c#如何在列表的开始和结束处修剪空元素

本文关键字：结束 修剪 元素 开始 列表 | 更新日期: 2023-09-27 18:06:10

给定一个值为

的对象列表
StatusList = new List<StatusData>
                {
                    new StatusData {Count = 0, Id = 1},
                    new StatusData {Count = 0, Id = 2},
                    new StatusData {Count = 1, Id = 3},
                    new StatusData {Count = 0, Id = 4},
                    new StatusData {Count = 2, Id = 5},
                    new StatusData {Count = 3, Id = 6},
                    new StatusData {Count = 0, Id = 7},
                    new StatusData {Count = 0, Id = 8},
                    new StatusData {Count = 0, Id = 2}
                };

如何通过删除带有0的元素来修剪列表的左侧和右侧?

c#如何在列表的开始和结束处修剪空元素

int start = 0, end = StatusList.Count - 1;
while (start < end && StatusList[start].Count == 0) start++;
while (end >= start && StatusList[end].Count == 0) end--;
return StatusList.Skip(start).Take(end - start + 1);

Using LINQ:

var nonEmptyItems = StatusList.Where(sd => sd.Count > 0);

nonEmptyItems将包含Count大于0的项，包括中间的项。

或者，如果你不想删除中心项，你可以使用while循环从前面和后面删除每个空项，直到不存在这样的项。

var trimmed = false;
while(!trimmed)
{
  if(StatusList[0].Count == 0)
     StatusList.RemoveAt(0);
  if(StatusList[StatusList.Count - 1].Count == 0)
    StatusList.RemoveAt(StatusList.Count - 1);
  if(StatusList[0].Count == 0 > StatusList[StatusList.Count - 1].Count > 0)
    trimmed = true;
}

// Remove until count != 0 is found
foreach (var item in StatusList.ToArray())
{
    if (item.Count == 0)
        StatusList.Remove(item);
    else
        break;
}
// Reverse the list
StatusList.Reverse(0, StatusList.Count);
// Remove until count != 0 is found
foreach (var item in StatusList.ToArray())
{
    if (item.Count == 0)
        StatusList.Remove(item);
    else
        break;
}
// reverse back
StatusList.Reverse(0, StatusList.Count);

不是很有效，但更容易理解的解决方案是:

StatusList.Reverse();
StatusList = StatusList.SkipWhile(x => x.Count == 0).ToList();
StatusList.Reverse();
StatusList = StatusList.SkipWhile(x => x.Count == 0).ToList();

我是这样解决的…

RemoveOutsideZeros(ref StatusList);
                StatusList.Reverse();
RemoveOutsideZeros(ref StatusList);

private void RemoveOutsideZeros(ref List<StatusData> StatusList)
{
    bool Found0 = false;
    foreach (StatusData i in StatusList.ToList())
    {
        if (i.Count != 0)
    {
        Found0 = true;
    }
        if (i.Count == 0 && Found0 == false)
        {
            StatusList.Remove(i);
        }
    }

}

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