Case with ranges and patterns in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a case statement used for in Ruby?

A case statement lets you check a value against multiple conditions and run code based on which condition matches. It's like choosing between many options.

beginner

How do ranges work inside a Ruby case statement?

Ranges like 1..5 represent a sequence of values. In a case, Ruby checks if the value falls inside the range to decide which code to run.

intermediate

What is pattern matching in Ruby's case statement?

Pattern matching lets you check if a value fits a certain shape or structure, like matching parts of an array or hash, and then run code based on that.

beginner

Explain this Ruby code snippet:<br>

case age
when 0..12 then "Child"
when 13..19 then "Teen"
else "Adult"
end

This code checks the value of age. If it's between 0 and 12, it returns "Child". If between 13 and 19, it returns "Teen". Otherwise, it returns "Adult".

intermediate

How does Ruby decide which when clause matches in a case statement?

Ruby compares the case value with each when condition using the === operator. The first match runs its code, and then Ruby stops checking further.

In Ruby, what does 1..5 represent inside a case statement?

A A range including numbers 1 through 5

B An array of numbers 1 to 5

C A pattern matching any number

D A string from '1' to '5'

The 1..5 syntax creates a range including numbers 1, 2, 3, 4, and 5.

What will this Ruby code output if score = 85?<br>

case score
when 90..100 then "Excellent"
when 75..89 then "Good"
else "Needs Improvement"
end

A "Needs Improvement"

B "Excellent"

C "Good"

D An error

85 falls in the range 75..89, so the output is "Good".

Which operator does Ruby use internally to check when conditions in a case statement?

A !=

B ==

C <=

D ===

Ruby uses the === operator to test if the case value matches a when condition.

What does pattern matching in a Ruby case statement allow you to do?

A Match exact values only

B Match values based on structure or shape

C Only match numbers

D Ignore the value completely

Pattern matching lets you check if a value fits a certain structure, like parts of an array or hash.

What will this Ruby code return?<br>

case [1, 2, 3]
when [1, 2, 3] then "Exact match"
when [1, 2] then "Partial match"
else "No match"
end

A "Exact match"

B "Partial match"

C "No match"

D An error

The array matches exactly the first when condition, so it returns "Exact match".

Explain how Ruby's case statement works with ranges and how it decides which block to execute.

Think about how Ruby checks if a value falls inside a range.

Describe what pattern matching means in Ruby's case statement and give an example of when it might be useful.

Consider matching parts of a data structure, not just simple values.