powershell - Powershell中foreach的不同输入

Question

我有两个关于 Powershell 中数据类型的初学者问题。

1. 为什么这两个命令的结果不同？

   PS > $test = {"a", "b", "c"}
   PS > foreach ($item in $test) { $item | Out-Host }
   "a", "b", "c"
   PS > $test = "a", "b", "c"
   PS > foreach ($item in $test) { $item | Out-Host }
   a
   b
   c
   

2. 一个命令返回数据，当格式化为列表时，数据如下所示：

   Changes              : {Change instance 10406282
                           ChangeType: Edit
                           (...)
   
                         , Change instance 25906333
                           ChangeType: Edit
                           (...)
                          }
   

   看起来这是某种项目列表。我怎样才能foreach通过它们？

Answer 1

第一个问题 如果您执行以下操作： $test = {"a", "b", "c"} $test.GetType()

$test = "a", "b", "c"
$test.GetType()

你会注意到第一个对象是ScriptBlock第二个对象是一个数组

第二个问题

将结果分配给一个对象并像上面那样简单地迭代。

简单的例子：

$result = (Get-TfsItemHistory $/<projectName> -all -user $name -Recurse -server $tfs)
$result | foreach {$item = $_; Write-Host $item; Write-Host $item.ChangeType;}

Answer 2

{...} creates a scriptblock, you might think that the loop runs 3 times but it's not (one iteration only), it just returns the content of the script block.

Items seperated by a comma creates a collection of items (array). When you loop over a collection you iterate over each item int he collection