PowerShell is a powerful scripting language that enables IT professionals to automate complex systems and manage configurations efficiently. One of the core features of PowerShell is the ability to define functions with input parameters, which enhances script modularity and reusability. This blog post will walk you through how to create a PowerShell function with input parameters, discuss parameter data types, and demonstrate how to call your custom functions.
Defining a Function with Parameters
A function in PowerShell encapsulates a block of code with a specific task. To define a function, you use the function
keyword followed by the function’s name and a code block. Input parameters are defined within a param
block inside the function. Here’s a basic example:
function Get-Multiplication {
param (
[int]$Number1,
[int]$Number2
)
$Product = $Number1 * $Number2
return $Product
}
Understanding Parameter Data Types
In the Get-Multiplication
function, the parameters $Number1
and $Number2
are typed as [int]
, which means they accept integers. PowerShell supports various data types for parameters to ensure input data is validated. Common data types include:
[string]
: Textual data[bool]
: Boolean (True/False) values[double]
: Floating-point numbers[datetime]
: Date and time values
Specifying data types is not mandatory but is a good practice to avoid data type errors in your scripts.
Calling Functions with Parameters
After defining your function, you can invoke it by passing values to its parameters. Here’s how to call the Get-Multiplication
function with two numbers:
$result = Get-Multiplication -Number1 10 -Number2 20
Write-Output $result
This script will output 200
, the product of 10 and 20.
Using Advanced Parameter Attributes
PowerShell also allows for advanced parameter behaviors using attributes, which can define a parameter as mandatory, accept input from the pipeline, or validate input ranges. For example:
function Get-Addition {
param (
[Parameter(Mandatory=$true)]
[int]$Number1,
[Parameter(Mandatory=$true)]
[int]$Number2
)
return $Number1 + $Number2
}
Setting Default Values for Parameters
You can also set default values for parameters to be used when no value is provided:
function Get-FullName {
param (
[string]$FirstName,
[string]$LastName = 'Doe'
)
return "$FirstName $LastName"
}
If Get-FullName
is called with only the first name, it will use ‘Doe’ as the last name by default.
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