Array in Ruby language

Ruby arrays are ordered collections of objects. They can hold objects like integer, number, hash, string, symbol or any other array.

An array is a list of variables enclosed in square brackets and separated by commas.

Each element in an array is referred to by an index which starts at 0 like in C. A negative index is assumed to be relative to the end of the array i.e -1 indicates the last element of the array, -2 is the 2nd last element and so on.

Creating Arrays

The two common ways to create arrays are:

• Using square brackets

  fruits = ['mango', 'banana', 'apple'] # output: fruits array with three fruits name
  

• Using Array.new

  numbers = Array.new(3, 0) # output: numbers array with 3 elements initialized to 0
  puts numbers # [0, 0, 0]
  
  languages = Array.new(5, 'ruby')
  puts languages # ['ruby', 'ruby', 'ruby', 'ruby', 'ruby]
  

  This approach is quite useful in creating an array with some default values.

Accessing element in Array

You can access array element by using its index value.

fruits = ['mango', 'banana', 'apple']
puts fruits[0] # output: 'mango'

Accessing multiple elements

One can access multiple elements as well. It can be achieved by passing two indices.

languages = ['C', 'Ruby', 'Python', 'Go']
high_level = languages[1,3]
puts high_level # ["Ruby", "Python", "Go"]

Adding element to an Array

If you want to add new element to Array, then you can achieve that through following methods.

• push method:

  languages = ['C', 'Ruby', 'Python', 'Go']
  languages.push('JavaScript')
  puts languages # ['C', 'Ruby', 'Python', 'Go', 'JavaScript']
  

• Using << operator:

  languages = ['C', 'Ruby', 'Python', 'Go']
  languages << 'JavaScript'
  puts languages # ['C', 'Ruby', 'Python', 'Go', 'JavaScript']
  

• If you want to add as the beginning, use unshift method:

  languages = ['C', 'Ruby', 'Python', 'Go']
  languages.unshift('JavaScript')
  puts languages # ['JavaScript', 'C', 'Ruby', 'Python', 'Go']
  

Removing element from an Array

Similar to addition, Ruby provide many methods to remove element from an Array. Following are few common methods:

• delete method: It will delete all the occurrences of the specified element from array.

  languages = ['C', 'Ruby', 'Python', 'Go', 'C']
  languages.delete('C')
  puts languages # ['Ruby', 'Python', 'Go']
  

• delete_at method: Delete the element at the specified index.

  languages = ['C', 'Ruby', 'Python', 'Go']
  languages.delete_at(2)
  puts languages # ['C', 'Ruby', 'Go']
  

• pop method: It is used to remove the element from end of the array.

  languages = ['C', 'Ruby', 'Python', 'Go']
  languages.pop
  puts languages # ['C', 'Ruby', 'Python']
  

• shift method: Removes the first element from the array.

  languages = ['C', 'Ruby', 'Python', 'Go']
  languages.shift
  puts languages # ['Ruby', 'Python', 'Go']
  

Iterating over an Array

There are many ways we can iterate over an Array.

• each method is the most common way to iterator over an Array.

  languages = ['C', 'Ruby', 'Python', 'Go']
  languages.each do |lang|
    puts "#{lang} is Nice"
  end
  
  # output
  C is Nice
  Ruby is Nice
  Python is Nice
  Go is Nice
  

  NOTE: Method each_index will only give index instead of element.

• each_with_index method provides you an index along with element while iterating over Array.

  languages = ['C', 'Ruby', 'Python', 'Go']
  languages.each_with_index do |lang, i|
    puts "#{i+1}. #{lang} is Nice"
  end
  
  # output
  1. C is Nice
  2. Ruby is Nice
  3. Python is Nice
  4. Go is Nice
  

Comparing Arrays

You can compare two arrays for equality using the == operator.

lang1 = ['C', 'Ruby', 'Python', 'Go']
lang2 = ['C', 'Ruby', 'Python', 'Go']
puts lang1 == lang2 # true

lang2.delete('C')
puts lang1 == lang2 # false

Common Array methods

include?

This method checks whether the argument given is included in the array or not.

languages = ['C', 'Ruby', 'Python', 'Go']
puts languages.include?('Ruby') # true

sort

This method helps to sort the Array elements.

languages = ['C', 'Ruby', 'Python', 'Go']
puts languages.sort # ["C", "Go", "Python", "Ruby"]

concat

This method will concat another method with the existing one.

languages = ['C', 'Ruby', 'Python', 'Go']
updated = languages.concat(['Rust', 'Dart'])
puts updated # ["C", "Ruby", "Python", "Go", "Rust", "Dart"]

NOTE: You can see all Array methods in their official documentation here. Go through it and familiarize yourself. There are many handy methods available.