Ruby: Built-In Methods

Cryptex Technologies
3 min readJul 13, 2021


By:Category: Ruby on Rails Technologies: Ruby on Rails

The Kernel module is incorporated by Object class, which makes its methods available throughout the Ruby program. They can be called without a receiver or functional form. Hence, they are often referred to as functions. With several built-in methods available in Ruby, they help to reduce manual calculations and lines of code and thereby helps to increase the performance and speed of the application. Some of the pre-defined methods are as mentioned below:

  1. Collect :

This function returns a new array by passing each element as a parameter to block and invoking a block for every element. The generated result is then used as the given element in a new array.

Ex: a = [ “a”, “d”, “b”, “e”]

a.collect {|x| x + “!” }


2. join() :

The join() function returns a string created by converting every element of the array to a string and separates them by a SepString.

Ex: [ “a”, “b”, “c” ].join => “abc”

[ “a”, “b”, “c” ].join(“-”) => “a-b-c”

3. uniq() :

This function returns a new array by removing all the duplicate values in arr.

Ex: a = [ “a”, “a”, “b”, “b”, “c” ]

a.uniq => [“a”, “b”, “c”]

4. include? :

This function returns the value “true” if the given object is present in arr [(that is, if any object == anObject), false otherwise].

Ex: a = [ “a”, “k”, “q”]

a.include?(“k”) => true

a.include?(“z”) => false

5. flatten :

It returns a new array in the form of one-dimensional flattening of the array (recursively). That is, for every element present, it extracts its elements into a new array.

Ex: a = [ 2, 3, [4, [5, 6] ] ]

6. Empty? :

The “.empty?” method returns the value “true” if the string length is zero.

Ex: a= 10

a.empty? => false

b = “”

b. empty? => true

7. Gsub :

The gsub method replaces every reference of the first parameter with the second parameter in the string.

Ex: “ruby is cool”.gsub(“cool”, “very cool”) #=> “ruby is very cool”

8. finite? :

It returns the value “true” if flt is a valid IEEE floating-point number.

Ex: flt.finite? → true or false

9. infinite? :

It returns the value ‘nil’, ‘-1’, or ‘+1’ depending on whether flt is ‘finite’, ‘-infinity’, or ‘+infinity’.

(0.0).infinite? → nil

(-1.0/0.0).infinite? → -1

(+1.0/0.0).infinite? → 1

10. round :

It returns a number rounded to the nearest integer or equivalent to.

def round

return floor(self+0.5) if self > 0.0

return ceil(self-0.5) if self < 0.0

return 0.0


Ex: 1.5.round → 2

11. sum :

It returns a basic n-bit checksum of the characters in the str, where n is the optional parameter, defaulting to 16. The result is the sum of the binary value of each character in (str modulo 2n — 1). This is not a good checksum.

Ex: str.sum(aFixnum=16 ) → anInteger

12. pluck :

The pluck function returns the array and splits the ActiveRecord query method chain. Hence it is suggested to be careful when the query is called on the result.

Ex: User.where(name: “ABC”).pluck(:id)

13. Convert string array to integer array and generating the sum of the elements :

Ex: quizz_score = [“20” “30” “50”]

quizz_exam_percentage =

quizz_exam_percentage = 100

Conclusion: With several ruby methods available, in the above-mentioned ways these methods can be called and executed.

Originally published at



Cryptex Technologies

Cryptex specializes in developing open source web applications and software solutions across all domains and verticals using Ruby on Rails (ROR) technology