在GUI中数据的传递

[hualiangzi]

首先非常感谢你的回复，可我做了，确实不行。我现在把我的主程序贴过来，你看看是不是这么回事。如下：
% --- Executes just before shi is made visible.
function shi_OpeningFcn(hObject, eventdata, handles, varargin)
% This function has no output args, see OutputFcn.
% hObject handle to figure
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
% varargin command line arguments to shi (see VARARGIN)
x=I;
X=fft(x);
handles.current_data=x;
plot(handles.current_data);

% Choose default command line output for shi
handles.output = hObject;

% Update handles structure
guidata(hObject, handles);

% UIWAIT makes shi wait for user response (see UIRESUME)
% uiwait(handles.figure1);


% --- Outputs from this function are returned to the command line.
function varargout = shi_OutputFcn(hObject, eventdata, handles)
% varargout cell array for returning output args (see VARARGOUT);
% hObject handle to figure
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)

% Get default command line output from handles structure
varargout{1} = handles.output;


% --- Executes on button press in dakai_pushbutton.
function dakai_pushbutton_Callback(hObject, eventdata, handles)
% hObject handle to dakai_pushbutton (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
H={'*.wav'};
[filename,pathname]=uigetfile(H,'请选择需要打开的声音');
file=strcat(pathname,filename);
I=wavread(file);
sound(I);
global I;


% --- Executes on button press in huatu_pushbutton.
function huatu_pushbutton_Callback(hObject, eventdata, handles)
% hObject handle to huatu_pushbutton (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
plot(handles.current_data);
我现在要用到向量I的值（正如上面我想调用它一样），可准是显示错误：找不到I的值。到底怎么办啊？