What will the following polymorphic code output in C ++

本題來源於Morgan Stanley暑期實習生招聘中的online test環節，考察了C++中多態、繼承方面的知識。

What will the following polymorphic code output in C ++？

#include <iostream>
#include <string>
#include <queue>
#include <map>
using namespace std;

class Base{
public:
	virtual int number(){return 0;}
	char letter(){ return 'b';}  //這個函數沒有聲明爲virtual虛函數
};

class Two:public Base{
	virtual int number(){ return 2;}
	char letter(){ return 't';}
};

class Four:public Base{
	virtual int number(){return 4;}
	char letter(){return 'f';}
};

void print(Base* base){
	cout<<base->letter()<<base->number()<<endl;
}

int main()
{
	Base base;
	Two two;
	Four four;
	print(&base); //cout: b0
	print(&two);  //cout: b2
	print(&four); //cout: b4

	return 0; 
}