英文:
How to add an array to pipeline in PowerShell
问题
$list1 = 'A','B';
$list2 = '1','2';
$result = foreach ($list1Item in $list1)
{
foreach ($list2Item in $list2)
{
($list1Item, $list2Item)
}
}
foreach ($resultItem in $result)
{
Write-Host "$($resultItem[0])-$($resultItem[1])"
}
我预期的结果是：
A-1
A-2
B-1
B-2
我实际得到的结果是：
A-
1-
A-
2-
B-
1-
B-
2-
我做错了什么？
英文:
I'm trying to combine two arrays into an array of arrays in PowerShell. Here's my script:
$list1 = 'A','B';$list2 = '1','2';$result = foreach ($list1Item in $list1){foreach ($list2Item in $list2){($list1Item, $list2Item)}}foreach ($resultItem in $result){Write-Host "$($resultItem[0])-$($resultItem[1])"}
The result I was expecting was:
A-1A-2B-1B-2
The result I'm actually getting is:
A-1-A-2-B-1-B-2-
What am I doing wrong?
答案1
得分: 3
PowerShell的默认行为是展开可枚举的输出，这就是为什么最终得到一个“扁平”数组的原因。
您可以通过使用 Write-Output -NoEnumerate 来避免这种行为：
$list1 = 'A','B';$list2 = '1','2';$result = foreach ($list1Item in $list1){foreach ($list2Item in $list2){Write-Output ($list1Item, $list2Item) -NoEnumerate}}
另一个选择是构造一个文字嵌套数组 - 这样管道处理器将展开第一维，然后您将得到数组对象：
$list1 = 'A','B';$list2 = '1','2';$result = foreach ($list1Item in $list1){foreach ($list2Item in $list2){,@($list1Item, $list2Item)# ^# 前置逗号充当一元数组运算符}}
或者您可以构造一些不可枚举的东西，比如每一对的对象：
$list1 = 'A','B';$list2 = '1','2';$result = foreach ($list1Item in $list1){foreach ($list2Item in $list2){# 这会创建一个标量对象，这里没有什么可以展开的[pscustomobject]@{Item1 = $list1ItemItem2 = $list2Item}}}foreach ($resultItem in $result){Write-Host "$($resultItem.Item1)-$($resultItem.Item2)"}
请参阅 关于about_Pipelines 帮助主题 以进一步讨论这种行为。
英文:
PowerShell's default behavior is to unroll enumerable output, which is why you end up with a "flat" array.
You can circumvent this behavior by using Write-Output -NoEnumerate:
$list1 = 'A','B';$list2 = '1','2';$result = foreach ($list1Item in $list1){foreach ($list2Item in $list2){Write-Output ($list1Item, $list2Item) -NoEnumerate}}
Another option is to construct a literal nested array - then the pipeline processor will unroll the first dimension and you're left with array objects:
$list1 = 'A','B';$list2 = '1','2';$result = foreach ($list1Item in $list1){foreach ($list2Item in $list2){,@($list1Item, $list2Item)# ^# prefixed comma acts as a unary array operator}}
Or you can construct something that isn't enumerable, like an object for each pair:
$list1 = 'A','B';$list2 = '1','2';$result = foreach ($list1Item in $list1){foreach ($list2Item in $list2){# this creates a scalar object, nothing to unroll here[pscustomobject]@{Item1 = $list1ItemItem2 = $list2Item}}}foreach ($resultItem in $result){Write-Host "$($resultItem.Item1)-$($resultItem.Item2)"}
See the about_Pipelines help topic for further discussion on this behavior
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