How to check if a template parameter is an iterator type or not?

Question

template
struct is_iterator
{
    static const bool value = ??? // What to write ???
};

int main()
{
    assert(false == is_iterator::valu         


        

Answer 1

Well, you could check for the type to have a nested typedef called iterator_category This can be done using SFINAE, and the exact technique can be found in wiki page for SFINAE. This isn't a 100% method, but all decent iterators should provide the common typedefs for iterators, and the iterator_category is one that is unique to iterators. Also don't forget to check if TYPE is simply a pointer. Pointers are iterators.