General Ruby

Question 1

General Ruby

check whether a value would be included in a given range

Answer 1

cover?(obj) => true or false

ex

(0. .100).cover? 50 #=> true
(0. .100).cover? 50.5 #=> true

Question 2

General Ruby

quotes used with string interpolation

Answer 2

”

double quote

Question 3

General Ruby

ternary syntax

Answer 3

expression ? true_value : false_value

Question 4

General Ruby

nameless methods that are passed to methods as a parameter

Answer 4

blocks

Question 5

General Ruby

object that is a block of code that can be bound to a set of local variables

Answer 5

proc

Question 6

General Ruby

anonymous functions that can be saved to variables

Answer 6

lambdas

Question 7

General Ruby

lambda syntax

Answer 7

prnt = lambda { |string| puts string }

prnt = -> (string) { puts string }

prnt.call (“my string”)

> my string => nil

Question 8

General Ruby

lambdas compared to procs

Answer 8

stricter argument passing and localized returns

Question 9

General Ruby

operator to signify when you are passing Procs/Lambdas/Methods as a block

Answer 9

&

Question 10

General Ruby

case syntax

Answer 10

case

when expression1

value1

when expression2

value2

else

default

end

Question 11

General Ruby

easy way to create an array of strings (with interpolation)

Answer 11

%W(one two three four) => [“one”, “two”, “three”, “four”]

Question 12

General Ruby

easy way to create a string without needing to escape quotation marks or line breaks (with interpolation)

Answer 12

%Q(John said, “My name is John”) => “John said, "My name is John"”

Question 13

General Ruby

easy way to create an array of symbols (with interpolation)

Answer 13

%I(array of symbols #{1+1}) => [:array, :of, :symbols, :”2”]

Question 14

General Ruby

difference between double quote and single quote strings

Answer 14

double quotes allow for interpolation and escape sequences (\n, \t, etc.), single quote does not allow for interpolation or escape sequences other than single quotes

Question 15

General Ruby

proc syntax

Answer 15

Proc.new { |…| block } => a proc

Question 16

General Ruby

gem that provides an alternative to irb

Answer 16

pry

Question 17

General Ruby

change the scope of the current pry session

Answer 17

cd

ex

i = 1

cd i

Question 18

General Ruby

list all of the methods available to a given object in a pry session

Answer 18

ls

ex

i = 1

ls i

ex

cd i

ls

Question 19

General Ruby

display more information about a method in the current scope in a pry session

Answer 19

show-method method_name

Question 20

General Ruby

allow a shell program to execute a script using the Ruby interpreter

Answer 20

! /usr/bin/env ruby

hash bang

ex

Question 21

General Ruby

hash bang

ex

Answer 21

allow a shell program to execute a script using the Ruby interpreter

Question 22

General Ruby

HEREDOC syntax to remove leading whitespace from each line

Answer 22

<<~HEREDOC

String text here, leading whitespace

will be stripped.

HEREDOC

Question 23

General Ruby

<<~HEREDOC

String text here, leading whitespace

will be stripped.

HEREDOC

Answer 23

HEREDOC syntax to remove leading whitespace from each line

Question 24

General Ruby

HEREDOC syntax that keeps whitespace intact

Answer 24

<<-HEREDOC

String text here, leading whitespace

will remain intact

HEREDOC

Question 25

# General Ruby \<\<-HEREDOC String text here, leading whitespace will remain intact HEREDOC

Answer 25

HEREDOC syntax that keeps whitespace intact

Question 26

# General Ruby read a single character from stdin

Answer 26

getch must require 'io/console' ex IO::console.getch $stdin.getch STDIN.getch

Question 27

# General Ruby getch must require 'io/console' ex IO::console.getch $stdin.getch STDIN.getch

Answer 27

read a single character from stdin

Question 28

# General Ruby handle an exception that would otherwise cause your program to stop execution

Answer 28

begin...end ex begin something which might raise an exception rescue SomeExceptionClass =\> some\_variable code that deals with some exception rescue SomeOtherException =\> some\_other\_variable code that deals with some other exception else code that runs only if \*no\* exception was raised ensure ensure that this code always runs, no matter what end

Question 29

# General Ruby a stream designed for use in scripts that process files given as command-line arguments or passed in via STDIN

Answer 29

ARGF ex ARGF.each do |line| puts line end

Question 30

global object that has information the current and parent processes; behaves much like a hash

Answer 30

ENV

Question 31

return the string resulting from applying format\_string to any additional arguments; within the format string, any characters other than format sequences are copied to the result

Answer 31

format(format\_string [, arguments...] ) =\> string

Question 32

Kernel#format format\_string syntax

Answer 32

%[flags][width][.precision]type