Quiz: Understanding Mutability

Objectives

1. Strengthen your understanding of method scopes.
2. Strengthen your understanding of mutability in Ruby.

???

Mutability Challenge

?: We have the following method that takes in an argument of an array and a string:

def quiz_method(array, object)
  array << object
end

If we call the method in the following manner:

array = ["hi", "there"]

quiz_method(array, "quizmaster")

What is the variable array now equal to?

( )["hi", "there"] (X)["hi", "there", "quizmaster"]

?: If we execute the same method in the following manner:

array = [1, 2, 3]
quiz_method(array, 4)

What is the array variable now equal to?

(X)[1, 2, 3, 4] ( )[1, 2, 3]

?: If we perform the following:

string = "hi there "
string << "quizmaster!"

What is the value of string?

( )"hi there" (X)"hi there quizmaster!"

?: What is the return value of the following method call?

array = [1, 2, 3, 4]
array.each do |num|
  num * 2
end

(X)[1, 2, 3, 4] ( )[2, 4, 6, 8]

?: Below we have a method that accepts two arguments of two numbers:

def change_the_number(num1, num2)
  num1 = num1 + num2
end

If we call it in the following way:

number_one = 5
number_two = 3
change_the_number(number_one, number_two)

What is the value of number_one?

(X)5 ( )8

???

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