Sandbox/ConstexprIf.cpp

   1 #include "ConstexprIf.h"
   2
   3 #include <iostream>
   4 #include <type_traits>
   5 #include <limits>
   6 using namespace std;
   7
   8 // Ep 18: https://www.youtube.com/watch?v=qHgM5UdzPQU
   9
  10 namespace ConstexprIf
  11 {
  12     template<typename T>
  13     constexpr bool is_integral_has_a_big_max_limit()
  14     {
  15         if constexpr (is_integral<T>::value && !is_same<bool, T>::value) // Because 'bool' is an integral type.
  16         {
  17             // Here we can use a '&&' to put this condition in the first 'if' because template do not use short-cirtcuit boolean operators.
  18             if constexpr (numeric_limits<T>::max() > numeric_limits<int>::max())
  19                 return true;
  20         }
  21
  22         return false;
  23     }
  24
  25     template<typename T>
  26     auto print_type_info(const T& v)
  27     {
  28         if constexpr (is_integral_has_a_big_max_limit<T>())
  29             return v + 1;
  30         else if constexpr (is_floating_point<T>::value)
  31             return v + 0.1;
  32         else
  33             return v;
  34     }
  35 }
  36
  37 void ConstexprIf::tests()
  38 {
  39     cout << print_type_info(5) << endl;
  40     cout << print_type_info(5LL) << endl;
  41     cout << print_type_info(2.3) << endl;
  42     cout << print_type_info("hello") << endl;
  43     cout << print_type_info(true) << endl;
  44 }