ForEach loop in PowerShell

Introduction

A ForEach loop helps you repeat a set of actions for each item in a list or collection. It saves time by automating repetitive tasks.

You want to print each name in a list of friends.

You need to check every file in a folder.

You want to send an email to each person in a contact list.

You want to add a prefix to every item in a list.

You want to calculate the total of numbers in a list.

Syntax

PowerShell

foreach ($item in $collection) {
    # commands to run for each $item
}

The variable $item holds the current element from the collection during each loop.

The collection can be an array, list, or any group of items.

Examples

Prints numbers from 1 to 5, one per line.

PowerShell

foreach ($number in 1..5) {
    Write-Output $number
}

Greets each name in the list.

PowerShell

foreach ($name in @('Anna', 'Bob', 'Cara')) {
    Write-Output "Hello, $name!"
}

Lists the names of all files in the current folder.

PowerShell

foreach ($file in Get-ChildItem -Path .) {
    Write-Output $file.Name
}

Sample Program

This script goes through each fruit in the list and prints a sentence saying you like that fruit.

PowerShell

foreach ($fruit in @('Apple', 'Banana', 'Cherry')) {
    Write-Output "I like $fruit"
}

Important Notes

You can use any variable name instead of $item; just keep it consistent inside the loop.

Make sure the collection is not empty, or the loop will not run.

Use curly braces { } to group the commands that run for each item.

Summary

ForEach loops repeat actions for every item in a list.

They help automate tasks that involve multiple items.

Use foreach ($var in $collection) { } syntax in PowerShell.

Practice

1. What does the foreach loop do in PowerShell?

easy

A. Creates a new collection from scratch

B. Runs code only once regardless of the collection

C. Repeats a block of code for each item in a collection

D. Stops the script immediately

Solution

1. Step 1: Understand the foreach loop purpose

   The foreach loop is designed to repeat actions for every item in a list or collection.

2. Step 2: Compare options to this purpose

   Only Repeats a block of code for each item in a collection correctly describes repeating code for each item in a collection.

3. Final Answer:

   Repeats a block of code for each item in a collection -> Option C

4. Quick Check:

   foreach = repeat for each item [OK]

Hint: Think: foreach means 'for each item' repeat [OK]

Common Mistakes:

• Confusing foreach with a one-time action
• Thinking foreach creates new collections
• Believing foreach stops the script

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

easy

A. foreach ($item in $list) { Write-Output $item }

B. foreach $item in $list { Write-Output $item }

C. foreach ($item : $list) { Write-Output $item }

D. foreach ($item; $list) { Write-Output $item }

Solution

1. Step 1: Recall correct foreach syntax

   PowerShell foreach loops use: foreach ($var in $collection) { ... }

2. Step 2: Match options to syntax

   Only foreach ($item in $list) { Write-Output $item } uses the correct 'in' keyword and parentheses.

3. Final Answer:

   foreach ($item in $list) { Write-Output $item } -> Option A

4. Quick Check:

   Syntax uses 'in' keyword inside parentheses [OK]

Hint: Look for 'foreach ($var in $collection)' pattern [OK]

Common Mistakes:

• Omitting parentheses around variable and collection
• Using ':' or ';' instead of 'in'
• Missing the 'in' keyword

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

foreach ($num in 1..3) { Write-Output ($num * 2) }

medium

A. 2 4 6

B. 1 2 3

C. 3 6 9

D. Error: Invalid syntax

Solution

1. Step 1: Understand the loop range

   The loop runs for numbers 1, 2, and 3.

2. Step 2: Calculate output for each iteration

   Each number is multiplied by 2, so outputs are 2, 4, and 6.

3. Final Answer:

   2 4 6 -> Option A

4. Quick Check:

   1*2=2, 2*2=4, 3*2=6 [OK]

Hint: Multiply each loop number by 2 mentally [OK]

Common Mistakes:

• Confusing the range operator '..'
• Thinking output is original numbers
• Expecting syntax error

4. Identify the error in this PowerShell foreach loop:

foreach $item in $array { Write-Output $item }

medium

A. No error, code is correct

B. Missing parentheses around the loop variable and collection

C. Using $item instead of $i as loop variable

D. Incorrect use of Write-Output

Solution

1. Step 1: Check foreach syntax

   PowerShell requires parentheses around the variable and collection in foreach loops.

2. Step 2: Identify missing parentheses

   The code lacks parentheses: it should be foreach ($item in $array) { ... }

3. Final Answer:

   Missing parentheses around the loop variable and collection -> Option B

4. Quick Check:

   foreach needs parentheses [OK]

Hint: Always use parentheses in foreach syntax [OK]

Common Mistakes:

• Omitting parentheses
• Confusing variable names
• Thinking Write-Output causes error

5. You have a list of filenames stored in $files. You want to print only those filenames that end with '.txt' using a foreach loop. Which script correctly does this?

hard

A. foreach ($file in $files) { if ($file -eq '*.txt') { Write-Output $file } }

B. foreach ($file in $files) { if ($file contains '.txt') { Write-Output $file } }

C. foreach ($file in $files) { Write-Output $file -match '.txt' }

D. foreach ($file in $files) { if ($file -like '*.txt') { Write-Output $file } }

Solution

1. Step 1: Understand filtering condition

   To check if a filename ends with '.txt', use the '-like' operator with '*.txt' pattern.

2. Step 2: Verify foreach loop and condition

   foreach ($file in $files) { if ($file -like '*.txt') { Write-Output $file } } correctly uses foreach with an if condition checking '-like "*.txt"' and outputs matching files.

3. Final Answer:

   foreach ($file in $files) { if ($file -like '*.txt') { Write-Output $file } } -> Option D

4. Quick Check:

   Use '-like' with wildcard for pattern match [OK]

Hint: Use '-like "*.txt"' inside if in foreach [OK]

Common Mistakes:

• Using '-eq' instead of '-like' for pattern matching
• Misusing '-match' without if condition
• Using 'contains' which is invalid here