What is the usage of index in python

index()

The general purpose is to retrieve parameters in a sequence and return the index of the first occurrence. If it is not found, an error will be reported, such as:

>>> t=tuple('Allen')
>>> t
('A', 'l', 'l', 'e', 'n')
>>> t.index('a')
Traceback (most recent call last):
 File "<pyshell#2>", line 1, in <module>
  t.index(&#39;a&#39;)
ValueError: tuple.index(x): x not in tuple
>>> t.index(&#39;e&#39;)
3
>>> t.index(&#39;l&#39;)
1

But the parameter may appear many times, how to do it?

Related recommendations: "Python Tutorial" The complete syntax of the

index() function is as follows:

str.index(str, beg=0, end=len(string))

str – specifies the string to be retrieved
beg – Starting index, default is 0.
end – end index, defaults to the length of the string.

So we can reset the starting index to continue searching, such as:

>>> t.index('l',2)
2

Because the first 'l' appears at 1, we will add 1 to the starting index to continue searching, and sure enough , and 'l' is found at index 2.

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