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Python | Methods for counting the number of substrings in a string

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Method # 1: Using re.findall()

# Python code for demo
# count the total
Number of substrings per string

 

import re

# Initializing string

ini_str = "ababababa"

sub_str = ’aba’

  
# Count the amount substrings using re.findall

res = len (re.findall ( ’(? = aba)’ , ini_str))

 
# Print result

print ( "Number of substrings" , res)

Exit:

 Number of substrings 0 

Method # 2: Using re.finditer()

# Python code for demo
# count the total
Number of substrings per string

 

import re

# Initializing i string

ini_str = "ababababa"

sub_str = ’aba’

 
# Counting the number of substrings using re.finditer

res = sum ( 1 for _ in re.finditer ( ’ (? = aba) ’ , ini_str))

 
# Print result

print ( "Number of substrings" , res)

Exit :

 Number of substrings 0 

Method # 3: Using startswith()

# Python code for demonstrations
# count the total
Number of substrings per string

 
# Initializing string

ini_str = "ababababa"

sub_str = ’aba’

  
# Counting the number of substrings using startwith

res = sum ( 1 for i in range ( len (ini_str)) 

  if ini_str.startswith ( "aba" , i))

  
# Print result

print ( "Number of substrings" , res)

Output:

 Number of substrings 4 

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