C#时间函数扩展-.NET教程,C#语言

//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;

}