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## Example files for the title:  

# Ruby Cookbook, by Lucas Carlson

[![Ruby Cookbook, by Lucas Carlson](http://akamaicovers.oreilly.com/images/9780596523695/cat.gif)](https://www.safaribooksonline.com/library/view/title/0596523696//)

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1 + 2                                                 # => 3

# On a long line, the expected value goes on a new line:

Math.sqrt(1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10)

# => 7.41619848709566

#---

puts "This string is self-referential."

# This string is self-referential.

#---

$ irb

irb(main):001:0> 1 + 2

=> 3

irb(main):002:0> Math.sqrt(1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10)

=> 7.41619848709566

irb(main):003:0> puts "This string is self-referential."

This string is self-referential.

=> nil

#---

$ irb

irb(main):001:0> 1 + 2      # => 3

=> 3

irb(main):002:0>

irb(main):003:0* # On a long line, the expected value goes on a new line:

irb(main):004:0* Math.sqrt(1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10)

=> 7.41619848709566

irb(main):005:0> # => 7.41619848709566

irb(main):006:0*

irb(main):007:0* puts "This string is self-referential."

This string is self-referential.

=> nil

irb(main):008:0> # This string is self-referential.

#---

#!/usr/bin/ruby -w

# sample_ruby_file.rb: A sample file

1 + 2

Math.sqrt(1 + 2 + 3 + 4 + 5 + 6 + 7 + 8 + 9 + 10)

puts "This string is self-referential."

#---

$ ruby sample_ruby_file.rb

This string is self-referential.

#---

$ ruby setup.rb

#---

$ gem install rails --include-dependencies

#---

$ ri Array                                  # A class

$ ri Array.new                              # A class method

$ ri Array#compact                          # An instance method

#---

string = 'My first string'

#---

=> "My first string"

#---

string = 'My first string'                   # => "My first string"

#---

string.length                                # => 15

#---

string.length()                              # => 15

#---

string.count 'i'                             # => 2   # "i" occurs twice.

string.count('i')                            # => 2

#---

string.length.next                           # => 16

#---

french_string = "il \xc3\xa9tait une fois"   # => "il \303\251tait une fois"

#---

french_string.length                         # => 18

#---

puts "This string\ncontains a newline"

# This string

# contains a newline

#---

puts 'it may look like this string contains a newline\nbut it doesn\'t'

# it may look like this string contains a newline\nbut it doesn't

puts 'Here is a backslash: \\ '

# Here is a backslash: \

#---

long_string = <<EOF

Here is a long string

With many paragraphs

EOF

# => "Here is a long string\nWith many paragraphs\n"

puts long_string

# Here is a long string

# With many paragraphs

#---

string                                    # => "My first string"

string.slice(3, 5)                        # => "first"

#---

string[3].chr + string[4].chr + string[5].chr + string[6].chr +

 string[7].chr

# => "first"

#---

string[3, 5]                             # => "first"

#---

string.upcase                            # => "MY FIRST STRING"

string                                   # => "My first string"

string.upcase!                           # => "MY FIRST STRING"

string                                   # => "MY FIRST STRING"

#---

string.empty?                            # => false

string.include? 'MY'                     # => true

#---

hash = { "key1" => "val1", "key2" => "val2" }

string = ""

hash.each { |k,v| string << "#{k} is #{v}\n" } 

puts string

# key1 is val1

# key2 is val2

#---

string = ""

hash.each { |k,v| string << k << " is " << v << "\n" } 

#---

puts hash.keys.join("\n") + "\n"

# key1

# key2

#---

data = ['1', '2', '3']

s = ''

data.each { |x| s << x << ' and a '}

s                                             # => "1 and a 2 and a 3 and a "

data.join(' and a ')                          # => "1 and a 2 and a 3"

#---

s = ""

data.each_with_index { |x, i| s << x; s << "|" if i < data.length-1 }

s                                             # => "1|2|3"

#---