有以下程序：#includeclassDate;classTime{public:Time(int,int,int);voiddisplay(Date&);private:inthour;intminute;intsec;};classDate{public:Date(int,int,int);friendvoidTime∷display(Date&);private:intmonth;intday;intyear;};Time

Question

有以下程序：
#include
class Date;
class Time
{
public:
Time(int,int,int);
void display(Date &);
private:
int hour;
int minute;
int sec;
};
class Date
{
public:
Date(int,int,int);
friend void Time∷display(Date &);
private:
int month;
int day;
int year;
};
Time∷Time(int h,int m,int s)
{
hour=h;
minute=m;
sec=s;
}
Date∷Date(int m,int d,int y)
{
month=m;
day=d;
year=y;
}
void Time∷display(Date &d)
{
cout

Answer 1

#include class Date; class Time {public:Time(int,int,int);void display(Date &); private:int hour;int minute;int sec;};class Date ...