Ruby-Basics Vol 2

Hi Everyone!

This our Second Fastrack series in which we will teach you the basics in a fastway..

Today we will learn the basics of Ruby.

This is Volume 2.

---

Content:

• Arrays
• Sets
• Hashes
• Methods

---

You can Types these commands on terminal (ruby interpreter) by typing

$ irb
irb(main):001:0> 

Arrays

• Arrays are lists in ruby, means they doesn't need to be homegenous.

a = [] #This creates an Empty Array

a = ["Amit", 1, [2,5,6]]

Output:

[]
["Amit",1,[2,5,6]]

• Arrays are continuous data structures

$ irb
> a = []
[]
> a[45] = 5
> puts a
[nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, nil, 5]

• a[45] = 0, created 45 empty spaces and then added 5 at 45th index. Indexing starts from zero.

$ irb
> puts a[45]
5
> puts a[0] # Would print nothing

> puts a.length
46

Sets

• Sets are used to keep unique elements, no duplicates are allowed.

my_set = Set.new() # New Empty Set
my_set.add(1) # Add one Element

my_set.each do |v|
  puts v
end

my_set.add([1,2,3,4,5]) # adding [1,2,3,4,5] as a single element

my_set.each do |v|
  puts v
end

Output :

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





#<Set: {1, [1, 2, 3, 4, 5]}>

• Another way to create a Set

Way 1

a = [1,2,3,4,5,1,2,3,4,5] 
my_set = a.to_set # Easy way to create a set from array
puts my_set.size

Output :

5

Way 2 :

my_set = Set.new([1,2,3,1,2,3])  # Easy way to create a set while initializing

Output:

#<Set: {1, 2, 3}>

Hashes

• Hashes are smilar to javascript dictionaries, the only difference is that they are ordered.

$ irb
> my_hash = {} # creates a new Hash
{}
> my_hash = Hash.new # creates a new Hash
{}
> my_hash = {:name => "Amit", :city => "ABC"} # Creates a hash 
{:name=>"Amit", :city=>"ABC"}
> my_hash[:name] # to access :name from my_hash
"Amit"

• :name and :city are actually symbols. they are used for faster accessing, we may use strings as well.

> my_hash = {"name" => "amit"}
{"name"=>"amit"}
> puts my_hash["name"]
amit
> puts my_hash[:name] # This won't work, you need to remember that strings and symbols are different

> my_hash = {:name => "Amit", :city => "Abc", :age => 21}

{:name=>"Amit", :city=>"Abc", :age=>21}

> my_hash.each do |key| # iterating over the keys
>* print key,"\n"
>* end
[:name, "amit"]
[:city, "Abc"]
[:age, 25]
=> {:name=>"amit", :city=>"Abc", :age=>21}

• If you look at the above code, the keys are ordered.

> my_hash.each do |key,value|
>* puts "#{key} : #{value}"
>* end

name : amit
city : Abc
age : 21
{:name=>"amit", :city=>"Abc", :age=>21}

Methods

Example:

def my_method
  puts "hello method"
end
my_method()

Output:

hello method

$ irb
> def is_odd number # parenthesis are optional
>* return number % 2 == 1
>* end

> is_odd 1 # parenthesis are optional
true

> def is_even number
>* number % 2 == 0 #last expression in every function is a return statement by default.
>* end
:is_even

> is_even 2
true

> def join_words words_array
>* result = ""
>* words_array.each do |word|
>*   result = result + word + " " # String concatenation
>*  end
>* result
>* end

> puts join_words ["Ruby","is","flexible"]
Ruby is flexible 

• What if you want to pass a variable number of arguments and you don't want to pass an array.

Voila, we have *args argument.

> def join_words *args
>* result = ""
>* args.each do |word|
>*   result = result + word + " " # String concatenation
>* end
>* result
>* end

> puts join_words "Ruby","is","flexible" # This code is more verbose
Ruby is flexible 
> puts join_words "Ruby","is","flexible",",", "This", "code" ,"is" ,"more" ,"verbose"
Ruby is flexible , This code is more verbose 

If you like such articles , please follow, share , comment and upvote to show your support.