Ruby

Question 0

What is an index?

Answer 0

Each item in an array. It begins and 0 and continues counting in increments of 1.

Question 1

In this array what position does the number 400 hold?

[100, 200, 300, 400, 500]

Answer 1

3

Question 2

What does // array[2] // mean?

Answer 2

It is asking for the 3rd index item in an array.

Question 3

What are arrays of arrays called?

Answer 3

Multidimensional arrays

Question 4

A built in module for mathematics

Answer 4

Math

Question 5

One role of a module is to…

Answer 5

group together similar methods under one familiar name

Question 6

a period or dot is used to…

Answer 6

identify the receiver of a message

Question 7

def

Answer 7

how we DEFINE a method

Question 8

end

Answer 8

tells Ruby we are done with whatever we were defining

Question 9

{ }

Answer 9

Ruby’s way of inserting something into a string

Question 10

==

Answer 10

is equal to

Question 11

!=

Answer 11

is not equal to

Question 12

.include?

Answer 12

evaluates to true if it finds what it’s looking for and false otherwise

Question 13

.gsub!

Answer 13

global substitution - replaces every instance of something with something else

Question 14

+=, -=, *=, and /=

Answer 14

increment or decrement by a value

Question 15

iterator

Answer 15

An iterator is just a Ruby method that repeatedly invokes a block of code. The code block is just the bit that contains the instructions to be repeated, and those instructions can be just about anything you like!

Question 16

number.times

Answer 16

quick way to do something over and over…

10.times { print “Chunky bacon!” }

Question 17

.split()

Answer 17

takes a string and returns it as an array separated by what ever you give it (commas, spaces, etc.)

Question 18

multidimensional arrays

Answer 18

arrays within arrays

Question 19

Histogram

Answer 19

A visual representation of data.

Answer 21

It returns 0 if the first operand (item to be compared) equals the second, 1 if first operand is greater than the second, and -1 if the first operand is less than the second.

Question 22

|=

Answer 22

conditional operator - can use to assign a variable ONLY if it has not already been assigned.

Question 23

implicit return

Answer 23

ruby will return the LAST evaluated expression whether or not you specifically ask it to “return” something to you

Question 24

&&

Answer 24

returns true when both sides are true

Question 25

||

Answer 25

returns true when one or other or both sides are true

Question 26

n.times { }

Answer 26

can specify to do the thing inside the block “n” number of times

Question 27

.each

Answer 27

iterates through a collection and looks at each item

Question 28

.even?

Answer 28

checks if number is even evaluates to true

Question 29

.upto

Answer 29

to print out an ascending range of values
Example: 95.upto(100) {|num| print num, “ “}
letters too!!

Question 30

.downto

Answer 30

to print out a descending range of values
95.downto(85) {|num| print num, “ “}
letters too!

Question 31

.respond_to?

Answer 31

takes a symbol and returns true if an object CAN receive that method and false otherwise
Example: [1, 2, 3].respond_to?(:push)

Question 32

.push OR

Answer 32

adds a value to the end of an array OR to the end of a string

Question 33

.to_s?

Answer 33

changes item to a string

Question 34

string interpolation

Answer 34

#{    }
Example:
drink = coffee
I love #{drink} in the mornings.

Question 35

one line if statement for:

if one is less than two puts “something”

Answer 35

if 1

Question 36

x**2

Answer 36

returns the square of a number

Question 37

refactoring

Answer 37

improving the code’s structure, appearance and performance without modifying overall behavior

Question 38

do one line “if” and “unless” statements need “ends”?

Answer 38

No

Question 39

give a definition of a ruby block

Answer 39

a bit of code to be executed

Question 40

name the two ways that ruby blocks start and end

Answer 40

curly braces { } OR do..end

Question 41

blocks CAN be combined with methods like .each and .times to …

Answer 41

complete an action for each element in a collection

Question 42

.collect

Answer 42

takes a block and applies it to every element in an array
Example:
my_nums = [1,2,3]
my_nums.collect {|num| num**2}
==> [1,4,9]

Question 43

Fill in the blanks

def double( \_\_\_)
yield(\_\_\_)
puts "This is a method including a yield"

double(___) {|n| puts n*2}

Answer 43

n, n, 9

instead of 9 any number would do

Question 44

to pass a proc to a method that normally would expect a block you must use the ____ sign in front of the saved proc

Answer 44

& sign
Example:
[4,5,6].map!(&cube) ==> [64, 125, 215]

Question 45

.call

Answer 45

calls a proc

Question 46

proc/lambda - name 2 differences

Answer 46

lambda check the number of arguments given to it, proc does not
lambda returns and passes control back to calling method/proc returns immediately without going back

Question 47

command line - ls

Answer 47

list directories

Question 48

command line - pwd

Answer 48

print working directory - shows you where you currently are

Question 49

command line - cd

Answer 49

change directory

Question 50

command line - cd ..

Answer 50

change one level up in the directory

Question 51

command line - mkdir

Answer 51

make directory

Question 52

command line - touch

Answer 52

creates a new file in teh working directory

Question 53

command line - -a

Answer 53

an option that modifies the behavior of ls. tells it to also list all contents including hidden files and directories (those starting with a .)

Question 54

command line - -l

Answer 54

option modifying ls. tells it to list all contents in long format

Question 55

command line - -t

Answer 55

option modifying ls. tells it to order files and directories by time last modified

Question 56

command line - -alt

Answer 56

a combination of options (a) (l) (t). multiple options can be typed together

Question 57

command line - cp

Answer 57

copies files or directories

cp frida.txt lincoln.txt copied the contents from frida into lincoln

Question 58

how to use command line cp

Answer 58

cp foldername/filename newfilename
AND
cp foldername/filename foldername/filename newfile name

Question 59

cp * foldername/

Answer 59

the * selects groups of files. it is known as a wildcard. It selects all files in the working directory

Question 60

command line - mv

as a mover

Answer 60

moves files and directories

mv filename.txt foldername/

Question 61

command line -mv

as a copier

Answer 61

mv batman.txt spiderman.txt

renames batman to spiderman

Question 62

command line - rm

Answer 62

removes files and directories - PERMANENT!

Question 63

command line - rm -r

Answer 63

modifies rm command. stands for recursive. says delete directory and all child directories -PERMANENT!