Improving the script for the user prompted average?

Maximiliane Quel this is great! This already goes way beyond the parameters of the extra credit. I like the use of arrays, and the fact that it can accept any length of array, not just 4. And using inject is super-advanced! That's one I don't use very often myself.

There are always improvements to be made, though. Ready? Some of this will be advanced. Look up what you can, ask me questions about what you can't.

One improvement is to use the =~ operator with your regular expression, which will make it so you no longer need to call match. This will work just like your existing numeric? method:

def numeric? test
  test =~ /\d/
end

Another improvement is to use the printf function to round the output the a reasonable number of decimal places.

printf("You entered the numbers %s. The average is %0.2f.\n", x, average)

Regular expressions in general are slow, so it's better to avoid matching when possible. If to_f returns a number other than 0, we can be certain the input was numeric (or that it started with a number, at least). If to_f returns 0, the input could be non-numeric. Or, it could be that the user input was 0 or 0.0. If we do a regular expression test on the input only when the result is 0, we'll do the matching much less often, which is more efficient.

Returning nil makes it clear that convert_to_f was unsuccessful. nil is treated as false, a sign we should break out of our loop.

def user_answer
  print "Please enter a number (or press another key to finish): "
  gets.chomp
end

def convert_to_f(input)
  # Attempt to convert string to a Float.
  float = input.to_f
  # If we got 0, and the input was not "0" or "0.0", return nil.
  if float == 0 && input !~ /\A0\.?0?\Z/
    return nil
  # Otherwise, return whatever number we got from to_f.
  else
    return float
  end
end


def create_arr
  arr = []

  loop do
    input = user_answer
    # Attempt to convert the input to a Float.
    number = convert_to_f(input)
    # If nil was returned, it wasn't a number, so exit the loop.
    break unless number
    # Otherwise, appent the number to the array and continue.
    arr = arr.push number
  end

  return arr
end

x = create_arr

sum = x.inject 0, &:+
average = sum / x.length

printf("You entered the numbers %s. The average is %0.2f.\n", x, average)

You probably have questions. :) Ask away!