I came to this somewhat picturesque solution:

    #include <string>

    bool is_palindromic(const std::string& s)
    {
        std::string::const_iterator start = s.begin();
        std::string::const_iterator end = s.end();
        while (start < end) {
            if (*(start++) != *(--end)) {
                return false;
            }
        }
        return true;
    }

...that copes with emptiness and automatically treats it as palindromic.