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;

}