class foo{
protected:
int *data;
public:
int& operator[](int i);
int operator[](int i)const;
};
class goo : public foo{
int& operator[](int i)
{
foo::opera
我使用MVC 5 ViewBag並嘗試做 @if (!ViewBag.UserLoggedIn) {
<a onclick="javascript:UserSessionManager.UserLogout()">LogOut</a>
}
但得到一個錯誤的操作數: Operator '!' cannot be applied to operand of type '<null>'