c++第3次作业

#include <iostream>
#include<cmath>
using namespace std;
class CPoint
{
public:
CPoint(double xx=0,double yy=0):xx(xx),yy(yy){}
void print();
friend double Distance(CPoint &pointa,CPoint &pointb);
double distance1(CPoint a);
double getxx() {return xx;}
double getyy() {return yy;}
private:
double xx;
double yy;
};
void CPoint::print()
{
cout<<"("<<xx<<","<<yy<<")"<<endl;
}
double Distance(CPoint &pointa,CPoint &pointb)
{
double dx=pointa.xx-pointb.xx;
double dy=pointa.yy-pointb.yy;
return sqrt(dx*dx+dy*dy);
}
double CPoint::distance1(CPoint a)
{
double dx=a.xx-xx;
double dy=a.yy-yy;
return sqrt(dx*dx+dy*dy);
}
double distance2(CPoint a,CPoint b)
{
double dx=a.getxx()-b.getxx();
double dy=a.getyy()-b.getyy();
return sqrt(dx*dx+dy*dy);
}
int main()
{
CPoint p1(2.0,4.0),p2(3.0,2.0);
p1.print();
p2.print();
cout<<"友元函数调用："<<endl;
double d=Distance(p1,p2);
cout<<d<<endl;
cout<<"成员函数调用："<<endl;
double d1=p1.distance1(p2);
cout<<d1<<endl;
cout<<"调用一般函数："<<endl;
double d2=distance2(p1,p2);
cout<<d2<<endl;
}

#include <iostream>
using namespace std;
class Date;
class Date
{
public:
Date(int,int,int);
friend class Time; //Time为Date的友元类
private:
int month;
int day;
int year;
};
Date::Date(int m,int d,int y)
{
month=m;
day=d;
year=y;
}//对Date类的提前引用声明
class Time
{
public:
Time(int,int,int);
void add_a_second(Date &);  //增加1秒，1秒后可能会到了下一天，乃到下一月、下一年
void display(Date &);  //显示时间，格式：月/日/年 时:分:秒
private:
int hour;
int minute;
int sec;
};

Time::Time(int h,int m,int s)
{
hour=h;
minute=m;
sec=s;
}
void Time::add_a_second(Date &d)
{
sec=sec+1;
if(sec>=60)
{
sec=0;
minute+=1;
}
if(minute>=60)
{
minute=0;
hour+=1;
}
if(hour>=24)
{
hour=0;
d.day+=1;

if(d.month==1||d.month==3||d.month==5||d.month==7||d.month==8||d.month==10||d.month==12)
{
if(d.day>=31)
{
d.day=1;
d.month+=1;

if(d.month>=12)
{
d.month=1;
d.year+=1;
}
}
}
if(d.month==11||d.month==4||d.month==6||d.month==9)
{
if(d.day>=30)
{
d.day=1;
d.month+=1;
if(d.month>=12)
{
d.month=1;
d.year+=1;
}
}
}
if(d.month==2)
{

if(d.year%4==0)

{
if(d.day>=29)
{
d.day=1;
d.month+=1;
if(d.month>=12)
{
d.month=1;
d.year+=1;
}
}
}

else

if(d.day>=28)
{
d.day=1;
d.month+=1;
if(d.month>=12)
{
d.month=1;
d.year+=1;
}
}

}
}
}
void Time::display(Date &d)
{
cout<<"格式："<<d.year<<"年"<<d.month<<"月"<<d.day<<"日"<<hour<<"时"<<minute<<"分"<<sec<<"秒"<<endl;
}

int main( )
{
Time t1(23,59,32);
Date d1(12,31,2013);   //测试时，再试试Date d1(2,28,2013)会如何
for(int i=0; i<=100; i++)
{
t1.add_a_second(d1);
t1.display(d1);
}
return 0;
}