Concepts for Ruby

Ruby is a dynamic, object-oriented programming language known for its simplicity and productivity. Created by Yukihiro Matsumoto (Matz) in the mid-1990s, Ruby emphasizes developer happiness and ease of use. Its syntax is elegant and expressive, resembling natural language, which contributes to its readability and maintainability. Ruby offers features such as dynamic typing, automatic memory management, and a powerful standard library. It also has a vibrant ecosystem of third-party libraries and frameworks, including Ruby on Rails for web development. Ruby's focus on developer convenience, combined with its flexibility and scalability, has made it popular for building web applications, scripting tasks, and automation.

• Print Text

  puts "Hello World!"
  print("Hello World!")

• Comments

  # one line comment
  
  =begin
  multi 
  line 
  comment
  =end
  

• Variables

  carCount = 2
  name = "Joe"
  isPurple = true
  

• Data Types

  carCount = 2
  age = 15
  seaLevel = -10000
  usBudget = 11000000000
  lightSpeed = 11799312874
  myGPA = 3.45
  piValue = 3.14159265
  lastLetter = "Z"
  isMale = true
  myName = "Joe"

• Math Op

  carCount = 6;
  truckCount = 3;
  
  total = carCount + truckCount
  puts total
  
  subtract = carCount - truckCount
  puts subtract
  
  multiple = carCount * truckCount
  puts multiple
  
  divisible = carCount / truckCount
  puts divisible
  
  #  performs division and gets remainder which is 0
  modulo = carCount % truckCount
  puts modulo

• Math Functions

  power = 3.pow(6)
  puts power
  
  root = Math.sqrt(16)
  puts root
  
  floorVal = 3.14.floor()
  puts floorVal
  
  ceilVal = 4.3.ceil()
  puts ceilVal
  
  roundVal = 3.4.round()
  puts roundVal
  
  # random number from 0 to 100
  ranNum = rand(0..100)
  puts ranNum

• If/Else

  carCount = 6;
  if carCount > 3
    puts "More than three cars"
  elsif carCount == 3
    puts "Equal to three cars"
  else
    puts "Less than three cars"

• Ternary

  carCount = 3
  result = carCount > 2 ? "Yes" : "No"
  puts result

• Switch

  $carCount = 3
  
  case $carCount
  when 1
    puts "One car"
  when 2
    puts "Two cars"
  when 3
    puts "Three cars"
  else 
    puts "More than three"
  end

• Functions

  def handleCars(cars, wheels)
    total = cars * wheels;
    return total
  end
  
  result = handleCars 3, 4
  puts result

• Interpolation

  name = "Joe"
  car = "Mazda"
  result = "#{name} drives a #{car}"
  print(result)

• Type Casting

  def squareA(length)
    result = length ** 2;
    return result.to_s;
  end
  
  squareL = "4"
  convertedVal = squareL.to_i
  area = squareA(convertedVal)
  print(area)

• Date and Time

  # current date
  date = Time.now
  puts date
  
  # epoch time
  milliseconds = Time.now.to_f
  puts milliseconds
  
  # current year
  year = Time.now.year
  puts year
  
  # current month
  month = Time.now.month
  puts month
  
  # formatted date
  day = Time.now.day
  formatted = "#{month}/#{day}/#{year}"
  puts formatted

• Classes

  class Cars
    def initialize
      @carList = []
    end
   
    def addCar(name)
      @carList << name
    end
    def removeFirst()
      @carList.shift()
    end
    def getFirstVal()
      if @carList.length > 0
        return @carList[0]
      end
      return ''
    end
  end
  
  newList = Cars.new
  newList.addCar("Honda")
  newList.addCar("Mazda")
  newList.addCar("Toyota")
  newList.removeFirst()
  
  firstCar = newList.getFirstVal()
  puts firstCar

• Inheritance

  class User
    def initialize(username, password)
      @username = username
      @password = password
    end
  end
  
  class Admin < User 
    def initialize(username, password, id)
      super(username, password)
      @id = id
    end
    
    def getUsername()
      return @username
    end
    
    def getAdminID()
      return @id
    end
  end
  
  newAdmin = Admin.new("alpha0", "pw1", "1FE")
  
  puts newAdmin.getUsername()
  puts newAdmin.getAdminID()

• Method Overload

  // No Native Support or Implementation
  

• Abstract Class

  // No Native Support or Implementation
  

• Static Class

  class Helper
    class << self
      def circleA(radius)
        return 3.14 * (radius ** 2)
      end
      
      def squareA(length)
        return length ** 2
      end
    end
  end
  
  puts Helper.circleA(3)
  puts Helper.squareA(4)

• Arrays/Lists

  names = Array["Joe", "Alex", "Bob"]
  names[1] = "Alex"
  name = names[1]
  numItems = names.length
  
  puts name
  puts numItems

• Array Methods

  cars = ["Honda", "Mazda", "Toyota"];
  
  # number of elements in array
  puts cars.length
  
  # first element of array
  puts cars.first
  
  # last element of array
  puts cars.last
  
  # new array with first 2 elements
  array1 = cars.take(2)
  puts array1
  
  # drops the 1st element from array
  array2 = cars.drop(1)
  puts array2
  
  # removes the first element
  cars.shift()
  puts cars.first
  
  # adds as new first element 
  cars.unshift("Ford")
  puts cars.first
  
  # deletes at index 0
  cars.delete_at(0)
  puts cars.first
  
  # checks for value Mazda
  puts cars.include?("Mazda")
  

• Concatenation

  carsListKr = ["Kia", "Hyundai", "Daewoo"]
  carsListJp = ["Honda", "Mazda", "Toyota"]
  combined = carsListKr.concat(carsListJp)
  
  printf(combined[1] + "\n")
  printf(combined[4])

