About Type Operators
SHORT DESCRIPTION
Describes the operators that work with Microsoft .NET Framework types.
LONG DESCRIPTION
The Boolean type operators (-is and -isNot) tell whether an object is an instance of a specified .NET Framework type. The -is operator returns a value of TRUE if the type matches and a value of FALSE otherwise. The -isNot operator returns a value of FALSE if the type matches and a value of TRUE otherwise.
The -as operator tries to convert the input object to the specified .NET Framework type. If it succeeds, it returns the converted object. It if fails, it returns $null. It does not return an error.
The following table lists the type operators in PowerShell.
| Operator | Description | Example |
|---|---|---|
-is |
Returns TRUE when the input | (get-date) -is [DateTime] |
| is an instance of the | True |
|
| specified .NET type. | ||
-isNot |
Returns TRUE when the input | (get-date) -isNot [DateTime] |
| not an instance of the | False |
|
| specified.NET type. | ||
-as |
Converts the input to the | "5/7/07" -as [DateTime] |
| specified .NET type. | Monday, May 7, 2007 12:00:00 AM |
The syntax of the type operators is as follows:
<input> <operator> [.NET type]
You can also use the following syntax:
<input> <operator> ".NET type"
To specify the .NET Framework type, enclose the type name in brackets ([ ]), or enter the type as a string, such as [DateTime] or "DateTime" for System.DateTime. If the type is not at the root of the system namespace, specify the full name of the object type. You can omit "System.". For example, to specify System.Diagnostics.Process, enter [System.Diagnostics.Process], [Diagnostics.Process], or "diagnostics.process".
The Boolean type operators (-is and -isNot) always return a Boolean value, even if the input is a collection of objects. The type operators always operate on the input object as a whole. That is, if the input object is a collection, it is the collection type that is tested, not the types of the collection's elements.
If the <input> is a type that is derived from the [.NET Type] -is
returns$True. If the <input> is a type that is derived from the [.NET
Type] -as passes through converts the input to the target type. For
example, (Get-Item /) -is [System.IO.FileSystemInfo] returns $True,
because the type of the input, [System.IO.DirectoryInfo], is derived from
the [System.IO.FileSystemInfo].
To find the .NET Framework type of an object, use the Get-Member cmdlet. Or, use the GetType method of all the objects together with the FullName property of this method. For example, the following statement gets the type of the return value of a Get-Culture command:
PS> (get-culture).gettype().fullname
System.Globalization.CultureInfo
EXAMPLES
The following examples show some uses of the Type operators:
PS> 32 -is [Float]
False
PS> 32 -is "int"
True
PS> (get-date) -is [DateTime]
True
PS> "12/31/2007" -is [DateTime]
False
PS> "12/31/2007" -is [String]
True
PS> (get-process PowerShell)[0] -is [System.Diagnostics.Process]
True
PS> (get-command get-member) -is [System.Management.Automation.CmdletInfo]
True
The following example shows that when the input is a collection of objects, the matching type is the .NET Framework type of the collection, not the type of the individual objects in the collection.
In this example, although both the Get-Culture and Get-UICulture cmdlets return System.Globalization.CultureInfo objects, a collection of these objects is a System.Object array.
PS> (get-culture) -is [System.Globalization.CultureInfo]
True
PS> (get-uiculture) -is [System.Globalization.CultureInfo]
True
PS> (get-culture), (get-uiculture) -is [System.Globalization.CultureInfo]
False
PS> (get-culture), (get-uiculture) -is [Array]
True
PS> (get-culture), (get-uiculture) | foreach {
$_ -is [System.Globalization.CultureInfo])
}
True
True
PS> (get-culture), (get-uiculture) -is [Object]
True
The following examples show how to use the -as operator.
PS> "12/31/07" -is [DateTime]
False
PS> "12/31/07" -as [DateTime]
Monday, December 31, 2007 12:00:00 AM
PS> $date = "12/31/07" -as [DateTime]
C:\PS>$a -is [DateTime]
True
PS> 1031 -as [System.Globalization.CultureInfo]
LCID Name DisplayName
---- ---- -----------
1031 de-DE German (Germany)
The following example shows that when the -as operator cannot convert the input object to the .NET Framework type, it returns nothing.
PS> 1031 -as [System.Diagnostic.Process]
PS>