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Subject: Re: [SG16-Unicode] Convert between std::u8string and std::string
From: Tom Honermann (tom_at_[hidden])
Date: 2019-05-03 10:54:54

Even with a locale (e.g., following a call to std::setlocale(LC_ALL,
"")), the conversion may be silently lossy ;)


On 5/3/19 11:32 AM, Steve Downey wrote:
> Also keep in mind that without a locale using a multibyte charset,
> i.e. not the default "C" locale, conversion will be silently lossy.
> On Fri, May 3, 2019, 11:26 Tom Honermann <tom_at_[hidden]
> <mailto:tom_at_[hidden]>> wrote:
> On 5/3/19 7:12 AM, Lyberta wrote:
>> So GCC 9 has been released and I'm starting migration to char8_t. The
>> first question is how to print std::u8string? Since std::cout works in
>> execution character set I need a way to convert string from UTF-8 to ECS.
> I wish I had a better suggestion for you then std::c8rtomb.
> JeanHeyd is working on a proposal for modern transcoding interfaces.
>> It looks like the only way is to use std::c8rtomb but the API is very
>> cryptic and I don't understand it. Can someone provide an example code?
> As far as I know, no one has actually implemented std::c8rtomb
> yet.  It has been on my todo list for a long time to contribute an
> implementation to glibc, but I haven't found the time yet.
> c8rtomb is intended to match the existing c16rtomb and c32rtomb
> functions, so inherits design and wording from them.  The wording
> in the C++ standard for c8rtomb is a lightly edited copy of the C
> standard's wording for c16rtomb.  That wording is, well, it could
> be improved.  A lot.  I intentionally chose to keep it aligned
> with the C standard so as not to cause confusion for implementors
> (presumably, they have already come to an understanding with C's
> wording).
> I suggest looking at the examples for c16rtomb on cppreference.com
> <http://cppreference.com>.
> - https://en.cppreference.com/w/cpp/string/multibyte/c16rtomb
> Tom.
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