Ruby Interview Questions (No Rails, for a Prospective Junior Developer / Intern)

interview.md

What does a ||= b mean?

What is the difference between a symbol and a string?

What is the difference between ' and " in Ruby?

Can you give me a function that takes a string and tells me true or false if it has any characters in it?

def empty?(s)
  s.size == 0
end

Can you give me a function that takes as its input an array of any number of strings and gives as its output an array with the number of characters in each string of the input array?

def count_strings(arr)
  arr.map { |str| str.length }
end

Extra credit: Difference between map and map!. Other ruby enumerables.

What is the difference between a class and a module?

What are the differences between public, private, and protected methods?

Extra credit: How, in Ruby, can you call a private method without being that instantiated class?

Can you make a Ruby class that represents a bank account, with methods to withdraw and deposit money?

class BankAccount
  def initialize
    @balance = 0
  end
  def deposit(amount)
    @balance += amount
  end
  def withdraw(amount)
    @balance -= amount
  end
end

Extra credit: How can you, in one line, create a method to write and read to the balance? (attr_accessor :account)

How would you test Ruby code?

Wouldn't instance methods be required for the last question so that new bankaccount objects could call the deposit, and withdraw methods?

Joe = BankAccount.new
Joe.deposit(400.00)

@Yorgg: Yep, I was wrong to make them class methods.