Ruby Quiz

gistfile1.txt

1. What is the difference between a local variable, and an instance variable?
    local variable is only applicable to immediate context
    instance variable is available throughout the class

2. What is the datatype of `"DevPoint Labs"`?
    string

3. Assign the number `10` to the local variable `n`.
    n = 10

4. Assign your name to the local variable `name`.
    name = "Lisa"

5. What is an Array?
    an array is a general collection of indexes

6. Give an example of when you’d use an Array.
    hotel room numbers

7. What is a method?
    a method is a performable action on an object; it is like a verb

8. Name 3 iterator methods for an Array.
    .each
    .collect
    .map

9. Name 3 methods for a String.
    .length
    .capitalize
    .reverse

10. What datatype does `5 / 2` return?
    string

11. What is a Hash?
    a hash is a collection of specific key-value pairs that can be called upon

12. Give an example of when you’d use a Hash.
    could be used for contact information (name, address, etc)

13. What is a class?
    a class is a blueprint for an object and is a constant

14. True or False; A class is a constant.
    True

15. `true` and `false` are called what?
    boolean values

16. Write 4 conditional operators.
    if
    elsif
    else
    end

    case
    when
    end

    while
    do
    end

    until
    do
    end

17. Create a method called bucket that returns an empty array.
    def bucket()
    return(array.new)
    end

18. Name 6 ruby special keywords. (a keyword is a word that already has a special meaning)
    true
    false
    case
    for
    unless
    initialize

19. How would you convert a number into a string?
    .to_s

20. How would you convert a string into a number?
    .to_i

21. What is class inheritance?
    class inheritance is when one class assumes all methods of another

22. What are modules used for?
    modules are used to contain multipul constants and methods so they
    can share functionality and be free of name conflicts

23. What is a gem?
    a gem is a packaged Ruby program

24. Name 4 gems, and their purposes.
    Rails - web framework to make developers' lives easier
    activeadmin - gem for generating adminstration style interfaces
    chronic - date/time parser
    money - ruby library for dealing with money and currency conversion

25. What are comments used for in programming?
    to leave notes to yourself and others that don't affect the program

26. In Ruby, only 2 things evaluate to `false`. What are they?
    false and nil

27. Write 2 comparison operators.
    >=
    <=

28. Write the code for “ if dave’s age is greater than or equal to 21”
    if daves_age >= 21

29. Instantiate a `Car` class.
    volkswagen = Car.new

30. What is a method chain?
    using several methods right after another

31. How would you capitalize and reverse a string then print it out to the console?
  puts string.capitalize.reverse

32. What is a method to add an object to an array?
     <<

33. How would you add an object to a hash?
    hash[:a] << "value"

34. What are 2 valid datatypes of keys for a hash?
    string and symbol

35. What is a writer method?
    method to assign a value to an attribute

36. What is a reader method?
    method that returns a value from an attribute

37. There are 4 types of variables. What are they?
    local, @instance, @@class, $global

38. What does the question mark at the end of a method in ruby mean?
    it is asking if the object is true or false only

39. What’s a common way to debug your code?
    use Ruby's debugger; -rdebug in command line

40. How would you return the string `"two"` from this array? `arr = ["one", "two", "three"]`
    puts arr[1]

41. How would you return the string `"DevPoint"` from this hash? `hsh = {:name => "DevPoint"}`
    puts hsh[:name]

42. What is the datatype for `:age`?
    symbol

43. What is the datatype for `-36.98`?
    float

44. What is the datatype for `[1, 2, 3]`?
    array

45. What is the datatype for `"BOOM goes the dynamite"`?
    string

46. What is the datatype for `123412`?
    fixnum

47. What is the datatype for `{:food => "burger"}`?
    hash

48. What is the datatype for `false`?
    FalseClass

49. What is the purpose of `nil`?
    to tell you something doesn't make sense; it can't evaluate to true or false

50. How would you print out the current date?
    I don't remember. I remember Jeremy showing us this stuff one class
    but I don't have notes on it and didn't figure it out with google.

51. How would you print out just the current year without using a Fixnum?
    as a string "2014"

52. What is String interpolation?
    a way to include a variable inside of a string

53. What is String concatenation?
    joining 2 strings into 1

54. What does OOP stand for?
    object oriented programming

55. What does instantiation mean?
    to create a new instance of an object

56. What is the name of the method that is called every time an object is instantiated?
    initialize

57. What are arguments?
    a way to pass a variable into a method

58. How do you pass an argument?
    by running the method with different variables

59. Write a method called `eat` that has an argument `food` with a default value of `"cheese"`.
    def eat(food = "cheese")
    end

60. What is a loop?
    a sequence of instructions that runs until conditions are met

61. How long has ruby been around?
    19 years

62. How are you doing on this quiz so far?
    alright I guess.

63. Is anyone else hungry?
    I'm sure somewhere.

64. What are the pipe characters used for in a block?
    the pipe characters give a variable to the block to be performed upon

65. What is the difference between single quote strings and double quote strings?
    string interpolation only works with double quotes and double quotes can use more
    escape sequences

66. Name some rules for naming a method?
    can't begin with a number, can contain upper and lower case, but should start
    with lower case, may contain _, !, ?, and =

67. How can you tell if a method is an instance or class method?
    class methods start with self.

68. In an instance method, what is `self`?
    nothing

69. How do you add a dependency to a file?
    I don't know.

70. I have a text file called `names.txt`. Each name is on it's own line. How would you print all the names in the file?
    don't know

71. When a method defines an argument that has a asterisk in front of a variable name, what is that asterisk referred to? e.g. `def thing(*stuff)`
    splat operator

72. When a method defines an argument that has an ampersand in front of a variable name, what is that ampersand and variable name collectivly called? e.g. `def thing(&stuff)`
    don't know

73. What is it called when you see the `do` and `end` keywords together?
    Do you mean literally, like do/end? or in the block sense where
    something is acted upon?

74. What does DRY stand for?
    Don't Repeat Yourself

75. What does DSL stand for?
    Domain Specific Language

76. This question left blank intentionally.

77. What does MRI stand for?
    Mat'z Ruby Interpreter

78. What is the difference between JRuby and MRI?
    MRI uses C code, and JRuby uses Java

79. What would you use RubyMotion for?
    for developing and testing applications for Apple products

80. Does your head hurt?
    yes

1. Indexes isn't the right word. Everything in Ruby is called an _______
2. The shovel operator '<<' doesn't work for hashes. Only arrays.
3. Look into Time.now and the strftime method.
4. See above.
5. Look into requiring files in Ruby.
6. Look into the encryptor app we made in class.
7. That's a hard one to Google, but it's there!
8. Block is the answer we were looking for.