如何找到列表中具有相同字符串的所有索引？

Question

In a game of Hangman, if the hidden word is hello and the player guesses l then I need to find the index of both locations.

Example:

word = "hello"
guess = "l"
position = word.index(guess)     #this helps me find the first one

I couldn't come up with any way to find the second. How am I able to do that?

Answer 1

Well, you could use enumerate and a list comprehension:

>>> s = "hello"
>>> indexes = [i for i, v in enumerate(s) if v == "l"]
>>> indexes
[2, 3]

Answer 2

Specifically for hangman:

>>> word = 'hello'
>>> guess = 'l'
>>> puzzle = ''.join(i if i == guess else '_' for i in word)
>>> print(puzzle)
__ll_

Answer 3

Another thing you could do, is preprocess the word and have the list of indexes already available in a map so you do not have to iterate trough the string all the time, only once.

word = "hello"

map = {}

for i, c in enumerate(word):
    if (c in map):
        map[c].append(i)
    else:
        map[c] = [i]

Than, check that the letter guessed is in map . If it is, the letter exists otherwise it does not.