红色的是问题语句，蓝色的是提示的错误

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date1.h

  #ifndef DATE1_H
  #define DATE1_H

class Date {
public:
    Date ( int = 1, int = 1, int = 1900 );
    void print() const;
    ~Date();
private:
    int month;
    int day;
    int year;
    int checkDay ( int );
};

#endif

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emply1.h


#ifndef EMPLY1_H
#define EMPLY1_H

#include "date1.h"
class Employee {
public:
    Employee ( char *, char *, int, int, int, int, int, int );
    void print() const;
    ~Employee();
private:
    char firstName[ 25 ];
    char lastName[ 25 ];
    const Date birthDate;
    const Date hireDate;
}

#endif

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test.cpp


#include <iostream.h>
#include <string.h>
#include "date1.h"

Date::Date ( int mn, int dy, int yr)
{
    if ( mn > 0 && mn <= 12 )
      month = mn;
    else {
        month = 1;
        cout < < "Month " < < mn < < " invalid. Set to month 1.\n";
  }
    year = yr;
    day = checkDay ( dy );
   
    cout < < "Date object consturctor for date ";
    print();
    cout < < endl;
}

void Date::print() const
  { cout < < month < < '/' < < day < < '/' < < year; }
  
Date::~Date()
{
    cout < < "Date object destructor for date ";
    print();
    cout < < endl;
}

int Date::checkDay ( int testDay )
{
    static const int daysPerMonth[ 13 ] =
      { 0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
      
    if ( testDay > 0 && testDay <= daysPerMonth[ month ] )
        return testDay;
      if ( month == 2 && testDay == 29 &&
            ( year % 400 == 0 ||
              ( year % 4 == 0 && year % 100 != 0 ) ) )
        return testDay;
        
      cout < < "Day " < < testDay < < " invalid. Set to day 1.\n";
      
      return 1;
}


// Fig. 7.4: emply1.cpp
// Member function definition for Employee class.
#include <iostream.h>
#include <string.h>
#include "emply1.h"
#include "date1.h"

Employee::Employee( char *fname, char *lname,
                    int bmonth, int bday, int byear,
                    int hmonth, int hday, int hyear )
:  birthDate ( bmonth, bday, byear ),
    hireDate ( hmonth, hday, hyear )
{
    int length = strlen ( fname );
    length = ( length < 25 ? length : 24 );
    strncpy ( firstName, fname, length );
    firstName[ length ] = '\0';
   
    length = strlen ( lname );
    length = ( length < 25 ? length : 24 );
    strncpy ( lastName, lname, length );
    lastName[ length ] = '\0';
   
    cout < < "Employee object constructor: "
        < < firstName < < ' ' < < lastName < < endl;
}

void Employee::print() const
{
    cout < < lastName < < ", " < < firstName < < "\nHired: ";
    hireDate.print();
    cout < < " Birth date: ";
    birthDate.print();
    cout < < endl;
}

Employee::~Employee()
{
    cout < < "Employee object destructor: "
        < < lastName < < ", " < < firstName < < endl;
}


// Fig. 7.4: fig07_04.cpp
// Demonstrating composition: an object with member objects.
#include <iostream.h>
#include <conio.h>
#include "emply1.h"

int main()
{
    Employee e ( "bob", "Jones", 7, 24, 1949, 3, 12, 1988 );
   
    cout < < '\n';
    e.print();
   
    cout < < "\nTest Date constructor with invalid values:\n";
    Date d ( 14, 35, 1994 );
    cout < < endl;
    getch();
    return 0;
}              

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ISO C++ forbids defining types within return type
return type specification for constructor invalid.

这代码太长了点儿吧！
看着晕，O(∩_∩)O~，我还没学到友元函数呢！
帮不了你啥忙了！
不过你如果将你的代码缩短点儿在写友元函数会不会更容易找出来错误？？

birthDate ( bmonth, bday, byear ),
    hireDate ( hmonth, hday, hyear )
这个两个是什么类？