A very fast split function in C++

utility.h

    /* Based on http://www.cplusplus.com/forum/beginner/114790/#msg626659
       and https://github.com/fenbf/StringViewTests/blob/master/StringViewTest.cpp#L151,
       which is the repo for this blog post: https://www.bfilipek.com/2018/07/string-view-perf-followup.html
    */
    template<typename Out = std::vector<std::string>>
    Out split(const std::string_view s, const char delim, const size_t maxFields = 0) {
        Out elems;
        size_t start{};
        size_t end{};
        size_t numFieldsParsed{};

        do {
            end = s.find_first_of(delim, start);
            elems.emplace_back(s.substr(start, end - start));
            start = end + 1;
        } while (end != std::string::npos && (maxFields == 0 || ++numFieldsParsed < maxFields));
        return elems;
    }