c++ template traits

#include
using namespace std;

template
class ddeque {
public:
class iterator {
public:
typedef std::random_access_iterator_tag iterator_category;

};

};

template
class dlist {
public:
class iterator {
public:
typedef std::bidirectional_iterator_tag iterator_category;

};

};

template
struct diterator_traits {
typedef typename IterT::iterator::iterator_category iterator_category;
};

template
void doAdvance(IterT& iter, DistT d, std::random_access_iterator_tag)
{
//iter += d;
cout<<“random access”< }

template
void doAdvance(IterT& iter, DistT d, std::bidirectional_iterator_tag)
{
/*
if (d>=0) {
while(d–) ++iter;
}
else {
while(d++) --iter;
}
*/
cout<<“bidirectional_iterator_tag”< }

template
void doAdvance(IterT& iter, DistT d, std::input_iterator_tag)
{
if(d<0) {
throw std::out_of_range(“Negative distance”);
}
while (d–) ++iter;
}

template
void dadvance(IterT& iter, DistT d)
{
doAdvance(iter, d, typename diterator_traits::iterator_category());
}

int main() {
ddeque d;
dadvance(d,5);

dlist c; 
dadvance, int>(c,5);
return 0;

}