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  1. #include <iostream>
  2. #include <algorithm>
  3. #include <vector>
  4. #include <initializer_list>
  5. #include <cassert>
  6. using namespace std;
  7.  
  8. template<typename T>
  9. std::ostream& operator<<(std::ostream& out, const std::vector<T>& v){
  10. 	for(const auto& el : v){
  11. 		out << el << '\n';
  12. 	}
  13. 	return out;
  14. }
  15.  
  16. class A {
  17. 	int a;
  18. 	int b;
  19. public:
  20. 	A(std::initializer_list<int> l){
  21. 		assert(l.size() == 2);
  22. 		auto i = l.begin();
  23. 		a = *i;
  24. 		++i;
  25. 		b = *i;
  26. 	}
  27.  
  28. 	friend std::ostream& operator<<(std::ostream& stream, const A& e){
  29. 		return stream << e.a << ' ' << e.b;
  30. 	}
  31.  
  32. 	static bool compareViaA(const A& lhs, const A& rhs){
  33. 		return rhs.a > lhs.a;
  34. 	}
  35.  
  36. 	static bool compareViaB(const A& lhs, const A& rhs){
  37. 		return rhs.b > lhs.b;
  38. 	}
  39. };
  40.  
  41. int main() {
  42. 	std::vector<A> v {{2,3}, {3,2}, {1,4}, {4,1}};
  43. 	//sort(v.begin(), v.end(), [](const A& a, const A& b){return a.a > b.a;}) // fails because of privacy violation
  44. 	sort(v.begin(), v.end(), A::compareViaA);
  45. 	std::cout << v << '\n';
  46. 	sort(v.begin(), v.end(), A::compareViaB);
  47. 	std::cout << v << '\n';
  48. 	return 0;
  49. }
Success #stdin #stdout 0s 3432KB
comments (?)
stdin 
Standard input is empty
stdout 
1 4
2 3
3 2
4 1

4 1
3 2
2 3
1 4
https://ideone.com/lDMujx
language:
C++14 (gcc 8.3)
created:
10 years ago
visibility:
public

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