Object arrays in PowerShell - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to create an array of objects with a single property 'Name'.

PowerShell

$array = @(@{Name='Alice'}, @{Name='Bob'}, @{Name='Charlie'})
$array | ForEach-Object { $_.[1] }

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

AObject

BValue

CName

DItem

Attempts:

3 left

💡 Hint

Common Mistakes

Using $_.Value or $_.Object which do not exist in the objects.

Trying to access the array directly without looping.

The property 'Name' is accessed using $_.Name to get each object's Name value.

2fill in blank

medium

Complete the code to add a new object with Name 'David' to the existing array.

PowerShell

$array += [1]

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

A@{Name='David'}

B@{Value='David'}

C@{Object='David'}

D@{Item='David'}

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong property names like 'Value' or 'Object'.

Not using a hashtable syntax.

To add a new object with property 'Name', use @{Name='David'}.

3fill in blank

hard

Fix the error in the code to filter objects where Name starts with 'A'.

PowerShell

$filtered = $array | Where-Object { $_.Name [1] '^A' }

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

A-contains

B-match

C-like

D-eq

Attempts:

3 left

💡 Hint

Common Mistakes

Using '-eq' which checks exact equality.

Using '-like' without wildcards.

Using '-contains' which is for collections.

The operator '-match' is used to match a regex pattern like '^A'.

4fill in blank

hard

Fill both blanks to create an array of objects with Name and Age properties.

PowerShell

$people = @(@{Name='Eve'; [1]=30}, @{Name='Frank'; [2]=25})

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

AAge

BValue

CYears

DCount

Attempts:

3 left

💡 Hint

Common Mistakes

Using different property names like 'Value' or 'Years' inconsistently.

Using property names that do not match.

The property for age is 'Age' in both objects.

5fill in blank

hard

Fill all three blanks to create a filtered array of people older than 28 with their names in uppercase.

PowerShell

$result = $people | Where-Object { $_.[1] [2] 28 } | ForEach-Object { $_.[3].ToUpper() }

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

AAge

B>

CName

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong property names or operators.

Trying to uppercase the Age property.

Filter by Age > 28 and convert the Name property to uppercase.

Practice

1. What is an object array in PowerShell?

easy

A. A type of function that returns objects

B. A single object with many properties

C. A command to create new objects

D. A variable that holds multiple objects together in a list

Solution

1. Step 1: Understand the definition of object arrays

   An object array is a collection that holds many objects in one variable, like a list.

2. Step 2: Compare options with the definition

   Only A variable that holds multiple objects together in a list correctly describes an object array as a variable holding multiple objects.

3. Final Answer:

   A variable that holds multiple objects together in a list -> Option D

4. Quick Check:

   Object array = list of objects [OK]

Hint: Remember: arrays hold many items together [OK]

Common Mistakes:

• Confusing object arrays with single objects
• Thinking object arrays are commands
• Mixing arrays with functions

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

easy

A. $array = ()

B. $array = @()

C. $array = new-object array

D. $array = {}

Solution

1. Step 1: Recall PowerShell syntax for empty arrays

   PowerShell uses @() to create an empty array.

2. Step 2: Check each option

   $array = @() uses @(), which is correct. $array = () uses (), which assigns $null, not an array. $array = new-object array is incorrect syntax. $array = {} uses {}, which creates a hashtable, not an array.

3. Final Answer:

   $array = @() -> Option B

4. Quick Check:

   Empty array syntax = @() [OK]

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

Common Mistakes:

• Using () which assigns null, not an array
• Confusing arrays with hashtables {}
• Trying to use new-object for arrays

3. What will be the output of this PowerShell code?

$array = @()
$array += 'apple'
$array += 'banana'
$array += 'cherry'
$array

medium

A. apple
banana
cherry

B. @('apple', 'banana', 'cherry')

C. apple banana cherry

D. Error: Cannot add to array

Solution

1. Step 1: Understand how += adds items to arrays

   Using += adds each string as a new element to the array.

2. Step 2: Output the array variable

   When output, PowerShell prints each element on a new line, so the output is three lines: apple, banana, cherry.

3. Final Answer:

   apple banana cherry -> Option A

4. Quick Check:

   Array elements print line by line [OK]

Hint: Arrays print each item on its own line [OK]

Common Mistakes:

• Expecting all items on one line separated by spaces
• Thinking += causes an error on arrays
• Confusing array output with string output

4. Identify the error in this PowerShell script:

$array = @()
$array += 'one'
$array = $array + 'two'
$array = $array + 3
$array

medium

A. No error; script runs and outputs all items

B. Using + operator on arrays causes error

C. Cannot add integer to string array

D. Array must be declared with fixed size

Solution

1. Step 1: Check adding different types to array

   PowerShell arrays can hold mixed types, so adding integer 3 is allowed.

2. Step 2: Check use of + operator on arrays

   Using + concatenates arrays or adds items; it works fine here.

3. Final Answer:

   No error; script runs and outputs all items -> Option A

4. Quick Check:

   PowerShell arrays accept mixed types and + works [OK]

Hint: PowerShell arrays can mix types and use + to add items [OK]

Common Mistakes:

• Thinking arrays only hold one data type
• Believing + operator causes errors on arrays
• Assuming arrays need fixed size

5. You have an array of objects representing people:

$people = @(
  [pscustomobject]@{Name='Alice'; Age=30},
  [pscustomobject]@{Name='Bob'; Age=25},
  [pscustomobject]@{Name='Carol'; Age=35}
)

How do you add a new person object with Name='Dave' and Age=40 to this array?

hard

A. $people = @($people, @{Name='Dave'; Age=40})

B. $people = $people + @{Name='Dave'; Age=40}

C. $people += [pscustomobject]@{Name='Dave'; Age=40}

D. $people.Add([pscustomobject]@{Name='Dave'; Age=40})

Solution

1. Step 1: Create a new person object correctly

   Use [pscustomobject]@{Name='Dave'; Age=40} to create the new object.

2. Step 2: Add the new object to the existing array

   Use += to add the new object to the $people array. $people += [pscustomobject]@{Name='Dave'; Age=40} does this correctly.

3. Final Answer:

   $people += [pscustomobject]@{Name='Dave'; Age=40} -> Option C

4. Quick Check:

   Add object to array using += [OK]

Hint: Use += with new [pscustomobject] to add to array [OK]

Common Mistakes:

• Forgetting [pscustomobject] and adding plain hashtable
• Using .Add() which does not work on arrays
• Reassigning array incorrectly causing nested arrays