Parameters in PowerShell - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

What is the output of this PowerShell script with parameters?

Consider this script saved as TestParams.ps1 and run with .\TestParams.ps1 -Name 'Alice' -Age 30. What will it output?

PowerShell

param(
    [string]$Name,
    [int]$Age
)

Write-Output "Name: $Name, Age: $Age"

A Name: , Age:

B Name: , Age: 30

C Name: Alice, Age: 30

D Name: Alice, Age:

💡 Hint

Look at how parameters are declared and passed in PowerShell scripts.

The script defines two parameters, Name and Age. When run with -Name 'Alice' and -Age 30, these values are assigned correctly and printed.

📝 Syntax

intermediate

Which option correctly declares a mandatory string parameter in PowerShell?

You want to declare a parameter named FilePath that is mandatory and must be a string. Which declaration is correct?

A param([string]$FilePath Mandatory=$true)

B param([Parameter(Mandatory=$true)][string]$FilePath)

C param([Mandatory] [string]$FilePath)

D param([string]$FilePath -Mandatory)

💡 Hint

Look for the correct syntax of the Parameter attribute.

Option B uses the correct syntax with the Parameter attribute and Mandatory property set to $true.

🔧 Debug

advanced

Why does this script fail when calling with no arguments?

Given this script snippet, what error occurs when run without arguments? param( [Parameter(Mandatory=$true)] [string]$User ) Write-Output "User is $User"

PowerShell

param(
    [Parameter(Mandatory=$true)]
    [string]$User
)

Write-Output "User is $User"

A The script throws an error: Missing an argument for the mandatory parameter 'User'.

B The script throws a syntax error due to missing default value.

C The script outputs: User is

D The script runs but outputs 'User is $User' literally.

💡 Hint

Think about what happens when a mandatory parameter is not provided.

Mandatory parameters require a value. If none is given, PowerShell throws an error indicating the missing argument.

🚀 Application

advanced

What is the output when using a default parameter value?

Consider this script run as .\Script.ps1 with no arguments. What will it output? param( [string]$City = "Seattle" ) Write-Output "City is $City"

PowerShell

param(
    [string]$City = "Seattle"
)

Write-Output "City is $City"

A Error: Parameter 'City' requires a value.

B City is

C City is $City

D City is Seattle

💡 Hint

Check how default values work for parameters.

If no argument is passed, the parameter uses its default value, here 'Seattle'.

🧠 Conceptual

expert

How many parameters does this script accept and what are their types?

Analyze this parameter block and answer how many parameters are declared and their types: param( [string]$Name, [int]$Count = 5, [switch]$Verbose ) Write-Output "$Name, $Count, $Verbose"

PowerShell

param(
    [string]$Name,
    [int]$Count = 5,
    [switch]$Verbose
)

Write-Output "$Name, $Count, $Verbose"

A Three parameters: Name (string), Count (int with default 5), Verbose (switch)

B Two parameters: Name (string), Count (int), Verbose is not a parameter

C Three parameters: Name (string), Count (string), Verbose (boolean)

D One parameter: Name (string), Count and Verbose are variables

💡 Hint

Look carefully at the param block and types.

The script declares three parameters: Name as string, Count as int with default 5, and Verbose as a switch (boolean flag).

Practice

1. What is the purpose of using param() in a PowerShell script?

easy

A. To declare input parameters that the script can accept

B. To define a function inside the script

C. To output results from the script

D. To comment lines in the script

Solution

1. Step 1: Understand the role of param()

   The param() block is used at the start of a PowerShell script to declare parameters that the script can accept as input.

2. Step 2: Differentiate from other script parts

   It is not used to define functions, output results, or comment lines. Those have different syntax and purposes.

3. Final Answer:

   To declare input parameters that the script can accept -> Option A

4. Quick Check:

   param() declares input parameters [OK]

Hint: Remember: param() is for input, not output or comments [OK]

Common Mistakes:

• Confusing param() with function declaration
• Thinking param() outputs data
• Using param() to comment code

2. Which of the following is the correct syntax to declare a mandatory string parameter named Name in PowerShell?

easy

A. param([string]$Name = "")

B. param([string]$Name)

C. param($Name:string Mandatory)

D. param([Parameter(Mandatory=$true)][string]$Name)

Solution

1. Step 1: Understand mandatory parameter syntax

   To make a parameter mandatory, use the [Parameter(Mandatory=$true)] attribute before the type and name.

