Windows Powershell强类型数组

PS C:Powershell> [int[]] $nums=@()
PS C:Powershell> $nums+=2012
PS C:Powershell> $nums+=12.3
PS C:Powershell> $nums+="999"
PS C:Powershell> $nums+="can not convert"
Cannot convert value "can not convert" to type "System.Int32". Error: "Input string was not in a correct format."
At line:1 char:6
+ $nums  +="can not convert"
  + CategoryInfo     : MetadataError: (:) [], ArgumentTransformationMetadataException
  + FullyQualifiedErrorId : RuntimeException