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about_Operators

Updated: December 16, 2009

Applies To: Windows PowerShell 2.0

TOPIC
    about_Operators

SHORT DESCRIPTION
    Describes the operators that are supported by Windows PowerShell. 

LONG DESCRIPTION
    An operator is a language element that you can use in a command or
    expression. Windows PowerShell supports several types of operators to
    help you manipulate values.


  Arithmetic Operators
      Use arithmetic operators (+, -, *, /, %) to calculate values in a command
      or expression. With these operators, you can add, subtract, multiply, or
      divide values, and calculate the remainder (modulus) of a division 
      operation.


      You can also use arithmetic operators with strings, arrays, and hash 
      tables. The addition operator concatenates elements. The multiplication
      operator returns the specified number of copies of each element.


      For more information, see about_Arithmetic_Operators. 


  Assignment Operators
      Use assignment operators (=, +=, -=, *=, /=, %=) to assign one or more
      values to variables, to change the values in a variable, and to append
      values to variables. You can also cast the variable as any Microsoft .NET
      Framework data type, such as string or DateTime, or Process variable.


      For more information, see about_Assignment_Operators.


  Comparison Operators
      Use comparison operators (-eq, -ne, -gt, -lt, -le, -ge) to compare values
      and test conditions. For example, you can compare two string values to 
      determine whether they are equal. 


      The comparison operators include the match operators (-match, -notmatch), 
      which find patterns by using regular expressions; the replace operator 
      (-replace), which uses regular expressions to change input values; the
      like operators (-like, -notlike), which find patterns using wildcard 
      characters (*); and the containment operators (-contains, -notcontains),
      which determine whether a test value appears in a reference set.


      They also include the bitwise operators (-bAND, -bOR, -bXOR, -bNOT) to 
      manipulate the bit patterns in values.


    For more information, see about_Comparison_Operators 


  Logical Operators
      Use logical operators (-and, -or, -xor, -not, !) to connect conditional
      statements into a single complex conditional. For example, you can use a
      logical -and operator to create an object filter with two different 
      conditions.


      For more information, see about_Logical_Operators.


  Redirection Operators
      Use redirection operators (>, >>, 2>, 2>, and 2>&1) to send the output of
      a command or expression to a text file. The redirection operators work 
      like the Out-File cmdlet (without parameters) but they also let you 
      redirect error output to specified files. You can also use the Tee-Object
      cmdlet to redirect output.


      For more information, see about_Redirection.


  Split and Join Operators
      The -split and -join operators divide and combine substrings. The -split 
      operator splits a string into substrings. The -join operator concatenates
      multiple strings into a single string.


      For more information, see about_Split and about_Join.


  Type Operators
      Use the type operators (-is, -isnot, -as) to find or change the .NET 
      Framework type of an object. 

      For more information, see about_Type_Operators.


  Unary Operators
      Use unary operators to increment or decrement variables or object 
      properties and to set integers to positive or negative numbers. For 
      example, to increment the variable $a from 9 to 10, you type $a++.


  Special Operators
      Use special operators to perform tasks that cannot be performed by the 
      other types of operators. For example, special operators allow you to 
      perform operations such as running commands and changing a value's data 
      type.

    

      @( ) Array subexpression operator
         Returns the result of one or more statements as an array. 
         If there is only one item, the array has only one member. 


             @(Get-WMIObject win32_logicalDisk)



      & Call operator
         Runs a command, script, or script block. The call operator, also known as
         the "invocation operator," lets you run commands that are stored in
         variables and represented by strings. Because the call operator does not
         parse the command, it cannot interpret command parameters. 

             C:\PS> $c = "get-executionpolicy"
             C:\PS> $c
             get-executionpolicy
 
             C:\PS> & $c
             AllSigned



      [ ] Cast operator
           Converts or limits objects to the specified type. If the objects
           cannot be converted, Windows PowerShell generates an error.

             [datetime]$birthday = "1/20/88"
             [int64]$a = 34  



      , Comma operator
         As a binary operator, the comma creates an array. As a unary
         operator, the comma creates an array with one member. Place the
         comma before the member.


             $myArray = 1,2,3 
             $SingleArray = ,1     



      . Dot sourcing operator
         Runs a script in the current scope so that any functions,
         aliases, and variables that the script creates are added to the current
         scope. 

             . c:\scripts.sample.ps1


         Note: The dot sourcing operator is followed by a space. Use the space to
               distinguish the dot from the dot (.) symbol that represents the 
               current directory.
 
               In the following example, the Sample.ps1 script in the current 
               directory is run in the current scope.

                 . .\sample.ps1



      -f Format operator
          Formats strings by using the format method of string 
          objects. Enter the format string on the left side of the operator 
          and the objects to be formatted on the right side of the operator.
        

             C:\PS> "{0} {1,-10} {2:N}" -f 1,"hello",[math]::pi
             1 hello      3.14

          For more information, see the String.Format method 
          (http://go.microsoft.com/fwlink/?LinkID=166450) and 
          Composite Formatting (http://go.microsoft.com/fwlink/?LinkID=166451).



      [ ] Index operator
           Selects objects from indexed collections, such as arrays and
           hash tables. Array indexes are zero-based, so the first object 
           is indexed as [0]. For arrays (only), you can also use negative
           indexes to get the last values. Hash tables are indexed by key
           value.

             C:\PS> $a = 1, 2, 3
             C:\PS> $a[0]
             1
             C:\PS> $a[-1]
             3


             C:\PS> (get-hotfix | sort installedOn)[-1]

           
             C:\PS> $h = @{key="value"; name="Windows PowerShell"; version="2.0"}
             C:\PS> $h["name"]
             Windows PowerShell


             C:\PS> $x = [xml]"<doc><intro>Once upon a time...</intro></doc>"
             C:\PS> $x["doc"]
             intro
             -----
             Once upon a time...

           



      | Pipeline operator
         Sends ("pipes") the output of the command that precedes it to the
         command that follows it. When the output includes more than one object
         (a "collection"), the pipeline operator sends the objects one at a time.

               get-process | get-member
               get-pssnapin | where {$_.vendor -ne "Microsoft"}                              



      . Property dereference operator
         Accesses the properties and methods of an object. 
         

             $myProcess.peakWorkingSet
             (get-process powershell).kill()



      .. Range operator
          Represents the sequential integers in an integer array, 
          given an upper and lower boundary.


             1..10
             10..1
             foreach ($a in 1..$max) {write-host $a}



      :: Static member operator
          Calls the static properties operator and methods of a .NET
          Framework class. To find the static properties and methods of an 
          object, use the Static parameter of the Get-Member cmdlet. 


             [datetime]::now
   



      $( ) Subexpression operator
         Returns the result of one or more statements. For a 
         single result, returns a scalar. For multiple results, returns an 
         array.


             $($x * 23)
             $(Get-WMIObject win32_Directory)

                       


       
SEE ALSO
    about_Arithmetic_Operators
    about_Assignment_Operators
    about_Comparison_Operators
    about_Logical_Operators
    about_Type_Operators
    about_Split
    about_Join
    about_Redirection
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