计数一周中工作的天数，不循环

Question

我需要计算工作的总天数，给定结构，说明一周中的哪些天是工作的，以及从和到日期。

我目前的算法是：

protected int TotalWorkDays(DateTime From, DateTime dtTo,WorkedDays days)
    {
        int Days = 0;
        DayOfWeek DOW;
        for (DateTime curDate = From; curDate.Date <= dtTo.Date; curDate = curDate.AddDays(1))
        {
            DOW = curDate.DayOfWeek;
            if ((DOW == DayOfWeek.Sunday &  days.Sunday) |
                (DOW == DayOfWeek.Monday &  days.Monday) |
                (DOW == DayOfWeek.Tuesday &  days.Tuesday) |
                (DOW == DayOfWeek.Wednesday &  days.Wednesday) |
                (DOW == DayOfWeek.Thursday &  days.Thursday) |
                (DOW == DayOfWeek.Friday &  days.Friday) |
                (DOW == DayOfWeek.Saturday &  days.Saturday)
               )
            {
                Days += 1;
            }
        }
        return Days;
    }

我几乎肯定这可以在没有循环的情况下完成，但我似乎不明白。有人能帮我找到一个更有效的算法吗？

Answer 1

查找开始日期和结束日期之间的周数（使用减法和除法）。然后乘以每周工作的天数。对结束情况做一些减法（开始/结束日期在一周的中间）。

Answer 2

hmmmm。。。。

创建一个从DayOfWeek（如果我没记错的话是int）到bool的字典，然后。。。。

var DaysWorked = (from dayoffset in Enumerable.Range(0, (To - From).TotalDays)
                  where WorkingDays[From.AddDays(dayoffset).DayOfWeek]
                  select dayoffset).Count();

但并不完全有效！

Answer 3

看看这篇代码项目文章，它解释了如何在不循环的情况下完成它；）

编辑：以下是它使用的公式：

1. 以周为单位计算时间跨度的数量。可以这么说，W
2. 从周数中减去第一周。W=W-1
3. 将周数乘以每周的工作天数。称之为D
4. 找出指定时间段内的假期。叫它吧，H
5. 计算第一周的天数。叫它吧，SD
6. 计算上周的天数。叫它吧，ED
7. 把所有的日子加起来。BD=D+SD+ED�H

Answer 4

您可以利用一周中每七天重复一次的事实。以下是一个算法的基本概述：

1. 计算第一个部分周的工作天数
2. 计算上一部分周的工作天数
3. 计算中间的整周数，然后乘以一周的工作天数
4. 将以上三个值相加

Answer 5

var workDays = new DayOfWeek[]{ DayOfWeek.Monday, DayOfWeek.Tuesday};
var days = TotalWorkDays(new DateTime(2005,1,12), new DateTime(2005,3,15), workDays);
protected int TotalWorkDays(DateTime start, DateTime end, DayOfWeek[] workDays)
{
    var weeks = (int)Math.Floor((end - start).TotalDays / 7); 
    var days = weeks * workDays.Length;
    //Calc rest
    var d = start.AddDays(weeks * 7);
    while (d <= end)
    {
        if(workDays.Contains(d.DayOfWeek)) 
            days++;
        d = d.AddDays(1);
    }   
    return days;
}

Answer 6

您可以使用以下算法：

• 计算开始一周的工作日（最多7次迭代）
• 计算开始/结束之间的周数以及工作日的周数
• 计算最后一周的工作日（最多7次迭代）

该示例使用的时间段库的类Week和DateDiff。净

// ----------------------------------------------------------------------
public int CountWorkingDays( DateTime start, DateTime end, IList<DayOfWeek> workingDays )
{
  if ( workingDays.Count == 0 )
  {
    return 0;
  }
  Week startWeek = new Week( start );
  Week endWeek = new Week( end );
  int dayCount = 0;
  // start week
  DateTime currentDay = start.Date;
  while ( currentDay < startWeek.End )
  {
    if ( workingDays.Contains( currentDay.DayOfWeek ) )
    {
      dayCount++;
    }
    currentDay = currentDay.AddDays( 1 );
  }
  // between weeks
  DateDiff inBetweenWeekDiff = new DateDiff( startWeek.End, endWeek.Start );
  dayCount += inBetweenWeekDiff.Weeks * workingDays.Count;
  // end week
  currentDay = endWeek.Start.Date;
  while ( currentDay < end )
  {
    if ( workingDays.Contains( currentDay.DayOfWeek ) )
    {
      dayCount++;
    }
    currentDay = currentDay.AddDays( 1 );
  }
  return dayCount;
} // CountWorkingDays

用法：

// ----------------------------------------------------------------------
public void CountWorkingDaysSample()
{
  DayOfWeek[] workingDays = new [] { DayOfWeek.Monday, DayOfWeek.Tuesday };
  DateTime start = new DateTime( 2011, 3, 1 );
  DateTime end = new DateTime( 2011, 5, 1 );
  Console.WriteLine( "working days: {0}", CountWorkingDays( start, end, workingDays ) );
  // > working days: 19
} // CountWorkingDaysSample