【求助】GUI中的popumenu如何传递参数

[Rhent]

在popupmenu的callback下的程序段：
val = get(hObject,'Value');
switch val
case 1
fid3=fopen('youth.txt','rt');
s=fscanf(fid3,'%c');
fclose(fid3);
set(handles.pushbutton6,'string',s);
case 2
fid3=fopen('Going Home.txt','rt');
s=fscanf(fid3,'%c');
fclose(fid3);

case 3
fid3=fopen('Thoughts for a new year.txt','rt');
s=fscanf(fid3,'%c');
fclose(fid3);
case 4
fid3=fopen('Relish the Moment.txt','rt');
s=fscanf(fid3,'%c');
fclose(fid3);
end
guidata(hObject,handles);

结果在其他函数中引用‘s’无效，请教如何解决