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  1. #include <memory>
  2. #include <string>
  3. #include <unordered_map>
  4. #include <iostream>
  5. #include <cstdlib>
  6.  
  7. using namespace std;
  8.  
  9.  
  10. struct Animal {
  11. 	virtual void say(ostream &ostr) const = 0;
  12. };
  13.  
  14. struct Dog: public Animal {
  15. 	virtual void say(ostream &ostr) const {
  16. 		ostr << "Bark!";
  17. 	}
  18. };
  19.  
  20. struct Cat: public Animal {
  21. 	virtual void say(ostream &ostr) const {
  22. 		ostr << "Meow!";
  23. 	}
  24. };
  25.  
  26. typedef unordered_map<string, unique_ptr<Animal>> AnimalMap;
  27.  
  28. static const char *ANIMAL_ENV = "ANIMAL";
  29. static const char *ANIMAL_DEFAULT = "Dog";
  30.  
  31. int main(int, char const *[])
  32. {
  33. 	static const AnimalMap animal_map = []() {
  34. 		AnimalMap res;
  35. 		res.emplace("Dog", make_unique<Dog>());
  36. 		res.emplace("Cat", make_unique<Cat>());
  37. 		return res;
  38. 	}();
  39.  
  40. 	const char *animal = getenv(ANIMAL_ENV);
  41. 	if (animal == nullptr) {
  42. 		animal = ANIMAL_DEFAULT;
  43. 	}
  44.  
  45. 	auto hit = animal_map.find(animal);
  46. 	if (hit != animal_map.cend()) {
  47. 		hit->second->say(cout);
  48. 		cout << endl;
  49. 	} else {
  50. 		cerr << "Error: Animal not found: " << animal << endl;
  51. 	}
  52.  
  53. 	return 0;
  54. }
  55.  
Success #stdin #stdout 0s 15248KB
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Standard input is empty
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Bark!
https://ideone.com/RZHJ3J
language:
C++14 (gcc 8.3)
created:
6 years ago
visibility:
public

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