Arrays in PowerShell - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create an array with three numbers.

PowerShell

$numbers = @([1])

Drag options to blanks, or click blank then click option'

A1 2 3

B1, 2, 3

C1; 2; 3

D1. 2. 3

Attempts:

3 left

💡 Hint

Common Mistakes

Using semicolons instead of commas to separate values.

Using dots instead of commas.

In PowerShell, arrays are created using @() with comma-separated values inside.

2fill in blank

medium

Complete the code to access the second element of the array.

PowerShell

$secondElement = $numbers[[1]]

Drag options to blanks, or click blank then click option'

A1

B3

C2

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using 2 or 3 as the index for the second element.

Forgetting that indexing starts at zero.

PowerShell arrays use zero-based indexing, so the second element is at index 1.

3fill in blank

hard

Fix the error in the code to add an element to the array.

PowerShell

$numbers [1] 4

Drag options to blanks, or click blank then click option'

A*=

B-=

C+

D+=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '+' which does not modify the original array.

Using '-=' or '*=' which are incorrect here.

Use '+=' to add an element to an existing array in PowerShell.

4fill in blank

hard

Fill both blanks to create an array of numbers from 4 to 12.

PowerShell

$evens = @((2[1]10)[2]2)

Drag options to blanks, or click blank then click option'

A..

B,

C-

D+

Attempts:

3 left

💡 Hint

Common Mistakes

Using commas instead of the range operator.

Using '-' instead of '+'.

Use the range operator '..' to create numbers from 2 to 10, then add 2 to each element to get numbers from 4 to 12.

5fill in blank

hard

Fill all three blanks to create a filtered array of numbers greater than 3.

PowerShell

$filtered = $numbers | Where-Object { $_ [1] [2] } | Sort-Object -Descending | Select-Object -First [3]

Drag options to blanks, or click blank then click option'

A-gt

B3

C2

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong comparison operators like '-lt'.

Selecting wrong number of elements.

Use '-gt' to filter numbers greater than 3, then select the first 5 after sorting descending.

Practice

1. What does an array in PowerShell do?

easy

A. Stores only one item at a time

B. Stores multiple items in one variable

C. Runs commands sequentially

D. Creates a new script file

Solution

1. Step 1: Understand the purpose of arrays

   Arrays hold multiple values together in one variable, unlike single variables that hold one value.

2. Step 2: Compare options with array definition

   Only Stores multiple items in one variable correctly describes storing multiple items in one variable, which matches the array concept.

3. Final Answer:

   Stores multiple items in one variable -> Option B

4. Quick Check:

   Arrays = store multiple items [OK]

Hint: Arrays hold many items together in one variable [OK]

Common Mistakes:

• Thinking arrays hold only one item
• Confusing arrays with scripts or commands
• Believing arrays create files

2. Which of the following is the correct way to create an empty array in PowerShell?

easy

A. $arr = []

B. $arr = array()

C. $arr = {}

D. $arr = @()

Solution

1. Step 1: Recall PowerShell array syntax

   PowerShell uses @() to create arrays, including empty ones.

2. Step 2: Check each option

   $arr = @() uses @() which is correct. Options A, B, and C use invalid or different syntax for arrays.

3. Final Answer:

   $arr = @() -> Option D

4. Quick Check:

   Empty array = @() [OK]

Hint: Use @() to create arrays in PowerShell [OK]

Common Mistakes:

• Using [] which is not valid for arrays in PowerShell
• Using {} which is for hashtables or script blocks
• Using array() which is not recognized in PowerShell

3. What is the output of this PowerShell code?

$arr = @('apple', 'banana', 'cherry')
Write-Output $arr[1]

medium

A. banana

B. apple

C. cherry

D. 1

Solution

1. Step 1: Understand array indexing in PowerShell

   Arrays start at index 0, so $arr[0] = 'apple', $arr[1] = 'banana', $arr[2] = 'cherry'.

2. Step 2: Identify the output of $arr[1]

   The code outputs the item at index 1, which is 'banana'.

3. Final Answer:

   banana -> Option A

4. Quick Check:

   Index 1 = banana [OK]

Hint: Arrays start at zero; index 1 is second item [OK]

Common Mistakes:

• Thinking index starts at 1
• Confusing item values with index numbers
• Expecting all items printed instead of one

4. Identify the error in this PowerShell code:

$arr = @()
$arr + 'orange'

medium

A. += operator is missing to add item

B. Array cannot be empty

C. Use [] instead of @() for arrays

D. Variable name must start with capital letter

Solution

1. Step 1: Check how to add items to arrays

   In PowerShell, to add an item to an array, use '+=' operator, not just '+'.

2. Step 2: Analyze the code

   The code uses '$arr + 'orange'' which does not update $arr. It should be '$arr += 'orange'' to add the item.

3. Final Answer:

   += operator is missing to add item -> Option A

4. Quick Check:

   Add item with += [OK]

Hint: Use += to add items to arrays, not just + [OK]

Common Mistakes:

• Using + without = to add items
• Thinking arrays cannot be empty
• Confusing array syntax with other languages

5. You have an array $arr = @('cat', 'dog', 'bird'). How do you add 'fish' to the end and then print all items one per line?

hard

A. $arr = $arr + 'fish'; Write-Host $arr

B. $arr + 'fish'; Write-Output $arr

C. $arr += 'fish'; $arr | ForEach-Object { Write-Output $_ }

D. $arr += 'fish'; Write-Host $arr[0], $arr[1], $arr[2], $arr[3]

Solution

1. Step 1: Add 'fish' to the array correctly

   Use '+=' operator to add 'fish' to $arr: $arr += 'fish'.

2. Step 2: Print each item on its own line

   Use pipeline with ForEach-Object and Write-Output to print each item separately.

3. Step 3: Check each option

   $arr += 'fish'; $arr | ForEach-Object { Write-Output $_ } correctly adds and prints items line by line. $arr + 'fish'; Write-Output $arr does not update $arr. $arr = $arr + 'fish'; Write-Host $arr uses Write-Host which prints all items on one line. $arr += 'fish'; Write-Host $arr[0], $arr[1], $arr[2], $arr[3] prints items but manually and is less flexible.

4. Final Answer:

   $arr += 'fish'; $arr | ForEach-Object { Write-Output $_ } -> Option C

5. Quick Check:

   Add with += and print with pipeline [OK]

Hint: Add with += and print each item using pipeline [OK]

Common Mistakes:

• Using + without = to add items
• Printing array without pipeline for separate lines
• Using Write-Host which prints all on one line