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  1.     #include <iostream>
  2. 	#include <memory>
  3. 	#include <vector>
  4.  
  5. 	class Base {};
  6. 	class A : public Base{};
  7. 	class B : public Base{};
  8. 	class C : public Base{};
  9.  
  10. 	class CollectionOfBase
  11. 	{
  12. 	public:
  13. 		void add (std::shared_ptr<Base> item){m_items.push_back(item);}
  14. 		std::vector<std::shared_ptr<Base>> const& getItems() const {return m_items;}
  15.  
  16. 	private:
  17. 		std::vector<std::shared_ptr<Base>> m_items;
  18. 	};
  19.  
  20. 	void identify( std::shared_ptr<A> const& )
  21. 	{
  22. 		std::cout << "A" << std::endl;
  23. 	}
  24.  
  25. 	void identify( std::shared_ptr<B> const& )
  26. 	{
  27. 		std::cout << "B" << std::endl;
  28. 	}
  29.  
  30. 	void identify( std::shared_ptr<C> const& )
  31. 	{
  32. 		std::cout << "C" << std::endl;
  33. 	}
  34.  
  35. 	//This function works in the below for loop, but this is not what I need to use
  36. 	void identify( std::shared_ptr<Base> const& )
  37.     {
  38. 	 	std::cout << "Base" << std::endl;
  39. 	}
  40.  
  41.  
  42.     int main()
  43. 	{
  44. 		using namespace std;
  45.  
  46. 		CollectionOfBase collection;
  47.  
  48. 		collection.add(make_shared<A>());
  49. 		collection.add(make_shared<A>());
  50. 		collection.add(make_shared<C>());
  51. 		collection.add(make_shared<B>());
  52.  
  53. 		for (auto const& x : collection.getItems())
  54. 		{
  55. 			// THE QUESTION:
  56. 			// How to distinguish different type of items
  57. 			// to invoke "identify" with object specific signatures ???
  58. 			// Can I cast somehow the object types that I push_back on my vector ???
  59.  
  60. 			identify(x);
  61. 		}
  62. 		/*
  63. 		The desired output of this loop should be:
  64.  
  65. 		A
  66. 		A
  67. 		C
  68. 		B
  69.  
  70. 		*/
  71.  
  72. 		return 0;
  73. 	}
  74.  
  75.  
Success #stdin #stdout 0s 16056KB
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Base
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https://ideone.com/xjCwPI
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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