用模板技术判断一个类型是否为类
以下代码是从《C++ Templates》第15.2.2节抄过来的，但是无论在VS2010还是在gcc上都无法通过编译。有没有对模板比较了解的朋友知道这是怎么回事？

C/C++ code

// traits/isclasst.hpptemplate <typename T>class IsClassT{private:    typedef char One;    typedef struct { char a[2]; } Two;    template<typename C> static One test(int C::*);    template<typename C> static Two test(...);public:    enum { Yes = sizeof(IsClassT<T>::test<T>(0)) == 1 };    enum { No = !Yes };};

C/C++ code

//traits/isclasst.cpp#include "isclasst.hpp"#include <iostream>using namespace std;class MyClass{};struct MyStruct{};union MyUnion{};void myfunc(){}enum E { e1 } e;// Check by passing type as template argumenttemplate <typename T>void check(){    if (IsClassT<T>::Yes)    {        cout << " IsClassT " << endl;    }    else    {        cout << " !IsClassT " << endl;    }}// Check by passing type as function call argumenttemplate <typename T>void checkT(T){    check<T>();}int main(){    cout << "int:       ";    check<int>();    cout << "MyClass:   ";    check<MyClass>();    cout << "MyStruct:  ";    MyStruct s;    checkT(s);    cout << "MyUnion:   ";    check<MyUnion>();    cout << "enum:      ";    checkT(e);    cout << "myfunc():  ";    checkT(myfunc);}