使用属性跟踪要删除的元素，并在处理后将它们全部删除。

using System.Linq;

List<MyProperty> _Group = new List<MyProperty>();
// ... add elements

bool cond = false;
foreach (MyProperty currObj in _Group)
{
    // here it is supposed that you decide the "remove conditions"...
    cond = true; // set true or false...
    if (cond) 
    {
        // SET - element can be deleted
        currObj.REMOVE_ME = true;
    }
}
// RESET
_Group.RemoveAll(r => r.REMOVE_ME);

当您希望在迭代Collection时从其中删除元素时，首先想到的应该是反向迭代。

幸运的是，有一个比编写for循环更优雅的解决方案，因为for循环涉及不必要的输入，而且容易出错。

ICollection<int> test = new List<int>(new int[] {1, 2, 3, 4, 5, 6, 7, 8, 9, 10});

foreach (int myInt in test.Reverse<int>())
{
    if (myInt % 2 == 0)
    {
        test.Remove(myInt);
    }
}

因为任何移除都是在你可以使用的条件下进行的

list.RemoveAll(item => item.Value == someValue);

我发现自己遇到了类似的情况，我必须删除给定List<T>中的每n个元素。

for (int i = 0, j = 0, n = 3; i < list.Count; i++)
{
    if ((j + 1) % n == 0) //Check current iteration is at the nth interval
    {
        list.RemoveAt(i);
        j++; //This extra addition is necessary. Without it j will wrap
             //down to zero, which will throw off our index.
    }
    j++; //This will always advance the j counter
}

我将从一个过滤掉您不想保留的元素的LINQ查询中重新分配列表。

list = list.Where(item => ...).ToList();

除非列表非常大，否则这样做应该不会有明显的性能问题。

Using Remove or RemoveAt on a list while iterating over that list has intentionally been made difficult, because it is almost always the wrong thing to do. You might be able to get it working with some clever trick, but it would be extremely slow. Every time you call Remove it has to scan through the entire list to find the element you want to remove. Every time you call RemoveAt it has to move subsequent elements 1 position to the left. As such, any solution using Remove or RemoveAt, would require quadratic time, O(n²).

如果可以，使用RemoveAll。否则，下面的模式将在线性时间O(n)内就地过滤列表。

// Create a list to be filtered
IList<int> elements = new List<int>(new int[] {1, 2, 3, 4, 5, 6, 7, 8, 9, 10});
// Filter the list
int kept = 0;
for (int i = 0; i < elements.Count; i++) {
    // Test whether this is an element that we want to keep.
    if (elements[i] % 3 > 0) {
        // Add it to the list of kept elements.
        elements[kept] = elements[i];
        kept++;
    }
}
// Unfortunately IList has no Resize method. So instead we
// remove the last element of the list until: elements.Count == kept.
while (kept < elements.Count) elements.RemoveAt(elements.Count-1);