Ruby/基本構文めも

• ドットインストール
• 公式のドキュメント
• ubuntuにインストール

• Cと違うとことか

  # はろわ
  print "Hello,World\n"
  puts "Hello,World" # 改行付
  p "Hello,World" # オブジェクト型が分かるように表示(""も表示される)
  
  =begin
  コメント
  	こめんと
  		comment
  =end
  
  # 変数 すべてオブジェクト
  val = 5 # 小文字または_で始める
  str = "Hello"
  str2 = "World"
  
  # 定数
  NUM = 2 # 大文字で始める
  
  # 演算
  print("2^5 = ", 2**5, "\n") # 32
  val**=NUM
  print("val**=NUM ,", val, "\n") # 25
  
  # if文
  if val > 100 then # then省略可
  	puts "val > 100"
  elsif val <= 50 then
  	puts "val <=50"
  else
  	puts "50 <= val < 100"
  end
  
  # unless文
  unless val > 100 then
  	puts "val <= 100"
  else
  	puts "val > 100"
  end
  
  # case文
  hoge = "b"
  case hoge
  when "a" then
  	puts "hoge is a"
  when "b","c" then
  	puts "hoge is b or c"
  when "d","e","f" then
  	puts "hoge is d or e or f"
  else
  	puts "hoge is not a-f"
  end
  
  # 三項演算子
  val = val > 50 ? 100 : 15
  print(val,"\n") # 0
  
  # 式修飾子
  puts "val < 50" if val < 50
  puts "NUM is not 5" unless NUM == 5
  
  # while文
  while val > 10 do # do省略可
  	val-=1
  	print("val = ",val,"\n")
  end
  
  # until文
  until val < 5 do # do省略可
  	val-=1
  	print("val = ",val,"\n")
  end
  
  # for文
  for i in 1..5 do
  	print("i = ",i,"\n")
  end

• オブジェクトとか

  # オブジェクトとメソッド
  x = "hello" # これもオブジェクト
  a = 10.8 # これもオブジェクト
  n = x.length # オブジェクトのメソッド
  p x # "hello"
  puts n # 5
  p "aaaaaa".length # 6
  
  y = Rational(2,n)
  puts y # 2/5
  puts y+Rational(n,2) # 29/10
  
  z = "123"
  p z # "123"
  p z.to_i #　123
  puts z.to_i * 5 # 615
  puts a.round # 11 (四捨五入)
  puts 11.3.ceil # 12 (切り上げ)
  puts 11.3.floor # 11 (切り捨て)
  p rand(100) # 1~100の乱数
  p Math.sqrt(2) # 1.41421356...
  
  puts "hello\nworld\n" # 特殊文字を展開 (\nで改行される)
  puts 'hello\nworld\n' # 特殊文字を展開しない (\nがそのまま表示される)
  
  puts "x is #{x}"  # x is hello
  puts "abcdef".reverse # fedcba
  puts "abcdef".index("d") # 3
  puts "abcdef".include?("e") # true
  puts "abcdef".include?("g") # false
  
  ## 破壊的メソッド
  x1 = x.upcase # 大文字にするメソッド
  p x # "hello"
  p x1 # "HELLO"
  
  x2 = x.upcase! # xの方も変わる(破壊的メソッド)
  p x # "HELLO"
  p x2 # "HELLO"
  
  ## 配列オブジェクト
  array = [1, 2.11, "hello", 1==1]
  p array
  puts array[1] # 2.11
  array[2] = "world"
  puts array[3] # true
  puts array[4] # nil (表示されない)
  puts array[-2] # world
  p array[1..3] # [2.11,"world",true]
  p array[1...3] # [2.11,"world"]
  array[1,2] = ["aaaa",3.14]
  p array # [1, "aaaa", 3.14, true]
  array[1,0] = ["add",100] # [1, "add", 100, "aaaa", 3.14, true]
  p array
  
  arr1 = [1,3,5,7,9]
  arr2 = [2,3,5,7,11]
  
  p arr1 & arr2 # [3, 5, 7]
  p arr1 | arr2 # [1, 3, 5, 7, 9, 2, 11]
  p arr1 + arr2 # [1, 3, 5, 7, 9, 2, 3, 5, 7, 11]
  p arr1 - arr2 # [1, 9]
  p (arr1 + arr2).uniq # 1, 3, 5, 7, 9, 2, 11]
  p (arr1 + arr2).uniq.sort # [1, 2, 3, 5, 7, 9, 11]
  
  arr3 = [4,1,5,8,2]
  p arr3.unshift 3 # [3, 4, 1, 5, 8, 2]
  p arr3.push 0 # [3, 4, 1, 5, 8, 2, 0]
  arr3.shift
  p arr3 # [4, 1, 5, 8, 2, 0]
  arr3.pop
  p arr3 # [4, 1, 5, 8, 2]
  
  # ハッシュオブジェクト(連想配列)
  map = {"a"=>100, "b"=>250, "c"=>500}
  p map["a"] # 100
  p map.size # 3
  p map.empty? # false
  p map.has_key?("c") # true
  p map.has_value?(200) # false
  
  # 日付時間とか
  t = Time.now
  p t # 2013-12-01 14:40:20 +0900
  p t.year # 2013
  p t.month # 12
  t2 = Time.mktime(2040,12,31,23,59,59)
  p t2 #2040-12-31 23:59:59 +0900
  p t2+1 # 2041-01-01 00:00:00 +0900
  p t.strftime("%Y/%m/%d") # 2013/12/01

• いろいろ

  # 繰り返し
  4.times do |i|
  	#4回繰り返される
  	puts i # 0..3
  end
  
  list = ["a","b","c","d"]
  for e in list do
  	puts e # a b c d
  end
  
  list.each do |e|
  	puts e # a b c d
  end
  
  map = {"a"=>100, "b"=>250, "c"=>500}
  map.each do |key,value|
  	printf("%s is %d\n",key,value)
  end
  
  
  # メソッドを定義
  def poyo
  	puts "poyo"
  end
  
  poyo() # poyo
  
  def poyopoyo(word,num)
  	num.times{
  		puts word + "poyo"
  	}
  	return word + "poyo"
  end
  
  ret = poyopoyo("hoge",3) # hogepoyo ×3
  p ret # "hogepoyo"
  
  
  # クラス作ろう
  class Foo # 大文字スタート
  	def initialize(value)
  		@id = rand(100)
  		@value = value
  		puts "initialize"
  	end
  
  	def print
  		puts "id : " + @id.to_s
  		puts "value : " + @value
  	end
  end
  
  foo = Foo.new("poyo")
  foo.print