# 注释
'foo' # 单引号字符串
"bar" # 双引号字符串
"foo" + "bar" # 字符串连接
first_name = "Michael" # 变量赋值
"#{first_name} Hartl" # 字符串插值
puts first_name # 打印字符串
p first_name # 打印字符串
print first_name # 打印字符串
单引号和双引号字符串的区别：插值和转义
在 Ruby 中,一切皆对象,包括字符串和 nil 都是，对象的作用:响应消息
"foobar".length
"foobar".empty?
"".empty?
nil.empty?
nil.to_s.empty?
x = "foo"
puts "x is not empty" if !x.empty?
string = "foobar"
puts "The string '#{string}' is nonempty." unless string.empty?
def string_message(str = '')
if str.empty?
"It's an empty string!"
else
"The string is nonempty."
end
end
参数可选和默认值，不用显式返回，方法调用括号可选
module ApplicationHelper
def full_title(page_title = '')
base_title = "Ruby on Rails Tutorial Sample App"
if page_title.empty?
base_title
else
page_title + " | " + base_title
end
end
end
"foo bar baz".split
"fooxbarxbazx".split('x')
a = [42, 8, 17]
a[0]
a[-1]
a.first
a.last
a.length
a.empty?
a.include?(42)
a.sort
a.reverse
a.shuffle
a.push 6
a.shift
a.pop
a << 7
a << "foo" << "bar"
a.join
a.join ","
r = 0..9
r.to_a
a = %w[foo bar baz quux]
a[0..2]
a = (0..9).to_a
a[2..(a.length-1)]
a[2..-1]
('a'..'e').to_a
块就是闭包(closure),是一种匿名函数,其中附带了一些数据。
(1..5).each { |i| puts 2 * i }
(1..5).each do |i|
puts 2 * i
end
3.times { puts "Betelgeuse!" }
(1..5).map { |i| i**2 }
%w[a b c].map { |char| char.upcase }
%w[A B C].map(&:downcase)
user = {}
user["first_name"] = "Michael"
user["last_name"] = "Hartl"
user["first_name"]
user
user = { "first_name" => "Michael", "last_name" => "Hartl" }
user = { :name => "Michael Hartl", :email => "michael@example.com" }
user[:name]
h2 = { name: "Michael Hartl", email: "michael@example.com" }
params = {}
params[:user] = { name: "Michael Hartl", email: "mhartl@example.com" }
params
params[:user][:email]
flash = { success: "It worked!", danger: "It failed." }
flash.each do |key, value|
puts "Key #{key.inspect} has value #{value.inspect}"
end
<%= stylesheet_link_tag 'application', media: 'all',
'data-turbolinks-track' => true %>
# 调用函数时可以省略括号
stylesheet_link_tag('application', media: 'all',
'data-turbolinks-track' => true)
# 如果最后一个参数是哈希,可以省略花括号
stylesheet_link_tag 'application', { media: 'all',
'data-turbolinks-track' => true }
# 换行 v.s 不换行
stylesheet_link_tag 'application', { media: 'all', 'data-turbolinks-track' => true }
s = "foobar"
s.class
a = [1,3,2]
a.class
h = {foo: 'bar'}
h.class
s = String.new("foobar")
a = Array.new([1,3,2])
h = Hash.new(0)
s = String.new("foobar")
s.class
s.class.superclass
s.class.superclass.superclass
class Word
def palindrome?(string)
string == string.reverse
end
end
w = Word.new
w.palindrome?("foobar")
w.palindrome?("level")
class Word < String
def palindrome?
self = self.reverse
end
end
s = Word.new("level")
s.palindrome?
s.length
Ruby和其他语言相比，最强大的特性之一
class String
def palindrome?
self == self.reverse
end
end
"deified".palindrome?
# example_user.rb
class User
attr_accessor :name, :email
def initialize(attributes = {})
@name = attributes[:name]
@email = attributes[:email]
end
def formatted_email
"#{@name} <#{@email}>"
end
end