迭代时如何从通用列表中删除元素?

How to remove elements from a generic list while iterating over it?(迭代时如何从通用列表中删除元素?)

问题描述

我正在寻找更好的 模式 来处理每个需要处理的元素列表，然后根据结果从列表中删除.

I am looking for a better pattern for working with a list of elements which each need processed and then depending on the outcome are removed from the list.

你不能在 foreach (var element in X) 中使用 .Remove(element) (因为它会导致 Collection 被修改；枚举操作可能无法执行. 异常)...您也不能使用 for (int i = 0; i < elements.Count(); i++) 和 .RemoveAt(i) 因为它会破坏您在集合中相对于 i 的当前位置.

You can't use .Remove(element) inside a foreach (var element in X) (because it results in Collection was modified; enumeration operation may not execute. exception)... you also can't use for (int i = 0; i < elements.Count(); i++) and .RemoveAt(i) because it disrupts your current position in the collection relative to i.

有没有优雅的方法来做到这一点?

Is there an elegant way to do this?

推荐答案

用 for 循环反向迭代你的列表:

Iterate your list in reverse with a for loop:

for (int i = safePendingList.Count - 1; i >= 0; i--)
{
    // some code
    // safePendingList.RemoveAt(i);
}

例子:

var list = new List<int>(Enumerable.Range(1, 10));
for (int i = list.Count - 1; i >= 0; i--)
{
    if (list[i] > 5)
        list.RemoveAt(i);
}
list.ForEach(i => Console.WriteLine(i));

或者，您可以使用带有谓词的 RemoveAll 方法测试:

Alternately, you can use the RemoveAll method with a predicate to test against:

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

这里有一个简化的例子来演示:

Here's a simplified example to demonstrate:

var list = new List<int>(Enumerable.Range(1, 10));
Console.WriteLine("Before:");
list.ForEach(i => Console.WriteLine(i));
list.RemoveAll(i => i > 5);
Console.WriteLine("After:");
list.ForEach(i => Console.WriteLine(i));

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