C++有关问题，帮小弟我看看，分大大地有

C++问题，帮我看看，分大大地有
//Date.h
#ifndef   DATE_H
#define   DATE_H

class   Date
{
public:
Date(int=1,int=1,int=1900);
void   print()   const;//此处为打印函数，声明成const类，有点问题
~Date();
private:
int   month;
int   day;
int   year;
int   checkDay(int)   const;//验证输入是否合法
};

#endif

//Date.cpp
#include <iostream>
using   namespace   std;

#include   "Date.h "

Date::Date(int   mn,int   dy,int   yr)
{
if(mn> 0   &&   mn <=12)
month=mn;
else
{
month=1;
cout < < "invalid   month( " < <mn < < ")set   to   1.\n ";
}
year=yr;
day=checkDay(dy);
cout < < "Date   object   construtor   for   date ";
print();//构造函数调用了const成员函数
cout < <endl;
};//end   Date   construtor

void   Date::print()   const
{
cout < <month < < '/ ' < <day < < '/ ' < <year;
}
Date::~Date()
{
cout < < "Date   object   destrutor   for   date ";
print();//析构函数调用const函数成员
cout < <endl;
}

int   Date::checkDay(int   testDay)   const
{//这个函数可以省略不看，没有问题，就是个验证日期是否合法的
static   const   int   daysPerMonth[13]=
{0,31,28,31,30,31,30,31,30,31,30,31};
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 < < "invalid   day   ( " < <testDay < < ")set   to   1.\n ";
return   1;
}//end   function   checkDay

//Employee.h
#ifndef   EMPLOYEE_H
#define   EMPLOYEE_H

#include   "Date.h "//include   Date   class   definition

class   Employee
{
public:
Employee(const   char   *   const,const   char   *   const,const   Date   &,const   Date   &);//这个也不太明白，为什么连用两个const，概念有点模糊
void   print()   const;
~Employee();
private:
char   firstName[25];
char   lastName[25];
const   Date   birthDate;
const   Date   hireDate;
};//end   class   Employee
#endif

//Employee.cpp
#include <iostream>
#include <cstring>
using   namespace   std;

#include   "Date.h "
#include   "Employee.h "

Employee::Employee(const   char   *   const   first,const   char   *   const   last,
const   Date   &dateOfBirth,const   Date   &dateOfHire)
:birthDate(dateOfBirth),hireDate(dateOfHire)
                                    //还有次处的两个const，不太清楚
{
int   length=strlen(first);
length=(length <25   ?   length:24);
strncpy(firstName,first,length);
firstName[length]= '\0 ';         //复制字符串没问题可以不看

length=strlen(last);
length=(length <25   ?   length:24);
strncpy(lastName,last,length);
lastName[length]= '\0 ';