使用.rfind ():

>>> s = 'hello'
>>> s.rfind('l')
3

另外，不要使用str作为变量名，否则会影响内置的str()。

您可以使用rindex()函数来获取字符串中字符的最后一次出现

s="hellloooloo"
b='l'
print(s.rindex(b))

如果你不想使用rfind，那么这个可以使用/

def find_last(s, t):
    last_pos = -1
    while True:
        pos = s.find(t, last_pos + 1)
        if pos == -1:
            return last_pos
        else:
            last_pos = pos

# Last Occurrence of a Character in a String without using inbuilt functions
str = input("Enter a string : ")
char = input("Enter a character to serach in string : ")
flag = 0
count = 0
for i in range(len(str)):
    if str[i] == char:
        flag = i
if flag == 0:
    print("Entered character ",char," is not present in string")
else:
    print("Character ",char," last occurred at index : ",flag)

more_itertools库提供了查找所有字符或所有子字符串索引的工具。

鉴于

import more_itertools as mit


s = "hello"
pred = lambda x: x == "l"

Code

字符

现在有rlocate工具可用:

next(mit.rlocate(s, pred))
# 3

一个补充的工具是定位:

list(mit.locate(s, pred))[-1]
# 3

mit.last(mit.locate(s, pred))
# 3

子字符串

还有一个window_size参数可用来定位几个项的前导项:

s = "How much wood would a woodchuck chuck if a woodchuck could chuck wood?"
substring = "chuck"
pred = lambda *args: args == tuple(substring)

next(mit.rlocate(s, pred=pred, window_size=len(substring)))
# 59

使用str.rindex方法。

>>> 'hello'.rindex('l')
3
>>> 'hello'.index('l')
2