This document provides an introduction to Ruby including: - Printing "Hello World" to demonstrate basic output - Describing how most things in Ruby are objects - Explaining common Ruby constructs like conditionals, methods, loops, arrays, hashes, symbols, classes, inheritance, and different variable types

1. Ruby Introduction

2. print “Hello World”
Hello World

3. Most things in Ruby is
Object

4. OObject of class String
OObject of class Fixnum

5. Conditionals
or elsif admin == false
paranthesis is optional

6. Methods No return type needed
Paranthesis is optional
Ruby method
returns the last line
Method is called

7. Loops

10. Arrays

11. Inserting into an Array

12. Deleting from an Array

13. Looping through an Array

14. Hash

15. KEY Value
Based on key, you can get the value

16. Changing the value

17. Adding a new Key value pair

18. Symbols

19. How it differs from a String
Saves memory and remains in memory always

20. Symbols can be used as keys in
Hash

21. Class Constructor
Method

22. Inheritance

23. ➢ Global - $
➢ Instance - @
➢ Class - @@
➢ Local - [a-z] or _
➢ Constants - CAPS
Variables

24. Global Variables
$myvar = “Its is a Place”
class Chennai
def what_is_that
puts $myvar
end
end
class NewYork
def what_is_that
puts $myvar
end
end
Output:
chennai = Chennai.new
newyork = NewYork.new
chennai.what_is_that
newyork.what_is_that
--------------------------------------
Its is a Place
Its is a Place

25. Instance Variables
class Place
def initialize(place)
@current_place = place
end
def show_me
puts @current_place
end
end
Output:
chennai =Place.new(“Chennai”)
newyork = Place.new(“New York”)
chennai.show_me
newyork.show_me
--------------------------------------
Chennai
New York

26. Class Variables
@@hotels=0
class Place
def more_hotels
@@hotels +=1
end
end
Output:
chennai =Place.new
newyork = Place.new
chennai.more_hotels
newyork.more_hotels
--------------------------------------
1
2

27. Local Variables
Output:
chennai =Place.new(“Chennai”)
newyork = Place.new(“New York”)
chennai.show_me
newyork.show_me
--------------------------------------
Chennai
New York
Local Variable
class Place
def initialize(place)
@current_place = place
end
def show_me
puts @current_place
end
end

28. Constants
class Place
MYVAR = 100
def show_me
puts “Value of constant is #{MYVAR}”
end
end
Output:
chennai =Place.new(“Chennai”)
chennai.show_me
--------------------------------------
Value of constant is 100

29. a version manager (RVM or rbenv or other)
Install ruby using

30. Thank You!