PowerShell Parameters

A parameter is an input that a function accepts. Parameters let one function work with different values each time it runs.

Take one parameter by name

The param block declares the input. The call passes a value with the parameter name.

function Get-Greeting {
    param([string]$Name)
    "Hello, $Name"
}
Get-Greeting -Name "Ana"

Take two parameters and use both

List each parameter in the param block, separated by a comma. The function body can use both values.

function Add-Numbers {
    param([int]$First, [int]$Second)
    $First + $Second
}
Add-Numbers -First 3 -Second 4

Pass values in order without names

Positional values match parameters in their declared order. The first value goes to the first parameter.

function Add-Numbers {
    param([int]$First, [int]$Second)
    $First + $Second
}
Add-Numbers 5 6

Example

function Get-FullName {
    param([string]$First, [string]$Last)
    "$First $Last"
}
Get-FullName -First "Ana" -Last "Silva"
Get-FullName "Sam" "Costa"

Key points

Parameter: an input that a function accepts.
Declare parameters in a param block at the start of the function.
Each parameter has a name that starts with a dollar sign.
Call with named values by writing a dash, the parameter name, and the value.
Call with positional values by writing the values in the declared order.

In this example, a function takes a first name and a last name and joins them with a space. The first call passes both values by name. The second call passes both values in order, without names.

Note

A parameter can carry a type, such as string or int, which shapes the value it accepts.

Try it Yourself

Edit the code, then press Run.

Running is simulated

function Get-FullName {
    param([string]$First, [string]$Last)
    "$First $Last"
}
Get-FullName -First "Ana" -Last "Silva"
Get-FullName "Sam" "Costa"

Exercise

Which call passes Ana to the Name parameter of Get-Greeting?

Get-Greeting Ana Name Get-Greeting "Ana" Get-Greeting -Ana "Name" Get-Greeting -Name "Ana"