ruby 语法基础

1.hello world

def hello
  puts "hello ruby"
end

2.String

a, b = "a double quoted string.\n", %Q|this is also a double quoted string.|
b, c = 'a single quoted string', %q{another single quoted string.}
d = <<EOF
This is a multi-line double 
quoted string
EOF
e = %/a string code\n/
f = 'perl rocks'
f['perl'] = 'ruby'
puts f, f.upcase, f.upcase!, f, f.capitalize
puts f.index('r'), f.index('ruby'), f.split, f.reverse, f.next, f.size, f.sub(/[or]/, '*'), f.gsub(/[or]/, '*'), "rub " + f.slice(0..2), "rock " + f.slice(5, 4)
g = 2
puts 'g * 3 = #{g * 3}', "g * 4 = #{g * 4}"
puts "hello".squeeze, "  nice   to           meet you  ".squeeze
puts "   ruby  ".strip, "\t\nruby\trocks\n".strip
puts "abcdef".slice(2), "abcdef".slice(2).chr
'a'.upto('z') { |x| print x }

3.Range

puts (1..10).to_a, (10..1).to_a, (1...10).to_a, ('a'..'z').to_a, ('z'..'a').to_a, ('abc'..'cde').to_a
puts (1..10).first, (1..10).last, (1...10).last, (1...10).to_a.last
puts (1..10) === 10, (1...10) === 10
for a in 1..10
  print a
end
(1..10).each { |x| print x}
(1..10).step(2) {|x| print x}

4.Numberic

puts (2**30).class, (-2**30).class
puts (2**30 -1).class, (-2**30-1).class
puts -1.9.class
puts "Hex " + 0x15
puts "Octal " + 015
puts "Binary " + 0b1101
puts 1.next, 1.8.floor,1.3.ceil, 1.8.ceil, 1.8.floor, 2.3.truncate, 2.8.truncate, 2.3.round, 2.8.round, -2.3.abs
puts "A B " , 65.chr, 66.chr
1.upto(9) {|x| print x}

5.Array

a = Array.new, b = []
b = [1, 'a', '3', [1,2,3], :ruby, /rocks/, {:ruby => 'rocks'}]
c = %w(1 b 23 d 4)
e = [1,2,3,4,5], a[1..3], a[1...3], a.slice(1..3), a.slice(1,3), a[-2], a.size, a.first, a.last, a.slice(1), a.fill(1)
f = [1,2,3,4,5,6,1,2,3], f.reverse, f.sort, f.uniq, f.uniq!, f.unshift 'ruby', f.shift, f.push 'rocks', f.pop, f.insert(2, 'hello'), f.delete('hello'), f.join('-'), f.join('-').split('-'), f.each {|x| print x }, f.map {|x| x * 2}, f.collect {|x| x * 2}, f.select {|x| x > 2}, f.find {|x| x > 4 }, f.find_all {|x| x > 4}, f.reject {|x| x < 2}, f.detect {|x| x > 5}, f.inject {|sum + n| sum + n}, f.inject(5) {|sum, n| sum + n}

6.Hash

a = {1 => 'a', 'b' => 2}, a[1], a['b'], a.size, a.invert
b = {1 => 'a', 2 => 'b', 3 => 'c'}, a.each {|key, value| puts "#{key} = #{value}"}, a.each_key {|key| puts "key: #{key}"}, a.each_value {|value| puts "value: #{value}"}
c = {1 => 'a', 2 => 'b', 3 => 'c'}, c[3] = 'e', c[4] = 'd', a.shift, a.inspect, a.delete 3, a.inpect
d = c.reject {|key, value| value == 'b' }, d.inject, d.merge({1 => 'A', 3 => 'C', 4 => 'd'}), d.inspect

7.Symbol

3.times { puts "ruby".object_id }, 3.times { puts :ruby.object_id}, 3.times { puts 12345.object_id}
class A
  attr_accessor :name
end
a = A.new, a.name, a.name = 'ruby', a.name
class B 
  def name
    @name
  end
  def name=(name)
    @name = name
  end
end
b = B.new, b.name, b.name = 'ruby', b.name
c = %w{aa, bb, cc, dd), d = c.map{|x| x.send(:capitalize)}, e = c.map{|x| x.capitalize}

