About Operators

Short description

Describes the operators that are supported by PowerShell.

Long description

An operator is a language element that you can use in a command or expression. 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.

The addition operator concatenates elements. The multiplication operator returns the specified number of copies of each element. You can use arithmetic operators on any .NET type that implements them, such as: Int, String, DateTime, Hashtable, and Arrays.

For more information, see about_Arithmetic_Operators.

Assignment Operators

Use assignment operators (=, +=, -=, *=, /=, %=) to assign, change, or append values to variables. You can combine arithmetic operators with assignment to assign the result of the arithmetic operation to a 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 also include operators that find or replace patterns in text. The (-match, -notmatch, -replace) operators use regular expressions, and (-like, -notlike) use wildcards *.

Containment comparison operators determine whether a test value appears in a reference set (-in, -notin, -contains, -notcontains).

Bitwise comparison operators (-bAND, -bOR, -bXOR, -bNOT) 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

Special operators have specific use-cases that do not fit into any other operator group. For example, special operators allow you to run commands, change a value's data type, or retrieve elements from an array.

@( ) 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 or script blocks. The call operator executes in a child scope. For more about scopes, see about_scopes.

This example stores a command in a string and executes it using the call operator.

PS> $c = "get-executionpolicy"
PS> $c
PS> & $c

The call operator does not parse strings. This means that you cannot use command parameters within a string when you use the call operator.

PS> $c = "Get-Service -Name Spooler"
PS> $c
Get-Service -Name Spooler
PS> & $c
& : The term 'Get-Service -Name Spooler' is not recognized as the name of a
cmdlet, function, script file, or operable program. Check the spelling of
the name, or if a path was included, verify that the path is correct and
try again.
At line:1 char:2
+ &$c
+  ~~
    + CategoryInfo          : ObjectNotFound: (Get-Service -Name Spooler:String) [], CommandNotFoundException
    + FullyQualifiedErrorId : CommandNotFoundException

The Invoke-Expression cmdlet can execute code that causes parsing errors when using the call operator.

PS> &"1+1"
& : The term '1+1' is not recognized as the name of a cmdlet, function, script
file, or operable program. Check the spelling of the name, or if a path was
included, verify that the path is correct and try again.
At line:1 char:2
+ &"1+1"
+  ~~~~~
    + CategoryInfo          : ObjectNotFound: (1+1:String) [], CommandNotFoundException
    + FullyQualifiedErrorId : CommandNotFoundException
PS> Invoke-Expression "1+1"

You can use the call operator to execute scripts using their filenames. The example below shows a script filename that contains spaces. When you try to execute the script, PowerShell instead displays the contents of the quoted string containing the filename. The call operator allows you to execute the contents of the string containing the filename.

PS C:\Scripts> Get-ChildItem

    Directory: C:\Scripts

Mode                LastWriteTime         Length Name
----                -------------         ------ ----
-a----        8/28/2018   1:36 PM             58 script name with spaces.ps1

PS C:\Scripts> ".\script name with spaces.ps1"
.\script name with spaces.ps1
PS C:\Scripts> &".\script name with spaces.ps1"
Hello World!

For more about script blocks, see about_Script_Blocks.

[ ] Cast operator

Converts or limits objects to the specified type. If the objects cannot be converted, 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


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.

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

For more information, see the String.Format method and Composite Formatting.

[ ] 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.

PS> $a = 1, 2, 3
PS> $a[0]
PS> $a[-1]
(Get-HotFix | Sort-Object installedOn)[-1]
$h = @{key="value"; name="PowerShell"; version="2.0"}
$x = [xml]"<doc><intro>Once upon a time...</intro></doc>"
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-Object {$_.vendor -ne "Microsoft"}

. Property dereferences operator

Accesses the properties and methods of an object.

(Get-Process PowerShell).kill()

.. Range operator

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

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.


$( ) 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