如何从数组中删除元素 [英] How to remove elements from an array

问题描述

嗨我工作的一些遗留code的推移沿

Hi I'm working on some legacy code that goes something along the lines of

for(int i = results.Count-1; i >= 0; i--)
{
  if(someCondition)
  {
     results.Remove(results[i]);
  }
}

要我好像不好的做法被删除的元素，同时还通过迭代循环，因为你会被修改索引。

To me it seems like bad practice to be removing the elements while still iterating through the loop because you'll be modifying the indexes.

这是一个正确的假设？

是否有这样做的更好的办法？我想使用LINQ，但我在2.0框架

Is there a better way of doing this? I would like to use LINQ but I'm in 2.0 Framework

推荐答案

去除实际上是OK，因为你会向下到零，只是你已经通过了将被修改的索引。这code居然会打破的另一个原因是：它以 results.Count ，而应 results.Count -1 因为数组的索引从0开始。

The removal is actually ok since you are going downwards to zero, only the indexes that you already passed will be modified. This code actually would break for another reason: It starts with results.Count, but should start at results.Count -1 since array indexes start at 0.

for(int i = results.Count-1; i >= 0; i--)
{
  if(someCondition)
  {
     results.RemoveAt(i);
  }
}

编辑：

正如指出的 - 实际上你必须处理一些在你的伪code的List。在这种情况下，它们在概念上是相同的（因为列表内部使用数组），但如果你使用一个数组你有一个长度属性（而不是计数属性），你不能添加或删除项目。

As was pointed out - you actually must be dealing with a List of some sort in your pseudo-code. In this case they are conceptually the same (since Lists use an Array internally) but if you use an array you have a Length property (instead of a Count property) and you can not add or remove items.

使用列表上方的解决方案肯定是简洁的，但可能不容易理解别人，必须维持code（在列表中即特别是迭代向后） - 另一种解决方案是先确定项目除去，然后在第二遍中除去那些项目。

Using a list the solution above is certainly concise but might not be easy to understand for someone that has to maintain the code (i.e. especially iterating through the list backwards) - an alternative solution could be to first identify the items to remove, then in a second pass removing those items.

刚刚替补的MyType 与您正在处理的实际类型：

Just substitute MyType with the actual type you are dealing with:

List<MyType> removeItems = new List<MyType>();

foreach(MyType item in results)
{
   if(someCondition)
   {
        removeItems.Add(item);
   }
}

foreach (MyType item in removeItems)
    results.Remove(item);

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