8.Regexp

/^abc/ === 'abcdef', /^abc/ === 'defabc', /abc$/ === 'defabc'
/abc/ =~ '012abc678', /abc/ =~ '012345678', 'yyy' =~ /^y/i, 'wwwyyy' =~ /^y/i
"I love ruby".sub(/[aeiou]/, '*')
"I love ruby".gsub(/[aeiou]/, '*')
"I love ruby".sub(/[aeiou]/i, '*')
"I love ruby".gsub(/[aeiou]/i, '*')

9.Conditional

a = 10
if a > 0
  puts 'a > 0'
elsif a < 0
 puts 'a < 0'
else
  puts 'a == 0'
end
str = if a > 0 then 'a > 0'
elsif a < 0 then 'a < 0'
else 'a == 0'
end
puts str
puts 'a == 10' unless a != 10
case a
  when 0
    puts 'a == 0'
  when 10
    puts 'a == 10'
  else
    puts 'Unknown'
end
str = case a
  when -10..0 then '-10 < a < 0'
  when 0 then 'a == 0'
  when 1..20 then '1 < a < 20'
  else 'Unknown'
end
puts str

10.Loop

a = 1
a *= 2 while a < 10, puts a
a -= 2 while a < 0, puts a
3.times do
  print 'ruby '
end
for x in (1..3)
  puts 'ruby rocks'
end
3.times { puts 'ruby rocks'}

11.Exception

begin
  5 / 0
rescue
  puts "Oops!"
else
  puts "Congratulations! No errors."
ensure
  puts "Here we go."
end

begin
  5 / 1
rescue
  puts "Oops!"
else
  puts "Congratulations! No errors."
ensure
  puts "Here we go."
end

a = -1
begin
  if a < 0
    raise 'a < 0!'
  end
rescue RuntimeError => e
  puts e
else
  puts "Congratulation! No errors."
ensure
  puts 'Here we go."
end

12.Class

class A
  def hello(people)
    puts "Hi, #{people}!"
  end
end
a = A.new
a.hello 'Matz'

class People
  def initialize(name, age)
    @name = name
    @age = age
  end
  def to_s
    "name = #{@name}, age = #{@age}"
  end
end

ruby = People.new('Ruby', 16)
puts ruby

class Teacher < People
  def initialize(name, age, gender)
    super(name, age)
    @gender = gender
  end
  def to_s
    super + ", gender => #{@gender}"
  end
end

lisa = Teacher.new('Lisa', 28, 'female')

13.Method

class A
  def instance_method
    'instance_method'
  end
  def self.class_method1
    'class_method1'
  end
  def A.class_method2
    'class_method2'
  end
  def << self
    def class_method3
      'class_method3'
    end
  end
end

A.new.instance_method
A.class_method1
A.class_method2
A.class_method3

def takeBlock(p)
  if block_given?
    yield(p)
  else
    puts p
  end
end

takeBlock 'a'
takeBlock('a') {|x| puts '+' * 10 + x}

14.AccessControl

class A
  def public_method
  end
  public
    def public_method1
    end
    def public_method2
    end
  
  protected
    def protected_method1
    end
    def protected_method2
    end

  private
  def private_method1
  end
  def private_method2
  end
end

class B
  def method1
  end
  def method2
  end
  def method3
  end
  def method4
  end
  def method5
  end
  def method6
  end
  
  public :method1, :method2
  protected :method3, :method4
  private :method5, :method6
end

15.Module

module A
  def say
    "hello ruby"
  end
end
a = A.new rescue "module can't be instantiated"
class B
  include A
  def test
    'test'
  end
end
b = B.new
b.say
b.test
class C
  class << self
    include A
  end
end

16.Proc

greeting = Proc.new {|someone| "Hi, #{someone}"}
greeting.call("ruby")

def add(m)
  return Proc.new {|n| n + m }
end

add10 = add(10)
add100 = add(100)

add10.call(40)
add100.call(400)