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Ruby Array.fill(start [, length] ) { |index| block }) Method

By IncludeHelp Last updated : December 01, 2024

In this article, we will study about Array.fill() method. You all must be thinking the method must be doing something related to populate the Array instance. Well, we will figure this out in the rest of our content.

Description and Usage

This method is one of the examples of the Public instance method which is specially defined in the Ruby library for Array class. This method is used to populate the Array instances. You can fill multiple objects in the object of the Array class with the help of this method. This method is one of the examples of Destructive methods. This method has many forms and we will be studying them in the rest of the content. There are two of its types are present in this article and are demonstrated with the help of syntaxes and program codes.

Type 1: fill(start [, length] ) { |index| block } -> arr

The Array instance will be populated with the indexes and you can manipulate the index as per your requirements.

Syntax

array_instance.fill(start [, length] ) { |index| block }

Example 1

=begin
  Ruby program to demonstrate fill method
=end

# array declaration
Array1 = ["Kumar","Ramesh","Apple","Pappu","Sana","Yogita","Satyam","Harish"]

puts "Array fill implementation."
puts "Enter the start index from where you want to start populating:"
st = gets.chomp.to_i

puts "Enter the number of times"
pp = gets.chomp.to_i

Array1.fill(st,pp){|i| i*i}

puts "Array elements are:"
puts Array1

Output

Array fill implementation.
Enter the start index from where you want to start populating:
 2
Enter the number of times
 2
Array elements are:
Kumar
Ramesh
4
9
Sana
Yogita
Satyam
Harish

Explanation

You can observe in the above example that we are asking the user about two inputs first one is the starting index and another one is the number of times. You can observe that the element on the 2^nd index is replaced by its index with some manipulation and though the user has entered two times then the element on the 3^rd index is replaced by the manipulation of its index.

Type 2: fill(range){|index|block }

The Array instance will be populated with the indexes and you can manipulate the index as per your requirements. You have to provide the range from where and up to where you want to populate the Array instance with indexes.

Syntax:

array_instance.fill(range){|index| block}

Example 2

=begin
  Ruby program to demonstrate fill method
=end

# array declaration
array1 = ["Kumar","Ramesh","Apple","Pappu","Sana","Yogita","Satyam","Harish"]

puts "Array fill implementation."
puts "Enter the starting index:"
st = gets.chomp.to_i

puts "Enter the ending index:"
pp = gets.chomp.to_i

array1.fill(st..pp){|i| i*i}

puts "Array elements are:"
puts array1

Output

Array fill implementation.
Enter the starting index:
 2
Enter the ending index:
 4
Array elements are:
Kumar
Ramesh
4
9
16
Yogita
Satyam
Harish

Explanation

In the above code, you can observe that we are asking the user for the first index and last index. The user has entered 2 as the starting index and 4 is the ending index. So, you can observe that on the 2^nd, 3^rd and 4^th index, the elements are overwritten with the index manipulation.