Operators

A detailed look on operators.

"." operator

The . operator (dot operator) can be used when you need properties.

The example below will be clear enough to understand what I mean.

PS C:\PwrShell.net> $a = Get-Date
PS C:\PwrShell.net> $a.Day
3
PS C:\PwrShell.net> $a.DayOfWeek
Thursday
PS C:\PwrShell.net> $a.TimeOfDay.Hours
2
		

Arithmetic Operators

• + - Addition, concatenation
• - - Subtraction
• * - Multiplication, string repetition
• / - Division
• % - Modulus

Array Operators

• .. - Range operator
• , - Array operator
• [] - Array operator

A few examples:

PS C:\> $a = 1..10
PS C:\> $a
1
2
3
4
5
6
7
8
9
10

PS C:\> $a = @(1..3)
PS C:\> $a
1
2
3

PS C:\> 7..3
7
6
5
4
3

Using the index number in an array:

PS C:\> $a = 5..7
PS C:\> $a
5
6
7
PS C:\> $a[1]
6

Assignment Operators

• = - Assigns a value to a variable
• += - Adds a value to a variable
• -= - Subtracts a value from a variable
• *= - Multiplies a variable by a value
• /= - Divides a variable by a value
• %= - Performs a modulus on a variable

Command Expansion Operators

• $( ) - Returns null
• $(1) - Returns 1
• $(1,2,3) - Returns an array : 1,2,3.
• @(get-alias;get-process) - Executes the two commands and returns the results in an array

Comparison Operators

• -eq - Equal To
• -lt - Less Than
• -gt - Greater Than
• -ge - Greater Than or Eqaul To
• -le - Less Than or Equal To
• -ne - Not Equal To
• -band - Bitwise And
• -bor - Bitwise Or
• -bnot - Bitwise Not
• -match - Regex pattern matching
• -notmatch - Regex pattern matching
• -like - Globbing pattern matching
• -notlike - Globbing pattern matching
• -is - Compare types (2 -is int)
• -

A few examples:

PS C:\PwrShell.net> 10 -eq 10
True
PS C:\PwrShell.net> 5 -lt 10
True
PS C:\PwrShell.net> 5 -gt 10
False
PS C:\PwrShell.net> 10 -ge 10
True
PS C:\PwrShell.net> 10 -le 10
True
PS C:\PwrShell.net> 10 -ne 10
False
PS C:\PwrShell.net> 5 -ne 10
True
		

When we compare strings, PowerShell is by default not case-sensitive. You can change it by appending a character to the operator.

• Append i - Case-insensitive
• Append c - Case-sensitive

Syntax examples of insensitive variants: -imatch, -inotmatch, -ilike, -inotlike, -ieq, -ine, -igt, -ige, -ilt, -ile.

Some examples to show the difference:

PS C:\PwrShell.net> # comparing in default mode
PS C:\PwrShell.net> "Hello" -eq "HELLO"
True
PS C:\PwrShell.net> "HELLO" -eq "HELLO"
True

PS C:\PwrShell.net> # comparing when case-insensitive
PS C:\PwrShell.net> "Hello" -ieq "HELLO"
True
PS C:\PwrShell.net> "HELLO" -ieq "HELLO"
True

PS C:\PwrShell.net> # comparing when case-senstivive
PS C:\PwrShell.net> "Hello" -ceq "HELLO"
False
PS C:\PwrShell.net> "HELLO" -ceq "HELLO"
True
		

Don't forget it's for example -ceq and not -eqc. If you make a mistake your error would look like this:

PS C:\PwrShell.net> "Hello" -eqc "HELLO"
You must provide a value expression on the right-hand side of the '-eq' operator.
At line:1 char:12
+ "Hello" -eqc <<<<  "HELLO"
		

Invoke Operator

• & - Invoke the contents of an object

Syntax of the invoke operator (&):

PS C:\PwrShell.net> $a = "Get-Process"
PS C:\PwrShell.net> &$a

Logical Operators

• -and - And
• -or - Or
• -not - Not
• ! - Not

A few examples:

PS C:\PwrShell.net> # all conditions must be true		
PS C:\PwrShell.net> if ( (6 -lt 10) -and (15 -gt 10) ) {
>> # your code here
>> }

PS C:\PwrShell.net> # 1 condition must be true
PS C:\PwrShell.net> if ( ($i -gt 10) -or ($i -lt 100) ) {
>> # your code here
>> }

PS C:\PwrShell.net> if ( !(10 -eq 10) ) {
>> # your code here
>> }

PS C:\PwrShell.net> !(10 -eq 10)
False
PS C:\PwrShell.net> -not(10 -eq 10)
False
PS C:\PwrShell.net> (10 -eq 10)
True
		

Redirection operators

• > - Create
• >> - Append
• 2> - Redirect error output
• 2>> - Redirect error output and append
• 2>&1 - Redirect error to output

String operators

• + - Concatenate two strings
• * - Repeat a string some number of times
• -f - Format a string
• -replace - Replace elements in a string

A few examples:

PS C:\PwrShell.net> "string1" + "string2"
string1string2

PS C:\PwrShell.net> $test = "string1"
PS C:\PwrShell.net> $test * 4
string1string1string1string1

PS C:\PwrShell.net> "{0:M}" -f $(Get-Date)
03 april

PS C:\PwrShell.net> $a = 1,2,3,4
PS C:\PwrShell.net> $a
1
2
3
4
PS C:\PwrShell.net> $OFS = ":"
PS C:\PwrShell.net> "$a"
1:2:3:4

PS C:\PwrShell.net> "Houston, we have a problem!" -replace "Houston","HOUSTON"
HOUSTON, we have a problem!

Unary Operators

• ++ - Increment a variable
• -- - Decrement a variable
• + - Indicate that a number is positive
• - - Indicate that a number is negative

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