For loop in PowerShell

Introduction

A for loop helps you repeat a set of actions many times without writing the same code again and again.

When you want to print numbers from 1 to 10.

When you need to process each item in a list one by one.

When you want to repeat a task a fixed number of times, like sending reminders.

When you want to create multiple files with similar names automatically.

Syntax

PowerShell

for (<initialization>; <condition>; <increment>) {
    <commands>
}

Initialization sets the starting point, like a counter.

Condition decides how long the loop runs.

Increment updates the counter each time the loop runs.

Examples

This prints numbers 1 to 5, increasing $i by 1 each time.

PowerShell

for ($i = 1; $i -le 5; $i++) {
    Write-Output $i
}

This counts down from 10 to 1, showing a message each time.

PowerShell

for ($count = 10; $count -gt 0; $count--) {
    Write-Output "Countdown: $count"
}

Sample Program

This script prints a greeting three times, showing the current number.

PowerShell

for ($i = 1; $i -le 3; $i++) {
    Write-Output "Hello number $i"
}

Important Notes

Remember to use -le for 'less than or equal' and -gt for 'greater than' in conditions.

PowerShell uses $ before variable names.

Use Write-Output to show text on the screen.

Summary

A for loop repeats actions a set number of times.

It has three parts: start, condition, and step.

Use it to automate repetitive tasks easily.

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