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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. class AbstractArray{   //<-- new class
  5.      public: virtual void* get(int index)=0;
  6. };
  7.  
  8. template<class T1> class MyArray : public AbstractArray{ //<-- modify
  9. 	T1* internal[20];
  10. 	public: T1* get(int index){return internal[index];}
  11. 	public: void set(int index,T1* t1){internal[index]=t1;}
  12. };
  13. template<class T2> class User{
  14. 	public: AbstractArray* arrayPtr;
  15. 	public: T2* getTheBestT2(){
  16. 		int bestIndex=0;
  17. 		//.... some code to find the "bestIndex" ....
  18. 		void* t1=arrayPtr->get(bestIndex);
  19. 		T2* t2=static_cast<T2*>(t1); 
  20. 		return t2;
  21. 	}
  22. };
  23. class Animal{public: int testAnimal=42;};
  24. class Dog:public Animal{public: int testDog=41;};
  25. int main() {
  26. 	User<Dog> user;
  27. 	MyArray<Animal> array;
  28. 	array.set(0,new Dog());
  29. 	user.arrayPtr = &array;
  30. 	Dog* dog=user.getTheBestT2();
  31. 	std::cout<<dog->testDog<<std::endl;
  32. 	std::cout<<dog->testAnimal<<std::endl;
  33. 	return 0;
  34. }
Success #stdin #stdout 0s 15240KB
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Standard input is empty
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41
42
https://ideone.com/fbUZGd
language:
C++14 (gcc 8.3)
created:
8 years ago
visibility:
public

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