I need to create an array of class template in C++ but compiler doesn't allow it. Example :
class CRefBase {
public:
virtual ~CRefBase() = 0;
};
template<class T>
class CRef : public CRefBase {
private:
T *Obj;
public:
CRef(T *Obj){ this->Obj=Obj; }
}
in main function
CRefBase *refs;
refs=new CRefBase[200]; // Error in this line : cannot allocate an object of abstract type ‘CRefBase’
I see this topic but this isn't my answer.
Thanks
Even if you were to try to instantiate a derived class, it's a terrible idea, as arrays cannot be indexed in this way- when you index a pointer to CRefBase with any index other than 0, they must only ever be CRefBase, and cannot be any derived class.
Furthermore, there is a massive bunch of exception unsafety and memory leakage in the use of new[], which is banned from all reasonable codebases. It would be safe to use something like std::vector<std::unique_ptr<CRefBase>>, and then you might actually create a program that works, if you create an object of a derived class type.
CRef is a class template, CRefBase is a (non-instantiable) abstract base class.
You're not doing what the title says:
How to create an array of templated class?
Oh, and you'll need an array of poitnters for polymorphism (and a virtual base class destructor):
CRefBase **refs = new CRefBase*[200];
for(size_t i = 0; i < 200; ++i)
refs[i] = new CRef<whatever>(pointer_to_whatever_instance);
That's it. Have a nice time managing its dynamically allocated memory.
the following code means a pure virtual function so that "CRefBase" is an abstract base class, which means that it can not be instantiated!
virtual ~CRefBase()=0;
As your question, the template supp.orts array. you can first fix your compilation problem then test it again
delete[]an array of derived objects via a base pointer?