Помогите с ошибкой

// fig8_6.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <iostream>
#include <conio.h>
#include "date1.h"
using namespace std;
int _tmain(int argc, _TCHAR* argv[])
{
    Date d1, d2(12, 27, 1992), d3(0, 99, 8045);
    cout << " d1 is " << d1 << endl
         << " d2 is " << d2 << endl
         << " d3 is " << d3 << endl << endl;
    cout << " d2 += 7 is " << (d2 += 7) << endl << endl;
    d3.setDate(2, 28, 1992);
    cout << " d3 is " << d3 << endl;
    cout << " ++d3 is " << ++d3 << endl << endl;
    Date d4(3, 18, 1969);
    cout << " Check to operations prefix increment: " << endl
         << " d4 is " << d4 << endl;
    cout << " ++d4 is " << ++d4 << endl;
    cout << " d4 is " << d4 << endl << endl;
    cout << "Check to operations postfix inrement: " << endl
         << " d4 is "  << d4 << endl;
    cout << " d4++ is " << d4++ << endl;
    cout << " d4 is " << d4 << endl << endl;
    _getch();
    return 0;
}

//--------date1.cpp-------------//
#include "stdafx.h"
#include <iostream>
#include <conio.h>
#include "date1.h"
int Date::days[] = {0,31,28,31,30,31,30,31,31,30,
                     31,30,31};
Date::Date(int m, int d, int y) { setDate(m, d, y); }
void Date::setDate(int mm, int dd, int yy)
{
    month = (mm >= 1 && mm <= 12) ? mm : 1;
    year = (yy >= 1900 && yy <= 2100) ? yy : 1900;
    if(month == 2 && leapYear(year))
        day = (dd >= 1 && dd <= 29) ? dd : 1;
    else
        day = (dd >= 1 && dd <= days[month]) ? dd : 1;
}
Date Date::operator ++()
{
    helpIncrement();
    return *this;
}
Date Date::operator ++(int)
{
    Date temp = *this;
    helpIncrement();
    return temp;
}
const Date &Date::operator +=(int additionalDays)
{
    for(int i = 1; i <= additionalDays; i++)
        helpIncrement();
    return *this;
}
int Date::leapYear(int y)
{
    if(y % 400 == 0 || (y % 100 != 0 && y % 4 == 0))
        return 1;
    else
        return 0;
}
int Date::endOfMonth(int d)
{
    if(month == 2 && leapYear(year))
        return d == 29;
    else
        return d == days[month];
}
void Date::helpIncrement()
{
    if(endOfMonth(day) && month == 12) {
        day = 1;
        month = 1;
        ++year;
    }
    else if(endOfMonth(day)) {
        day = 1;
        ++month;
    }
    else
        ++day;
}
ostream &operator << (ostream &output, const Date &d)
{
    static char *monthName[13] = {"", "January",
        "February", "March", "April", "May", "June",
        "July", "August", "September", "October",
        "November", "December"};
    output << monthName[d.month] << ' '
           << d.day << ", " << d.year;
    return output;
}

//------date1.h------------//
#ifndef DATE1_H
#define DATE1_H
#include <iostream>
class Date {
    friend ostream &operator << (ostream &, const Date &);
public:
    Date(int m = 1, int d = 1, int y = 1900);
    void setDate(int, int, int);
    Date operator++();
    Date operator++(int);
    const Date &operator+=(int);
    int leapYear(int);
    int endOfMonth(int);
private:
    int month;
    int day;
    int year;
    static int days[];
    void helpIncrement();
};
#endif