Array#reverse

Added in v1.8 · Updated March 14, 2026 · Array Methods

ruby array reverse

.reverse returns a new array with elements in reverse order. .reverse! reverses the array in place.

Brief Intro

reverse creates a new array with elements in reverse order. reverse! modifies the original array. Both are useful when you need to process elements backward, display data in reverse order, or implement algorithms that work from the end toward the beginning.

Signature

Method	Parameters	Return Type
`reverse`	none	Array
`reverse!`	none	Array (self)

Code Examples

Basic Reverse

array = [1, 2, 3, 4, 5]

array.reverse
# => [5, 4, 3, 2, 1]

array
# => [1, 2, 3, 4, 5]  (original unchanged)

In-Place Reverse with `reverse!`

array = [1, 2, 3, 4, 5]

array.reverse!
# => [5, 4, 3, 2, 1]

array
# => [5, 4, 3, 2, 1]  (original modified)

Reversing Strings in an Array

words = ["apple", "banana", "cherry"]

words.reverse
# => ["cherry", "banana", "apple"]

Practical Use: Processing Last Items First

tasks = ["design", "code", "test", "deploy"]

# Process tasks in reverse order
tasks.reverse.each do |task|
  puts "Cleaning up: #{task}"
end

# Output:
# Cleaning up: deploy
# Cleaning up: test
# Cleaning up: code
# Cleaning up: design

Using with Other Array Methods

numbers = [1, 2, 3, 4, 5]

# Get last 3 elements, reversed
numbers.last(3).reverse
# => [5, 4, 3]

# Reverse after sorting
numbers.sort.reverse
# => [5, 4, 3, 2, 1]

# Reverse each element (for arrays of strings)
["dog", "cat", "bird"].map(&:reverse)
# => ["god", "tac", "drib"]

Building a Stack-Based Processing Pipeline

history = ["page1", "page2", "page3", "page4"]

# Navigate back through history
history.reverse.each do |page|
  puts "Caching: #{page}"
end

# Output:
# Caching: page4
# Caching: page3
# Caching: page2
# Caching: page1

Reversing Multi-Dimensional Arrays

matrix = [[1, 2], [3, 4], [5, 6]]

# Reverse the rows
matrix.reverse
# => [[5, 6], [3, 4], [1, 2]]

# Reverse each row
matrix.map(&:reverse)
# => [[2, 1], [4, 3], [6, 5]]

# Both: reverse rows then reverse each row
matrix.reverse.map(&:reverse)
# => [[6, 5], [4, 3], [2, 1]]

Return Value

reverse returns a new array with elements in reverse order. The original array remains unchanged.
reverse! returns self (the modified array), allowing method chaining.

Edge Cases

Empty array returns a new empty array.

[].reverse
# => []

[].reverse!
# => []

Single-element array returns itself (new array for reverse, same object for reverse!).

[42].reverse
# => [42]

[42].reverse!
# => [42]