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  1. #include <iostream>
  2. #include <utility>
  3. #include <tuple>
  4.  
  5.  
  6. template <typename ... Args>
  7. void f(Args... args)
  8. {
  9. 	int dummy[] = {0, (std::cout << " " << std::forward<Args>(args), 0)...};
  10. }
  11.  
  12. namespace detail
  13. {
  14.  
  15.     template<class T> auto modifier(T&& arg, std::size_t i, std::size_t pos) {
  16.         if (i == pos)
  17.             return arg + 40;
  18.         else
  19.             return std::forward<T>(arg);
  20.     }
  21.  
  22. 	template <std::size_t... Is, typename... Args>
  23. 	void bar(std::size_t pos, std::index_sequence<Is...>, Args&&... args) {
  24. 		return f(modifier(std::forward<Args>(args), Is, pos)...);
  25. 	}
  26.  
  27. }
  28.  
  29. template<typename... Args>
  30. void bar(std::size_t pos, Args&&... args) {
  31.     detail::bar(pos, std::index_sequence_for<Args...>(), std::forward<Args>(args)...);
  32. }
  33.  
  34. int main() {
  35. 	bar(2, 0, 1, 2, 3, 4, 5, 6);
  36.  
  37. }
Success #stdin #stdout 0s 3140KB
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Standard input is empty
stdout
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 0 1 42 3 4 5 6
https://ideone.com/14EHgs
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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