Begging Ruby Chapter 1

Question 1

What is object orientation

Answer 1

everything is an object guitar amps studio

Question 2

Data Types

Answer 2

variable can hold these

Question 3

Control Structures

Answer 3

variable can hold these

Question 4

Is Ruby Open Source?

Answer 4

Yes

Question 5

Ruby Interpreter

Answer 5

This is a ruby program that understands other programs written in the Ruby language, along with a collection of extensions and libraries to make your Ruby more fully featured

Question 6

irb: Interactive Ruby

Answer 6

irb stands for “Interactive Ruby.” “Interactive” means that as soon as you type something, your computer will immediately attempt to process it. Sometimes this sort of environment is called an immediate or interactive environment.

Question 7

object-oriented programming language

Answer 7

In the simplest sense, this means that your Ruby programs can define and operate upon concepts in a real-world fashion. Your program can contain concepts such as “people,” “boxes,” “tickets,” “maps,” or any other concept you want to work with. Object-oriented languages make it easy to implement these concepts in
a way that you can create objects based upon them. Object oriented languages can then act upon and understand the relationships between these concepts in any way you define.

Question 8

nouns / verbs

Answer 8

Objects are nouns, methods are verbs.

Question 9

3 corners of OOP

Answer 9

Encapsulation, Inheritance, Polymorphism

Question 10

OOP

Answer 10

Style of programming where you create representations of “types” of objects like guitars and amps (Classes), and then can create specific objects like 69 strat, black les paul, 80s peavey, (instance of an object) that intend to use with each other.

Question 11

attr_accessor

Answer 11

attr stands for “attribute,” and accessor roughly means “make these attributes accessible to be set and changed at will.”

Question 12

print vs puts

Answer 12

puts automatically moves the output cursor to the next line

Question 13

what can a ruby variable contain

Answer 13

numbers, text, and other data structures

Question 14

class

Answer 14

A class is the definition of a single type of object

Question 15

standard attribute syntax

Answer 15

attr_accessor :name, :age, :gender

Question 16

what does inheritance allow you to do

Answer 16

Inheritance allows different classes to relate to one another and group concepts by their similarities

Question 17

classless method

Answer 17

def guitar_strum
puts “brrriiing”
end

guitar_strum

Question 18

Class

Answer 18

Class: A class is a definition of a concept in an object-oriented language such as Ruby. We created classes called Pet, Dog, Cat, Snake, and Person. Classes can inherit features from other classes, but still have unique features of their own.

Question 19

Method

Answer 19

Method: A method represents a set of code (containing multiple commands and statements) within a class and/or an object. For example, our Dog class objects had a bark method that printed “Woof!” to the screen. Methods can also be directly linked to classes, as with fred = Person.new, where new is a method that creates a new object based upon the Person class. Methods can also accept data—known as arguments or parameters—included in parentheses after the method name, as with puts(“Test”).

Question 20

Arguments/parameters

Answer 20

Arguments/parameters: These are the data passed to methods in parentheses (or, as
in some cases, following the method name without parentheses, as in puts “Test”). Technically, you pass arguments to methods, and methods receive parameters, but for pragmatic purposes, the terms are interchangeable.

Question 21

Kernel

Answer 21

Some methods don’t require a class name to be usable, such as puts. These
are usually built-in, common methods that don’t have an obvious connection to any classes. Many of these methods are included in Ruby’s Kernel module, a module that provides functions that work from anywhere within Ruby code without being explicitly referred to.

Question 22

Experimentation

Answer 22

One of the most fulfilling things about programming is that you can turn your dreams into reality. The amount of skill you need varies with your dreams, but generally if you want to develop a certain type of application or service, you can give it a try. Most software comes from necessity or a dream, so keeping your eyes and ears open for things you might want to develop is important. It’s even more important when you first get practical knowledge of a new language, as you are while reading this book. If an idea crosses your mind, break it down into the smallest components that you can represent as Ruby classes and see if you can put together the building blocks with the Ruby you’ve learned so far. Your programming skills can only improve with practice.

Question 23

simple do if syntax

Answer 23

age = 10

puts “You’re too young to use this system” if age

Question 24

string literal

Answer 24

When a string is embedded directly into code, using quotation marks as earlier, the con- struction is called a string literal. This differs from a string whose data comes from a remote source, such as a user typing in text, a file, or the Internet. Any text that’s pre-embedded within a program is a string literal.

