Welcome to the large numbers library for C++. It was created to make working with large numbers so convenient that you won't notice the difference between regular int and bignam (a new type added by this library). The library is dynamically developing, new functions and goodies are added. The documentation is embedded in the library itself, as well as on the site: link.
For ease of use, download two files: bignum.cpp, bignum.h. Paste the files into your project location and use include"bignum.h". Good luck!