MSVC performance compared to std::to_string?

[emmenlau]

I'm completely new to numeric-string-conversion, so please forgive if my question is naiive.

I implemented a replacement for std::to_string(vNumber) using std::string(fmt::format("{}", vNumber)) to convert floating point values (double and float) to std::string. On Linux (gcc-6, gcc-7) and MacOSX 10.11 (Apple clang) I get twice the performance of std::to_string() for double! But on MSVC 2015 and 2017, the performance is typically slightly worse than std::to_string(), typically ~120% of the execution time.

I'm confused if this is to be expected? I've seen the nice work in #147 but I'm not knowledgabe enough to understand if I need to wait for this or if already now the performance could be better.

[vitaut]

{fmt} relies on snprintf for floating-point formatting right now, so it all depends how snprintf and to_string are implemented. On MSVC snprintf is known to be of a very poor quality. This will be addressed by #147 once the new floating-point formatter which is mostly complete is fully tested and enabled.