Ruby: 編程語言

#!/usr/bin/env ruby puts "Hello, world!" 

>>puts "Hello, world!" Hello, world! => nil 

a = '\n这是一个单引号的字符串，反斜线和变量插值不会被转义'  b = %q{这是一个不可转义的字符串}  c = "\n这是一个双引号的字符串，反斜线和变量插值会被转义\n#{a}"  d = %Q{\n這是一個常量字串，特殊内容同样会被转义\n}  e = <<BLOCK 这是一个以Heredoc方式书写的常量字符串，可转义，结尾标志不可缩进 BLOCK  f = <<-BLOCK       这是一个可以缩进的Heredoc字符串     BLOCK  g = <<~BLOCK       这是一个可以缩进的Heredoc字符串       缩进会被自动去掉，在2.3版本中引入     BLOCK  h = %/\t这是一个可转义的的字符串\n/ 

class MyClass   def the_method     "general method"   end end  mc = MyClass.new def mc.the_method   "special for this instance." end  mc.the_method 

class Project < ActiveRecord::Base   belongs_to :portfolio   has_one    :project_manager   has_many   :milestones end 

# 使用 for，在 1 到 3 取出值 1、2、3 到 outer_i 裡操作。 for outer_i in 1..3 do   puts "for: #{outer_i * 100}" end  # 在 1 到 3 的集合裡針對每個值，放到 i 裡操作。 (1..3).each do |i|   puts "each: #{i * 100}" end  # 只要符合 outer_i 小於等於 300，則進入迴圈。 outer_i = 100 while outer_i <= 300   puts "while: #{outer_i}"   outer_i += 100 end  # 直到 outer_i 大於 300 前，都可以進入迴圈。 outer_i = 100 until outer_i > 300   puts "until: #{outer_i}"   outer_i += 100 end  # 無限迴圈，用 break 來打斷迴圈。 outer_i = 100 loop do   break if outer_i > 300    puts "loop: #{outer_i}"   outer_i += 100 end  # 作 3 次迴圈，i 從 0 開始遞增 1。 3.times do |i|   puts "times: #{(i + 1) * 100}" end  # 從 1 遞增 1 到 3，值傳入 i 來操作。 1.upto(3) do |i|   puts "upto: #{i * 100}" end  # 從 3 遞減 1 到 1，值傳入 i 來操作。 3.downto(1) do |i|   puts "downto: #{400 - i * 100}" end  # 從 100 開始以每步 +100 邁向 300。 100.step(300, 100) do |i|   puts "step: #{i}" end 

# Everything, including a literal, is an object, so this works: -199.abs                                                        # 199 "ruby is cool".length                                           # 12 "Rick Astley".index("c")                                        # 2 "Never gonna let you down".sub('let you down', 'give you up')   # "Never gonna give you up" "Nice Day Isn't It?".downcase.split(//).sort.uniq.join          # " '?acdeinsty" 

puts "What's your favorite number?" number = gets.chomp outputnumber = number.to_i + 1 puts outputnumber.to_s + ' is a bigger and better favorite number.' 

a = [1,'hi', 3.14, 1, 2, [4, 5]]  p a[2]           # 3.14 p a.[](2)# 3.14 p a.reverse      # [[4, 5], 2, 1, 3.14, 'hi', 1] p a.flatten.uniq # [1, 'hi', 3.14, 2, 4, 5] 

hash = { :water => 'wet', :fire => 'hot' } puts hash[:fire] # Prints:  hot  hash.each_pair do |key, value| # Or:  hash.each do |key, value| puts "#{key} is #{value}" end  # Prints:  water is wet #          fire is hot  hash.delete :water # Deletes :water => 'wet' hash.delete_if {|k,value| value=='hot'} # Deletes :fire => 'hot' 

{ puts "Hello, World!" } # Note the { braces } #or do puts "Hello, World!" end 

# In an object instance variable (denoted with '@'), remember a block. def remember(&a_block)   @block = a_block end  # Invoke the above method, giving it a block which takes a name. remember {|name| puts "Hello, #{name}!"}  # When the time is right (for the object) -- call the closure! @block.call("Jon") # => "Hello, Jon!" 

def create_set_and_get(initial_value=0) # Note the default value of 0   closure_value = initial_value   return Proc.new {|x| closure_value = x}, Proc.new { puts closure_value } end  setter, getter = create_set_and_get  # ie. returns two values setter.call(21) getter.call # => 21 

def use_hello   yield "hello" end  # Invoke the above method, passing it a block. use_hello {|string| puts string} # => 'hello' 

array = [1, 'hi', 3.14] array.each { |item| puts item } # => 1 # => 'hi' # => 3.14  array.each_index { |index| puts "#{index}: #{array[index]}" } # => 0: 1 # => 1: 'hi' # => 2: 3.14  (3..6).each { |num| puts num } # => 3 # => 4 # => 5 # => 6 

[1,3,5].inject(10) {|sum, element| sum + element} # => 19 

File.open('file.txt', 'w') do |file| # 'w' denotes "write mode".   file.puts 'Wrote some text.' end                                  # File is automatically closed here  File.readlines('file.txt').each do |line| puts line end # => Wrote some text. 

(1..10).collect {|x| x*x} # => [1, 4, 9, 16, 25, 36, 49, 64, 81, 100] 

class Person   attr_reader :name, :age   def initialize(name, age)     @name, @age = name, age   end   def <=>(person) # Comparison operator for sorting     @age <=> person.age   end   def to_s     "#@name (#@age)"   end end  group = [   Person.new("Bob", 33),   Person.new("Chris", 16),   Person.new("Ash", 23) ]  puts group.sort.reverse