Teachers Notes.txt

BASICS OF A RUBY PROGRAM

To print something out use 
    -> print "Steve"
    -> puts "Steve"
    When using puts, items are printed out followed by a new line. On the other hand, 
    when using print items are printed out on the same line.

DRAWING A SHAPE 
puts "   /|"
puts "  / |"
puts " /  |"
puts "/___|"
 
Ruby executes line by line. In the order written

VARIABLES
They are containers used to store data.

****
puts "There once was a man named Steve"
puts "He was a programmer"
puts "He really liked being a programmer"
puts "but didn't like the name Steve."
****

In the above I have to manually change the characters name. To solve for that we put the name in a container

character_name = "Steve"
character_job = "programmer"

****
puts ("There once was a man named " + character_name)
puts ("He was a " + character_job)
puts ("He really liked being a " + character_job)
puts ("but didn't like the name "  + character_name)
****

DATA TYPES IN RUBY
name = "Steve" -> String
age = 75  -> integer
weight = 70.9 -> float
ismale = true -> bool
flaws = nil 

WORKING WITH STRINGS
phrase = "Digikids Academy"
#string methods
puts phrase.upcase()
puts phrase.downcase()
puts phrase.strip() #removes leading and trailing spaces
puts phrase.length()
puts phrase.include? "Academy"
puts phrase[0] #Accesing characters using indexes
puts phrase[0, 4]
puts phrase.index("D")

MATH AND NUMBERS
puts 6 #prints out number 6
puts 8 + 6 #Does basic arithmetics

num = 20.907
puts ("my fav num " + num.to_s) #converts nums to string

puts num.abs()
puts num.round()
puts num.ceil()
puts num.floor()
puts Math.sqrt(36)


USER INPUT
puts "Enter your name"
name = gets

use the gets.chomp() to remove the new line.

BUILDING A MADLIBS GAME

puts "Enter a color: "
color = gets.chomp()
puts "Enter a plural_noun: "
plural_noun = gets.chomp()
puts "Enter a celebrity: "
celebrity = gets.chomp()

 
puts ("Roses are " + color)
puts (plural_noun + " are blue")
puts ("I love " + celebrity)

ARRAYS IN RUBY
Variables stores only one value. Arrays stores lots of data.

friends = Array["Kelvin", "Karen", "Oscar]
puts friends
puts friends[0] #working with array index
puts friends[-2]
puts friends[0, 2] #range of items
friends[0] = "Dorothy"
friends = Array.new #Empty array
friends.lenght()
friends.include? "Karens"
friends.reverse()
friends.sort()

HASHES 
Stores data in key:value pair

states = {
    "Pennsylvania" => "PA", 
    "New York" => "NY", 
    :Oregon => "OR"
}
puts states[:Oregon]

METHODS 
def sayhi
    puts "Hello User"
end


Return Statements 
def cube(num)
    return num * num * num
end

Any code that comes after the return key word is not executed

IF STATEMENTS
I wake up
If I'm hungry
    I eat breakfast

I leave my house
If its's cloudy
    I bring an umbrella
otherwise
    I bring sungalasses

Im at the restaurant
if I want meat
    I order a steak
Otherwise if I want pasta
    I order spaghetti & meatballs
otherwise
    I order a salad

While using key word 'and' both the conditions must be true

USING COMPARISONS WITH IF STATEMENTS

CASE EXPRESSIONS
Are special types of IF STATEMENTS used to check multiple conditions
mon -> Monday
teu -> Teusday
wed -> Wednesday
They are ussually appropriate when checking one value against many different values

WHILE LOOPS ***GOOGLE
FOR LOOPS ***GOOGLE

EXPONENT METHOD
It basically takes in two numbers and squares them accordingly

READING FILES 
Must be in the same directory

EXEPTION HANDLING
Make sure you are able to handle errors

Functions are "self contained" modules of code that accomplish a specific task. 
Functions usually "take in" data, process it, and "return" a result. 
Once a function is written, it can be used over and over and over again. 
Functions can be "called" from the inside of other functions.

CLASSES AND OBJECTS