For loop in PowerShell - Mini Project: Build & Apply

Using a For Loop in PowerShell

📖 Scenario: You are organizing a small event and have a list of guests. You want to greet each guest with a personalized message.

🎯 Goal: Build a PowerShell script that uses a for loop to print a greeting message for each guest in the list.

📋 What You'll Learn

Create an array of guest names

Create a variable to hold the number of guests

Use a for loop to iterate over the guest names

Print a greeting message for each guest

💡 Why This Matters

🌍 Real World

Automating repetitive tasks like sending personalized messages to a list of contacts.

💼 Career

Understanding loops is essential for scripting tasks in system administration, automation, and DevOps roles.

1

Create the guest list array

Create an array called guests with these exact names: "Alice", "Bob", "Charlie", "Diana".

PowerShell

# Create an array called guests with the names "Alice", "Bob", "Charlie", "Diana"
# Your code here

Hint

Use @() to create an array in PowerShell.

2

Create a variable for the number of guests

Create a variable called count that stores the number of guests in the guests array using the .Count property.

PowerShell

$guests = @("Alice", "Bob", "Charlie", "Diana")
# Create a variable called count that stores the number of guests
# Your code here

Hint

Use $guests.Count to get the number of items in the array.

3

Write the for loop to greet each guest

Write a for loop that uses a variable i starting at 0 and runs while i is less than count. Inside the loop, access each guest by $guests[i].

PowerShell

$guests = @("Alice", "Bob", "Charlie", "Diana")
$count = $guests.Count
# Write a for loop with variable i from 0 to count - 1
# Your code here

Hint

Use for ($i = 0; $i -lt $count; $i++) to loop through the array indexes.

4

Print greeting messages inside the loop

Inside the for loop, add a Write-Host statement to print: "Hello, $guest! Welcome to the event.".

PowerShell

$guests = @("Alice", "Bob", "Charlie", "Diana")
$count = $guests.Count
for ($i = 0; $i -lt $count; $i++) {
    $guest = $guests[$i]
    # Print greeting message for each guest
    # Your code here
}

Hint

Use Write-Host to print messages in PowerShell.

Practice

1.

What does a for loop in PowerShell do?

easy

A. Defines a function

B. Runs code only once

C. Stops the script immediately

D. Repeats a block of code a set number of times

Solution

1. Step 1: Understand the purpose of a for loop

   A for loop is designed to repeat code multiple times based on a condition.

2. Step 2: Compare options with the definition

   Only Repeats a block of code a set number of times correctly describes repeating code a set number of times.

3. Final Answer:

   Repeats a block of code a set number of times -> Option D

4. Quick Check:

   For loop = repeat code [OK]

Hint: For loops repeat code multiple times [OK]

Common Mistakes:

• Thinking for loop runs only once
• Confusing for loop with function definition
• Believing for loop stops script

2.

Which of the following is the correct syntax for a for loop in PowerShell?

for (init; condition; increment) { code }

easy

A. for ($i=0; $i -lt 5; $i++) { Write-Output $i }

B. for $i in 0..5 { Write-Output $i }

C. foreach ($i=0; $i -lt 5; $i++) { Write-Output $i }

D. while ($i=0; $i -lt 5; $i++) { Write-Output $i }

Solution

1. Step 1: Identify correct for loop syntax

   PowerShell for loops use parentheses with init; condition; increment separated by semicolons.

2. Step 2: Check each option

   for ($i=0; $i -lt 5; $i++) { Write-Output $i } matches correct syntax. A uses while keyword. B has invalid 'for $i in' syntax. C uses foreach keyword. [OK]

3. Final Answer:

   for ($i=0; $i -lt 5; $i++) { Write-Output $i } -> Option A

4. Quick Check:

   Correct for loop syntax = for ($i=0; $i -lt 5; $i++) { Write-Output $i } [OK]

Hint: For loop uses semicolons inside parentheses [OK]

Common Mistakes:

• Using foreach instead of for
• Using spaces instead of semicolons
• Confusing while loop syntax

3.

What will be the output of this PowerShell code?

for ($i=1; $i -le 3; $i++) { Write-Output ($i * 2) }

medium

A. 0 2 4

B. 1 2 3

C. 2 4 6

D. 3 6 9

Solution

1. Step 1: Understand loop iterations

   The loop runs with $i values 1, 2, and 3 because condition is $i -le 3.

2. Step 2: Calculate output for each iteration

   Output is $i * 2: 1*2=2, 2*2=4, 3*2=6.

3. Final Answer:

   2 4 6 -> Option C

4. Quick Check:

   Multiply each i by 2 = 2 4 6 [OK]

Hint: Multiply loop variable by 2 each iteration [OK]

Common Mistakes:

• Confusing loop range
• Multiplying after loop ends
• Printing loop variable instead of calculation

4.

Identify the error in this PowerShell for loop:

for (; $i < 5; $i++) { Write-Output $i }

medium

A. The increment operator '++' is invalid in PowerShell

B. The loop variable $i is not initialized

C. The condition uses '<' instead of '-lt'

D. The loop body is missing curly braces

Solution

1. Step 1: Check initialization syntax in for loop

   The initialization part is empty; $i needs to be initialized (e.g., $i=0).

2. Step 2: Verify other parts

   Increment '++' is valid, condition '<' works for numbers, braces are present.

3. Final Answer:

   The loop variable $i is not initialized -> Option B

4. Quick Check:

   Always initialize $i in for loop [OK]

Hint: Initialize loop variable in for loop [OK]

Common Mistakes:

• Forgetting to initialize loop variable
• Thinking '++' is invalid
• Using C-style operators like '<' in PowerShell

5.

You want to print only even numbers from 2 to 10 using a for loop in PowerShell. Which code snippet achieves this?

hard

A. for ($i=2; $i -le 10; $i+=2) { Write-Output $i }

B. for ($i=1; $i -lt 10; $i++) { if ($i % 2 -eq 0) { Write-Output $i } }

C. for ($i=2; $i -lt 10; $i++) { Write-Output $i }

D. for ($i=0; $i -le 10; $i+=3) { Write-Output $i }

Solution

1. Step 1: Understand the goal

   We want to print even numbers from 2 to 10 inclusive.

2. Step 2: Analyze each option

   for ($i=1; $i -lt 10; $i++) { if ($i % 2 -eq 0) { Write-Output $i } } goes to i<10 so prints 2,4,6,8 (misses 10). for ($i=2; $i -le 10; $i+=2) { Write-Output $i } starts at 2, increments by 2 up to 10: 2,4,6,8,10. for ($i=2; $i -lt 10; $i++) { Write-Output $i } prints 2-9 all numbers. for ($i=0; $i -le 10; $i+=3) { Write-Output $i } wrong start/step.

3. Final Answer:

   for ($i=2; $i -le 10; $i+=2) { Write-Output $i } -> Option A

4. Quick Check:

   Increment by 2 from 2 to 10 = even numbers [OK]

Hint: Increment by 2 starting at 2 for even numbers [OK]

Common Mistakes:

• Using wrong increment step
• Starting from 1 instead of 2
• Not filtering for even numbers