wtfunctional/examples/04_cpp17.cpp

#include <iostream>
// compile using std=c++1z-option
// tested with clang++ and g++
// using:
// $CC -Wall -Werror -pedantic -pedantic-errors -std=c++1z -o $OUT $IN

/* "Old" code:
 * The usage of auto to implicitly get the return type is C++14,
 * the main part is using C++11 variadic templates and overloading
 */
auto sum1() { return 0;}

template<typename T>
auto sum1(T t) { return t; }

template<typename T, typename... Ts>
auto sum1(T t, Ts... ts) {return t + sum1(ts...);}

/* New code:
 * Using c++17 fold expressions, this gets way shorter and
 * less error prone
 */
template <typename... T >
auto sum2 (T... args){
  return (... + args);
}

int main() {
  std::cout << sum1(1,2,3,4,5,6,7,8,9,10) << std::endl;
  std::cout << sum2(1,2,3,4,5,6,7,8,9,10) << std::endl;
  return 0;
}