Python String index() Method



The method index() determines if string str occurs in string or in a substring of string if starting index beg and ending index end are given. This method is same as find(), but raises an exception if sub is not found.


Following is the syntax for index() method:

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


  • str -- This specifies the string to be searched.

  • beg -- This is the starting index, by default its 0.

  • end -- This is the ending index, by default its equal to the length of the string.

Return Value

This method returns index if found otherwise raises an exception if str is not found.


The following example shows the usage of index() method.


str1 = "this is string!!!";
str2 = "exam";

print str1.index(str2);
print str1.index(str2, 10);
print str1.index(str2, 40);

When we run above program, it produces following result:

Traceback (most recent call last):
  File "", line 8, in 
  print str1.index(str2, 40);
ValueError: substring not found

shell returned 1

Note: We would see how to handle exceptions in subsequent chapters. So for the time being leave it as it is.