比较python中的字符串

Question

def find_last(search, target):
    for index, character in reversed(list(enumerate(search))):
        if character in target:
            return index
        else:
            return -1

suppose search="aaaaa" and target="aa", output should=3, not 4. I am trying to get the last position where the two strings compare

Answer 1

Currently what you're doing is comparing each character from the search string in reverse order and seeing if it's in target . If it is, you prematurely return the wrong index.

Instead, I would recommend using the str.rfind method:

>>> 'aaaaa'.rfind('aa')
3

str.rfind is basically the same thing as the str.index method except it searches for the first needle from the right of the haystack.

Edit: In order to treat empty needles as being present at the rightmost index, you can use the following return expression:

def find_last(search, target):
        return target and search.rfind(target) or len(search)