#include <stdlib.h>
#include <stdio.h>
#include <string.h>

class Foo {
public:
	void nv() {
		printf("Hello from a NON-VIRTUAL method in Foo!\n");
	}

virtual	void v() {
		printf("Hello from a VIRTUAL method in Foo!\n");
	}
};

class FooBar : public Foo {
public:
	void nv() {
		printf("Hello from a NON-VIRTUAL method in FooBar!\n");
	}

	void v() {
		printf("Hello from a instantiated VIRTUAL method in FooBar!\n");
	}
};

int main(int argc, char **argv){
	Foo foo;
	FooBar foobar;

	foobar.nv();		// FooBar::nv()
	foobar.v();		// FooBar::v()

	Foo *fooptr = (Foo *)&foobar;
	fooptr->nv();		// Foo::nv()    <--- here's the difference
	fooptr->v();		// FooBar::v()

	printf("---------\n");

	// FooBar is just a pointer to the FooBar vtable.
	// Foo is just a pointer to the Foo vtable.

	printf("sizeof(foobar) = %d, sizeof(foo) = %d\n", sizeof(foobar), sizeof(foo));

	long *foobarAsLong = (long *)&foobar;
	long *fooAsLong = (long *)&foo;
	printf("FooBar vtable pointer: %p\n", foobarAsLong[0]);
	printf("Foo vtable pointer: %p\n", fooAsLong[0]);

	long **foobarVtable = (long **)&foobar;
	long **fooVtable = (long **)&foo;

	// This is the address of FooBar::v()
	printf("First entry of FooBar VTABLE: %p\n", foobarVtable[0][0]);

	// This is the address of  Foo::v()
	printf("First entry of Foo VTABLE: %p\n", fooVtable[0][0]);

	// If FooBar had more than one virtual method,
	// then you would access the second's address
	// with foobarVtable[0][1], the third's with
	// foobarVtable[0][2], and so on.
}