Chunk IEnumerable / ICollection Class C＃2.0 [英] Chunk IEnumerable/ICollection Class C# 2.0

问题描述

我正在处理尝试在C＃2.0中实现IEnumerable（和ICollection）的自定义集合类中的项目。比方说，我一次只需要1000个项目，我的收藏中有3005个项目。我有一个工作的解决方案，我在下面演示，但它似乎很原始，我认为有一个更好的方法来做这个。

I am dealing with trying to chunk up items in a custom collection class that implements IEnumerable (and ICollection) in C# 2.0. Let's say, for example, that I only want 1000 items at a time and I have 3005 items in my collection. I've got a working solution that I demonstrate below, but it seems so primitive that I figure there has to be a better way to do this.

这是我有（例如，我使用C＃3.0的Enumerable和var，只是在你心目中用自定义类替换这些引用）：

Here's what I have (for example's sake, I'm using C# 3.0's Enumerable and var, just replace those references with a custom class in your mind):

var items = Enumerable.Range(0, 3005).ToList();
int count = items.Count();
int currentCount = 0, limit = 0, iteration = 1;

List<int> temp = new List<int>();

while (currentCount < count)
{
    limit = count - currentCount;

    if (limit > 1000)
    {
        limit = 1000 * iteration;
    }
    else
    {
        limit += 1000 * (iteration - 1);
    }
    for (int i = currentCount; i < limit; i++)
    {
        temp.Add(items[i]);
    }

    //do something with temp

    currentCount += temp.Count;
    iteration++;
    temp.Clear();
}

任何人都可以在C＃2.0中使用更优雅的方式吗？我知道如果这个项目是从过去5年，我可以使用Linq（如演示此处和这里）。我知道我的方法会工作，但我不想让我的名字与这样丑陋的（在我看来）代码相关联。

Can anyone suggest a more elegant way of doing this in C# 2.0? I know if this project was from the past 5 years I could use Linq (as demonstrated here and here). I know my method will work, but I'd rather not have my name associated with such ugly (in my opinion) code.

谢谢。 $ b

推荐答案

首先。 yield 是你的朋友，它是用2.0介绍的。考虑：

Firstly . yield is your friend here, and it was introduced with 2.0. Consider:

public static IEnumerable<List<T>> Chunk<T>(IEnumerable<T> source, int chunkSize)
{
  List<T> list = new List<T>(chunkSize);
  foreach(T item in source)
  {
    list.Add(item);
    if(list.Count == chunkSize)
    {
      yield return list;
      list = new List<T>(chunkSize);
    }
  }
  //don't forget the last one!
  if(list.Count != 0)
    yield return list;
}

然后我们灵活的类型和大小，所以它是很好的可重复使用。唯一被限制为2.0意味着，我们不能使它成为一个扩展方法。

Then we're flexible in type and size, so it's nicely reusable. The only that being restricted to 2.0 means, is that we can't make it an extension method.

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