pass value between two callback function in matlab GUI

Are you using GUIDE or a "programmatic" gui? The following is a little example for a programmatic gui; similar concepts may apply for GUIDE. (I personally like the added flexibility of the programmatic gui route, plus I always end up irrevocably breaking any GUIDE gui's I create...)

Anyway, a few things to note in this example:

1. use of the gui's figure handle UserData field to store "global" information. This is a way to pass data between callbacks.

2. the pause statement within the "infinite" loop is needed so that the interrupt from cb_button2 is processed. From Matlab help: "If the Interruptible property of the object whose callback is executing is on , the callback can be interrupted. However, it is interrupted only when it, or a function it triggers, calls drawnow, figure, getframe, pause, or waitfor."

   function my_gui(varargin)
   
       mainfig = figure;
   
       out.h_button1 = uicontrol(mainfig,...
                                   'Style','pushbutton',...
                                   'Units','Normalized',...
                                   'Position',[0,0.5,1,0.5],...
                                   'String','Button 1',...
                                   'Callback',@cb_button1);
   
       out.h_button2 = uicontrol(mainfig,...
                                   'Style','pushbutton',...
                                   'Units','Normalized',...
                                   'Position',[0,0,1,0.5],...
                                   'String','Button 2',...
                                   'Callback',@cb_button2);
   
       out.button2_flag = 0; %flag indicating whether button 2 has been pressed yet
   
       set(mainfig,'UserData',out);%store "global" data in mainfig's UserData (for use by callbacks)          
   
   
   function cb_button1(varargin)
   
       out = get(gcbf,'UserData'); %gcbf: handle of calling object's figure
   
       while ~out.button2_flag
           disp('Aaaahhh, infinite loop! Quick press Button 2!');
           out = get(gcbf,'UserData'); %reload "global" data
           pause(0.1); %need this so this callback may be interrupted by cb_button2
       end
   
       disp('Thanks!  I thought that would never end!');
   
   
   function cb_button2(varargin)
       out = get(gcbf,'UserData'); %gcbf: handle of calling object's figure
       out.button2_flag = 1;
       set(gcbf,'UserData',out); %save changes to "global" data