Question

有人可以告诉我，为什么这个函数调用不起作用以及为什么参数总是空的？

function check([string]$input){
  Write-Host $input                             #empty line
  $count = $input.Length                        #always 0
  $test = ([ADSI]::Exists('WinNT://./'+$input)) #exception (empty string) 
  return $test
}

check 'test'

如果用户或用户组存在，请尝试获取信息..

祝你好运

Answer 1

也许使用param块作为参数。

https://technet.microsoft.com/en-us/magazine/jj554301.aspx

更新：如果您不使用$input作为参数名称，问题似乎已得到修复，拥有正确的变量名称可能不是一件坏事;）

此外，Powershell没有return关键字，您只需将对象作为语句推送，这将由函数返回：

function Get-ADObjectExists
{
  param(
    [Parameter(Mandatory=$true, ValueFromPipeline=$true)]
    [string]
    $ObjectName
  )
  #return result by just calling the object (no return statement in powershell)
  ([ADSI]::Exists('WinNT://./'+$ObjectName)) 
}

Get-ADObjectExists -ObjectName'test'

Answer 2

$ input是自动变量。

https://technet.microsoft.com/ru-ru/library/hh847768.aspx

$Input

   Contains an enumerator that enumerates all input that is passed to a
   function. The $input variable is available only to functions and script
   blocks (which are unnamed functions).  In the Process block of a
   function, the $input variable enumerates the object that is currently
   in the pipeline. When the Process block  completes, there are no objects
   left in the pipeline, so the $input variable enumerates an empty
   collection. If the function does not have a Process block, then in the
   End block, the $input variable enumerates the collection of all input to
   the function.

函数参数总是为空？为什么？

2 个答案: