第一次写c++遇到问题

看书上一个例子，为什么运行有问题 ？
//Date.h
#include <iostream.h>

class Date
{

private:
    int mouth;
    int date;
    int year;

public:
    Date(int m = 2, int d = 1, int y = 2008)
    {
        mouth = m;
        date = d;
        year = y;
    }

    Date(Date &d)
    {
        mouth = d.mouth;
        date = d.date;
        year = d.year;
    }

    ~Date()
    {}

    void printDate()
    {
        cout<<month<<"-"<<date<<"-"<<year<<endl;
    }
}

//Date.cpp
#include "Date.h"

void main()
{
    Date today(2, 3, 2008);
    Date someday;
    Date someday2(today);

    today.printDate();
    someday.printDate();
    someday2.printDate();

    //return 0;
}