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;
};