Introduction

Now that I'm studying ruby on rails, I'll write down the basic syntax so that I can understand it.

What is ruby

What is ruby?

--Interpreter language (<-> compiler language) --Dynamic typed language (<-> statically typed language) --Object-oriented (<->)

Is a characteristic language. (I think there are many others)

Basic syntax

output


count = 10
hello = "Hello"

puts count #42
puts hello #"Hello"

puts "#{hello} #{42}tokyo"  #Hello 42tokyo

Hashes and arrays

#Array

colors = [red, blue, green, pink, white]

#hash

#All three lines below are the same
exam1 = {"subject" => "math", "score" => 100}
exam1 = {:subject=> "math", :score => 100}
exam1 = {subject: "math", score: 100}

exams = [
    {subject: "math", score: 100},
    {subject: "english", score: 40},
    {subject: "japanese", score: 60},
    {subject: "science", score: 90}
]

for, while

for i in [0,1,2,3] do
    puts i
end

index = 0
while index <= 10 do
    puts index
end

each

colors = [red, blue, green, pink, white]

colors.each do |color|
    puts color
end

Method (function)

def hello
    puts "Hello World"
end

def hello(num, name)
   puts "Hello #{num}#{name}"
end

#hello(42, tokyo) -> Hello 42tokyo

Food ordering system


require "./menu"

menu1 = Menu.new(name: "sushi", price: 1000)
menu2 = Menu.new(name: "apple", price: 120)
menu3 = Menu.new(name: "banana", price: 100)
menu4 = Menu.new(name: "lemon", price: 80)

menus = [menu1, menu2, menu3, menu4]

puts "=== this is menu ==="
index = 0
menus.each do |menu|
    puts "#{index} : #{menu.info}"
    index += 1
end
puts "===================="

puts "choose menu : "

order = gets.chomp.to_i

selected_menu = menus[order]

puts "selected menu : #{selected_menu.name}"

puts "how many?"

count = gets.chomp.to_i

puts "your check is #{selected_menu.get_total_price(count)}"

class Menu
    attr_accessor :name
    attr_accessor :price
    
    def initialize(name:, price:) #Here is the instance variable
      self.name = name
      self.price = price
    end
    
    def info
      return "#{self.name} #{self.price}Circle"
    end
    
    def get_total_price(count)
      total_price = self.price * count
      if count >= 3
        total_price -= 100
      end
      return total_price
    end
  end

=== this is menu ===
0 :sushi 1000 yen
1 :apple 120 yen
2 :banana 100 yen
3 :lemon 80 yen
====================
choose menu : 
3
selected menu : lemon
how many?
20
your check is 1500

ruby basic syntax memo