Re: charconv for C++11

From: Gavin Lambert (boost_at_[hidden])
Date: 2023-05-12 00:33:02

On 12/05/2023 10:59, Peter Dimov wrote:
> The work-in-progress documentation is here: https://develop.charconv.cpp.al/

> Hex format will be of the form +1.0e2p+5. The integer part will
> always be 0 or 1. The exponent will be with a p instead of an e like
> in base 10 formats.
This is some strange definition of "hex" with which I was previously 
unfamiliar.

It also contradicts itself, by saying "a p instead of an e" while the 
example contains both.  (And isn't a very good example, lacking actual 
hex digits.)

I've now found the reference to it -- 
https://en.cppreference.com/w/cpp/utility/to_chars says that "hex" uses 
as-if printf %a, and https://en.cppreference.com/w/cpp/io/c/fprintf says 
printf %a appears *somewhat* like the above (but I still think there is 
an error in the above).

I also still think that whoever came up with that specification needs a 
whap upside the head, but then I've never encountered a reason to print 
a floating-point value in hex, so I assume there's some justification 
for it.