Question 25

interpolation

Answer 25

interpolation refers to the process of inserting the result of an expression into a string literal “#{x+y}”

Question 26

“Test” + “Test”

Answer 26

TestTest

Question 27

“Test”.capitalize

Answer 27

Test

Question 28

“Test”.downcase

Answer 28

test

Question 29

“Test”.chop

Answer 29

Tes

Question 30

“Test”.next

Answer 30

Tesu

Question 31

“Test”.reverse

Answer 31

tseT

Question 32

“Test”.sum

Answer 32

416

Question 33

“Test”.swapcase

Answer 33

tEST

Question 34

“Test”.upcase

Answer 34

TEST

Question 35

“Test”.upcase.reverse

Answer 35

TSET

Question 36

“Test”.upcase.reverse.next

Answer 36

TSEU

Question 37

regular expression (string)

Answer 37

A regular expression, therefore, is a string that describes a pattern for matching elements in other strings.

Question 38

basic substitution

Answer 38

puts “yo la tango”.sub(‘tango’, ‘mango’)

Question 39

regular expression

Answer 39

puts “foobar”.sub(‘bar’, ‘foo’)

Question 40

regular expression substitution of first two characters syntax

Answer 40

x.sub(/^../, ‘Hello’)

Question 41

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

Answer 41

“xyz”.scan (/./) { |character| puts character }

Question 42

any alphanumeric character or an underscore

Answer 42

\w

Question 43

regular expression argument general syntax

Answer 43

(/something/)

Question 44

Anchor for the beginning of a line

Question 45

Anchor for the end of a line

Answer 45

$

Question 46

Anchor for the start of a string

Answer 46

\A

Question 47

Anchor for the end of a string

Answer 47

\Z

Question 48

Any character

Answer 48

.

Question 49

Any letter, digit, or underscore

Answer 49

\w

Question 50

Anything that \w doesn’t match

Answer 50

\W

Question 51

Any digit

Answer 51

\d

Question 52

Anything that \d doesn’t match (non-digits)

Answer 52

\D

Question 53

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

Answer 53

\s

Question 54

Non-whitespace (any visible character)

Answer 54

\S

Question 55

scanning for each character but adding them together to make a word

Answer 55

.scan (/.+/)

Question 56

scan for vowels syntax

Answer 56

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

Question 57

matching operator

Answer 57

=~

Question 58

array to string syntax

Answer 58

x.join(‘ ‘)

Question 59

turning a string into an array syntax

Answer 59

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

Question 60

basic hash iteration syntax

Answer 60

x.each { |key, value| something happens here with each }

Question 61

ternary operator

Answer 61

2 > 1 ? “yes” : “no”

Question 62

ternary syntax

Answer 62

2 > 1 ? “yes” : “no”

Question 63

x y

Answer 63

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

Question 64

turn beginning two elements of array into string with dash

Answer 64

array.first(2).join(“-“)

Question 65

discarding hash elements

Answer 65

x.delete(key)

Question 66

discard hash conditional example

Answer 66

hash_name.delete_if { |key, value| value

Question 67

fruit case example

Answer 67

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

Question 68

code block

Answer 68

essentially an anonymous, nameless method or function

[{} or do end]

Question 69

how to turn letters a through z into an array

Answer 69

(‘A’..’Z’).to_a

Question 70

hash basic syntax

Answer 70

s = { :key => ‘value’ }

Question 71

Variable

Answer 71

A placeholder that can hold an object—from numbers, to text, to arrays, to objects of your own creation.

Question 72

Operator

Answer 72

Something that’s used in an expression to manipulate objects such as +(plus), - (minus), * (multiply), and / (divide). You can also use operators to do comparisons, such as with , and &&.

Question 73

Integer

Answer 73

A whole number, such as 5 or 923737.

Question 74

Float

Answer 74

A number with a decimal portion, such as 1.0 or 3.141592.

Question 75

Character

Answer 75

A single letter, digit, unit of space, or typographic symbol.

Question 76

String

Answer 76

A collection of characters such as Hello, world! or Ruby is cool.

Question 77

Constant

Answer 77

A variable with a fixed value. Constant variable names begin with a capital letter.

Question 78

Iterator

Answer 78

A special method such as each, upto, or times that steps through a list element by element. This process is called iteration, and each, upto, and times are iterator methods.

Question 79

Interpolation

Answer 79

The mixing of expressions into strings.

