Block syntax (do..end and curly braces) in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a block in Ruby?

A block is a chunk of code enclosed between do..end or curly braces { } that can be passed to methods and executed.

beginner

When should you use do..end versus curly braces { } for blocks?

do..end is usually used for multi-line blocks, while curly braces { } are preferred for single-line blocks.

beginner

How do you pass a block to a method in Ruby?

You write the method call followed by a block using either do..end or { }. The method can then execute the block using yield.

beginner

Example: What does this code print?<br>

3.times do
  puts "Hello"
end

It prints "Hello" three times, each on a new line.

intermediate

Can you use both do..end and curly braces { } interchangeably?

Yes, both define blocks, but style and readability guide when to use each. Curly braces for short blocks, do..end for longer ones.

Which block syntax is preferred for single-line blocks in Ruby?

A do..end

B square brackets []

C parentheses ()

D {} (curly braces)

Curly braces {} are preferred for single-line blocks in Ruby.

What keyword inside a method executes the passed block?

A yield

B call

C execute

D run

The keyword yield runs the block passed to the method.

Which of these is a valid way to write a block in Ruby?

A method do |x| x * 2 end

B method (|x| x * 2)

C method { |x| x * 2 }

D method [|x| x * 2]

Blocks are written with do..end (A) or curly braces {} (C).

What will this code output?<br>5.times { print "*" }

A *****

B * * * * *

C 5

D Error

It prints five stars in a row without spaces.

Which block syntax is usually used for multi-line blocks?

A {} (curly braces)

B do..end

C () parentheses

D <> angle brackets

do..end is preferred for multi-line blocks in Ruby.

Explain the difference between do..end and curly braces { } when writing blocks in Ruby.

Think about block length and style.

Describe how a Ruby method can use a block passed to it.

Focus on method and block interaction.