• Sort Method

  ages = [5, 3, 1, 6, 7, 4, 19]
  ages.sort
  
  puts ages

• Objects

  class User
    attr_reader:first,:last,:carBrands
    def initialize(
      first,
      last,
      age,
      retired,
      carBrands
      )
      @first = first
      @last = last
      @age = age
      @retired = retired
      @carBrands = carBrands
    end
    def getVal(val)
      return val
    end
    def fullName()
      return "#{first} #{last}"
    end
  end
  
  brands = Array["Mazda", "Toyota"]
  user = User.new(
    "Joe",
    "Doe",
    23,
    false,
    brands
  )
  
  puts user.first
  puts user.carBrands[1]
  puts user.fullName()

• Maps (Key/Value)

  carMap = Hash.new
  carMap["Joe"] = "Toyota"
  carMap["Bob"] = "Mazda"
  carMap["Tom"] = "Ford"
  
  puts carMap["Tom"]
  
  carMap.delete("Tom")
  puts carMap.include?("Tom")

• Sets

  require 'set'
  
  cars = Set.new
  cars.add("Mazda")
  cars.add("Toyota")
  cars.add("Honda")
  
  puts cars.include?("Honda")
  
  cars.delete("Honda")
  puts cars.include?("Honda")

• Stack

  cars = []
  cars << "Mazda"
  cars << "Toyota"
  cars << "Honda"
  
  puts cars[cars.length - 1]
  
  cars.pop()
  puts cars[cars.length - 1]

• Queues

  cars = []
  cars << "Mazda"
  cars << "Toyota"
  cars << "Honda"
  
  puts cars[0]
  
  cars.shift()
  puts cars[0]

• Linked List

  class Node
    # full access to class properties
    attr_accessor :value,:next
    def initialize(value, nextVal = nil)
      @value = value
      @next = nextVal
    end
  end
  
  class LinkedList
    attr_accessor :head
    def initialize
      @head = nil
    end
    
    def add(value)
      newNode = Node.new(value)
      
      if @head == nil
        @head = newNode
        
      else
        current = @head
        while current.next != nil
          current = current.next
        end
        current.next = newNode
        
      end
    end
    
    def returnHead()
      return head.value
    end
     
    def traverse()
      current = head
      
      while current != nil
        print(current.value + "\n")
        current = current.next
      end
    end
  end
  
  carList = LinkedList.new()
  carList.add("Mazda")
  carList.add("Toyota")
  carList.add("Honda")
  
  puts carList.returnHead()
  carList.traverse()

• Graphs

  class Graph
    def initialize
      @graphMap = Hash.new
    end
    
    def addNode(value)
      @graphMap[value] = []
    end
    
    def addVertices(node1, node2)
      if @graphMap.include?(node1) == false
        @graphMap[node1] = []
      end
  
      if @graphMap.include?(node2) == false
        @graphMap[node2] = []
      end
  
      @graphMap[node1] << node2
      @graphMap[node2] << node1
    end
  
    def breadthTraverse(start)
      queue = [start]
      visited = Hash.new
      visited[start] = true;
  
      while queue.length > 0
        currentVal = queue.shift()
        puts currentVal
        
        tempArr = @graphMap[currentVal]
        for tempVal in tempArr do
          if visited.include?(tempVal) == false
            queue << tempVal
            visited[tempVal] = true
          end
        end
      end
    end
  
    def depthTraverse(start)
      stack = [start]
      visited = Hash.new
      visited[start] = true;
  
      while stack.length > 0
        currentVal = stack.pop()
        puts currentVal
        
        tempArr = @graphMap[currentVal]
        for tempVal in tempArr do
          if visited.include?(tempVal) == false
            stack << tempVal
            visited[tempVal] = true
          end
        end
      end
    end
  end
  
  newGraph = Graph.new
  newGraph.addNode("a")
  newGraph.addVertices("a", "b")
  newGraph.addVertices("a", "c")
  newGraph.addVertices("b", "d")
  newGraph.addVertices("b", "e")
  newGraph.addVertices("d", "f")
  newGraph.addVertices("d", "g")
  newGraph.addVertices("d", "h")
  newGraph.addVertices("e", "i")
  newGraph.addVertices("e", "j")
  newGraph.breadthTraverse("a")
  newGraph.depthTraverse("a")
  

• For Loops

  names = ['Joe', 'Alex', 'Bob'];
  
  for name in names do
   puts name
  end

• While Loops

  carList = Array["Mazda", "Toyota", "Honda"]
  
  while carList.length > 0
    puts carList[0]
    carList.shift()
  end
  
  puts carList.length

• Loop Breaks

  cars = ['Toyota', 'Honda', 'Mazda']
  i = 0;
  
  for car in cars do
    if car == "Honda"
      puts "Found at index #{i}"
      break
    else
      puts "Visited index #{i}"
      i += 1
    end
  end

• Recursion

  def getSum(arr)
    return 0 if arr.empty?
    
    firstVal = arr[0];
    arr.shift();
    return firstVal + getSum(arr);
  end
  
  testArr = Array[1, 2, 4, 5]
  sum = getSum(testArr)
  puts sum

• Regex Words

  phrase = "I am legend"
  pattern = /[a-zA-Z]+/
  result = pattern.match(phrase)
  
  puts result;

• Regex Numbers

  phrase = "I am 23"
  pattern = /[0-9]+/
  result = pattern.match(phrase)
  
  puts result;

• Regex Test

  phrase = "Bob Lee"
  pattern = "Lee"
  result = phrase.include? pattern
  
  puts result;

• Regex Characters

  phrase = "##I am legend##"
  pattern = /\#+\w+/
  result = pattern.match(phrase)
  
  puts result;