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john v kumpf's questions

Martin Hope
john v kumpf
Asked: 2024-12-29 00:56:27 +0800 CST
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由于某种原因，powershell 不允许我将 a 转换string[]为 an，object[]但允许将所有其他类型转换为 an。下面的示例显示它适用于除字符串之外的几种类型。

     [int[]]$intary = 2,4
    [char[]]$chrary = 'a','b'
    [bool[]]$booary = $true,$false
[DateTime[]]$datary = (Get-Date),(Get-Date)
  [string[]]$strary = 'c','d'
            $splary = 'e,f' -split ','  # -split returns [string[]] type specifically
  [object[]]$objaryi = @()
  [object[]]$objaryc = @()
  [object[]]$objaryb = @()
  [object[]]$objaryd = @()
  [object[]]$objarys = @()
  [object[]]$objarysp = @()
$intary.GetType()           # Int32[]
$chrary.GetType()           # Char[] 
$booary.GetType()           # Boolean[]
$datary.GetType()           # DateTime[]
$strary.GetType()           # String[]
$splary.GetType()           # String[]
$objaryi.GetType()          # Object[]

'conversions'
$objaryi = $intary          # Int32[] converted to Object[]
$objaryi.GetType()          # Object[]

$objaryc = $chrary          # Char[] converted to Object[]
$objaryc.GetType()          # Object[]

$objaryb = $booary          # Boolean[] converted to Object[]
$objaryb.GetType()          # Object[]

$objaryd = $datary          # DateTime[] converted to Object[]
$objaryd.GetType()          # Object[]

$objarys = $strary          # NOT converted to Object[]; instead changes type of $objarys to String[]
$objarys.GetType()          # String[]

$objarysp = $splary         # NOT converted to Object[]; instead changes type of $objarysp to String[]
$objarysp.GetType()         # String[]

$objarys = @($strary)       # the array subexpression operator @() DOES convert to Object[]
$objarys.GetType()          # Object[]

$objarysp = @($splary)       # the array subexpression operator @() DOES convert to Object[]
$objarysp.GetType()          # Object[]

'inline cast'
$objarys = @([string[]]@(1,2)) # the array subexpression operator @() does not work on an inline cast [1]
$objarys.GetType()          # String[]

这很重要的一个原因是，如果您尝试将哈希存储在类型为string[]powershell 的数组中，则会默默地将您的哈希定义转换为字符串。该字符串是哈希的完整路径类型名称的字符串。

$objaryi[0] = @{a=1;b=2}    # can hold a hashtable because it's now an Object[]
$objaryi[0].GetType()       # Hashtable
$objaryi[0]['b']            # 2

$objarys[0] = @{a=1;b=2}    # silently converts to a string because it's a String[]
$objarys[0].GetType()       # String
$objarys[0]['b']            # $null; perhaps unexpected
$objarys[0]                 # the String value "System.Collections.Hashtable"
$objarys[0].Length          # 28
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