如何从一个泛型列表在遍历它删除元素？ [英] How to remove elements from a generic list while iterating over it?

问题描述

我要寻找一个更好的模式的与每个需要处理的元素列表的工作，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.

您不能使用上卸下摆臂（元素）在的foreach（在X VAR元素）（因为它导致集合已修改;枚举操作可能不会执行除外）......你也不能使用的for（int i = 0; I＆LT; elements.Count（）;我++）和 .RemoveAt（我），因为它会破坏在收集相对你的当前位置 I 。

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.

有一种优雅的方式来做到这一点？

Is there an elegant way to do this?

推荐答案

有一个for循环迭代的反向列表：

Iterate your list in reverse with a for loop:

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

例如：

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));

另外，你可以使用 RemoveAll方法了predicate要测试的

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

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

下面是一个简单的例子来说明：

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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