just Programme

//calendar.cpp----打印某年年歷
#include <iostream.h>
#include <iomanip.h>
int year;
int weekday;

//---------------------------------------
void PrintMonth(int m);//打印每個月
void PrintHead(int m);//打印月標題
int DaysOfMonth(int m);//計算每個月天數
bool IsLeapYear(int m);//閏年判斷
long WeekdayOfYear(int y);//某年的第一天
//---------------------------------------
int main()
{
?//打印年歷頭
?cout << "please enter the year:";
?cin >> year;
?if (year<1)
??cout << "輸入的年不能小于1!"<<endl;
?cout <<"＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝"<<endl;
?cout << "?????????????????????? "<<year<<"年?????????????? "<<endl;
?cout <<"＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝＝"<<endl;
?//求開頭第一天星期幾
?weekday=WeekdayOfYear(year);
?//打印每個月
?for (int i=1;i<=12;i++)
??PrintMonth(i);
?
?return (0);
}

//-----------------------------------------
void PrintMonth(int m)
{
?//打印月標題
?PrintHead(m);
?//計算每個月天數
?int days=DaysOfMonth(m);
?//打印日期
?for (int i=1;i<=days;i++)
?{
??cout << setw(5)<<i;
??weekday=(weekday+1)%7;
??if (weekday%7==0)
??{
???cout << endl;
???cout << "????????? ";
??}
?}
?cout <<endl;
}

//-------------------------------------------
void PrintHead(int m)
{
?cout << setw(3)<<m<<"月"<<"????????日???一???二???三??四???五?? 六"<<endl;
?cout <<"????????? ";
?for (int i=0;i<weekday;i++)
??cout << "???? ";
}

//--------------------------------------------
int DaysOfMonth(int m)
{
?switch (m)
?{
?case 1:
?case 3:
?case 5:
?case 7:
?case 8:
?case 10:
?case 12: return(31);break;
?case 4:
?case 6:
?case 9:
?case 11: return(30);break;
?default:
??if(IsLeapYear(year))
???return(29);
??else
???return(28);
?}
}

//---------------------------------------------
bool IsLeapYear(int y)
{
?return (((y%4==0)&&(y%100!=0))||(y%400==0));
}

//----------------------------------------------
long WeekdayOfYear(int y)
{
?long TotalDay=0;
?//求總天數
?for (int i=1;i<=y;i++)
??TotalDay+=365;
?//加上閏年天數
?for (int j=0;j<=y;j++)
??TotalDay+=IsLeapYear(y);
?TotalDay%=7;

?return(TotalDay);
}