Python3 index() Method
Description
The index()
method checks if the string contains the substring str
. If the beg
(start) and end
(end) ranges are specified, it checks if it is included within that range. This method is similar to the Python find()
method, except that it raises an exception if str
is not found in the string.
Syntax
The syntax for the index()
method is:
str.index(str, beg=0, end=len(string))
Parameters
str
-- The substring to be searched.beg
-- The starting index, default is 0.end
-- The ending index, default is the length of the string.
Return Value
Returns the starting index if the substring is found, otherwise raises an exception.
Example
The following example demonstrates the index()
method:
#!/usr/bin/python3
str1 = "tutorialpro example....wow!!!"
str2 = "exam";
print (str1.index(str2))
print (str1.index(str2, 5))
print (str1.index(str2, 10))
The output of the above example is (with exceptions for unfound substrings):
7
7
Traceback (most recent call last):
File "test.py", line 8, in <module>
print (str1.index(str2, 10))
ValueError: substring not found
Note: In the next few sections, we will detail the use of Python Exceptions.