ln3

Description
ln3 is a C++ library for arithmetic with large integers.  The fundamental feature of the library is the class ln, which can be used like any of the built-in C++ integer types.
Example
#include <lnv3/lnv3.h>
main( )
{
    ln X = "123123123";
    ln Y = "234234234";
    ln Z = X + Y;
    cout << Z << endl;
}
Reference
User's Guide and Tutorial

Library Reference