What does this If statement do to be exact?-CodePudding

I was watching a tutorial to make hangman game using Python on YouTube and they used below code in it and didn't explain it.

How does this line work?

    word_list = [letter if letter in used_letters else '-' for letter in word]

What does that '-' mean/do in this statement?

    if user_letter in alphabet - used_letters:
        used_letters.add(user_letter)

CodePudding user response：

Your first line contains a list comprehenshion.

It is equivalent to:

word_list = []
for letter in word:
    if letter in used_letters:
        word_list.append(letter)
    else:
        word_list.append('-')

The second part:

alphabet = set(['a', 'b', 'c', 'd', 'e'])
used_letters = set(['a', 'b', 'c'])

alphabet - used_letters  # produces a set: {'d', 'e'}