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About Operators

JuanPablo Jofre|Last Updated: 11/17/2016
|
2 Contributors

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 (-in, -notin, -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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