This is the useful information I was hoping to get when I asked the question. Unfortunately, I had to dig a little deeper than I expected and have a few more questions: On 5/11/23 11:05 AM, Peter Dimov via Boost wrote:

Robert Ramey wrote: lexical_cast can convert any streamable type to any other streamable type. It's defined as `ss << input; ss >> output; return output;` where `ss` is a default-constructed `std::stringstream`.

Hmmm - cannot not an ss be associated with a local of choice via std::imbue? Looking at the documentation for lexical cast I don't see this. I'm not sure what the issues would be with this.

This has a number of implications. One, the conversion is locale-dependent. Hmmm - conversion to/from strings isn't locale dependent, how does one deal with string numeric formats which depend on locality - e.g. some countries use , while others use . as a decimal separator.

Two, for conversion to string, you use lexical_caststd::string, which can allocate.

There is a section in the lexical_cast docs titled "converting to string without dynamic memory allocation". Actually it would never occur to me that one could return a string from a conversion without a dynamic memory allocation. But I guess that's me. Three, errors are signaled via exceptions (although there's

try_lexical_convert that can avoid this.)

Right

lexical_cast does a good job of optimizing the from_chars and to_chars cases when it detects it can do so, but that by definition can't be better than the programmer just calling the primitive operations from_chars and to_chars directly, as they are (a) locale-independent, (b) non- allocating, (c) non-throwing. OK

In addition to all that, from/to_chars are standard C++17, so Charconv can be used by libraries that want to support C++11 (or 14) today, but at the same time want to be able to switch to the standard functions later when increasing the minimal supported standard to C++17.

So this is an implementation in C++11 of a library which is already accepted (and presumably shipping) in C++17 ? And the only user who would use this is someone who has C++11 but can't upgrade to C++17? Doesn't seem like very many people to me. I didn't find an documentation for this. May I presume that it's not deemed necessary as C++17 is documented and this is an exact equivalent? Note that there is another boost library, Boost.Convert, which purports to address short comings in lexical cast. https://www.boost.org/doc/libs/1_82_0/libs/convert/doc/html/index.html Has anyone looked at or evaluated this? Is there overlap? I actually never knew about this. Robert Ramey