C＃如何计算排除特定日期的工作日（假期）

Question

我阅读了一些与C＃中的函数有关的问题/答案来计算工作日（星期一至星期五的工作日）;有些使用扩展的代码来实现这一点。

我有一个超过50,000行的数据表，我需要一个有效的方法来计算这些信息。

Answer 1

/// <summary> Get working days between two dates (Excluding a list of dates - Holidays) </summary> 
/// <param name="dtmCurrent">Current date time</param> 
/// <param name="dtmFinishDate">Finish date time</param> 
/// <param name="lstExcludedDates">List of dates to exclude (Holidays)</param> 
public static int fwGetWorkingDays(this DateTime dtmCurrent, DateTime dtmFinishDate, List<DateTime> lstExcludedDates) 
{ 
    Func<DateTime, bool> workDay = currentDate => 
      (
       currentDate.DayOfWeek == DayOfWeek.Saturday || 
       currentDate.DayOfWeek == DayOfWeek.Sunday || 
       lstExcludedDates.Exists(evalDate => evalDate.Date.Equals(currentDate.Date)) 
      ); 

    return Enumerable.Range(0, 1 + (dtmFinishDate - dtmCurrent).Days).Count(intDay => workDay(dtmCurrent.AddDays(intDay))); 
} 

我创造了这个扩展，基本上有两个日期，日期的列表中排除（节假日）。 令人惊讶的是，此方法速度非常快，并且具有验证功能，可以在与排除列表进行比较时从DateTime中排除时间。

Answer 2

基于@MiBols回答一个更有效的解决方案将是使用的HashSet<DateTime>代替List<DateTime>其中搜索是那么O(1)：

/// <summary> Get working days between two dates (Excluding a list of dates - Holidays) </summary> 
/// <param name="dtmCurrent">Current date time</param> 
/// <param name="dtmFinishDate">Finish date time</param> 
/// <param name="excludedDates">Collection of dates to exclude (Holidays)</param> 
public static int fwGetWorkingDays(this DateTime dtmCurrent, DateTime dtmFinishDate, 
            HashSet<DateTime> excludedDates) 
{ 
    Func<DateTime, bool> workDay = currentDate => (
     currentDate.DayOfWeek == DayOfWeek.Saturday || 
     currentDate.DayOfWeek == DayOfWeek.Sunday || 
     excludedDates.Contains(currentDate.Date)); 

    return Enumerable.Range(0, 1 + (dtmFinishDate - dtmCurrent).Days) 
     .Count(intDay => workDay(dtmCurrent.AddDays(intDay))); 
}