How to detect the first and the last argument in the variadic templates?

Question

How to detect the first and the last argument in the variadic templates?

For the 1st argument it is easy (just compare sizeof...(T) with 0), but is ther

Answer 1

I'm not positive if this is what you want. But here are two utilities named first and last that take variadic templates and typedef the first and last type respectively:

#include 
#include 

template 
struct first
{
    typedef T1 type;
};

template 
struct last
{
    typedef typename last::type type;
};

template 
struct last
{
    typedef T1 type;
};

template 
struct A
{
    typedef typename first::type first;
    typedef typename last::type  last;
};

struct B1 {};
struct B2 {};
struct B3 {};

int main()
{
    typedef A T;
    std::cout << typeid(T::first).name() << '\n';
    std::cout << typeid(T::last).name() << '\n';
}