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  1. #include <algorithm>
  2. #include <iostream>
  3. #include <vector>
  4. #include <set>
  5. #include <string>
  6.  
  7. class Person {
  8. 	private:
  9. 		int age;
  10. 		std::string name;
  11. 	public:
  12. 		Person(int a, std::string n) : age(a), name(n) {}
  13. 		int getAge() const { return age; }
  14. 		std::string getName() const { return name; }
  15. 		bool operator<(const Person& rhs) const {return name < rhs.name; }
  16. };
  17.  
  18. template <typename T>
  19. class PtrProxy {
  20.     private:
  21.         const T* m_object;
  22.  
  23.     public:
  24.         PtrProxy(const T& obj) : m_object(&obj) {}
  25.         PtrProxy(const T* obj) : m_object(obj)  {}
  26.  
  27.         const T& operator*() const { return *m_object; }
  28.         const T* operator->() const { return m_object; }
  29. };
  30.  
  31. int main()
  32. {
  33. 	std::set<Person> p1;
  34. 	auto var = p1.insert(Person(30, "Bill"));
  35.  
  36. 	// Pur the address of the Person in p1 into p2
  37. 	std::vector<Person*> p2;
  38. 	p2.push_back(const_cast<Person*>(&(*(var.first))));
  39.  
  40.  
  41.  
  42. 	std::vector<int> data;
  43.  
  44. 	auto the_lambda = [](const PtrProxy<Person> pp) {return pp->getAge();};
  45.  
  46. 	std::transform(p1.begin(), p1.end(), std::back_inserter(data), the_lambda);
  47. 	std::transform(p2.begin(), p2.end(), std::back_inserter(data), the_lambda);
  48.  
  49. 	for (int age : data)
  50. 	{
  51. 		std::cout << age << "\n";
  52. 	}
  53.  
  54. }
Success #stdin #stdout 0s 3432KB
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https://ideone.com/X3XWVz
language:
C++14 (gcc 8.3)
created:
11 years ago
visibility:
public

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