w1d1_revisions

Question 1

The following notation in Ruby is invalid, because commas have a separate meaning:

1,000,000

What is an alternate and correct way to notate the comma?

Answer 1

With an underscore (‘_’):

1_000_000

Question 2

T/F: When handling cases where an input will return an exceptional/unique value, it is better to deal with that in the beginning of the function.

Answer 2

T

Question 3

When should you use Array#take_while ?

Answer 3

When you want all the elements of an array UP TO a certain point.

Question 4

If you find yourself using an if statement where you are checking for a negation, what is a more elegant way to write the solution?

Answer 4

Use ‘unless’:

def my_uniq(array) 
  uniq_array = [] 

array.each do |el|
uniq_array &laquo_space;el unless uniq_array.include?(el)
end
7

8 uniq_array
9 end

Question 5

What does Integer#upto do, and when should it be used?

Answer 5

It iterates (+=1 each iteration) over the given block until it hits the limit given (the argument).

It should be used when you want to do something to a number while it is increasing:

5.upto(10) { |i| print i, " " }
#=> 5 6 7 8 9 10

Question 6

What should you do when you have an unnecessary iteration?

Answer 6

Use the ‘next’ keyword

Question 7

T/F: The following syntax is invalid:

next if sell_date < buy_date

Answer 7

F; It is valid b/c ‘next if’ can be used as a compound keyword without an ‘end’ keyword

Question 8

What is an extremely efficient way to create an array of incremental values?

Answer 8

(rangeStart..rangeEnd).to_a

Question 9

Explain the following code:

stack_num = move_hash[gets.chomp]

Answer 9

Sets ‘stack_num’ to the value of the key the in move_hash, which the user enters with ‘gets.chomp’

Question 10

Explain Hash#values_at

Answer 10

Takes an argument (an series of keys), and returns, in the order the keys are given, an array of the values associated with the given keys.