Detecting int128 support

Some compilers have support for extended arithmetic types such as 128-bit floats or integers. Let's take a quick glance at how to use them using Boost.

We'll be creating a method that accepts three parameters and returns the multiplied value of those methods. If compiler supports 128-bit integers, then we use them. If compiler supports long long, then we use it; otherwise, we need to issue a compile-time error.

Getting ready

Only the basic knowledge of C++ is required.

How to do it...

What do we need to work with 128-bit integers? Macros that show that they are available and a few typedefs to have portable type names across platforms.

1. Include a header:

#include <boost/config.hpp>

2. Now, we need to detect int128 support:

#ifdef BOOST_HAS_INT128

3. Add some typedefs and implement the method as follows:

typedef boost::int128_type int_t;
typedef boost::uint128_type uint_t;

inline int_t mul(int_t v1, int_t v2, int_t v3) {
    return v1 * v2 * v3;
}

4. For compilers that do not support...