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Python String - index() Method



The Python index() method is used to find out the index number for first occurrence of specified character(s) in the given string. This method is very similar to find() method. Only difference is that find() method returns -1 when character(s) is not found in the string and index() method gives exception error.

This method has two optional parameters also which can be used to specify starting point and end point within the string for this operation. Default values are start and end of the string.

Syntax

string.index(value, start, end)

Parameters

value Required. value of the character(s) which need to be searched in the string.
start Optional. An integer specifying start position of search. default value is 0.
end Optional. An integer specifying end position of search. default value is end of the string.

Return Value

Returns the index number of first occurrence of the specified character(s) in the given string.

Example: index() method when value is present

In the example below, index() method is used to find out the index number for first occurrence of specified character(s) in the given string.

MyString = "Python is a programming language and learning Python is fun."
print(MyString.index("Python"))

print(MyString.index("Python", 40, 55))

The output of the above code will be:

0
46

Example: index() method when value is not present

The index() method raises exception when the specified character(s) is not present in the string.

MyString = "Python is a programming language and learning Python is fun."
print(MyString.index("Python", 10, 20))

The output of the above code will be:

Traceback (most recent call last):
  File "Main.py", line 2, in <module>
    print(MyString.index("Python", 10, 20))
ValueError: substring not found

❮ Python String Methods

5