The document is an introduction to the Ruby programming language. It discusses that Ruby is a simple, beautiful, and easy to learn open source programming language. It is dynamically typed and has an elegant syntax. The document provides examples of key Ruby features like variables, objects, classes, modules, blocks and more. It also lists resources for learning Ruby like the interactive IRB shell and popular websites.

1. Ruby – An Introduction
T.Arulalan
tarulalan@gmail.com
II Year, M.C.A,
Saveetha Enginnering College,
Chennai – 602 105

2. Ruby is a Programming Language

3. There are so many
Programming Languages.
Why Ruby?

6. Ruby is simple and beautiful

7. Ruby is Easy to Learn

8. Ruby is Free Open Source Software

9. Ruby on Rails – Web Framework

10. RAA
● Ruby Application Archive
● 1648 projects
● http://raa.ruby-lang.org

11. Rubyforge
● 5070 projects and libraries
● http://rubyforge.org/

12. Can do
●
Text Handling ●
Games
●
System Administration ●
NLP
●
GUI programming
●
Web Applications ●
...
●
Database Apps
●
Scientific Applications

13. History

14. Ruby
Yukihiro “Matz” Matsumoto
Japan
February 24, 1993

15. Perl Java Python Ruby PHP
1987 1991 1993 1995

16. What is Ruby?

17. Ruby is…
A dynamic, open source
programming language with a focus on
simplicity and productivity. It has an
elegant syntax that is natural to read
and easy to write.

18. Quick and Easy
●
Intrepreted Scripting Language
●
Variable declarations are unnecessary
●
Variables are not typed
●
syntax is simple and consistent
●
memory management is automatic

19. Object Oriented Programming
●
Everything is an object
●
classes, methods, inheritance, etc.
●
singleton methods
●
quot;mixinquot; functionality by module
●
iterators and closures

20. Examples!

21. 5.times { print “Ruby! quot; }

22. 5.times { print “Ruby! quot; }
Ruby! Ruby! Ruby! Ruby! Ruby!

23. Everything is
an object

24. 100.next

25. 100.next
101

26. “I love Ruby” 
.reverse.capitalize

27. “I love Ruby” 
.reverse.capitalize
“Ybur evol i”

28. 3.hours.from_now

29. 3.hours.from_now
Thu Jan 19 22:05:00 Eastern 
Standard Time 2006

30. Conventions

31. Variables
colored_index_cards

32. Class Names
Person

33. Symbols
:street_name

34. Instance Variables
@school_name

35. Constants
Kilograms_Per_Pound

36. Input

37. puts “What is Your name?”
name = gets
name = name.chomp
puts quot;Helloquot; + name + quot; .Welcomequot;

38. Flow

39. if ( score >= 5000 )
puts “You win!”
elsif ( score <= 0 )
puts “Game over.”
else
puts “Current score: #{score}”
end

40. puts “PASS” if mark > 35

41. Loop

42. count = 0
5.times do
count += 1
puts quot;Count =quot; + count.to_s
end

43. Count = 1
Count = 2
Count = 3
Count = 4
Count = 5

44. count = 0
while count < 10
puts quot;Count = quot; +count.to_s
count += 1
end

45. Blocks

46. 1.upto(5) { |x| puts x }
1
2
3
4
5

47. 5.downto(1) do |time|
print “#{time}... ”
puts “!” if time <= 3
end
5... 4... 3... !
2... !
1... !

48. Array

49. Array
numbers = [ quot;zeroquot;, quot;onequot;, quot;twoquot;,
quot;threequot;, quot;fourquot; ]

50. Array
numbers = [ quot;zeroquot;, quot;onequot;, quot;twoquot;,
quot;threequot;, quot;fourquot; ]
>> numbers[0]
=> quot;zeroquot;
>> numbers[4]
=> quot;fourquot;

51. Array
numbers = [ quot;zeroquot;, quot;onequot;, quot;twoquot;,
quot;threequot;, quot;fourquot; ]
>> numbers[3].upcase
=> quot;THREEquot;
>> numbers[3].reverse
=> quot;eerhtquot;

52. Sort Array
primes = [ 11, 5, 7, 2, 13, 3 ]

53. Sort Array
primes = [ 11, 5, 7, 2, 13, 3 ]
primes.sort

54. Sort Array
primes = [ 11, 5, 7, 2, 13, 3 ]
primes.sort
=> [2, 3, 5, 7, 11, 13]

55. Sort Array
names = [ quot;Shriniquot;, quot;Balaquot;,
quot;Sureshquot;, quot;Arulquot;]

56. Sort Array
names = [ quot;Shriniquot;, quot;Balaquot;,
quot;Sureshquot;, quot;Arulquot;]
names.sort

57. Sort Array
names = [ quot;Shriniquot;, quot;Balaquot;,
quot;Sureshquot;, quot;Arulquot;]
names.sort
=>[quot;Arulquot;, quot;Balaquot;, quot;Shriniquot;,
quot;Sureshquot;]

58. Multi Type Array
names = [ quot;Shriniquot;, quot;Balaquot;,
quot;Sureshquot;, quot;Arulquot;, 1, 14, 45,
77, 98.3, 3.14 ]

59. More on Arrays
●
Reverse
●
Length
●
Delete
●
Join
●
Find
●
More than 100 methods

60. Hashes

61. menu = {
:idly => 2.50,
:dosai => 10.00,
:coffee => 5.00,
:ice_cream => 5.00
}
menu[:idly]
2.50

62. Methods

63. Methods
def say_hello(name)
result = “Hello, #{name}!”
return result
end
puts say_hello(“world”)

64. Methods
def say_hello(name)
“Hello, #{name}!”
end
puts say_hello(“world”)

65. Class

66. Classes
class MathWhiz
def say_square(value)
puts value * value
end
end
sam = MathWhiz.new
sam.say_square(5)

67. Inheritance
class Dog < Animal
@catagory = “mammal”
@legs = 4
end

68. Module

69. Modules
module Trig
PI = 3.141592654
def Trig.sin(x)
# ..
end
def Trig.cos(x)
# ..
end
end

70. Modules
require quot;trigquot;
y = Trig.sin(Trig::PI/4)
0.707106780551956

71. Attributes
class PlainOldRubyObject
attr_accessor :food, :drinks
attr_reader :advice
attr_writer :write_only
end

72. Scope
class Poet
#public by default
def poetry
end
protected
def family_legacy
end
private
def hopes_and_dreams
end
end

73. THE END
of code :-)

74. How to Learn?

75. irb
● interactive ruby
● A ruby Shellnce response
● learn as you type

77. Web sites
Web Sites

78. http://ruby­lang.org
www.ruby­lang.org

79. www.rubyforge.net

80. http://www.ruby­forum.com/