Object arrays in PowerShell - Practice Problems & Coding Challenges

Challenge - 5 Problems

💻 Command Output

intermediate

Output of creating and accessing object arrays

What is the output of this PowerShell script?

PowerShell

$arr = @()
$arr += [PSCustomObject]@{Name='Alice'; Age=30}
$arr += [PSCustomObject]@{Name='Bob'; Age=25}
$arr[1].Name

A 30

B Alice

C 25

D Bob

💡 Hint

Remember arrays start at index 0.

The array has two objects. Index 1 is the second object with Name 'Bob'.

📝 Syntax

intermediate

Correct syntax to create an array of objects

Which option correctly creates an array of two objects with properties Name and Age?

A $arr = @([PSCustomObject]([Name='Tom'; Age=40]), [PSCustomObject]([Name='Jerry'; Age=35]))

B $arr = @([PSCustomObject]@{Name='Tom'; Age=40}, [PSCustomObject]@{Name='Jerry'; Age=35})

C $arr = @([PSCustomObject]{Name='Tom'; Age=40}, [PSCustomObject]{Name='Jerry'; Age=35})

D $arr = [PSCustomObject]@{Name='Tom'; Age=40}, [PSCustomObject]@{Name='Jerry'; Age=35}

💡 Hint

Use @() to create an array and @{} to create objects.

Option B correctly uses @() for array and [PSCustomObject]@{} for objects.

🔧 Debug

advanced

Identify the error in adding objects to an array

What error does this script produce? $arr = @() $arr += @{Name='Anna'; Age=28} $arr[0].Name

A No error, outputs 'Anna'

B Runtime error: Cannot index into a null array

C Runtime error: Property 'Name' not found

D Syntax error: Missing [PSCustomObject]

💡 Hint

Check the type of object added to the array.

The script adds a hashtable, not a PSCustomObject, so accessing .Name fails.

🚀 Application

advanced

Filter object array by property value

Given an array of objects with property Age, which command returns only objects where Age is greater than 30?

A $arr | Where-Object { $_.Age -gt 30 }

B $arr | Where-Object Age > 30

C $arr | Where { Age -gt 30 }

D $arr | Filter-Object { $_.Age -gt 30 }

💡 Hint

Use Where-Object with a script block and $_ for current object.

Option A uses correct syntax with Where-Object and $_ to filter by Age.

🧠 Conceptual

expert

Understanding object array property modification

If you modify a property of an object inside a PowerShell array, what happens to the array?

A The array updates because objects are referenced, so changes reflect in the array.

B The array remains unchanged because objects are copied when added.

C The array throws an error because objects are immutable.

D The array duplicates the object with the new property value.

💡 Hint

Think about how PowerShell handles objects in arrays.

PowerShell arrays hold references to objects, so modifying an object changes it inside the array.