c# - 我如何找到最后一个类次开始的时间？ (按 24 小时时间表)

Question

当你有不同的人组每天 24 小时在不同的轮类工作时(假设一组工作三个 8 小时轮类，另一个工作两个 12 小时轮类，最后一组工作两个 10 小时轮类，其中 4 小时无人值守)给定一个时间点，返回哪个类次最近开始的最直接方法是什么？

举个例子，我有一个 8 小时 Shift 列表(BeginTime 分别是早上 6 点、下午 2 点、晚上 10 点)

 public class Shift
    {
        public string Name { get; set; }
        public TimeSpan BeginTime { get; set; }
        public int LengthHours { get; set; }
    }

我当前的代码有效(出于我的目的)但并不理想，因为它需要 startTime 并且集合中的轮类顺序。

public Shift FindCurrentShift(DateTime startTime, DateTime endTime, List<Shift> shifts)
{
    Shift mostRecentShift = null;
    foreach (Shift aShift in shifts) {
        DateTime shiftBeginTime = DateTime.Parse(endTime.Date.Add(aShift.BeginTime).ToString());
        if (startTime.Date != endTime.Date) {
            if (shiftBeginTime.TimeOfDay > startTime.TimeOfDay) {
                shiftBeginTime = shiftBeginTime.AddDays(-1);
            }
        }
        //does this shift fall in between start and stop time
        if ((startTime < shiftBeginTime && endTime > shiftBeginTime)) {
            mostRecentShift = aShift;
        }
    }
    return mostRecentShift;
}

鉴于当前时间，我处于第几类？执行此操作的更简单方法是什么？

Answer 1

使用 LINQ 试试这个:

public Shift FindCurrentShift(DateTime currentDateTime, List<Shift> shifts)
{
    DateTime startOfDay = currentDateTime.Date;

    // Get most recent shift that started today and has not ended yet
    Shift shift = 
        shifts.Where(s => startOfDay.Add(s.BeginTime) <= currentDateTime
                     && startOfDay.Add(s.BeginTime).AddHours(s.LengthHours) <= currentDateTime)
              .OrderByDescending(s => s.BeginTime)
              .FirstOrDefault();

    // If none were found that had a start date today, get the latest shift
    // (would be one that started yesterday) as long as its end time today has not passed yet
    if (shift == null) {
        shift =
            shifts.Where(s => startOfDay.AddDays(-1).Add(s.BeginTime).AddHours(s.LengthHours) <= currentDateTime
                  .OrderByDescending(s => s.BeginTime)
                  .FirstOrDefault();
    }

    return shift;
}