smallestint.hpp

The following code example is taken from the book
C++ Templates - The Complete Guide, 2nd Edition
by David Vandevoorde, Nicolai M. Josuttis, and Douglas Gregor,
Addison-Wesley, 2017
© Copyright David Vandevoorde, Nicolai M. Josuttis, Douglas Gregor 2017


#include <limits>
#include "ifthenelse.hpp"

template<auto N>
struct SmallestIntT {
 using Type =
   typename IfThenElseT<N <= std::numeric_limits<char>::max(), char,
    typename IfThenElseT<N <= std::numeric_limits<short>::max(), short,
     typename IfThenElseT<N <= std::numeric_limits<int>::max(), int,
      typename IfThenElseT<N <= std::numeric_limits<long>::max(), long,
       typename IfThenElseT<N <= std::numeric_limits<long long>::max(),
                            long long,  // then
                            void        // fallback
                           >::Type
                          >::Type
                         >::Type
                        >::Type
                       >::Type;
};