c# - 如何将此双 foreach 循环转换为 lambda？

Question

有没有办法让这些 foreach 循环只有一个lambda 表达式？

    private int getNextEventId()
    {
        int numOfEvents = 0;

        foreach (MonthModel eventMonth in eventsForAllMonths)
        {
            foreach (DayModel eventDay in eventMonth.AllDays)
            {
                numOfEvents += eventDay.CalEvents.Count;
            }
        }

        return numOfEvents + 1;
    }

Answer 1

int numOfEvents = eventsForAllMonths.SelectMany(m => m.AllDays)
                                    .Select(d => d.CalEvents.Count)
                                    .Sum();

Answer 2

return (eventsForAllMonths.SelectMany(eventMonth => eventMonth.AllDays).Sum(eventDay => eventDay.CalEvents.Count) + 1);

Answer 3

试试这个：

    private int getNextEventId()
    {
        int numOfEvents = eventsForAllMonths.SelectMany(eventMonth => eventMonth.AllDays).Aggregate(0, (current, eventDay) => current + eventDay.CalEvents.Count);

        return numOfEvents + 1;
    }

Answer 4

这个怎么样？

return
    (from m in eventsForAllMonths
    from d in m.AllDays
    select d.CalEvents.Count).Sum() + 1;

Answer 5

我ForEach()以谋生为生，所以：

eventsForallMonths.ForEach(em=>em.ForEach(ed=>numOfEvents+=ed.CalEvents.Count));

Answer 6

如何在 lambda 中转换它？

List<Item> listItem = new List<Item>();
foreach (StackPanel sp in spPhotos.Children)
{
    foreach(Item item in sp.Children)
    {
        listItem.Add(item);
    }
    sp.Children.Clear();
}
spPhotos.Children.Clear();