Ruby 有4种数据类型：String, Boolen, Array, Hashes
Ruby 有3种操作方法：Method, attribute, ??
Ruby 有xxx: Classes, Object....

====先来看数据类型====

1. String and Declaring the variables: 

name = "Wonder Woman"   #declare a var and store a string
puts name  <span style="white-space:pre">		</span>#puts -- print out the var
sum = 5 + 1.4
puts sum
correct = 1 == 1
puts correct

2. Arrays:

cities = ["chongqing","beijing","shanghai"]
puts cities[1];		#print out the SECOND city

3.Hashes:

注意这句话：We can access any value by naming its key

seasons = { "Spring" => 20, "Summer"=>30, "Autumn"=>20, "Winter"=>02}
puts seasons["Winter"]
#{ ? , ? , ? }
"key"
"key" => value
access: HashName[ "key" ] = value

4. Declare and Refer the variables

foods = ["apple", "pear", "orange"]
puts "my favourite foods are #{foods}"
# here we use #{} to refer to the variables.

5. Methods

For all object types, Ruby has a number of built in methods that allow us to change the object. Let's look at a few common ones:

    a. Strings:     .reverse, .capitalize

    b. Numbers: + , - , * , /

    c. Arrays:      .delete, .count

    d. Hashes:    .compare, .flatten

colors = ["oo", "tt" , "tt", "ff"]
puts colors.first  # call the method .first on array

6. Define our own methods

def clock(time)
	puts "It's #{time}!"
end
clock("10:00pm")  #note the ""

7. if ... else ... end

num = 6
if num.even?
  puts "This int is even."
else
  puts "This int is odd."
end  # don't forget the end

8. Iterator - 迭代器

for Array and Hash ，使用迭代器来遍历Access each element.

names = ["Tommy","Catty","Barry","Sunny"]
names.each do |nname|
	puts "hello #{nname}!"
end

9. Classes - 类

关于Class的声明和使用：

class Person
def hello
puts "hello"
end
end
person1 = Person.new
person1.hello
person2 = Person.new
person2.hello

another e.g.

class Person
def initialize(name, age)
@name = name
@age = age
end
def intro
puts "My name is #{@name} and I am #{@age} years old"
end
end
person1 = Person.new("Lupe", 8)
person1.intro
class Dog
def initialize(name,color)
@name = name
@color= color
end
def describe
puts "My name is #{@name} and I am #{@color}"
end
end
dog1 = Dog.new("Rover","beige")
dog1.describe