Recursive template function with multiple types
c++, recursion, templates
Solution
(AFAIK) there is no support for partial specialization of function templates, to obtain this functionality, you need to do it slightly differently, something like:
template <int N>
struct scalar
{
template <typename Iterator>
static int product(Iterator a, Iterator b)
{ (*a) * (*b) + scalar<N - 1>::product(a + 1, b + 1); }
};
template <>
struct scalar<0>
{
template <typename Iterator>
static int product(Iterator a, Iterator b)
{ return 0; }
};
Problem
I'm trying to write function that counts scalar product for two vectors. Here is the code and it works. ``` template <int N> int scalar_product (std::vector<int>::iterator a, std::vector<int>::iterator b) { return (*a) * (*b) + scalar_product<N - 1>(a + 1, b + 1); } template <> int scalar_product<0>(std::vector<int>::iterator a, std::vector<int>::iterator b) { return 0; } ``` But here is the problem - i want to replace this iterators with template type, so that signature of function will look smth like this ``` template <typename Iterator ,int N> int scalar_product (Iterator a, Iterator b) { return (*a) * (*b) + scalar_product<N - 1>(a + 1, b + 1); } template <typename Iterator> int scalar_product<0>(Iterator a, Iterator b) { return 0; } ``` But this doesn't work - I get compile error C2768: illegal use of explicit template arguments. It seems silly, but I couldn't find out what should I change to avoid this error.