Why Ruby has multiple control flow styles - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to print numbers from 1 to 5 using a simple loop.

Ruby

for i in 1..[1]
  puts i
end

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

A7

B3

C10

D5

Attempts:

3 left

💡 Hint

Common Mistakes

Using a range that ends too high or too low.

The range 1..5 includes numbers from 1 to 5, so the loop prints these numbers.

2fill in blank

medium

Complete the code to use an 'if' statement to check if a number is even.

Ruby

number = 4
if number [1] 2 == 0
  puts "Even"
end

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

A%

B+

C-

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using addition or subtraction instead of modulo.

The modulo operator % gives the remainder. If number % 2 == 0, the number is even.

3fill in blank

hard

Fix the error in the 'case' statement to match the variable 'grade'.

Ruby

grade = 'B'
case [1]
when 'A'
  puts 'Excellent'
when 'B'
  puts 'Good'
else
  puts 'Try again'
end

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

Aresult

Bscore

Cgrade

Dmark

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable name that does not exist or is unrelated.

The case statement must check the variable grade to match the when clauses.

4fill in blank

hard

Fill both blanks to create a hash with word lengths for words longer than 3 characters.

Ruby

words = ['cat', 'house', 'tree', 'a']
lengths = {}
for word in words
  if word[1] [2] 3
    lengths[word] = word[1]
  end
end

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

A.length

B>

C<

D==

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect comparison operators or forgetting the length method.

Use .length to get the length of the word and > to check if it is greater than 3.

5fill in blank

hard

Fill all three blanks to create a hash of uppercase words and their lengths for words longer than 2 characters.

Ruby

words = ['dog', 'apple', 'it']
result = {}
for word in words
  if word.length [3] 2
    result[[1]] = [2]
  end
end

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

Aword.upcase

Bword.length

C>

Dword

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up keys and values or using wrong comparison operators.

The key is the uppercase word using word.upcase, the value is the length word.length, and the condition checks if length is greater than 2.

Practice

1. Why does Ruby have multiple control flow styles like if, case, and loops?

easy

A. To let programmers choose the best style for different situations

B. Because Ruby is based on many other languages

C. To make the language slower but more complex

D. To force programmers to write longer code

Solution

1. Step 1: Understand the purpose of control flow styles

   Control flow styles help decide how the program runs based on conditions or repeats actions.

2. Step 2: Match styles to coding needs

   Ruby offers different styles so programmers can pick the easiest and clearest way to express their logic.

3. Final Answer:

   To let programmers choose the best style for different situations -> Option A

4. Quick Check:

   Multiple styles = flexible coding [OK]

Hint: Think: multiple styles mean flexible choices [OK]

Common Mistakes:

• Thinking Ruby has multiple styles to slow down code
• Believing all styles do the same thing exactly
• Assuming multiple styles make code longer

2. Which of the following is the correct syntax for a simple if statement in Ruby?

easy

A. if x > 10: puts 'Big'

B. if x > 10 then puts 'Big' end

C. if (x > 10) { puts 'Big' }

D. if x > 10 -> puts 'Big'

Solution

1. Step 1: Recall Ruby's if syntax

   Ruby uses if condition then code end or multiline with end to close.

2. Step 2: Check each option

   Only if x > 10 then puts 'Big' end matches Ruby syntax. The others use colons (Python-style), braces and parentheses (C/JavaScript-style), or arrows (invalid).

3. Final Answer:

   if x > 10 then puts 'Big' end -> Option B

4. Quick Check:

   Ruby if uses then and end [OK]

Hint: Remember Ruby uses 'then' and 'end' for if [OK]

Common Mistakes:

• Using braces {} like in JavaScript or C
• Using colon : after condition
• Using arrow -> instead of then

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

score = 85
case score
when 90..100
  puts 'Excellent'
when 75..89
  puts 'Good'
else
  puts 'Needs Improvement'
end

medium

A. Excellent

B. Needs Improvement

C. Good

D. No output

Solution

1. Step 1: Understand the case statement ranges

   The case checks if score is in 90 to 100, then 75 to 89, else other.

2. Step 2: Check where 85 fits

   85 is between 75 and 89, so it matches the second when clause.

3. Final Answer:

   Good -> Option C

4. Quick Check:

   85 in 75..89 = Good [OK]

Hint: Match value to range in case when clauses [OK]

Common Mistakes:

• Choosing 'Excellent' for 85
• Thinking else runs for 85
• Confusing ranges with single values

4. Find the error in this Ruby loop:

i = 0
while i < 3
  puts i
  i = i + 1
end
puts i

medium

A. There is no error; the code runs correctly

B. The loop will never run because i is 0

C. Missing 'end' keyword to close the while loop

D. The variable i is not initialized

Solution

1. Step 1: Check loop initialization and condition

   Variable i starts at 0, condition is i < 3, so loop runs while i is 0,1,2.

2. Step 2: Verify loop syntax and increment

   Loop has correct 'end', increments i by 1 each time, so it will stop after i reaches 3.

3. Final Answer:

   There is no error; the code runs correctly -> Option A

4. Quick Check:

   Loop runs 3 times, i increments properly [OK]

Hint: Check loop start, condition, increment, and end [OK]

Common Mistakes:

• Thinking loop never runs with i=0
• Missing the 'end' keyword (but it's present here)
• Assuming variable i is uninitialized

5. You want to print different messages based on a variable status that can be 'open', 'closed', or 'pending'. Which Ruby control flow style is best and why?

hard

A. Use multiple if statements because they are simpler

B. Use a for loop to iterate over status values

C. Use a while loop to repeat checking status

D. Use a case statement because it clearly handles multiple fixed choices

Solution

1. Step 1: Identify the nature of the problem

   Status has multiple fixed values and needs different messages for each.

2. Step 2: Choose the control flow style

   A case statement is best for multiple fixed options because it is clear and concise.

3. Final Answer:

   Use a case statement because it clearly handles multiple fixed choices -> Option D

4. Quick Check:

   Multiple fixed choices = case statement [OK]

Hint: Multiple fixed options? Use case statement [OK]

Common Mistakes:

• Using multiple ifs making code longer and less clear
• Using loops which are for repetition, not choice
• Confusing for loops with case statements