c++ 偏特化 求解释为什么编译不了？

Question

 #include <iostream>
#include <cstdio>
#include <string>
using namespace std;
#if 0
template< class T>
struct iterator_traits
{
    typedef typename T::iterator_category   iterator_category;
    typedef typename T::value_type      value_type;
    typedef typename T::difference_type difference_type;//表示两迭代器之间的距离
    typedef typename T::pointer     pointer;
    typedef typename T::reference       reference;
};
#endif
template<class T>
class iterator<const T*>
{
    puclic:
    iterator(){cout<<"ok?"<<endl;}
};
int main(void)
{   
     iterator< const int*> ok;
}

Answer 1

http://www.jb51.net/article/42099.htm

模板类的使用。。。