how i can use the value of a in other function?

how i can use the value of a in other function? and my code is here.

function pushbutton1_Callback(hObject, eventdata, handles)
[a , b] = uigetfile({'*.*' , 'all files'});
imread(a);
imshow(a);
% --- Executes on button press in pushbutton2.
function pushbutton2_Callback(hObject, eventdata, handles)
v = imread(a);
bw = im2bw(a);

[sana saleeme]

i did it by using global.but now no function apply on a like im2bw and rgb2gray not working on it.please guide me what should a i do?

Answer 1

[Jan]

function pushbutton1_Callback(hObject, eventdata, handles)
[a , b] = uigetfile({'*.*' , 'all files'});
imread(a);
imshow(a);
handles.a = a;
guidata(hObject, handles);

% --- Executes on button press in pushbutton2.
function pushbutton2_Callback(hObject, eventdata, handles)
handles = guidata(hObject);
v = imread(handles.a);
bw = im2bw(handles.a);

Note: Better use absolute file names with path:

a = fullfile(b, a);

[sana saleeme]

thanks sir jan simon

Answer 2

[Image Analyst]

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