Are there any bignum libraries that are good for Windows use? I looked at GMP, but unfortunately it does not look like it can be compiled on Windows...(I\'m going to be doin
People provide pre-compiled binaries for gmp on Windows; there are also instructions for compiling it yourself. Another option would be the bignum library of OpenSSL.
Another option is MPIR. MPIR is a fork of GMP that specifically support compilation on Windows.
http://www.openssl.org/ is stable and time proven library. It also includes well separable bignum libray
Also have a look at MAPM, A Portable Arbitrary Precision Math Library in C. It also contains C++ wrappers.