这段代码用VS2013调试出来能够有黑窗口，且正常运行，但是VS2013总是提示错误，说是Date类的month，day , year不可访问，他们虽然声明为private，但是友元
函数不能访问Date类的私有成员吗？
#include
using namespace std;
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;
}
void Time::display(Date &d)
{
cout << d.month << "/" << d.day << "/" << d.year << endl;
cout << hour << ":" << minute << ":" << sec << endl;
}
Date::Date(int m, int d, int y)
{
month = m;
day = d;
year = y;
}
int main()
{
Time t1(10, 13, 56);
Date d1(10,01,2011);
t1.display(d1);
return 0;
}
