MATLAB gui单步调试时，下面set_param函数可以设置，进去运行时set_param就不可以设置！

Question

function pushbutton_APK_Callback(hObject, eventdata, handles)
% hObject handle to pushbutton_APK (see GCBO)
% eventdata reserved - to be defined in a future version of MATLAB
% handles structure with handles and user data (see GUIDATA)
a=str2num(get_param('Logicnew/apk','value'));%获取到的是符号类型数“’0‘”，需转换为数字“0”。
if a>0
a=0;
else
a=0;
end
for i=1:1:7
if((i>0)&&(i<6))
a=1;
else
a=0;
end
i=i+1;
set_param('Logicnew/apk','value',num2str(a));
end