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A substring is the part of a string. Python string provides various methods to create a substring, check if it contains a substring, index of substring etc. In this tutorial, we will look into various operations related to substrings.
Let’s first look at two different ways to create a substring.
We can create a substring using string slicing. We can use split() function to create a list of substrings based on specified delimiter.
s = 'My Name is Pankaj' # create substring using slice name = s[11:] print(name) # list of substrings using split l1 = s.split() print(l1)
Pankaj ['My', 'Name', 'is', 'Pankaj']
We can use in operator or find() function to check if substring is present in the string or not.
s = 'My Name is Pankaj' if 'Name' in s: print('Substring found') if s.find('Name') != -1: print('Substring found')
Note that find() function returns the index position of the substring if it’s found, otherwise it returns -1.
We can use count() function to find the number of occurrences of a substring in the string.
s = 'My Name is Pankaj' print('Substring count =', s.count('a')) s = 'This Is The Best Theorem' print('Substring count =', s.count('Th'))
Substring count = 3 Substring count = 3
There is no built-in function to get the list of all the indexes for the substring. However, we can easily define one using find() function.
def find_all_indexes(input_str, substring): l2 =  length = len(input_str) index = 0 while index < length: i = input_str.find(substring, index) if i == -1: return l2 l2.append(i) index = i + 1 return l2 s = 'This Is The Best Theorem' print(find_all_indexes(s, 'Th'))
[0, 8, 17]
You can checkout complete python script and more Python examples from our GitHub Repository.
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program executed,but the list is not printed
Thanks for the examples and explanations, are great.