C#时间函数扩展

 

// 本周是本年第几周

private   int  DatePart(System.DateTime dt)

{

int  weeknow  =  Convert.ToInt32(dt.DayOfWeek); // 今天星期几

int  daydiff  =  ( - 1 )  *  (weeknow + 1 ); // 今日与上周末的天数差

int  days  =  System.DateTime.Now.AddDays(daydiff).DayOfYear; // 上周末是本年第几天

int  weeks  =  days / 7 ;

if (days % 7   !=   0 )

{

weeks ++ ;

}

// 此时，weeks为上周是本年的第几周

return  (weeks + 1 );

}

// 本周起止日期

private   string  WeekRange(System.DateTime dt)

{

int  weeknow  =  Convert.ToInt32(dt.DayOfWeek);

int  daydiff  =  ( - 1 )  *  weeknow;

int  dayadd  =   6 - weeknow;

string  dateBegin  =  System.DateTime.Now.AddDays(daydiff).Date.ToString( " MM月dd日 " );

string  dateEnd  =  System.DateTime.Now.AddDays(dayadd).Date.ToString( " MM月dd日 " );

return  dateBegin  +   "  -  "   + dateEnd;

}