Python內(nèi)置函數(shù)：index

>>> str = 'abc'
>>> str.index('a')
0
>>> str.index('b')
1
>>> str.index('bc')
1
>>> str.index('a',1)
Traceback (most recent call last):
  File "<pyshell#19>", line 1, in <module>
    str.index('a',1)
ValueError: substring not found
>>> str.index('b',1)
1