Question 80

Array

Answer 80

A collection of objects or values with a defined, regular order.

Question 81

• Hash

Answer 81

A collection of objects or values associated with keys. A key can be used to find its respective value inside a hash, but items inside a hash have no specific order. It’s a lookup table, much like the index of a book or a dictionary.

Question 82

Regular expression

Answer 82

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

Question 83

Flow control

Answer 83

The process of managing which sections of code to execute based on certain conditions and states.

Question 84

Code block

Answer 84

A section of code, often used as an argument to an iterator method, that has no discrete name and that is not a method itself, but that can be called and handled by a method that receives it as an argument. Code blocks can also be stored in variables as objects of the Proc class (or as lambdas).

Question 85

Range

Answer 85

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

Question 86

Symbol

Answer 86

A unique reference defined by a string prefixed with a colon (for example, :blue or :name). Symbols don’t contain values as variables do, but can be used to maintain a consistent reference within code. They can be considered as identifiers or constants that stand alone in what they abstractly represent.

Question 87

. .

Answer 87

including

Question 88

. . .

Answer 88

not including

Question 89

how would you check if letters a through z has r in it

Answer 89

(‘a’..’z’).include?(‘r’)

Question 90

create a new triangle

Answer 90

Triangle.new(1,2,3)

Question 91

what is the benefit of inheritence?

Answer 91

classes lower down the hierarchy get the features of those higher up, but can also add specific features of their own

Question 92

what is the escape charecter

Answer 92

backslash \

Question 93

print first 3 letters of “string”

Answer 93

p “string”[0..2]

Question 94

how to create a lambda

Answer 94

l = lambda { “Do or do not” }

puts l.call

Question 95

increase of all menu items by 10%

Answer 95

menu_items = {:curry => 4, :roti => 6}
menu_items.each do |item, price|
menu_times[item] = price * 1.1
end

Question 96

.count

Answer 96

.count(argument) goes through an array and counts how many time argument appears

Question 97

Select random elements from an array

Answer 97

def random_select(array, n)
result = []
n.times do
result

Question 98

newest hash syntax

Answer 98

{ k: v }

Question 99

how to spell initialize

Answer 99

Init i alize

Question 100

summing elements in an array

Answer 100

inject(0) { |sum, num| sum + num }

Question 101

syntax for simple do if w/ two conditionals

Answer 101

do if condition1 == true && condition2 == true

Question 102

do using unless

Answer 102

do unless conditional1==true

Question 103

not equal to comparison operator

Answer 103

!=

Question 104

how to loop from n to m

Answer 104

n.upto(m) { code to loop }

Question 105

how to code loop from m down to n

Answer 105

m.downto(n) { code to loop }

Question 106

0 to 50 in 5 steps

Answer 106

0.step(50, 5) { code to loop }

Question 107

using string delimiters

Answer 107

x =

Question 108

result of “abc” * 5

Answer 108

abcabcabcabcabc

Question 109

basic interpolation

Answer 109

”#{something}”

Question 110

define regular expression

Answer 110

a search query

Question 111

how to iterate through a string

Answer 111

‘string’.scan(/./){ |char| do something }

Question 112

returning a string with no spaces

Answer 112

“this is a crazy sentence 123”.scan(/\S+/).join

Question 113

matching operator

Answer 113

=~

Question 114

.scan vs .match

Answer 114

.scan goes though everything, . match returns one match value

Question 115

method to check if array has no elements

Answer 115

array.empty?

Question 116

does an array have an element

Answer 116

array.include?(ImptArrgument)

Question 117

methods for array and hash

Answer 117

.delete
.delete_if
.first
.collect
.each

Question 118

methods for array

Answer 118

.first
.first(arg)
.last
.last(arg)
.reverse

Question 119

hash methods

Answer 119

.size
.each
.keys
.values
.delete
.delete_if
.first

Question 120

how to create a new hash which saves changed old hash

Answer 120

new_hash = {}; old_hash.each { |key,val| new_hash[key] = val + something }

Question 121

demonstration of a class method

Answer 121

class Thing
  def self.thing_method
     puts "hello from class method"
  end

Question 122

%w{ this is a long sentence }

Answer 122

[ “this”, “is”, “a”, “long”, “sentence” ]

Question 123

%q{ this is a long sentence }

Answer 123

” this is a long sentence “

Question 124

.collect

Answer 124

Returns a new array with the results of running block once for every element in enum.