友元

来源：互联网发布：php项目开发视频教程编辑：程序博客网时间：2024/05/01 18:05

设计一个日期类date，包括年份，月份，和日号，编写一个友元函数，求两个日期相差的天数。

#include<iostream.h>

class date

{

public:

intyear;

intmonth;

intday;

date(inty,int m,int d)

{

year=y;month=m;day=d;

}

voiddisp()

{

cout<<year<<"年"<<month<<"月"<<day<<"日"<<endl;

}

friendint coun_day(date &d,int);

friendint leap(int year);

friendint subs(date &d1,date &d2);

};

int count_day(date &d,int flag)

{

staticint day_tab[2][12]={{31,28,31,30,31,30,31,31,30,31,30,31},

{31,29,31,30,31,30,31,31,30,31,30,31}};

intp,i,s;

if(leap(d.year))

p=1;

elsep=0;

if(flag)

{

s=d.day;

for(i=1;i<d.month;i++)

s+=day_tab[p][i-1];

}

else

{

s=day_tab[p][d.month]-d.day;

for(i=d.month+1;i<=12;i++)

s+=day_tab[p][i-1];

}

returns;

}

int leap(int year)

{

if(year%4==0&&year%100!=0||year%400==0)//闰年

return 1;

else

return 0;//不是闰年

}

int subs(date &d1,date &d2)

{

intdays,day1,day2,y;

if(d1.year<d2.year)

{

days=count_day(d1,0);

for(y=d1.year+1;y<d2.year;y++)

if(leap(y))

days+=365L;

else

days+=365L;

days+=count_day(d2,1);

}

elseif(d1.year==d2.year)

{

day1=count_day(d1,1);

day2=count_day(d2,1);

days=day2-day1;

}

else

days=-1;

return days;

}

void main()

{

date d1(2000,1,1),d2(2002,10,1);

intds=subs(d1,d2);

cout<<"输出结果"<<endl;

if(ds>=0)

{

d1.disp();cout<<"与";

d2.disp();cout<<"之间有"<<ds<<"天"<<endl;

}

else

cout<<"时间有误!"<<endl;

}