Real ruby

Question 1

alias

Answer 1

To create a second name for the variable or method.

Question 2

and

Answer 2

A command that appends two or more objects together.

Question 3

BEGIN

Answer 3

Designates code that must be run unconditionally at the beginning of the program before any other.

Question 4

begin

Answer 4

Delimits a “begin” block of code, which can allow the use of while and until in modifier position with multi-line statements.

Question 5

break

Answer 5

Gives an unconditional termination to a code block, and is usually placed with an argument.

Question 6

case

Answer 6

starts a case statement; this block of code will output a result and end when it’s terms are fulfilled, which are defined with when or else.

Question 7

class

Answer 7

Opens a class definition block, which can later be reopened and added to with variables and even functions.

Question 8

def

Answer 8

Used to define a function.

Question 9

defined?

Answer 9

A boolean logic function that asks whether or not a targeted expression refers to anything recognizable in Ruby; i.e. literal object, local variable that has been initialized, method name visible from the current scope, etc.

Question 10

do

Answer 10

Paired with end, this can delimit a code block, much like curly braces; however, curly braces retain higher precedence.

Question 11

else

Answer 11

Gives an “otherwise” within a function, if-statement, or for-loop, i.e. if cats = cute, puts “Yay!” else puts “Oh, a cat.”

Question 12

elsif

Answer 12

Much like else, but has a higher precedence, and is usually paired with terms.

Question 13

END

Answer 13

Designates, via code block, code to be executed just prior to program termination.

Question 14

end

Answer 14

Marks the end of a while, until, begin, if, def, class, or other keyword-based, block-based construct.

Question 15

ensure

Answer 15

Marks the final, optional clause of a begin/end block, generally in cases where the block also contains a rescue clause. The code in this term’s clause is guaranteed to be executed, whether control flows to a rescue block or not.

Question 16

FALSE

Answer 16

denotes a special object, the sole instance of FalseClass. false and nil are the only objects that evaluate to Boolean falsehood in Ruby (informally, that cause an if condition to fail.)

Question 17

for

Answer 17

A loop constructor; used in for-loops.

Question 18

if

Answer 18

Ruby’s basic conditional statement constructor.

Question 19

in

Answer 19

Used with for, helps define a for-loop.

Question 20

module

Answer 20

Opens a library, or module, within a Ruby Stream.

Question 21

next

Answer 21

Bumps an iterator, or a while or until block, to the next iteration, unconditionally and without executing whatever may remain of the block.

Question 22

nil

Answer 22

A special “non-object”; it is, in fact, an object (the sole instance of NilClass), but connotes absence and indeterminacy. nil and false are the only two objects in Ruby that have Boolean falsehood (informally, that cause an if condition to fail).

Question 23

not

Answer 23

Boolean negation. i.e. not true # false, not 10 # false, not false # true.

Question 24

or

Answer 24

Boolean or. Differs from || in that or has lower precedence.

Question 25

redo

Answer 25

Causes unconditional re-execution of a code block, with the same parameter bindings as the current execution.

Question 26

rescue

Answer 26

Designates an exception-handling clause that can occur either inside a begin/end block, inside a method definition (which implies begin), or in modifier position (at the end of a statement).

Question 27

retry

Answer 27

Inside a rescue clause, causes Ruby to return to the top of the enclosing code (the begin keyword, or top of method or block) and try executing the code again.

Question 28

return

Answer 28

Inside a method definition, executes the ensure clause, if present, and then returns control to the context of the method call. Takes an optional argument (defaulting to nil), which serves as the return value of the method. Multiple values in argument position will be returned in an array.

Question 29

self

Answer 29

The "current object" and the default receiver of messages (method calls) for which no explicit receiver is specified. Which object plays the role of self depends on the context.

Question 30

super

Answer 30

Called from a method, searches along the method lookup path (the classes and modules available to the current object) for the next method of the same name as the one being executed. Such method, if present, may be defined in the superclass of the object's class, but may also be defined in the superclass's superclass or any class on the upward path, as well as any module mixed in to any of those classes.

Question 31

then

Answer 31

Optional component of conditional statements (if, unless, when). Never mandatory, but allows for one-line conditionals without semi-colons.

Question 32

TRUE

Answer 32

The sole instance of the special class TrueClass. true encapsulates Boolean truth; however, all objects in Ruby are true in the Boolean sense (informally, they cause an if test to succeed), with the exceptions of false and nil.

Question 33

undef

Answer 33

Undefines a given method, for the class or module in which it's called. If the method is defined higher up in the lookup path (such as by a superclass), it can still be called by instances classes higher up.

Question 34

unless

Answer 34

The negative equivalent of if. i.e. unless y.score > 10 puts "Sorry; you needed 10 points to win." end.

Question 35

until

Answer 35

The inverse of while: executes code until a given condition is true, i.e., while it is not true. The semantics are the same as those of while.

Question 36

when

Answer 36

Same as case.

Question 37

while

Answer 37

Takes a condition argument, and executes the code that follows (up to a matching end delimiter) while the condition is true.

Question 38

yield

Answer 38

Called from inside a method body, yields control to the code block (if any) supplied as part of the method call. If no code block has been supplied, calling yield raises an exception.

Question 39

check if an integer is even

Answer 39

integer.even?

Question 40

check if an integer is odd

Answer 40

integer.odd?

Question 41

find the next integer

Answer 41

integer.next

Question 42

is an integer between two to others?

