# READING FILES
#file modes r=read, w=write, r+= read-write, w+= read write, a=write only, b=binary, t=textfile
File.open("employees.txt","r") do |file| #you can open in different modes: r=read, w=write
puts file #prints metadata
puts file.read() #prints data from the file
puts file.read().include? "Jim" #Search if there is a string
pits file.readLine() #reads 1 line
pits file.readLines() #reads all line, stores in array
pits file.readchar() #reads 1 char
for line in file.readLines()
puts line
end
end
#Another way need to close the file
file = File.open("employees.txt","r")
file.close()
# WRITING FILES
# Append data to a file "a"
File.open("employees.txt","a") do |file|
file.write("\nJohn, Accounting")
end
# Override file "w"
File.open("employees.txt","w") do |file|
file.write("\nJohn, Accounting")
end
# Create new file "w"
File.open("newFile.txt","a") do |file|
file.write("\nJohn, Accounting")
end
# Read and write file "r+"
File.open("newFile.txt","r+") do |file|
file.readLine()
file.write("Overriden") #it's added after the first line
end
# HANDLING ERRORS
begin
lucky_nums = [4, 5, 6, 8, 9]
lucky_nums["dog"]
#num = 10 / 0
rescue ZeroDivisionError
puts "Division by 0 error"
rescue TypeError => e
puts e
puts "WrongType"
end
# CLASSES
class Book
attr_accessor :title, :author, :pages
end
book1 = Book.new()
book1.title = "Jurassic Park"
book1.author = "Michael Chrickton"
book1.pages = 400
puts book1.title
# INITIALIZE METHOD / CONSTRUCTOR
class Book
attr_accessor :title, :author, :pages
def initialize(title, author, pages)
@title = title
@author = author
@pages = pages
end
end
book2 = Book.new("Harry Potter", "JK Rowling", 250)
# OBJECT METHODS, CLASS METHODS
class Student
attr_accessor :name, :major, :gpa
def initialize(name, major, gpa)
@name = name
@major = major
@gpa = gpa
end
# METHOD
def has_honors
if @gpa >= 3.5
return true
end
return false
end
end
student1 = Book.new("Pam", "Art", 3.6)
puts student1.has_honors
# BUILDING A QUIZ
class Question
attr_accessor :prompt, :answer
def initialize(prompt, answer)
@prompt = prompt
@answer = answer
end
end
p1 = "What color are apples?\n(a)red\n(b)purple,\n(c)orange"
p2 = "What color are bananas?\n(a)pink\n(b)purple,\n(c)yellow"
p3 = "What color are pears?\n(a)blue\n(b)green,\n(c)red"
questions = [
Question.new(p1, "a"),
Question.new(p2, "c"),
Question.new(p3, "b"),
]
def run_test(questions)
answer = ""
score = 0
for question in questions
puts question.prompt
answer = gets.chomp()
if answer == quest.answer
score += 1
end
end
puts "Your score is "+ score.to_s + "/"+score.length.to_s"
end
run_test(questions)
# INHERITANCE
#Super class
#define subclasses
#override methods
#create new methods
class Chef
def make_chicken
puts "The chef makes chicken"
end
def make_salad
puts "The chef makes salad"
end
def make_special_dish
puts "The chef makes bbq ribs"
end
end
chef = Chef.new()
chef.make_chicken
#inherit
class ItalianChef < Chef
def make_special_dish
puts "The chef makes spaguetti"
end
def make_pizza
print "The chef makes Pasta"
end
end
italian_chef = ItalianChef.new()
italian_chef.make_special_dish
# MODULES
# Container to store groups of methods
#in a different file, needs capital letter
module Tools
def sayhi(name)
puts "hello #{name}"
end
def saybyname)
puts "bye bye #{name}"
end
#In another File
require_relative "useful_tools.rb"
include Tools
Tools.sayhi("mike")
# INTERACTIVE RUBY
#Test in sandbox environment. Open cmd
write to check:
irb -v
write irb
Commands:
num = 123
puts num
# Can create variables, methods, conditional statements etc in the terminal to test