2. Step 2: Check each option

   param([Parameter(Mandatory=$true)][string]$Name) correctly uses [Parameter(Mandatory=$true)][string]$Name. param([string]$Name = "") sets a default empty string, so not mandatory. param([string]$Name) lacks the mandatory attribute. param($Name:string Mandatory) is invalid syntax.

3. Final Answer:

   param([Parameter(Mandatory=$true)][string]$Name) -> Option D

4. Quick Check:

   Mandatory parameter needs [Parameter(Mandatory=$true)] [OK]

Hint: Mandatory parameters use [Parameter(Mandatory=$true)] attribute [OK]

Common Mistakes:

• Omitting the Mandatory attribute
• Using default value instead of mandatory
• Incorrect attribute syntax

3. What will be the output of this script when run with -Count 3?

param([int]$Count = 1)
for ($i = 1; $i -le $Count; $i++) { Write-Output "Number $i" }

medium

A. Number 1
Number 2
Number 3

B. Number 1

C. Number 3

D. Error: Missing parameter

Solution

1. Step 1: Understand parameter default and input

   The parameter $Count has a default of 1 but is overridden by passing -Count 3.

2. Step 2: Trace the loop output

   The for loop runs from 1 to 3, outputting "Number 1", "Number 2", and "Number 3" each on a new line.

3. Final Answer:

   Number 1 Number 2 Number 3 -> Option A

4. Quick Check:

   Loop runs 3 times with Count=3 [OK]

Hint: Parameter overrides default; loop runs Count times [OK]

Common Mistakes:

• Ignoring passed parameter and using default
• Expecting single output instead of looped output
• Confusing parameter name or type

4. Identify the error in this parameter declaration:

param([int]$Age = "twenty")

medium

A. Missing mandatory attribute

B. Type mismatch: assigning string to int parameter

C. Parameter name cannot be Age

D. Default value must be null

Solution

1. Step 1: Check parameter type and default value

   The parameter $Age is declared as [int] but the default value is the string "twenty".

2. Step 2: Understand type mismatch error

   PowerShell cannot convert the string "twenty" to an integer, causing a type mismatch error.

3. Final Answer:

   Type mismatch: assigning string to int parameter -> Option B

4. Quick Check:

   Default value must match parameter type [OK]

Hint: Default values must match declared parameter type [OK]

Common Mistakes:

• Assigning string default to int parameter
• Ignoring type mismatch errors
• Assuming parameter name restrictions

5. You want to create a script that accepts two parameters: Path (string, mandatory) and Verbose (switch, optional). Which is the correct way to declare these parameters?

hard

A. param([string]$Path, [Parameter(Mandatory=$true)][switch]$Verbose)

B. param([string]$Path = "", [switch]$Verbose = $false)

C. param([Parameter(Mandatory=$true)][string]$Path, [switch]$Verbose)

D. param([switch]$Path, [string]$Verbose)

Solution

1. Step 1: Identify mandatory and optional parameters

   Path must be mandatory string, so use [Parameter(Mandatory=$true)][string]$Path. Verbose is an optional switch, so [switch]$Verbose without mandatory attribute.

2. Step 2: Evaluate each option

   param([Parameter(Mandatory=$true)][string]$Path, [switch]$Verbose) correctly declares Path as mandatory string and Verbose as optional switch. param([string]$Path, [Parameter(Mandatory=$true)][switch]$Verbose) wrongly makes Verbose mandatory. param([string]$Path = "", [switch]$Verbose = $false) sets default empty string for Path, so not mandatory. param([switch]$Path, [string]$Verbose) swaps types incorrectly.

3. Final Answer:

   param([Parameter(Mandatory=$true)][string]$Path, [switch]$Verbose) -> Option C

4. Quick Check:

   Mandatory string + optional switch = param([Parameter(Mandatory=$true)][string]$Path, [switch]$Verbose) [OK]

Hint: Mandatory uses [Parameter(Mandatory=$true)], switches don't [OK]

Common Mistakes:

• Making switches mandatory
• Setting default values instead of mandatory
• Mixing parameter types