Object Types

Question 1

To find information on objects, classes, methods, etc… Where would you find these answers?

Answer 1

www.ruby-doc.org/core/

Question 2

To find information on a method within Ruby, what command do you issue in Ruby to find more information?

Answer 2

ri object name
for example ri upcase
or
.inspect shows human readable form

Question 3

True of False:

Variables are objects?

Answer 3

False

However, once a variable is defined, it will act like an object

Question 4

What does this error code mean?

NameError: undefined local variable or method `x’ for main:Object

Answer 4

It means you have not defined your variable, in this case, the variable ‘x’

Question 5

Variables should be named in what format?

Answer 5

lower case with underscores

for example: articles_written = 100

Question 6

The scope indicator of the Global scope is what?

Answer 6

Dollar sign

example: $variable

Question 7

The scope indicator of the Class scope is what?

Answer 7

Two at symbols

example: @@variable

Question 8

The scope indicator of the Instance scope is what?

Answer 8

The at symbol

example: @variable

Question 9

The scope indicator of the Local scope is what?

Answer 9

nothing, just the variable name

example: variable

Question 10

The scope indicator of the Block scope is what?

Answer 10

nothing, just the variable name

example: variable

Question 11

Ruby separates integers in two categories, what are they?

Answer 11

> integers

> floats

Question 12

If integers are objects, what two subclasses must they belong to?

Answer 12

Fixnum and Bignum

examples:
1234. class => Fixnum
12345678. class => Bignum

Question 13

What would the result be in Ruby?

-200.abs

Answer 13

=> 200

Since .abs returns the absolute value

Question 14

What would the result be in Ruby?

200.next

Answer 14

=> 201

Since .next returns the next value

Question 15

Floats or Floating point numbers are also known as what?

Answer 15

decimal numbers or precision numbers

Question 16

x = 10
y = 10.0

what would x and y equal in Ruby?

Answer 16

10.0

Question 17

10 / 3 in Ruby would return what value?

Answer 17

3

Question 18

10.0 / 3.0 in Ruby would return what?

Answer 18

3.33333333333333

Question 19

If you wanted to round this number, what would you enter in Ruby?
12345.6789

Answer 19

12345.6789.round

=> 12346

Question 20

If you wanted to make this number an integer, what would you enter in Ruby?
12345.6789

Answer 20

12345.6789.to_i

=> 12345

Question 21

If you wanted to round this number UP, what would you enter in Ruby?
12345.6789

Answer 21

12345.6789.floor

=> 12345

Question 22

If you wanted to round this number DOWN, what would you enter in Ruby?
12345.6789

Answer 22

12345.6789.ceil

=> 12346

Question 23

strings are a sequence of what?

Answer 23

characters

Question 24

what does this return in irb?

“Lamda”*3

Answer 24

“LamdaLamdaLamda”

Question 25

Which character lets you escape a quote?

Answer 25

\

also known as a backslash

Question 26

What does this yield?

greeting = “hello”
target = “world”
puts “I want to say #{greeting} #{target}.”

Answer 26

I want to say hello world.

Question 27

What method makes a string backward?

Answer 27

.reverse

example: “Hello”.revers
=> “olleH”

Question 28

What method makes a string capitalized?

Answer 28

.capitalize

example: “hello”.capitalize
=> “Hello”

Question 29

What method makes a string all lower cased?

Answer 29

.downcase

example: “Hello”.downcase
=> “hello”

Question 30

What method makes a string all upper cased?

Answer 30

.upcase

example: “Hello”.upcase
=> “HELLO”

Question 31

If you wanted to count how many letters there were in the string “Hello”, what would you enter?

Answer 31

“Hello”.length

=> 5

Question 32

Take “hello” and reverse it, make it all upper case, and count the letters

Answer 32

“Hello”.reverse.upcase.length

=> 5

Question 33

Define an array.

Answer 33

An ORDERED INTEGER-INDEXED collection of OBJECTS

Question 34

Name 4 things that can go in an array

Answer 34

1. Strings
2. Numbers
3. Other arrays
4. Mixed Types

Question 35

Enter what to make an empty array called master_array

Answer 35

master_array = []

Question 36

put the letters a, b, and c in an array named my_first_letters

Answer 36

my_first_letters = [“a”, “b”, “c”]

Question 37

given this array:
my_first_letters = [“a”, “b”, “c”]
what would this return:
my_first_letters[1]

Answer 37

“b”

Question 38

given this array:
my_first_pets = [“dog”, “pig”, “cat”]
what would you enter to turn “cat” into “goat”

Answer 38

my_first_pets[2] = “goat”

Question 39

to clear out an array, what method would you use?

Answer 39

my_array.clear

Question 40

if you wanted to append “goat” onto the array my_first_pets = [“dog”, “pig”, “cat”]
what would you enter?

Answer 40

my_first_pets &laquo_space;“goat”

Question 41

Given this array:
my_first_pets = [“dog”, “pig”, “cat”, “goat”, “cat”, “dog”]
What would you enter to get an array containing only one type of animal (no duplicates)

Answer 41

my_first_pets.uniq

Question 42

Given this array:
my_first_pets = [“dog”, “pig”, “cat”, “goat”, “dog”]
What would you enter to get an array containing only dogs and pigs?

Answer 42

my_first_pets.delete_at(2)

=> [“dog”, “pig”, “goat”, “dog”]

Question 43

Define hashes

Answer 43

UNORDERED collection of objects connected by KEY-VALUE PAIRS

Question 44

Make a hash named my_hash

Answer 44

my_hash = {}

Question 45

Make a hash named my_hash with the key value pairs of ‘first item’ and ‘bong’

Answer 45

my_hash = {“first_item”=>”bong”}

Question 46

Given this hash>
name = {“first_name” => “Roberto”, “last_name”=>”Sanchez”}

how would you get the first name out?

Answer 46

name[“first_name”]

Question 47

Given this hash>
name = {“first_name” => “Roberto”, “last_name”=>”Sanchez”}

What would this return?
name.index(“Sanchez”)

Answer 47

=> “last_name”

Question 48

create a symbol named after your test project

Answer 48

:test_project

Question 49

create a hash with two symbols for first and last names

Answer 49

name = {:first_name => “Roberto”, :last_name => “Sanchez”}

Question 50

Define a boolean

Answer 50

something that is either True or False

Question 51

What is the comparison & logic operator for ‘equal’?

Answer 51

==

Question 52

What is the comparison & logic operator for ‘less than or equal to’?

Answer 52

<=

Question 53

What is the comparison & logic operator for ‘Not’?

Answer 53

!

Question 54

What is the comparison & logic operator for ‘Not equal’?

Answer 54

!=

Question 55

What is the comparison & logic operator for ‘and’?

Answer 55

&&

Question 56

What is the comparison & logic operator for ‘or’?

Answer 56

||