#include <iostream>
#include <numeric>
using namespace std;
/* not really *args */
template<typename T>
T isum(initializer_list<T> args) {
return accumulate(args.begin(), args.end(), T());
}
/* template pack expansion */
template<typename T>
T tsum(T v) {
return v;
}
template<typename T, typename... Targs>
T tsum(T first, Targs... rest) {
return first + tsum(rest...);
}
/* auto (-std=gnu++2a, but glot.io's gcc 5.1 doesn't support it XD)
* see https://wandbox.org/permlink/MTyYnmP8ChQvkEol
*/
// auto asum = [](auto... xs) {
// return xs + ...;
// };
/* auto (-std=c++14) */
auto asum = [](auto... values) {
std::common_type_t<decltype(values)...> ret = {};
decltype(ret) _[] = { (ret += values)... };
(void)_;
return ret;
};
int main() {
cout << isum({ 1, 2, 3 }) << endl;
cout << tsum( 1, 2, 3 ) << endl;
cout << asum( 1, 2, 3 ) << endl;
return 0;
}
