Comparison operators (-eq, -ne, -gt, -lt) in PowerShell - Mini Project: Build & Apply

Using Comparison Operators in PowerShell

📖 Scenario: You are helping a store manager check product stock levels to decide if they need to reorder items.

🎯 Goal: Build a PowerShell script that uses comparison operators -eq, -ne, -gt, and -lt to compare stock counts and print messages.

📋 What You'll Learn

Create a dictionary of products with their stock counts

Add a reorder threshold variable

Use comparison operators to check stock levels

Print messages based on the comparisons

💡 Why This Matters

🌍 Real World

Store managers often need to check stock levels to decide when to reorder products. Automating this saves time and avoids running out of items.

💼 Career

Knowing how to use comparison operators in scripts helps automate routine checks and decisions in IT, operations, and inventory management roles.

1

Create the product stock dictionary

Create a dictionary called products with these exact entries: 'Apples' = 50, 'Bananas' = 20, 'Oranges' = 0, 'Grapes' = 15.

PowerShell

# Create the products dictionary with stock counts
# Your code here

Hint

Use @{} to create a dictionary in PowerShell with keys and values separated by =.

2

Add a reorder threshold variable

Create a variable called reorderThreshold and set it to 10.

PowerShell

$products = @{ 'Apples' = 50; 'Bananas' = 20; 'Oranges' = 0; 'Grapes' = 15 }
# Create reorderThreshold variable and set to 10
# Your code here

Hint

Just assign the number 10 to the variable $reorderThreshold.

3

Check stock levels using comparison operators

Use a foreach loop with variables product and stock to iterate over $products.GetEnumerator(). Inside the loop, use -lt to check if stock is less than $reorderThreshold and store the result in a variable called needsReorder.

PowerShell

$products = @{ 'Apples' = 50; 'Bananas' = 20; 'Oranges' = 0; 'Grapes' = 15 }
$reorderThreshold = 10
# Loop through products and check stock against reorderThreshold
# Your code here

Hint

Use $products.GetEnumerator() to loop through the dictionary. Use -lt to compare stock with threshold.

4

Print messages based on stock comparison

Inside the foreach loop, use if with $needsReorder to print "Reorder needed for $product" if true, else print "Stock is sufficient for $product".

PowerShell

$products = @{ 'Apples' = 50; 'Bananas' = 20; 'Oranges' = 0; 'Grapes' = 15 }
$reorderThreshold = 10
foreach ($item in $products.GetEnumerator()) {
    $product = $item.Key
    $stock = $item.Value
    $needsReorder = $stock -lt $reorderThreshold
    # Print message based on $needsReorder
    # Your code here
}

Hint

Use if ($needsReorder) to decide which message to print with Write-Output.

Practice

1. Which PowerShell operator checks if two values are equal?

easy

A. -eq

B. -ne

C. -gt

D. -lt

Solution

1. Step 1: Understand the meaning of each operator

   -eq means equals, -ne means not equals, -gt means greater than, -lt means less than.

2. Step 2: Identify the operator for equality

   The operator that checks if two values are equal is -eq.

3. Final Answer:

   -eq -> Option A

4. Quick Check:

   Equals operator = -eq [OK]

Hint: Remember: eq means equal, ne means not equal [OK]

Common Mistakes:

• Confusing -eq with -ne
• Mixing -gt and -lt
• Using == instead of -eq

2. Which of the following is the correct syntax to check if variable $a is greater than 10 in PowerShell?

easy

A. if ($a -gt 10) { }

B. if ($a > 10) { }

C. if ($a -lt 10) { }

D. if ($a -eq 10) { }

Solution

1. Step 1: Recall PowerShell comparison syntax

   PowerShell uses -gt for greater than, not > like some other languages.

2. Step 2: Match the correct operator

   The correct syntax to check if $a is greater than 10 is if ($a -gt 10) { }.

3. Final Answer:

   if ($a -gt 10) { } -> Option A

4. Quick Check:

   Greater than operator = -gt [OK]

Hint: Use -gt for greater than, not > in PowerShell [OK]

Common Mistakes:

• Using > instead of -gt
• Confusing -lt with -gt
• Missing parentheses in if statement

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

$x = 5
if ($x -ne 5) { 'No' } else { 'Yes' }

medium

A. 5

B. No

C. Yes

D. False

Solution

1. Step 1: Evaluate the condition $x -ne 5

   $x is 5, so $x -ne 5 means 5 not equal to 5, which is False.

2. Step 2: Determine which block runs

   Since condition is False, the else block runs, outputting 'Yes'.

3. Final Answer:

   Yes -> Option C

4. Quick Check:

   5 not equal 5 is False, so else runs [OK]

Hint: -ne means not equal; false triggers else block [OK]

Common Mistakes:

• Thinking -ne means equal
• Confusing output with variable value
• Ignoring else block

4. Identify the error in this PowerShell snippet:

$num = 10
if ($num -gt 5) { 'Greater' } elseif ($num -lt 5) { 'Smaller' } else { 'Equal' }

medium

A. Missing closing brace for if block

B. No error, code runs correctly

C. Incorrect use of elseif instead of else if

D. Using -gt instead of > operator

Solution

1. Step 1: Check syntax of if-elseif-else

   PowerShell supports elseif as one word; braces are balanced.

2. Step 2: Verify operators and structure

   -gt and -lt are correct operators; no syntax errors present.

3. Final Answer:

   No error, code runs correctly -> Option B

4. Quick Check:

   elseif is valid in PowerShell [OK]

Hint: PowerShell uses elseif as one word, not else if [OK]

Common Mistakes:

• Thinking elseif is invalid
• Expecting > instead of -gt
• Missing braces confusion

5. You want to write a PowerShell script that prints 'Valid' only if a variable $score is greater than or equal to 70. Which code snippet correctly uses comparison operators to achieve this?

hard

A. if ($score -gt 70) { 'Valid' } else { 'Invalid' }

B. if ($score -lt 70) { 'Valid' } else { 'Invalid' }

C. if ($score -eq 70) { 'Valid' } else { 'Invalid' }

D. if ($score -ge 70) { 'Valid' } else { 'Invalid' }

Solution

1. Step 1: Understand the requirement

   We want to check if $score is greater than or equal to 70.

2. Step 2: Identify the correct operator

   -ge means greater than or equal to, which matches the requirement.

3. Final Answer:

   if ($score -ge 70) { 'Valid' } else { 'Invalid' } -> Option D

4. Quick Check:

   Greater or equal operator = -ge [OK]

Hint: Use -ge for greater or equal comparisons [OK]

Common Mistakes:

• Using -gt excludes 70
• Using -eq only matches exactly 70
• Using -lt reverses logic