Methods

Question 1

.gsub!

Answer 1

Global Substitution

example_string.gsub!(/x/, “y”)

Question 2

.include?

Answer 2

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

Question 3

string interpolation

Answer 3

example_string = "Andy"
print "Hello, my name is #{example_string}"
# ==> "Hello, my name is Andy"

Question 4

while

Answer 4

loop method
example:
i = 1
while i

Question 5

until

Answer 5

loop method
a complement to the while loop method.
a condition is set in a ‘until loop’ that breaks the loop

example:
i = 0 
until i == 6
    i += 1 
end

Question 6

assignment operators

Answer 6

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

example:

example_variable += 1
You’re telling Ruby: “Add 1 to ‘example_variable’, then assign that new value back to ‘example_variable’.” This provides a succinct way of updating variable values in our programs.

Question 7

for

Answer 7

loop method for when you do know how many times you’ll be looping

example:

for example_variable in 1…10

Question 8

Inclusive and Exclusive Ranges

Answer 8

You saw a bit of new syntax in the previous exercise:

for num in 1…10

What this says to Ruby is: “For the variable num in the range 1 to 10, do the following.” The following was to print “#{num}”, so as num took on the values of 1 to 9, one at a time, those values were printed to the console.

The reason Ruby counted to 9 and not 10 was because we used three dots in the range; this tells Ruby to exclude the final number in the count: for num in 1…10 means “go up to but don’t include 10.” If we use two dots, this tells Ruby to include the highest number in the range.

Question 9

iterator

Answer 9

A Ruby method that repeatedly invokes a block of code. The code block is just the bit that contains the instructions to be repeated.
The simplest iterator is the ‘loop’ method.

Question 10

{}

Answer 10

do (to open the block)

example:
i = 0
loop do
  i += 1
  print "#{i}"
  break if i > 5
end

Question 11

end

Answer 11

to close the block

example:
i = 0
loop do
  i += 1
  print "#{i}"
  break if i > 5
end

Question 12

break

Answer 12

breaks a loop as soon as its condition is met.

example:
i = 0
loop do
  i += 1
  print "#{i}"
  break if i > 5
end

Question 13

next

Answer 13

can be used to skip over certain steps in the loop.

example:
for i in 1..5
  next if i % 2 == 0
  print i
end

1. In the above example, we loop through the range of 1 through 5, assigning each number to i in turn.
2. If the remainder of i / 2 is zero, we go to the next iteration of the loop.
3. Then we print the value of i. This line only prints out 1, 3, and 5 because of the previous line.

Question 14

array

Answer 14

a method where we can store multiple numbers or objects in a variable.

example:
my_array = [1, 2, 3, 4, 5]

Question 15

.each

Answer 15

A method which can apply an expression to each element of an object, one at a time. The syntax looks like this:

object. each do |item| # Do something
- The variable name between | | can be anything you like: it’s just a placeholder for each element of the object you’re using .each on.

Question 16

.times

Answer 16

a method thats like a super compact ‘for loop’: it can perform a task on each item in an object a specified number of times. The syntax looks like this:

10.times { print “Chunky bacon!” }

Question 17

.split

Answer 17

a method to divide the user’s input into individual words.

it takes in a string and returns an array.

Question 18

multidimensional array

Answer 18

array of an array

example:
multi_d_array = [[0,0,0,0],[0,0,0,0],[0,0,0,0],[0,0,0,0]]

Question 19

hash

Answer 19

a collection of key-value pairs.

example:

hash = {
  key1 => value1,
  key2 => value2,
  key3 => value3
}

Values are assigned to keys using =>. You can use any Ruby object for a key or value.

Question 20

literal notation hash

Answer 20

literally describes what you want in the hash: you give it a name and you set it equal to a bunch of key => value pairs inside curly braces.
my_hash = { "name" => "Eric",
  "age" => 26,
  "hungry?" => true
}

puts my_hash[“name”]
puts my_hash[“age”]
puts my_hash[“hungry?”]

Question 21

hash.new

Answer 21

Setting a variable equal to Hash.new creates a new, empty hash; it’s the same as setting the variable equal to empty curly braces ({}).

example:

my_hash = Hash.new

Question 22

splat arguments

Answer 22

arguments preceded by a *, which signals to Ruby: “Hey Ruby, I don’t know how many arguments there are about to be, but it could be more than one.”

example:

def what_up(greeting, *bros)

Question 23

return

Answer 23

Sometimes we don’t just want a method to print something to the console, but we actually want that method to hand us (or another method!) back a value.

example:

Question 24

blocks

Answer 24

You can think of blocks as a way of creating methods that don’t have a name.
Blocks can be defined with either the keywords do and end or with curly braces ({}).

Question 25

Abstraction / Abstracting

Answer 25

an important idea in computer science, and you can think of it as meaning “making something simpler.”

Question 26

.sort!

Answer 26

.sort! sorts an array in-place (that is, it destroys the original array and replaces it with the sorted version).

Question 27

combined comparison operator

Answer 27

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 28

.sort

Answer 28

returns a sorted array while leaving the original array alone.

Question 29

.to_sym

Answer 29

converts strings to symbols
example:

“example”
“example”.to_sym => :example

Question 30

.intern

Answer 30

to internalize.

another way to convert strings to symbols

Question 31

.select

Answer 31

to filter a hash for values that meet a certain criteria