python求字符串中单词出现的索引

可以使用Python内置的字符串方法 `find` 或者正则表达式来求字符串中单词出现的索引。

使用 `find` 方法：

s = "Hello world, welcome to Python world."
word = "world"
start_index = 0
while True:
    index = s.find(word, start_index)
    if index == -1:
        break
    print(f"{word} found at index {index}")
    start_index = index + 1

输出：

world found at index 6
world found at index 28

使用正则表达式：

import re

s = "Hello world, welcome to Python world."
word = "world"
pattern = re.compile(rf"\b{word}\b")
for match in pattern.finditer(s):
    print(f"{word} found at index {match.start()}")

输出：

world found at index 6
world found at index 28