Spaceship operator (<=>) in Ruby - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the spaceship operator (<=>) do in Ruby?

It compares two values and returns -1 if the left is less, 0 if equal, and 1 if the left is greater.

beginner

What is the return value of 5 <=> 10 in Ruby?

It returns -1 because 5 is less than 10.

intermediate

How can the spaceship operator help in sorting arrays?

It provides a simple way to define custom comparison logic for sorting by returning -1, 0, or 1.

beginner

What will be the result of 'apple' <=> 'banana' in Ruby?

It returns -1 because 'apple' comes before 'banana' alphabetically.

advanced

Can the spaceship operator be used with custom objects in Ruby?

Yes, by defining the <=> method inside the object's class to specify how to compare instances.

What does the spaceship operator (<=>) return when the left value is greater than the right?

A 0

B -1

C nil

D 1

It returns 1 when the left value is greater than the right.

Which of these is a valid use of the spaceship operator in Ruby?

A 5 => 3

B 5 <=> 3

C 5 =< 3

D 5 ==< 3

Only '5 <=> 3' is the correct syntax for the spaceship operator.

What does the spaceship operator return if two values are equal?

A 0

B 1

C -1

D nil

It returns 0 when both values are equal.

How can the spaceship operator be used in sorting an array?

A By replacing the sort method

B By using it as a method to reverse the array

C By providing a block that returns <=> between elements

D By converting elements to strings

You use <=> inside a block to tell Ruby how to compare elements during sorting.

What happens if you use the spaceship operator on objects without defining <=> method?

A It returns nil

B It returns 0

C It raises an error

D It always returns 1

If <=> is not defined for objects, it returns nil indicating they can't be compared.

Explain how the spaceship operator (<=>) works in Ruby and give an example.

Think about how it tells if one value is less, equal, or greater than another.

Describe how you can use the spaceship operator to sort an array with custom objects.

Custom objects need a way to compare themselves for sorting.