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  1. #include <iostream>
  2. #include <map>
  3. using namespace std;
  4.  
  5. class SomeClass {
  6. 	public:
  7. 	SomeClass(const std::string& name): m_name(name) {}
  8. 	std::string GetName()const {return m_name; }
  9.     bool operator <(const SomeClass& rhs) const
  10.     {
  11.         return m_name < rhs.m_name;
  12.     }
  13. 	private:
  14. 	std::string m_name;
  15. };
  16.  
  17. auto print_seq  = [](const auto& seq) { for (const auto& itr: seq) {std::cout << itr.second << ":";} std::cout << std::endl;};
  18.  
  19. int main() {
  20. 	// your code goes here
  21. 	std::map<SomeClass*, std::string> pointer_keyed_map;
  22. 	SomeClass s3("object3");
  23. 	SomeClass s1("object1");
  24. 	SomeClass s2("object2");
  25. 	pointer_keyed_map.insert(std::make_pair(&s1, s1.GetName()));
  26. 	pointer_keyed_map.insert(std::make_pair(&s2, s2.GetName()));
  27. 	pointer_keyed_map.insert(std::make_pair(&s3, s3.GetName()));
  28. 	std::cout << "Pointer based keys: object order" << std::endl;
  29. 	print_seq(pointer_keyed_map);
  30.  
  31. 	std::map<SomeClass, std::string> int_keyed_map;
  32. 	int_keyed_map.insert(std::make_pair(s3, s3.GetName()));
  33. 	int_keyed_map.insert(std::make_pair(s1, s1.GetName()));
  34. 	int_keyed_map.insert(std::make_pair(s2, s2.GetName()));
  35. 	std::cout << "String based keys: object order" << std::endl;
  36. 	print_seq(int_keyed_map);
  37. 	return 0;
  38. }
Success #stdin #stdout 0s 3460KB
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stdin
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Standard input is empty
stdout
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Pointer based keys: object order
object3:object1:object2:
String based keys: object order
object1:object2:object3:
https://ideone.com/VKirct
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
secret

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