std::array<char, 23> buffer;
std::string s{};
if (auto [ptr, ec] = std::to_chars(buffer.data(), buffer.data() + buffer.size(), x, std::chars_format::fixed, 2); ec == std::errc{}) {
s = std::string(buffer.data(), ptr);
} else {
s = std::make_error_code(ec).message();
}