Case/when statement in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a case/when statement in Ruby?

It is a control structure that lets you compare a value against multiple conditions and execute code based on the first matching condition.

beginner

How do you write a simple case/when statement in Ruby?

Use case followed by the value, then multiple when clauses for conditions, and else for default. Example:<br>

case x
when 1
  puts "One"
when 2
  puts "Two"
else
  puts "Other"
end

intermediate

Can a when clause check multiple values at once?

Yes! You can separate values with commas to check if the case value matches any of them. Example:<br>

case x
when 1, 3, 5
  puts "Odd number"
end

intermediate

What happens if no when condition matches and there is no else clause?

The case statement returns nil and no code inside the when blocks runs.

intermediate

How is case/when different from multiple if/elsif statements?

Both control flow choices check conditions, but case/when is cleaner when comparing one value against many options, making code easier to read.

What keyword starts a case statement in Ruby?

A when

B case

C if

D switch

The case keyword starts the case statement.

How do you specify multiple values in a single when clause?

A Use parentheses

B Use multiple <code>when</code> lines

C Use semicolons

D Separate values with commas

Separate values with commas to check if the case value matches any of them.

What does the else clause do in a case statement?

A Runs if no <code>when</code> matches

B Runs before any <code>when</code>

C Ends the case statement

D Is required for case to work

The else clause runs if no when condition matches.

What value does a case statement return if no conditions match and no else is given?

A 0

B false

C nil

D An error

It returns nil and does not run any code inside when blocks.

Which is a benefit of using case/when over multiple if/elsif?

A Cleaner code when checking one value against many options

B Runs faster always

C Allows complex boolean expressions

D Requires less typing for all conditions

case/when is cleaner and easier to read when comparing one value to many options.

Explain how a case/when statement works in Ruby and give a simple example.

Think about how you check one value against many choices.

Describe how you can check multiple values in a single when clause and why that might be useful.

Imagine you want to run the same code for several possible values.