Ruby中alphabetize方法的rev默认参数及调用逻辑疑问咨询

Hey there! I totally get why this might feel confusing at first—let's break it down piece by piece, nice and simple:

1. What's rev=false in the method definition? #

That's a default parameter. Think of it as a pre-set value the method uses if you don't explicitly give it something else.

• When you call alphabetize(books) (without a second argument), the method automatically sets rev to false—no extra work needed from you.
• If you want to override that default, you pass a different value (like true) when you call the method.

2. What does the if rev logic do? #

This is the method's way of deciding how to sort your array. Let's say the full logic looks something like this:

def alphabetize(arr, rev=false)
  if rev
    arr.sort.reverse
  else
    arr.sort
  end
end

• If rev is true (you asked for reverse order), it sorts the array normally first, then flips it to Z-A order.
• If rev is false (the default), it just sorts the array A-Z like you'd expect.

3. What's up with puts "Z-A: #{alphabetize(books, true)}"? #

This line is calling your alphabetize method and telling it:

• Use the books array as the first argument.
• Set rev to true (so we want Z-A order, not the default A-Z).

The #{} part is Ruby's string interpolation—it takes the result of the method call (your sorted array) and plugs it directly into the string, so when you run the code, it prints something like Z-A: ["Zebra", "Yak", "Apple"].

I hope this clears things up—this is a super common point of confusion for folks learning Ruby on Codecademy, so you're definitely not alone!

内容的提问来源于stack exchange，提问作者Wilke Jones