How to multiply integers larger than uint64?

Question

#include <iostream>
#include <limits>
int main(void) {
    cout << std::numeric_limits<uint64_t>::max();
    return 0;    
}

The code above outputs (on my machine) 18446744073709551615, but I'm trying to multiply numbers that have at least 25 digits. How to properly handle a multiplication of 2 integers that are larger than uint64?

Answer 1

You need to use a library that handles big numbers. Here are some of them:

• The GNU Multiple Precision Arithmetic Library

  https://gmplib.org/

• C++ Big Integer Library

  https://mattmccutchen.net/bigint/

• Boost.Multiprecision

  http://www.boost.org/doc/libs/1_55_0/libs/multiprecision/doc/html/index.html