','pushbutton','String','GENERATE','Position',[100 365 100 40],'Callback',@b1_Callback);
function b1_Callback(source,eventdata)
 x=get(handles.t1,'string');
  if(isempty(x))
     msgbox('enter the text');
 else
     msgbox('ds');
 end

Please solve this error

[Stephen23]

Where in your code is the variable handles defined?

[ARYA NAYAK]

i don't know.

i'm learning matlab one week ago. i don't know anything.

will you please make that code proper to execute.

in script i want to make one textbox and one push button.

then i wrote push button call back. then i got that error.

please help me to solve that particular error

Answer 1

[Walter Roberson]

handles is not automatically passed by MATLAB. When you create a callback using GUIDE then GUIDE arranges for the callback to be passed but when you create your own callback then you have to pass it yourself if you want it. (You also have to create the handles structure yourself)

[ARYA NAYAK]

how to pass handles?? please tell me sir

[Walter Roberson]

handles.f=figure;
handles.t1= uicontrol(f,'Style','edit','String','','Position',[180 580 130 20]);
handles.b1 = uicontrol(f,'Style','pushbutton','String','GENERATE','Position',[100 365 100 40],);
set(handles.b1, 'Callback', {@b1_Callback, handles});

function b1_Callback(source, eventdata, handles)
 x=get(handles.t1,'string');
  if(isempty(x))
     msgbox('enter the text');
 else
     msgbox('ds');
 end

[ARYA NAYAK]

Thank you so much sir. it works