Polymorphism method issues

[DeadEli]

I have an abstract class called "Element" and in another class I have a variable
std::vector<Element> elements;
and a method

void MyClass::addElement(Element* element)
{
    elements.push_back(element);
    delete element;
}

this doesn't work. I just want this method to fill the vector with objects of subclasses of Element. How can I do this?

[o1vk4iN6]

If you intend to use polymorphism you can't define the space required for it as it is unknown.

class A { int a; };
class B : public A { int b; };

std::vector<A> values = { B() }; // trying to store 8 bytes into 4 bytes 

In either case why are you calling delete on a variable passed through as a parameter, that is very sketchy. Whoever is passing an element through the addElement should be responsible for destruction.

[andywestken]

To be consistent with the signature of your method MyClass::addElement, you need to declare your vector with Element pointer.

std::vector<Element*> elements;

And the delete on line 4 needs to go. If you delete the element after adding its pointer to the vector, then the pointer in the vector will be invalidated.

Andy