Comparison operators in Ruby - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to check if a is equal to b.

Ruby

if a [1] b
  puts "Equal"
end

Drag options to blanks, or click blank then click option'

A==

B=

C!=

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using '=' instead of '==' for comparison.

The operator == checks if two values are equal in Ruby.

2fill in blank

medium

Complete the code to check if x is greater than 10.

Ruby

if x [1] 10
  puts "x is big"
end

Drag options to blanks, or click blank then click option'

A<

B<=

C>

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' for checking greater than.

The operator > checks if the left value is greater than the right value.

3fill in blank

hard

Fix the error in the code to check if num is not equal to 5.

Ruby

if num [1] 5
  puts "Not five"
end

Drag options to blanks, or click blank then click option'

A==

B=

C<>

D!=

Attempts:

3 left

💡 Hint

Common Mistakes

Using '=' instead of '!=' for not equal comparison.

The operator != means 'not equal' in Ruby.

4fill in blank

hard

Fill both blanks to check if age is between 18 and 65 inclusive.

Ruby

if age [1] 18 && age [2] 65
  puts "Adult"
end

Drag options to blanks, or click blank then click option'

A>=

B<

C<=

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '<=' or '>' instead of '>='.

Use >= to check if age is at least 18, and <= to check if age is at most 65.

5fill in blank

hard

Fill all three blanks to create a hash with keys as uppercase words and values as word lengths greater than 3.

Ruby

result = words.select { |word| word.length [3] 3 }.map { |word| [ [1], [2] ] }.to_h

Drag options to blanks, or click blank then click option'

Aword.upcase

Bword.length

C>

Dword

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'word' instead of 'word.upcase' for keys.

Using '<' instead of '>' for length comparison.

This creates a hash where keys are uppercase words and values are their lengths, but only for words longer than 3 characters.

Practice

1. Which of the following comparison operators in Ruby checks if two values are equal?

easy

A. ==

B. =

C. !=

D. >

Solution

1. Step 1: Understand the purpose of each operator

   == checks equality, = assigns values, != checks inequality, and > checks if left is greater than right.

2. Step 2: Identify the equality operator

   The operator that compares two values for equality is ==.

3. Final Answer:

   == -> Option A

4. Quick Check:

   Equality operator = == [OK]

Hint: Equality uses double equals (==), not single equals (=) [OK]

Common Mistakes:

• Confusing assignment (=) with equality (==)
• Using != instead of ==
• Thinking > checks equality

2. Which of the following is the correct syntax to check if variable a is not equal to variable b in Ruby?

easy

A. a !== b

B. a =! b

C. a <> b

D. a != b

Solution

1. Step 1: Recall Ruby's not equal operator

   Ruby uses != to check if two values are not equal.

2. Step 2: Check each option's syntax

   a != b is correct. a =! b is invalid syntax. a <> b is not Ruby syntax. a !== b is JavaScript syntax, not Ruby.

3. Final Answer:

   a != b -> Option D

4. Quick Check:

   Not equal operator = != [OK]

Hint: Not equal in Ruby is !=, not =! or !== [OK]

Common Mistakes:

• Using =! instead of !=
• Using !== which is JavaScript, not Ruby
• Using <> which is invalid in Ruby

3. What will be the output of the following Ruby code?

a = 5
b = 10
puts a < b

medium

A. true

B. false

C. 5

D. 10

Solution

1. Step 1: Understand the comparison

   The code compares if a (5) is less than b (10).

2. Step 2: Evaluate the comparison

   Since 5 is less than 10, the expression a < b is true.

3. Final Answer:

   true -> Option A

4. Quick Check:

   5 < 10 = true [OK]

Hint: Less than is <, returns true or false [OK]

Common Mistakes:

• Confusing output with variable values
• Expecting numeric output instead of boolean
• Mixing up < and > operators

4. Identify the error in the following Ruby code:

if x = 10
  puts "x is 10"
end

medium

A. Variable x is not declared

B. Missing end keyword

C. Should use == to compare, not =

D. puts syntax is wrong

Solution

1. Step 1: Analyze the if condition

   The code uses = which assigns 10 to x, not compares.

2. Step 2: Correct the comparison operator

   To check if x equals 10, use == instead of =.

3. Final Answer:

   Should use == to compare, not = -> Option C

4. Quick Check:

   Comparison needs ==, = is assignment [OK]

Hint: Use == for comparison, = is for assignment [OK]

Common Mistakes:

• Using = instead of ==
• Thinking missing end keyword causes error
• Assuming variable must be declared before use

5. You want to check if a number n is between 10 and 20 inclusive in Ruby. Which expression correctly uses comparison operators to do this?

hard

A. n > 10 || n < 20

B. n >= 10 && n <= 20

C. 10 <= n <= 20

D. n == 10 && n == 20

Solution

1. Step 1: Understand the range check

   We want n to be at least 10 and at most 20, so both conditions must be true.

2. Step 2: Evaluate each option

   n >= 10 && n <= 20 uses n >= 10 && n <= 20, which correctly checks both limits.
   10 <= n <= 20 uses chained comparison which is invalid in Ruby.
   n > 10 || n < 20 uses OR (||), which allows values outside the range.
   n == 10 && n == 20 checks if n equals both 10 and 20 simultaneously, which is impossible.

3. Final Answer:

   n >= 10 && n <= 20 -> Option B

4. Quick Check:

   Use && to combine two comparisons [OK]

Hint: Use && to combine two comparisons for range checks [OK]

Common Mistakes:

• Trying chained comparisons like 10 <= n <= 20
• Using || instead of && for range
• Checking equality to both ends simultaneously