Python | Ways to count number of substring in string
Given a string and a substring, write a Python program to find how many numbers of substring are there in the string (including overlapping cases). Let’s discuss a few methods below.
Method #1: Using re.findall()
# Python code to demonstrate # to count total number# of substring in string import re# Initialising stringini_str = "ababababa"sub_str = 'aba' # Count count of substrings using re.findallres = len(re.findall('(?= aba)', ini_str)) # Printing resultprint("Number of substrings", res) |
Output:
Number of substrings 0
Method #2: Using re.finditer()
# Python code to demonstrate # to count total number# of substring in string import re# Initialising stringini_str = "ababababa"sub_str = 'aba' # Count count of substrings using re.finditerres = sum(1 for _ in re.finditer('(?= aba)', ini_str)) # Printing resultprint("Number of substrings", res) |
Output:
Number of substrings 0
Method #3: Using startswith()
# Python code to demonstrate # to count total number# of substring in string # Initialising stringini_str = "ababababa"sub_str = 'aba' # Count count of substrings using startswithres = sum(1 for i in range(len(ini_str)) if ini_str.startswith("aba", i)) # Printing resultprint("Number of substrings", res) |
Output:
Number of substrings 4
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