From: Boost-users <boost-users-boun...@lists.boost.org> On Behalf Of
A.Dmitrovsky via Boost-users
Sent: 15 May 2020 11:03
To: boost-users@lists.boost.org
Cc: A.Dmitrovsky <td...@yandex.ru>
Subject: [Boost-users] [Multiprecision] number conversion to __int128
Hi,
Boost::multiprecision docs [1] mentions that the type parameter of
number::convert_to method should be "fundamental", pointing to the list of
standard types ('A number can be converted to any
https://en.cppreference.com/w/cpp/language/types type)'.
This is different to number::convert_to reference [2], which states that "Type
T may be any arithmetic type".
Can [unsigned] __int128 be treated as "fundamental" on compilers/platforms
which support it?
[1]
https://www.boost.org/doc/libs/1_73_0/libs/multiprecision/doc/html/boost_multiprecision/tut/conversions.html
[2]
https://www.boost.org/doc/libs/1_73_0/libs/multiprecision/doc/html/boost_multiprecision/ref/number.html
Does
“
*Interconversions between number types of the same family are allowed and are
implicit conversions if no loss of precision is involved, and explicit if it is:
…
"
In
https://www.boost.org/doc/libs/1_73_0/libs/multiprecision/doc/html/boost_multiprecision/tut/conversions.html
Not cover your case _uint128 ? and thus allowed for conversion.
Even if the _uint* and _int* types are not fundamental builtin types
(regrettably - blame the glacial process of C and C++ standardization and the
millstone of C (don't ask) - but they might as well be for most purposes,
including this one).
HTH
Paul
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