hot_or_cold.rb

# Method name: hot_or_cold(num_to_guess)
# Input: a single number, num_to_guess
# Returns: Nothing
# Behavior: Prompts the user to guess the number "num_to_guess", saying "hot" or
#           "cold" depending on whether the user's guess is too high or too low.
#           Once the user has guessed correctly, the method prints a victory
#           message and returns.
#
# This is meant to be a demonstration of how command-line user input works.

def get_user_guess
  print "Guess a number and press enter: "
  gets.chomp.to_i  # See below for what this does
end

def hot_or_cold(num_to_guess)
  # This is called a "while loop"
  # "while true" will loop for ever, unless something inside the loop tells
  # us to stop.  In our case, we'll stop the while loop once a user guesses
  # correctly.

  # Hint: you might want to put some temporary print/puts/p statements
  # in this method while you're filling it out, so you can tell
  # everything is working as your expect.

  while true
    guess = get_user_guess()   # "guess" is now an integer

    if guess < num_to_guess    # The guess is too cold
      ____
    elsif guess > num_to_guess # The guess is too hot
      ____
    else                       # The guess is juuuust right
      ____

      # This "return" will make the program return from hot_or_cold, even from
      # inside the while loop.
      return
    end
  end
end

if __FILE__ == $PROGRAM_NAME
  # rand(1000) returns a random integer between 0 and 999, so this method call
  # starts the "Hot or Cold" game with a random number to guess.

  puts "Welcome to Hot or Cold!"
  puts "We've picked a number between 0 and 999. Can you guess it?"
  hot_or_cold(rand(1000))
end

# What is "gets.chomp.to_i"? First, gets, chomp, and to_i are methods.  We could
# re-write this as
#
#   gets().chomp().to_i()
#
# which makes it slightly clearer than gets() is returning something on which
# we're calling the chomp() method and chomp() is returning something on
# which we're calling the to_i() method.
#
# The question remains what each method returns, though.
#
#   gets() pauses program execution and waits for a user to type a string
#   and hit enter
#
#   chomp() removes the new line at the end of a string, in this case
#     corresponding to the "enter" key that our user pressed
#
#   to_i() converts a string to an integer, e.g.,
#     "5".to_i == 5
#     "10".to_i == 10
#     "-123".to_i == -123
#
# So all together, gets().chomp().to_i() [1] prompts the user for input and
# returns that input to our program as a string, [2] removes the the extra
# "newline character" introduced because the user had to hit the enter key to
# send us the input, and finally [3] converts the user's input from a Ruby
# String into a Ruby Integer.