foreach循环，确定哪个是循环的最后一次迭代 [英] Foreach loop, determine which is the last iteration of the loop

问题描述

我有一个的foreach 循环，需要执行一些逻辑，当最后一个项目从列表选择，例如：

I have a foreach loop and need to execute some logic when the last item is chosen from the List, e.g.:

 foreach (Item result in Model.Results)
 {
      //if current result is the last item in Model.Results
      //then do something in the code
 }

我可以知道哪个循环是最后不使用循环和计数器？

Can I know which loop is last without using for loop and counters?

推荐答案

如果您只是需要做一些事情的最后一个元素（而不是东西的不同的的最后一个元素，然后使用LINQ将帮助这里：

If you just need to do something with the last element (as opposed to something different with the last element then using LINQ will help here:

Item last = Model.Results.Last();
// do something with last

如果你需要做的最后一个元素不同的东西，那么你会需要这样的：

If you need to do something different with the last element then you'd need something like:

Item last = Model.Results.Last();
foreach (Item result in Model.Results)
{
    // do something with each item
    if (result.Equals(last))
    {
        // do something different with the last item
    }
    else
    {
        // do something different with every item but the last
    }
}

虽然你可能需要编写一个自定义比较，以确保您能告诉该项目是一样通过退回产品的最后（）。

此方法应谨慎使用，因为最后可能不得不通过集合进行迭代。虽然这可能不是小集合的一个问题，如果它得到大型它可能会影响性能。

This approach should be used with caution as Last may well have to iterate through the collection. While this might not be a problem for small collections, if it gets large it could have performance implications.

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