The following code example is taken from the book
The C++ Standard Library - A Tutorial and Reference, 2nd Edition
by Nicolai M. Josuttis, Addison Wesley Longman, 2012
Copyright © 2012 by Pearson Education, Inc. and Nicolai M. Josuttis
#include <tuple>
#include <iostream>
// helper: print elements with index IDX and higher of tuple t having MAX elements
template <int IDX, int MAX, typename... Args>
struct PRINT_TUPLE {
static void print (std::ostream& strm, const std::tuple<Args...>& t) {
strm << std::get<IDX>(t) << (IDX+1==MAX ? "" : ",");
PRINT_TUPLE<IDX+1,MAX,Args...>::print(strm,t);
}
};
// partial specialization to end the recursion
template <int MAX, typename... Args>
struct PRINT_TUPLE<MAX,MAX,Args...> {
static void print (std::ostream& strm, const std::tuple<Args...>& t) {
}
};
// output operator for tuples
template <typename... Args>
std::ostream& operator << (std::ostream& strm,
const std::tuple<Args...>& t)
{
strm << "[";
PRINT_TUPLE<0,sizeof...(Args),Args...>::print(strm,t);
return strm << "]";
}