#include <iostream>
struct Base {
	virtual void sayHi() {
		std::cout << "Hi from Base!\n";
	}
 
	virtual ~Base() {}
};
 
struct Derived : Base {
	virtual void sayHi() {
		std::cout << "Hi from Derived!\n";
	}
};
 
void sayHelloToMyValue(Base o) {
	o.sayHi();
}
 
void sayHelloToMyReference(Base &o) {
	o.sayHi();
}
 
void sayHelloToMyPointer(Base *o) {
	o->sayHi();
}
 
int main(int, char**) {
	Derived d;	// No dynamic allocation!
	Base &base = d;
 
	sayHelloToMyValue(base);
	sayHelloToMyReference(base);
	sayHelloToMyPointer(&base);
 
	return 0;
}

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