01. Ruby Basic

Ruby console

irb

Hello world

puts "Hello world"

Function

basic function

# function without parameters
def hello
    puts "Hello world"
end
hello

parameter

default parameter

Class

Define a class

Basic Class

class Player
    def initialize(name="Haiyue")
        @name=name
    end
    def show()
        puts "Player: #{@name}"
    end
end

obj = Player.new()
obj.show()

Static method

class Game
    def initialize(id, title, price)
        @id = id
        @title = title
        @price = price
    end

    def showGame()
        puts @id + "," + @title + "," + @price.to_s
    end

    # static method: could be invoked with no need an instance
    def  self.toStr
        puts "I love this game"
    end
end

Game.toStr
Game::toStr

inherit

class Game
    def initialize(id, title, price)
        @id = id
        @title = title
        @price = price
    end

    def showGame()
        puts @id + "," + @title + "," + @price.to_s
    end

    # static method: could be invoked with no need an instance
    def  self.toStr
        puts "I love this game"
    end
end

class SteamGame < Game
    def SteamInfo
        puts "child class class"
    end
end


mygame = SteamGame.new('sfefsef', 'name', 1234)
SteamGame.toStr

methods

instance_methods & respond_to?

• instance_methods: list all members inside of the class
• respond_to?: check whether a method or property is valid

instance_methods

class Player
    def initialize(name="Haiyue")
        @name=name
    end
    def show()
        puts "Player: #{@name}"
    end
end

# List all the member of a class
Player.instance_methods()
# List all user defined methods
Player.instance_methods(false)

respond_to?

class Player
    def initialize(name="Haiyue")
        @name=name
    end
    def show()
        puts "Player: #{@name}"
    end
end
# Check whether method show is valid outside class
obj = Player.new()
if obj.respond_to?("show")
   obj.send("show")
end

attributes

class Game
    attr_accessor :price #,title
    def initialize(title="马里奥", price=200)
        @title = title
        @price = price
    end
    def show()
        puts "标题：#{@title}"
        puts "价格：#{@price}"
    end
end

mygame = Game.new()
mygame.show()

#check whether the attribute is avaliable outside class
puts "title is " + mygame.respond_to?("title").to_s
puts "title is " + mygame.respond_to?("price").to_s

# Please specify title as attr_accessor, then you could invoke it outside class
#mygame.title="New Game"

mygame.price=150
mygame.show()

Array

define an array

games = ["game1", "game2", "game3"]
puts games

iterate

each

games = ["game1", "game2", "game3"]
games.each do |game|
    puts "Love #{game}"
end

each_with_index

games = ["game1", "game2", "game3"]
games.each_with_index do |game, i|
    puts "Love #{i}, #{game}"
end

concatenate

games = ["game1", "game2", "game3"]
games.join(",")

whether is an array

if games.respond_to?("each")

Comments

one line comment

# comment here

multi line comment

=begin
comment here
=end

all comments after

__END__
All comments here
Comment 1
Comment 2

operator

basic operator

• + 加
• - 减
• * 乘
• ** 阶乘
• / 除法
• % 取余

compare operator

• ==
• !=
• >
• >=
• <
• <=

logical operator

• &&
• ||
• !

bit operator

• &
• |
• ^ 异或
• ~ 位反转
• <<
• >>

three item operator

condition ? operation1 : operation2

String operator

• + : concatenate
• << : append
• * : repeat

Difference of Quotation

" : parse the formula
' : original string

Hash

# similar with dictionary in python
# Hash variable
mvp_rank = {
  "curry" => 28.1,
  "harden" => 30.3,
  "lebron" => 26
}
mvp_rank['curry']

# similar with JSON
player = {
  name: "harden",
  age: 28,
  point: 30.3
}

puts player
player[:name]

Type Convert

FG = "50"
FG.to_i
FG.to_f
FG.to_f.to_s

References

小马技术【Ruby入门】

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