difference between find and index

January 9, 2023 by Tarik

str.find returns -1 when it does not find the substring.

>>> line="hi, this is ABC oh my god!!"
>>> line.find('?')
-1

While str.index raises ValueError:

>>> line.index('?')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: substring not found

Both the functions behave the same way if a sub-string is found.