Default parameter values in PowerShell - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this PowerShell function call?

Consider this PowerShell function with a default parameter value:

function Greet($name = 'Guest') { Write-Output "Hello, $name!" }

What will be the output of Greet when called without arguments?

PowerShell

function Greet($name = 'Guest') { Write-Output "Hello, $name!" }
Greet

A Error: Missing argument for parameter 'name'

B Hello, Guest!

C Hello, $name!

D Hello, !

💡 Hint

Think about what happens when you call a function without providing a value for a parameter that has a default.

The function Greet has a default value 'Guest' for the parameter $name. When called without arguments, it uses this default and outputs "Hello, Guest!".

📝 Syntax

intermediate

Which option correctly defines a parameter with a default value in PowerShell?

Choose the correct syntax to define a function parameter $count with a default value of 5.

A param([int]$count <- 5)

B param([int]$count:5)

C param([int]$count => 5)

D param([int]$count = 5)

💡 Hint

PowerShell uses the equals sign = to assign default values to parameters.

The correct syntax to assign a default value to a parameter in PowerShell is param([type]$paramName = defaultValue). Options A, B, and D use invalid syntax.

🔧 Debug

advanced

Why does this PowerShell function throw an error when called without arguments?

Look at this function:

function Show-Info {
  param(
    [Parameter(Mandatory=$true)]
    [string]$name,
    [int]$age = 30
  )
  Write-Output "$name is $age years old."
}

Show-Info

Why does calling Show-Info without arguments cause an error?

PowerShell

function Show-Info {
  param(
    [Parameter(Mandatory=$true)]
    [string]$name,
    [int]$age = 30
  )
  Write-Output "$name is $age years old."
}

Show-Info

A Because $name has no default value and is required, so calling without it causes an error.

B Because $age has a default value, but $name must be an integer.

C Because the function syntax is invalid; default values must be last parameters.

D Because Write-Output cannot handle variables without explicit values.

💡 Hint

Check which parameters have default values and which do not.

The parameter $name has no default value, so it is required. Calling the function without providing $name causes an error. The parameter $age has a default value and is optional.

🚀 Application

advanced

What is the output of this script using default parameter values?

Given this PowerShell script:

function Calculate-Sum {
  param(
    [int]$a = 10,
    [int]$b = 20
  )
  return $a + $b
}

$result1 = Calculate-Sum
$result2 = Calculate-Sum -a 5
$result3 = Calculate-Sum -b 15
$result4 = Calculate-Sum -a 3 -b 7

Write-Output "$result1,$result2,$result3,$result4"

What will be the output?

PowerShell

function Calculate-Sum {
  param(
    [int]$a = 10,
    [int]$b = 20
  )
  return $a + $b
}

$result1 = Calculate-Sum
$result2 = Calculate-Sum -a 5
$result3 = Calculate-Sum -b 15
$result4 = Calculate-Sum -a 3 -b 7

Write-Output "$result1,$result2,$result3,$result4"

A 30,25,25,10

B 30,25,35,10

C 30,25,30,10

D 30,15,25,10

💡 Hint

Remember that parameters with default values use those defaults if not provided.

Calculations:
- $result1: defaults 10 + 20 = 30
- $result2: 5 + default 20 = 25
- $result3: default 10 + 15 = 25
- $result4: 3 + 7 = 10

🧠 Conceptual

expert

How does PowerShell handle default parameter values when using splatting?

Consider this function:

function Show-Message {
  param(
    [string]$text = 'Hello',
    [string]$color = 'Blue'
  )
  Write-Output "$text in $color"
}

And this splatting call:

$params = @{ text = 'Hi' }
Show-Message @params

What will be the output and why?

PowerShell

function Show-Message {
  param(
    [string]$text = 'Hello',
    [string]$color = 'Blue'
  )
  Write-Output "$text in $color"
}

$params = @{ text = 'Hi' }
Show-Message @params

A Hello in Blue - because splatting ignores default values.

B Hi in - because $color is empty when not passed in splatting.

C Hi in Blue - because $color uses its default value when not provided in splatting.

D Error - because splatting requires all parameters to be specified.

💡 Hint

Think about how splatting passes only specified parameters and how defaults fill in missing ones.

Splatting passes only the text parameter with value 'Hi'. The color parameter is not passed, so PowerShell uses its default 'Blue'. The output is "Hi in Blue".