about_Type_Operators

Applies To: Windows PowerShell 2.0

TOPIC
    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 nothing. It does not return an error.


    The following table lists the type operators in Windows PowerShell.


    Operator  Description                 Example  
    --------  ------------------------    -------------------------------------
    -is       Returns TRUE when the       C:\PS> (get-date) -is [datetime]
              input is an instance        True
              of the specified
              .NET Framework type.

    -isnot    Returns TRUE when the       C:\PS> (get-date) -isnot [datetime]
              input is not an instance    False
              of the specified
              .NETFramework type.
 
    -as       Converts the input to       C:\PS> 12/31/07 -as [datetime]
              the specified               Monday, December 31, 2007 12:00:00 AM
              .NET Framework type.


    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 type operators always return a Boolean value, even if the input is a
    collection of objects. However, when the input is a collection, the type 
    operators match the .NET Framework type of the collection. They do not 
    match the type of each object, even when all of the objects are of the 
    same type.

    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:

        C:\PS> (get-culture).gettype().fullname
        System.Globalization.CultureInfo
 

EXAMPLES
    The following examples show some uses of the Type operators:

        C:\PS> 32 -is [Float]
        False

        C:\PS> 32 -is "int"
        True

        C:\PS> (get-date) -is [DateTime]
        True

        C:\PS> "12/31/2007" -is [DateTime]
        False

        C:\PS> "12/31/2007" -is [String]
        True

        C:\PS> (get-process powershell)[0] -is [System.Diagnostics.Process]
        True

        C:\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.

        C:\PS> (get-culture) -is [System.Globalization.CultureInfo]
        True

        C:\PS> (get-uiculture) -is [System.Globalization.CultureInfo]
        True

        C:\PS> (get-culture), (get-uiculture) -is [System.Globalization.CultureInfo]
        False

        C:\PS> (get-culture), (get-uiculture) -is [Array]
        True
 
        C:\PS> (get-culture), (get-uiculture) | foreach {$_ -is [System.Globalization.CultureInfo])
        True
        True

        C:\PS> (get-culture), (get-uiculture) -is [Object]
        True
 

    The following examples show how to use the -as operator.

        C:\PS> "12/31/07" -is [datetime]
        False

        C:\PS> "12/31/07" -as [datetime]
        Monday, December 31, 2007 12:00:00 AM

        C:\PS> $date = "12/31/07" -as [datetime]

        C:\PS>$a -is [datetime]
        True

        C:\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.


        C:\PS> 1031 -as [System.Diagnostic.Process]
        C:\PS>
 

SEE ALSO
    about_Operators