# define

french_string = "il \xc3\xa9tait une fois"

long_string = <<EOF

Here is a long string

With many paragraphs

EOF

puts long_string.empty?

puts long_string.include? "many"

puts french_string + long_string

# concatenate

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

string = ""

str2 = ""

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

hash.each{|k,v| str2 << "#{k}" << " is " << "#{v}" << "\n"}

puts string

puts str2

# join

data = ['', '', '']

s = ''

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

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

puts data.join(' and a ')

# number

number = 5

puts "The number is #{number}." # => "The number is 5."

puts "The number is #{5}." # => "The number is 5."

puts "The number after #{number} is #{number.next}."

# => "The number after 5 is 6."

puts "The number prior to #{number} is #{number-1}."

# => "The number prior to 5 is 4."

puts "We're ##{number}!" # => "We're #5!"

puts "I've set x to #{x = 5; x += 1}."

# Escaping

puts "\#{foo}"

puts '#{foo}'

# puts "#{foo}" # error because no variable of foo defined.

template = 'Oceania has always been at war with %s.'

puts template % 'Eurasia' # => "Oceania has always been at war with Eurasia."

puts 'To 2 decimal places: %.4f' % Math::PI

puts 'Zero-padded: %.3d' % Math::PI

require 'erb'

template = ERB.new %q{Chunky <%= food %>!}

food = "bacon"

puts template.result(binding) # => "Chunky bacon!"

food = "peanut butter"

puts template.result(binding) # => "Chunky peanut butter!"

puts template.result

s = ".sdrawkcab si gnirts sihT"

puts s.reverse

puts s

puts s.reverse!

puts s.split(/(\s+)/) # ["This", " ", "string", " ", "is", " ", "backwards."]

puts s.split(/\s+/) # => ["This", "sting", "is", "backwards."]

puts s.split(' ')     # => ["This", "sting", "is", "backwards."]

octal = "\000\001\010\020"

octal.each_byte { |x| puts x }

#

#

#

#

hexadecimal = "\x00\x01\x10\x20"

hexadecimal.each_byte { |x| puts x }

#

#

#

#

open('smiley.html', 'wb') do |f|

    f << '<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">'

    f << "\xe2\x98\xBA"

end

"\a" == "\x07" # => true # ASCII 0x07 = BEL (Sound system bell)

"\b" == "\x08" # => true # ASCII 0x08 = BS (Backspace)

"\e" == "\x1b" # => true # ASCII 0x1B = ESC (Escape)

"\f" == "\x0c" # => true # ASCII 0x0C = FF (Form feed)

"\n" == "\x0a" # => true # ASCII 0x0A = LF (Newline/line feed)

"\r" == "\x0d" # => true # ASCII 0x0D = CR (Carriage return)

"\t" == "\x09" # => true # ASCII 0x09 = HT (Tab/horizontal tab)

"\v" == "\x0b" # => true # ASCII 0x0B = VT (Vertical tab)

"\x10\x11\xfe\xff" # => "\u0010\u0011\xFE\xFF"

"\x48\145\x6c\x6c\157\x0a" # => "Hello\n"

"\\".size # => 1

"\\" == "\x5c" # => true

"\\n"[0] == ?\\ # => true

"\\n"[1] == ?n # => true

"\\n" =~ /\n/ # => nil

"\C-a\C-b\C-c" # => "\u0001\u0002\u0003"

"\M-a\M-b\M-c" # => "\xE1\xE2\xE3"

?\C-a # => "\u0001"

?\M-z # => "\xFA"

contains_control_chars = /[\C-a-\C-^]/

'Foobar' =~ contains_control_chars # => nil

"Foo\C-zbar" =~ contains_control_chars # => 3

def snoop_on_keylog(input)

    input.each_char do |b|

        case b

          when ?\C-c; puts 'Control-C: stopped a process?'

          when ?\C-z; puts 'Control-Z: suspended a process?'

          when ?\n; puts 'Newline.'

          when ?\M-x; puts 'Meta-x: using Emacs?'

        end

     end

end

snoop_on_keylog("ls -ltR\003emacsHello\012\370rot13-other-window\012\032")

# Control-C: stopped a process?

# Newline.

# Meta-x: using Emacs?

# Newline.

# Control-Z: suspended a process?

puts "foo\tbar"

# foo bar

puts %{foo\tbar}

# foo bar

puts %Q{foo\tbar}

# foo bar

puts 'foo\tbar'

# foo\tbar

puts %q{foo\tbar}

# foo\tbar

class String

    def word_count

        frequencies = Hash.new(0)

        self.downcase.scan(/(\w+([-'.]\w+)*)/) { |word, ignore| frequencies[word] += 1 }

        return frequencies

    end

end

puts %{"The F.B.I. fella--he's quite the man-about-town."}.word_count

# => {"f.b.i"=>1, "fella"=>1, "he's"=>1,

# "quite"=>1, "the"=>2, "man-about-town"=>1}