Converting from sub_match

I am trying to map std::match_results data to my std::multimap variable. Here's the code:

int main()
{
    ...

    auto begin = view.get();
    auto end = begin + size.QuadPart;

    auto logValues = multimap<char, double>{};

    auto i = cregex_iterator{ begin, end, r };

    int d = 0;

    for (i; i != cregex_iterator{}; ++i, ++d);

    for (auto e = 0; e < d; e++, ++i)
    {
        logValues.emplace((*i)[1], (*i)[4]);
    }

    TRACE(L"%d\n", d);

    return 0;
}

I get the following error:

cannot convert argument 1 from 'const std::sub_match' to 'const char *const &'

I tried static_cast but it doesn't work. Do I need to write conversion operator to std::sub_match to convert first value to char or is there something I am missing?

Also, in my second for loop, I want to go through i which is std::cregex iterator, since it has been incremented while it was being filled up with data, how do I reset it to go through it again? or is that done automatically? I couldn't find answer to this in the documentation.