#include <iostream>
#include <memory>
struct Base
{
int a;
virtual void f() const { std::cout << "I am base!\n";}
virtual ~Base(){}
};
struct Derived : Base
{
void f() const override
{ std::cout << "I am derived!\n"; }
~Derived(){}
};
int main(){
auto basePtr = std::make_shared<Base>();
std::cout << "Base pointer says: ";
basePtr->f();
auto derivedPtr = std::make_shared<Derived>();
std::cout << "Derived pointer says: ";
derivedPtr->f();
// static_pointer_cast to go up class hierarchy
basePtr = std::static_pointer_cast<Base>(derivedPtr);
std::cout << "Base pointer to derived says: ";
basePtr->f();
// dynamic_pointer_cast to go down/across class hierarchy
auto downcastedPtr = std::dynamic_pointer_cast<Derived>(basePtr);
if(downcastedPtr)
{
std::cout << "Downcasted pointer says: ";
downcastedPtr->f();
}
// All pointers to derived share ownership
std::cout << "Pointers to underlying derived: "
<< derivedPtr.use_count()
<< "\n";
}