EDIT: when I first wrote this boost::multiprecision::uint128_t
wasn’t a thing yet. Keeping this answer for historical reasons.
I’ve made a uint128 class before, you can check it out at: http://www.codef00.com/code/uint128.h.
It is dependent on boost for automatically providing all of the variants of the math operators, so it should support everything a native unsigned int
type does.
There are some minor extensions to built in types such as initializing it with a string like this:
uint128_t x("12345678901234567890");
There is a convenience macro which works similary to the ones in C99 which you can use like this:
uint128_t x = U128_C(12345678901234567890);