Beginner stuff

Question 1

x valid name?

Answer 1

yes

Question 2

y2 valid name

Answer 2

yes

Question 3

_x valid name?

Answer 3

yes

Question 4

7x valid name?

Answer 4

nope (starts with digit)

Question 5

this_is_a_test valid name?

Answer 5

yes

Question 6

this is a test valid name?

Answer 6

no(not a single word)

Question 7

this’is@a’test!

Answer 7

no (contains invalid characters: ‘@!

Question 8

this-is-a-test

Answer 8

invalid (looks like subtraction)

Question 9

unless means the opposite of if (t/f)

Answer 9

True

Question 10

x y

Answer 10

returns 0 if x and y are equal, 1 if x is higher, and -1 if y is higher

Question 11

5. times do puts “Test” end

5. times do { puts “Test” }

Answer 11

Test
Test
Test
Test
Test

Question 12

loop that counts from 1 up to 5

Answer 12

1.upto(5) {…}

Question 13

loop that counts from 10 down to 1

Answer 13

10.downto(1) {…}

Question 14

loops that counts every 5th number up to 100

Answer 14

0.step(100, 5) {…}

Question 15

1.upto(5) { |number puts number } // what is |number| mean?

Answer 15

allows you to get hold of the number being iterated. The number being iterated is being passed down to the variable “number”.

Question 16

10 / 3 = ?

Answer 16

3

Question 17

10.0 / 3 = ?

Answer 17

3.333…

Question 18

x.to_f

Answer 18

converts x to floating point

Question 19

Pi = 3.141592

Answer 19

constant that shouldnt me changed, but can

Question 20

x = %q{…}

Answer 20

using quotation marks is only viable for a single line, but if you want to span multiple lines, you can use this.

Question 21

x = «YOLO hi YOLO

Answer 21

&laquo_space;marks the start of the string literal and is followed by a delimeter of your choice (YOLO) to end the block of code

Question 22

“abc” * 3

Answer 22

abcabcabc

Question 23

puts “x” > “y”

Answer 23

false (ruby compares the numbers that represent the characters in the string)

Question 24

puts “y” > “x”

Answer 24

true (ruby compares the numbers that represent the characters in the string)

Question 25

?a, ?A, ?x (120), 120.chr

Answer 25

number, number, 120, x

Question 26

x= 10, y = 20

puts “#{x} + #{y} = #{x+y}”

Answer 26

10+20=30

Question 27

interpolation

Answer 27

process of inserting the expressions into a string literal.

Question 28

puts “its a #{“bad “ * 3} idea

Answer 28

its a bad bad bad idea

Question 29

concatenation

Answer 29

joining strings together

Question 30

puts x.to_s + “ + “ + y.to_s (x=10, y=10)

Answer 30

10 + 10 (string literal)

Question 31

concatenate “test” and “test”

Answer 31

“test” + “test” (testtest)

Question 32

capitalize “test”

Answer 32

“test”.capitalize

Question 33

down case “TEST”

Answer 33

“TEST”.downcase

Question 34

“test”, take off the last index

Answer 34

“test”.chop

Question 35

“test” reverse

Answer 35

“test”.reverse

Question 36

“Test”.swapcase

Answer 36

“tEST”

Question 37

“test”.length

Answer 37

4

Question 38

puts “foobar”.sub(‘bar, ‘foo’)

Answer 38

“foofoo”

Question 39

puts “this is a test”.gsub(‘i’, ‘’)

Answer 39

ths s a test

Question 40

x = “This is a test”

puts x.sub(/..$/, ‘Hello’)

Answer 40

“This is a teHello”

Question 41

“This is a test”.sub(/^../, ‘Hello’)

Answer 41

“Hellois a test”

Question 42

/ foward slash or backwards

Answer 42

foward

Question 43

\ foward slash or backwards

Answer 43

backwards

Question 44

regular expression

Answer 44

starts with /, end with /.

Question 45

^ anchor expression

Answer 45

start from the beginning of any lines within the string

Question 46

.. regular expression

Answer 46

any two characters

Question 47

“xyz”.scan(/./) { |letter| puts letter {

Answer 47

x
y
z

Question 48

“This is a test”.scan(/\w\w/) { |x| puts x }

Answer 48

Th
is
is
te
st

Question 49

\w

Answer 49

any alphanumeric character or underscore (letter, digits, or underscore)

Question 50

$

Answer 50

anchor at the end of a line

Question 51

\d

Answer 51

any digit

Question 52

\s

Answer 52

whitespace(spaces, tabs, newlines, and so on)

Question 53

“The car costs $1000 and the cat costs $10”.scan(/\d+/) do |x|
puts x
end

Answer 53

d+ matches as many digits in a row

Question 54

\S

Answer 54

any non-whitespace (any visible character)

Question 55

“This is a test”.scan(/[aeiou]/) { |x| puts x }

Answer 55

i
i
a
e

Question 56

“This is a test”.scan(/[a-m]/) { |x| puts x }

Answer 56

h
i
i
a
e

Question 57

character classes

Answer 57

allows you to match against a specific set of characters

Question 58

puts “String has vowels” if “This is a test” =~ /[aeiou]/

Answer 58

=~ matching operator

Question 59

puts “String contains no digits” unless “This is a test” =~ /[0-9]/

Answer 59

puts String unless someString contains a digit

Question 60

puts “String has vowels” if “This is a test”.match(/[aeiou]/)

Answer 60

returns

Question 61

x = “This is a test”.match(/(\w+) (\w+)/)
puts x[0]
puts x[1]
puts x[2]

Answer 61

This is
This
is

x[0] contains the data matched by the entire regular expression. x[1,2] match each match group.

