powershell@foreach@foreach-object@continue的行为
ref
- about Continue - PowerShell | Microsoft Learn
- powershell - Why does ‘continue’ behave like ‘break’ in a Foreach-Object? - Stack Overflow
foreach@foreach-object
-
about Foreach - PowerShell | Microsoft Learn
- powershell/module/microsoft.powershell.core/about/about_foreach
- 这是一个powershell 遍历可迭代对象的基本语法,属于循环(loop)中的一种
- 不妨称它为
loop-foreach
-
ForEach-Object (Microsoft.PowerShell.Core) - PowerShell | Microsoft Learn
- powershell/module/microsoft.powershell.core/foreach-object
- 这是一个powershell cmdlet(powershell命令),不是一种循环,可能是基于基本语法编制而成的功能性命令
- 不妨称它为
cmdlet-foreach
-
这一点区别将会在使用continue的时候显现出来文章来源：https://www.toymoban.com/news/detail-464068.html
- continue放在在某个Loop中时(比如foreach),那么它的行为就像c语言那样
- 如果是放在foreach-object(有时候简写为foreach,区分loop-foreach),充当
scriptblock - 这时候,会尝试跳过最近的loop语法层(如果存在的话)
-
What is a PowerShell command? - PowerShell | Microsoft Learn文章来源地址https://www.toymoban.com/news/detail-464068.html
What is a cmdlet?
- Cmdlets are native PowerShell commands, not stand-alone executables.
- Cmdlets are collected into PowerShell modules that can be loaded on demand.
- Cmdlets can be written in any compiled .NET language or in the PowerShell scripting language itself.
break@continue
- about Break - PowerShell | Microsoft Learn
- about Continue - PowerShell | Microsoft Learn
案例
foreach@continue
loop-foreach
-
Write-Output 'foreach-loop' $l = 1..5 foreach ($elem in $l) { if ($elem -eq 3) { continue; # not return here } Write-Output $elem }
cmdlet-foreach
-
Write-Output 'foreach-object(cmdlet)' 1..5 | ForEach-Object { if ($_ -eq 3 ) { return #not continue here } Write-Output $_ }
运行结果
-
foreach-loop 1 2 4 5 foreach-object(cmdlet) 1 2 4 5
其他方案
- 加一层
if-else可以在cmdlet中模拟continue的字面行为- 但是这增加了不必要的代码
- 而且不够优雅
- 做过滤的时候
where-object有时候比foreach-object更加合适
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