An arbitrary-precision arithmetic library for C++
arb was created for both.
After discovering Project Euler and solving the first few problems, I have found the need to calculate quite heavy sums and products (things on the order of 2^1000). Instead of giving up and switching to a language that uses arbitrary-precision arithmetic by default (e.g. Python), I decided to implement arbitrary precision in C++ myself.
arb currently supports only simple integer arithmetic. After deploying most of the basic operations, I will tackle fractional arithmetic and eventually work on turning arb into a usable library.