가변인자 템플릿 파라미터 팩 재귀호출 예제

#include <iostream>
 
using namespace std;
 
void print() {
    cout << endl;
}
 
template <typename T> void print(const T& t) {
    cout << t << endl;
}
 
template <typename First, typename... Rest> void print(const First& first, const Rest&... rest) {
    cout << first << ", ";
    print(rest...); // recursive call using pack expansion syntax
}
 
int main()
{
    print(); // calls first overload, outputting only a newline
    print(1); // calls second overload
 
    // these call the third overload, the variadic template,
    // which uses recursion as needed.
    print(10, 20);
    print(100, 200, 300);
    print("first", 2, "third", 3.14159);
}

// The base case: we just have a single number.
template <typename T>
double sum(T t) {
  return t;
}
 
// The recursive case: we take a number, alongside
// some other numbers, and produce their sum.
template <typename T, typename... Rest>
double sum(T t, Rest... rest) {
  return t + sum(rest...);
}