Block parameters in Ruby - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to pass the block parameter correctly.

Ruby

5.times do |[1]|
  puts [1]
end

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

Aindex

Bitem

Cnum

Di

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable name not inside the pipes.

Leaving the block parameter empty.

The block parameter index receives the current iteration number.

2fill in blank

medium

Complete the code to use block parameters to sum numbers.

Ruby

sum = 0
[1, 2, 3].each do |[1]|
  sum += [1]
end
puts sum

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

Avalue

Bnum

Celement

Ditem

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable name not matching the block parameter.

Trying to use the array name inside the block instead of the parameter.

The block parameter value represents each element in the array.

3fill in blank

hard

Fix the error in the block parameter to print each key and value.

Ruby

{a: 1, b: 2}.each do |[1]|
  puts "#{ [1][0] }: #{ [1][1] }"
end

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

Akey

Bpair

Cvalue

Ditem

Attempts:

3 left

💡 Hint

Common Mistakes

Using separate parameters without parentheses.

Trying to access key and value directly without indexing.

The block parameter pair holds each key-value array from the hash.

4fill in blank

hard

Fill both blanks to correctly unpack key and value in the block parameters.

Ruby

{x: 10, y: 20}.each do |[1], [2]|
  puts "Key: #{ [1] }, Value: #{ [2] }"
end

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

Akey

Bvalue

Ck

Dv

Attempts:

3 left

💡 Hint

Common Mistakes

Using only one block parameter when two are needed.

Mixing up the order of key and value.

The block parameters k and v unpack the key and value from the hash.

5fill in blank

hard

Fill all three blanks to create a hash with word lengths using block parameters and condition.

Ruby

words = ["apple", "bee", "cat"]
lengths = {}
words.each do |[1]|
  [2] = [1].[3]
  lengths[[1]] = [2] if [2] > 3
end

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

Aword

Blen

Clen(word)

Dlength

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect variable names.

Not matching the condition with the value.

The block parameter word receives each word from the array. len stores the length computed using the length method. The condition filters words longer than 3 characters to build the hash.

Practice

1.

What are block parameters in Ruby?

Choose the best description.

easy

A. Variables inside | | that receive values passed to the block.

B. Methods that define how a block works.

C. Special keywords to start a block.

D. Constants used only outside blocks.

Solution

1. Step 1: Understand block parameters role

   Block parameters are variables placed inside | | after do or { to receive values passed into the block.

2. Step 2: Compare options with definition

   Only Variables inside | | that receive values passed to the block. correctly describes block parameters as variables inside | | that get values passed to the block.

3. Final Answer:

   Variables inside | | that receive values passed to the block. -> Option A

4. Quick Check:

   Block parameters = variables inside | | [OK]

Hint: Block parameters are always inside | | after do or { [OK]

Common Mistakes:

• Confusing block parameters with methods
• Thinking block parameters are keywords
• Assuming block parameters are constants

2.

Which of the following is the correct syntax for block parameters in Ruby?

array.each do ?

easy

A. [item] puts item

B. (item) puts item

C. |item| puts item

D. {item} puts item

Solution

1. Step 1: Recall block parameter syntax

   Block parameters are placed inside vertical bars | | after do or {.

2. Step 2: Match syntax with options

   Only |item| puts item uses |item| which is the correct syntax for block parameters.

3. Final Answer:

   |item| puts item -> Option C

4. Quick Check:

   Block parameters use | | [OK]

Hint: Block parameters always go inside | | after do or { [OK]

Common Mistakes:

• Using parentheses () instead of | |
• Using curly braces {} for parameters
• Using square brackets [] for parameters

3.

What is the output of this Ruby code?

numbers = [1, 2, 3]
numbers.each do |n|
  puts n * 2
end

medium

A. 2
4
6

B. 1
2
3

C. Error: undefined variable n

D. nil

Solution

1. Step 1: Understand the block parameter usage

   The block parameter n takes each element from the array numbers one by one.

2. Step 2: Calculate output for each element

   For each n, the code prints n * 2. So outputs are 2, 4, and 6 on separate lines.

3. Final Answer:

   2 4 6 -> Option A

4. Quick Check:

   Each number doubled = 2,4,6 [OK]

Hint: Block parameter holds each item; multiply inside block [OK]

Common Mistakes:

• Confusing block parameter with array variable
• Expecting original numbers printed
• Thinking block parameter is undefined

4.

Find the error in this Ruby code:

fruits = ['apple', 'banana']
fruits.each do fruit|
  puts fruit
end

medium

A. Block parameter should be in parentheses

B. Missing closing | after block parameter

C. No error, code runs fine

D. Missing opening | before block parameter

Solution

1. Step 1: Check block parameter syntax

   Block parameters must be enclosed inside vertical bars | |. Here, only the closing bar is present.

2. Step 2: Identify missing part

   The opening | before fruit is missing, causing a syntax error.

3. Final Answer:

   Missing opening | before block parameter -> Option D

4. Quick Check:

   Block parameters need both | | [OK]

Hint: Block parameters always need both | at start and end [OK]

Common Mistakes:

• Forgetting the opening |
• Using parentheses instead of | |
• Assuming code runs without |

5.

Given this code, what will be the output?

pairs = [[1, 2], [3, 4], [5, 6]]
pairs.each do |a, b|
  puts a + b
end

hard

A. [1, 2]
[3, 4]
[5, 6]

B. 3
7
11

C. Error: wrong number of block parameters

D. 1
3
5

Solution

1. Step 1: Understand multiple block parameters

   The block parameters a and b receive each inner array's two elements separately.

2. Step 2: Calculate sum for each pair

   For each pair, the code prints the sum: 1+2=3, 3+4=7, 5+6=11.

3. Final Answer:

   3 7 11 -> Option B

4. Quick Check:

   Sum of pairs = 3,7,11 [OK]

Hint: Use multiple block parameters to unpack arrays inside each [OK]

Common Mistakes:

• Expecting array printed instead of sum
• Thinking block parameters can't unpack arrays
• Assuming syntax error with two parameters