Week_1_Diagnostic_Jacques

Floats and Integers

What’s the difference between a float and integer?
  >>  A Float has decimals while an integer is only whole numbers
What’s are the similarities and differences between BigNum and FixNum?
  >>  BigNum and FixNum are both classes.
  >> * Bignum and FixNum both hold whole numbers, can't accomodate decimal points, both types of integers
  >> * BigNum are over 18/19 digits
What will 4.0 / 2 return?
  >>  2.0
What will 1.5.to_i.to_f return?
  >> 1.0
What part of this expression ("hi" * 5?) is “syntactic sugar”? What does that mean?
  >>  You can't really multiply a word by a number but ruby gives you the ability to use a multiplier on a string
      to print it multiple times.  
What will 10 % 3 return?
  >>  1
What will 5 == 10/2 return?
  >>  True
How can you write 5 to the 2nd power?
  >>  (5 ** 2)


Strings

How can you grab the substring “ell” from “hello”?
  >>  "hello"[1..3]
Give an example of string concatenation and string interpolation.
  >> h = "Happy" 
  >> f = "Festivus"
  >>  "Happy" + " " + "Festivus"  => "Happy Festivus" 
  >>  "Happy #{f}" => "Happy Festivus
  >>Concatenation: 
Give examples of three variable names: a “valid name” (it will work) that goes against Ruby style, an “invalid” name (it will trigger an error), and a valid and stylistically conventional name.
  >>  firstchal  - Goes against ruby style because it does not use an underscore and abbreviates the word challenge.
  >>  1stchal - invalid because number first
  >>  first_challenege - valid

Arrays

How do you add to an array?
  >>  you can use shovel or push or unshift
What will [1,2,3].shuffle do?
  >>  It will randomly shuffle the values within the array.
What do shift and unshift do?
  >>  shift removes the first element in an array, unshift removes the last.
Name 3 ways to retrieve 4 from this array: [4,3,5]
  >>  array = [4,3,5]     array[0]
  >>  array.first
  >> array[-3]
How would you print each word from this list (["hello", "goodbye", "cactus"]) to terminal within this output:
The word is "hello".
The word is "goodbye".
The word is "cactus".
  >> array.each do { |item| puts "The word is #{item}" }

Flow control

What’s the difference between a while and until loop?
  >>  A while loop will iterate until the while is no longer true.  An until loop will iterate until 'until' is true.
How do you escape a pry in the middle of a loop?
  >> ctrl 'c' or type exit multiple times. If neither of those work then ctrl 'd'.


Enumerables (.each)

What is the purpose of an enumerable?
  >>  An enumerable evaluates every item in an array.
  >> * works with collections
What are the two different ways that you can represent a block?
  >>  One line syntax: array.each do { |value| argument }
  >>  Multi line syntax:  array.each do |value|
                            arguement
                           end
Given this array ["Beth", "Lauren", "Ilana"]. How would you create a new array of just the first initials of each name?
  >>  array.each do |name|
        initial << name[0]
       end

  >> * array.map { |name| name[0] }

Classes and instance methods

When you’re defining a class, how do you store attributes?
  >>  Attributes are stored in instance variables
  >> @name = name
What is the difference between attr_readers, attr_writers, and attr_accessors? What do each do?
  >>  attr_writer can be used to create a method that can assign every instance variable but not call them.
    * replaces a setter method 
  >>  attr_reader can be used to create a method that can call every instance variable but not change them.
    * replaces getter method
  >>  attr_accessor can both read and write attributes.
    * does both
What method corresponds with .new when you create a new instance of a class?
  >>  instance variables? .new()
  >> * initialize


Methods, arguments and scopes

Describe the scope that methods create. Are variables created in that scope accessible elsewhere?
  >>  The scope of a method is local.  Variables created within that method can only be accesed within that method.
What does the method scope have access to?
  >>  The method scope can access variables that are passed into it as well as its own local variables
  
  >>  Elapsed time:
  >>  10:25 -10:48