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  1. #include <algorithm>
  2. #include <vector>
  3. #include <array>
  4. #include <iostream>
  5.  
  6. const struct in_op final
  7. {
  8. 	template<typename T>
  9. 	struct impl
  10. 	{
  11. 		T const& x;
  12.  
  13. 		template<typename Container>
  14. 		bool operator>(Container const& c) const
  15. 		{
  16. 			return std::find(std::begin(c), std::end(c), x) != std::end(c);
  17. 		}
  18. 	};
  19.  
  20. 	template<typename T>
  21. 	friend auto operator<(T const &x, in_op) {
  22. 		return impl<T>{x};
  23. 	}
  24. } in;
  25.  
  26. int main()
  27. {
  28. 	const std::array<int, 3>         a{ 1, 2, 3 };
  29. 	const std::vector<int>           b{ 1, 2, 3 };
  30. 	const std::initializer_list<int> c{ 5, 6, 7 };
  31.  
  32. 	std::cout << "5 in { 1, 2, 3 } = " << std::boolalpha << (5 <in> a) << '\n';
  33. 	std::cout << "2 in { 1, 2, 3 } = " << std::boolalpha << (2 <in> b) << '\n';
  34. 	std::cout << "7 in { 5, 6, 7 } = " << std::boolalpha << (7 <in> c) << '\n';
  35. 	return 0;
  36. }
Success #stdin #stdout 0s 4544KB
comments (?)
stdin 
Standard input is empty
stdout 
5 in { 1, 2, 3 } = false
2 in { 1, 2, 3 } = true
7 in { 5, 6, 7 } = true
https://ideone.com/wnpoqL
language:
C++14 (gcc 8.3)
created:
4 years ago
visibility:
public

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