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  1. #include <iostream>
  2. #include <vector>
  3. using namespace std;
  4.  
  5. struct A {
  6. 	virtual ~A() {};  // to make A and its descendents polymorphic, you need at least one virtual function
  7. };
  8. struct B : A {
  9. 	void foo () { cout<<"this is a B object: foo!"<<endl; }
  10. };
  11. struct C : A {};
  12.  
  13. int main() {
  14. 	vector<A*> va; 
  15. 	va.push_back (new A);
  16. 	va.push_back (new B); 
  17. 	va.push_back(new C); 
  18. 	for (auto x : va) {
  19. 		auto maybe = dynamic_cast<B*>(x);
  20. 		if (maybe) // yes, it's a B*
  21. 	       maybe->foo(); 
  22. 	    else cout << "still not a B"<<endl; 
  23. 	}
  24. 	return 0;
  25. }
Success #stdin #stdout 0s 15240KB
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Standard input is empty
stdout
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still not a B
this is a B object: foo!
still not a B
https://ideone.com/a9fC4c
language:
C++14 (gcc 8.3)
created:
7 years ago
visibility:
public

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