Some C++ libraries I've encountered for managing currency manipulation:
- vpiotr / decimal_for_cpp - this is the one I use for my currency work, is header based, succinct, and easy to use.
- I was wondering if boost.multiprecision could be used, and came up with mariusbancila / moneycpp - a bit too much for me as it also handles currency codes. There is a a blog entry: moneycpp – a C++ library for handling monetary values.
- General Decimal Arithmetic goes into some detail about the related IEEE 754 standard, as well as a link to a C language implementation.