Sandbox/FoldExpressions.cpp

   1 #include "FoldExpressions.h"
   2
   3 #include <iostream>
   4 using namespace std;
   5
   6
   7 // Ep 20: https://www.youtube.com/watch?v=nhk8pF_SlTk
   8 // https://en.cppreference.com/w/cpp/language/fold
   9
  10 namespace FoldExpressions
  11 {
  12     // Old fashion (before C++17).
  13     template<typename ... T>
  14     auto sum(T ... t)
  15     {
  16         typename common_type<T...>::type result{};
  17         initializer_list<int>{ (result += t, 0)... };
  18         return result;
  19     }
  20
  21     // With C++17.
  22     template<typename ... T>
  23     auto sum2(T ... t)
  24     {
  25         const double n = 5;
  26         return (5 + ... + t);
  27     }
  28
  29     template<typename ... T>
  30     auto avg(T ... t)
  31     {
  32         return (t + ...) / sizeof...(t);
  33     }
  34 }
  35
  36 void FoldExpressions::tests()
  37 {
  38     cout << sum(1, 2.2, 3, 4, 5) << endl;
  39     cout << sum2(1, 2.2, 3, 4, 5) << endl;
  40
  41     cout << avg(1, 2.2, 3, 4, 5) << endl;
  42 }