C#判断两个日期是否在同一周，某日期是本月的第几周

判断两个日期是否在同一周

/// <summary> 
/// 判断两个日期是否在同一周 
/// </summary> 
/// <param name="dtmS">开始日期</param> 
/// <param name="dtmE">结束日期</param>
/// <returns></returns> 
private bool IsInSameWeek(DateTime dtmS, DateTime dtmE) 
{ 
TimeSpan ts=dtmE - dtmS; 
double dbl=ts.TotalDays; 
int intDow=Convert.ToInt32(dtmE.DayOfWeek); 
if(intDow==0) intDow=7; 
if(dbl>=7 || dbl>=intDow) return false; 
else return true; 
}


某日期是本月的第几周

private int WeekOfMonth(DateTime dtSel, bool sundayStart) 
{ 
//如果要判断的日期为1号，则肯定是第一周了 
if (dtSel.Day == 1) return 1; 
else
{ 
//得到本月第一天 
DateTime dtStart = new DateTime(dtSel.Year, dtSel.Month, 1); 
//得到本月第一天是周几 
int dayofweek = (int)dtStart.DayOfWeek; 
//如果不是以周日开始，需要重新计算一下dayofweek，详细风DayOfWeek枚举的定义 
if (!sundayStart) 
{ 
dayofweek = dayofweek - 1; 
if (dayofweek < 0) dayofweek = 7; 
} 
//得到本月的第一周一共有几天 
int startWeekDays = 7 - dayofweek; 
//如果要判断的日期在第一周范围内，返回1 
if (dtSel.Day <= startWeekDays) return 1; 
else
{ 
int aday = dtSel.Day + 7 - startWeekDays; 
return aday / 7 + (aday % 7 > 0 ? 1 : 0); 
} 
} 
}