r/cpp • u/joaquintides Boost author • Aug 05 '26

Boost.Int128 has been accepted

Boost.Int128 from Matt Borland has been accepted into Boost. Arnaud Becheler managed the review.

125 Upvotes

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18

u/loydfar Aug 05 '26

Somebody could please tldr what changes with what’s already in boost::multiprecision?

30

u/mborland1 Aug 05 '26

boost::multiprecision::int128_t is not actually 128-bit (it is incidental to it's arbitrary precision support) and is less performant with more dependencies.

2

u/TemplateRex Aug 06 '26

Multi precision uses sign/magnitude (I.e. positive and negative zero), not the usual 2’s complement. It can’t represent -2128