Question 62

x=[]
x &laquo_space;“word”
x.push(“word”)

Answer 62

adding elements to an empty array

Question 63

x.pop

Answer 63

pop element from an array

Question 64

x = [“hello”, “world”]

x.join

Answer 64

Helloworld

Question 65

x = [“Word”, “Play”, “Fun”]

puts x.join(‘, ‘)

Answer 65

word, play, fun

Question 66

puts “This is a test”.scan(/\w/).join(‘,’)

Answer 66

T,h,i,s,i,s,a,t,e,s,t

Question 67

puts “Short sentence. Another. No more.”.split(/./).inspect

Answer 67

[“Short sentence”, “ Another”, “ No more”]

Question 68

puts “Words with lots of spaces”.split(/\s+/).inspect

Answer 68

[“Words”, “with”, “lots”, “of”, “spaces”]

Question 69

[1, “test”, 2, 3, 4].each { |element| puts element.to_s + “X” }

Answer 69

1X
testX
2X
3X
4X

Question 70

[1, 2, 3, 4].collect { |element| element * 2 }

Answer 70

[2, 4, 6, 8]. convert array on the fly

Question 71

a = [1, "test", 2, 3, 4]
i = 0
while (i < a.length)
puts a[i].to_s + "X"
i += 1
end

Answer 71

1X
testX
2X
3X
4X

Question 72

x = [1, 2, 3]
y = [“a”, “b”, “c”]
z = x + y
p z

Answer 72

[1, 2, 3, “a”, “b”, “c”]

Question 73

x = []

puts “x is empty” if x.empty?

Answer 73

x is empty

Question 74

x = [1, 2, 3, 4, 5]
y = [1, 2, 3]
z = x - y
p z

Answer 74

[4, 5]

Question 75

x = [1, 2, 3]
p x.include?(“x”)
p x.include?(3)

Answer 75

false

true

Question 76

x = [1, 2, 3]
puts x.first
puts x.last

Answer 76

1

3

Question 77

x = [1, 2, 3]

puts x.first(2).join(“-“)

Answer 77

1-2

Question 78

x = [1, 2, 3]

p x.reverse

Answer 78

[3, 2, 1]

Question 79

Hashes

Answer 79

defined as key value pairs

Question 80

dictionary = { ‘cat’ => ‘feline animal’, ‘dog’ => ‘canine animal’ }.size

Answer 80

keys point to the values of the dictionary declaration

size : 2

Question 81

x = { “a” => 1, “b” => 2 }

x.each { |key, value| puts “#{key} equals #{value}” }

Answer 81

a equals 1

b equals 2

Question 82

x = { “a” => 1, “b” => 2, “c” => 3 }

p x.keys

Answer 82

[“a”, “b”, “c”]

Question 83

x = { “a” => 1, “b” => 2 }
x.delete(“a”)
p x

Answer 83

{“b” => 2}

Question 84

x = { “a” => 100, “b” => 20 }
x.delete_if { |key, value| value < 25 }
p x

Answer 84

{“a”=>100}

Question 85

age = 10
unless age >= 18
puts “You’re too young to use this system”
puts “So we’re going to exit your program now”
exit
end

Answer 85

prints out the text

Question 86

age = 10
type = age < 18 ? “child” : “adult”
puts “You are a “ + type

Answer 86

? :

Question 87

ternary operator

Answer 87

ternary operator makes it possible for an expression to contain a mini if/else statement.

Question 88

age = 10

puts “You are a “ + (age < 18 ? “child” : “adult”)

Answer 88

You are a child

Question 89

fruit = "orange"
if fruit == "orange"
color = "orange"
elsif fruit == "apple"
color = "green"
elsif fruit == "banana"
color = "yellow"
else
color = "unknown"
end

Answer 89

color = “orange”

Question 90

fruit = "orange"
case fruit
when "orange"
color = "orange"
when "apple"
color = "green"
when "banana"
color = "yellow"
else
color = "unknown"
end

Answer 90

color = “orange”

Question 91

fruit = "orange"
color = case fruit
when "orange"
"orange"
when "apple"
"green"
when "banana"
"yellow"
else
"unknown"
end

Answer 91

“orange”

Question 92

i = 1
i = i * 2 until i > 1000
puts i

Answer 92

1024

Question 93

x = [1, 2, 3]
x.each do |y|
puts y
end

Answer 93

1
2
3

Question 94

Code Block

Answer 94

anonymous, nameless method or function. passed to the method, which then runs the code block for each element.

Question 95

def each_vowel(&code_block)
%w{a e i o u}.each { |vowel| code_block.call(vowel) }
end
each_vowel { |vowel| puts vowel }

Answer 95

a
e
i
o
u

Question 96

code_block.call(vowel)

Answer 96

call method on code_block to execute the code blockfor each vowel passing in the vowel variable as a parameter each time

Question 97

def each_vowel
%w{a e i o u}.each { |vowel| yield vowel }
end
each_vowel { |vowel| puts vowel }

Answer 97

a
e
i
o
u

Question 98

yield

Answer 98

yield method which automatically detects any passed code block and passes control to it

Question 99

print_parameter_to_screen = lambda { |x| puts x }

print_parameter_to_screen.call(100

Answer 99

store code block within variables

prints 100

Question 100

(‘A’..’Z’).to_a.each { |letter| print letter }

Answer 100

ABCDEF….XYZ

Question 101

(‘A’..’Z’).include?(‘r’)

Answer 101

false

Question 102

symbols

Answer 102

dont contain values or objects like variables do. instead, used to maintain a consistent reference within code.

Question 103

Range

Answer 103

The representation for an entire range of values between a start point and an
endpoint.

Question 104

Regular expression

Answer 104

A way to describe patterns in text that can be matched and

compared against.