如何在迭代时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元素列表，每个元素都需要处理，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)(因为它导致 Collection was modified; enumeration operation可能不会执行. 异常)...你也不能使用 for (int i = 0; i 和 .RemoveAt(i) 因为它破坏了你当前在集合中相对于 i 的位置.

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.

有没有一种优雅的方法来做到这一点?

Is there an elegant way to do this?

推荐答案

使用 for 循环反向迭代您的列表:

Iterate your list in reverse with a for loop:

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

示例:

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);

这是一个简单的示例来演示:

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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