如何同时循环两个列表？ [英] How to loop through two lists simultaneously?

问题描述

我已经提到了以下问题：使用foreach循环遍历两个列表。我的问题是，关于选择的答案：o.DoSomething是一个比较吗？如：

 对于ListA.Concat（ListB）中的每个a 
如果（a来自ListA = a来自ListB ）然后
在这里做点什么
结束如果
下一个
  

你可能已经猜到了，我正在使用VB.Net，并想知道如何才能做到我在这里显示的东西。这基本上是分开/独立地遍历连接列表。谢谢！

解决方案您的问题表明您需要加入操作，因为它不是你想迭代两个列表，但你也想匹配从一个列表到另一个列表的项目。

  Dim joinedLists =从item1在list1中_ 
加入item2在列表2中_ 
在item1.Bar Equals item2.Bar _ 
在{item1，item2}中选择New 
 
对于每个对在joinedLists中
'在这里处理组合商品'
'pair.item1' 
'pair.item2'
下一个
  

其他答案建议邮编。这只是一个函数，它接受两个序列并产生一个结果，就像连接一样，但它适合在两个列表中以FIFO方法工作。如果你需要基于平等的连接， Join 是专门为这项工作建立的。

I have referred to the following question at: Using foreach loop to iterate through two lists. My question is this, with regards to the chosen answer: Can the o.DoSomething be a comparison? As in:

For Each a in ListA.Concat(ListB)
    If(a from ListA=a from ListB) Then
        Do Something here
    End If
Next

As you might've guessed, I'm using VB.Net and would like to know how I can do what I have shown here. That would basically be to iterate through a joined list separately/independently. Thanks!

解决方案

Your question indicates that you need a Join operation, because it's not that you want to iterate over two lists, but you also want to match like items from one list to the other.

    Dim joinedLists = From item1 In list1 _
                    Join item2 In list2 _
                    On item1.Bar Equals item2.Bar _
                    Select New With {item1, item2}

    For Each pair In joinedLists
        'Do work on combined item here'
        'pair.item1'
        'pair.item2'
    Next

Other answers recommend Zip. That is simply a function that takes two sequences and produces a single result, much like join, but it is geared to work in a FIFO method over both lists. If you need connections made based on an equality, Join is the specifically built to be right tool for this job.

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