Answer 42

integer.between? 1,3

Question 43

reverse a string

Answer 43

string.reverse

Question 44

find out how long a string is

Answer 44

string.length

Question 45

make a string all capitals

Answer 45

string.upcase

Question 46

make a string all small letters

Answer 46

string.downcase

Question 47

reverse the cases of a string

Answer 47

string.swapcase

Question 48

capitalize the first letter of a string

Answer 48

string.capitalize

Question 49

justify a string to the middle

Answer 49

string.center

Question 50

pad the right side of a string with repeating zeroes

Answer 50

string.ljust(5,'0')

Question 51

pad the left side of a string with repeating zeroes

Answer 51

string.rjust(5,'0'

Question 52

find out if a string starts with a substring

Answer 52

string.start_with? 'Substring'

Question 53

find out if a string ends with a substring

Answer 53

string.end_with? 'susbstring

Question 54

find the index of a particular letter in a string

Answer 54

string.index 'A'

Question 55

split a string into an array

Answer 55

string.split('')

Question 56

find and replace the first instance of a string in another string

Answer 56

string.sub('I','We)

Question 57

find and replace all instances of a string in another string

Answer 57

string.gsub('I','We')

Question 58

return a substring

Answer 58

newString = string[2..6]

Question 59

extract all the a-z words from a sentence

Answer 59

senA = sen.downcase.gsub(.[^a-z\s]/,'').split(' ')

Question 60

generate a random decimal between 0 and 1

Answer 60

rand

Question 61

generate a number between 1 and 10

Answer 61

rand(11)

Question 62

pi

Answer 62

Math::PI

Question 63

e (as in logarithm)

Answer 63

Math::E

Question 64

cosine

Answer 64

Math.cos

Question 65

tangent

Answer 65

Math.tan

Question 66

square root

Answer 66

Math.sqrt(x)

Question 67

retrieve an item from an array using an index

Answer 67

array[index]

Question 68

retrieve an item from the end of an array using index

Answer 68

array[-index]

Question 69

retrieve an items index from an array

Answer 69

array.index('thing')

Question 70

print an array as a string with a divider

Answer 70

array.join(' ')

Question 71

add item to the end of an array

Answer 71

array.push 'item' OR array << 'item'

Question 72

remove item from the end of an array

Answer 72

array.pop

Question 73

get the length of an array

Answer 73

array.length

Question 74

return the unique elements of an array

Answer 74

array.uniq

Question 75

do an action on every element of an array, altering array

Answer 75

array.map{|i| i*3}

Question 76

filter the elements of an array into a new array

Answer 76

array.select{|thing| thing.length > 5}

Question 77

delete an element of an array

Answer 77

array.delete('item')

Question 78

delete an element of an array on a condition

Answer 78

array.delete(|thing| thing%2==0)

Question 79

create a new time object

Answer 79

time = Time.new

Question 80

add one minute to a time object

Answer 80

time2 = time + 60

Question 81

create new hash

Answer 81

newHash = {} or newHash = Hash.new

Question 82

pad the right side of a string with blank space

Answer 82

string.ljust(20)

Question 83

pad the left side of a string with blank space

Answer 83

string.rjust(20)

Question 84

determine whether a hash has a certain key

Answer 84

hash.include?('key')

Question 85

print ascii codes for a string

Answer 85

str.each_byte{|c| put c}

Question 86

print ascii character from code

Answer 86

int.chr

Question 87

get ascii code for a single char

Answer 87

char.ord

Question 88

remove all nils from an array

Answer 88

array.compact

Question 89

return the maximum value from a hash

Answer 89

hash.max_by{|k,v| v}

Question 90

return permutations of an array as an array

Answer 90

array.permutation.to_a

Question 91

go through a loop, iterating by a number other than 1

Answer 91

0.step(0,50) {loop the code in here...}

Question 92

declare a variable as a constant

Answer 92

Pi = 3.1415

Question 93

return ASCII code for a character (not .ord)

Answer 93

?a, ?Z

Question 94

regular expression meaning any two characters immediately after the beginning of a line

Answer 94

/^../

Question 95

regular expression meaning the last two characters of a line

Answer 95

/..$/

Question 96

regex first two characters of absolute start of a string

Answer 96

/\A../

Question 97

regex last two characters of absolute end of a string

Answer 97

/..\Z/

Question 98

iterate through a string and have access to each section of it

Answer 98

This is a test.scan(/../) {|x| puts x}

Question 99

regex anchor for beginning of line

Answer 99

^

Question 100

regex anchor for end of line

Answer 100

$

Question 101

regex anchor for beginning of a string

Answer 101

\A

Question 102

regex anchor for the end of a string

Answer 102

\Z

Question 103

regex any character

Answer 103

.

Question 104

regex any letter, digit, or underscore

Answer 104

\w

Question 105

regex any character that \w doesn't match

Answer 105

\W

Question 106

regex any digit

Answer 106

\d

Question 107

regex any non-digit

Answer 107

\D

Question 108

regex whitespace

Answer 108

\s

Question 109

regex non-whitespace

Answer 109

\S

Question 110

regex match one or more of a certain type of character

Answer 110

+, e.g. string.scan(/\d+/) do |x| gives all numbers in a string

Question 111

return first number of elements of an array, e.g. first 3 element

Answer 111

array.first(3)

Question 112

return an array of all the keys of a hash

Answer 112

hash.keys

Question 113

the ternary operator

Answer 113

?

Question 114

.collect

Answer 114

Array#collect, iterates over the array with code block and returns new array

Question 115

.strptime

Answer 115

DateTime#strptime